What's in the Simulator 11.0 Patch?

PowerWorld Simulator 11.0 Patch addresses problems found in Simulator 11.0 following its official release in April 2005.  New features are also added via the patch as appropriate. You can view patch descriptions by date or view summary descriptions of New Features/Minor Improvements or Bug Fixes by selecting the appropriate links.

SimAuto 11.0 Users

If you have not already done so, please download and run the following program:  UnRegSimAuto.exe Running this will clean up your Windows registry settings allowing SimAuto to work properly.

This patch was first introduced on May 10, 2005.

The patch was last modified July 18, 2006.

Click here to go to the patch download page.

Select one of the following links to view descriptions of the changes incorporated via the PowerWorld Simulator Patch files

View Change
 Descriptions by Date:

• May 2005
• June 2005
• July 2005
• August 2005
• Sept. 2005
• October 2005
• November 2005
• December 2005
• January 2006
• February 2006
• March 2006
• April  2006
• May 2006
• June, 2006
• July, 2006

View All New Features/Improvements by Topic: 

• File Formats
• Auxiliary Files (SCRIPT and DATA Sections)
• Simulator Automation Server (SimAuto)
• Case Information Displays 
• User Interface Dialogs
• Oneline Diagrams
• Bus View and Substation View Onelines
• Power Flow Solution
• Sensitivity Calculations
• Contingency Analysis Tool
• PV and QV Curve (PVQV) Tool
• Available Transfer Capability (ATC) Tool
• Optimal Power Flow (OPF) and Security Constrained OPF (SCOPF) Tool
• Fault Analysis
• Help

View All Bug Fixes by Topic:

• File Formats
• Auxiliary Files (SCRIPT and DATA Sections)
• Simulator Automation Server (SimAuto)
• Case Information Displays 
• User Interface Dialogs
• Oneline Diagrams
• Bus View and Substation View Onelines
• Power Flow Solution
• Sensitivity Calculations
• Contingency Analysis Tool
• PV and QV Curve (PVQV) Tool
• Available Transfer Capability (ATC) Tool
• Optimal Power Flow (OPF) and Security Constrained OPF (SCOPF) Tool
• Fault Analysis
• Memory

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May 10, 2005

New Features/Minor Improvements

• Auxilliary Files - When using the LoadScript(filename, ScriptName) and LoadData(filename, DataName) script commands to load a particular SCRIPT or DATA section, previously we would read all the sections that had the ScriptName or DataName specified. This has been left that way for the LoadData() command. For the LoadScript command however, if multiple SCRIPT sections with the same ScriptName exist, only the first one is read.
• Auxilliary Files - Added new script command: ZeroOutMismatches;
• Auxilliary Files - Added new script command: CalculateVoltSelfSense(filter);
• Auxilliary Files - Added new script command: CalculateVoltToTransferSense([transactor seller],[transactor buyer],TransferType,TurnOffAVR)
• Case Information Displays - When pasting in data from the clipboard into a case information display, the column headers are now trimmed of leading and trailing spaces. Previously we did not do this, so " Num " would not be interpreted as "Num" thus preventing a paste from occurring.
• Sensitivity Calculations - Under Tools, Other Sensitivities, previously all the sensitivities were used to calculate the sensitivity at a single metered point to multiple transfers (transfer from each bus to the slack bus). New tabs have been added for calculating the voltage sensitivity at all the buses for transfer of real or reactive power, and a tab the self sensitivity of voltage with respect to P and Q injection at each individual bus.
• Oneline Diagrams -  Modified how the underlying drawing on oneline diagrams occurs so that the memory footprint of PowerWorld will remain consistent while you are resizing and moving around a set of open onelines. While this results in a larger memory footprint on average it will not change over time and result in memory fragmentation.
• Oneline Diagrams -  Modified so that when setting the Undo Memory Limit Per Oneline to zero MB, this has the same effect as disabling the undo feature.
• Oneline Diagrams -  Modified the oneline link so that it can also be used to open an Auxiliary File from the oneline diagram.
• Oneline Diagrams - Added support for reading comments from a PTI Draw (*.drw) file.
• Contingency Analysis Tool - Added ability to report contingency analysis violations based on the relative change in the dV/dQ self-sensitivity at a bus. The user specifies a list of buses to look at dV/dQ and will then report a violation if the dV/dQ changes by a specified multiple.
• Contingency Analysis Tool - Add the ability to "merge contingencies". This is done by selecting a set of contingencies on the Contingency Dialog and then creating all possible combinations of two of the selected contingencies.
• PVQV Tool - Added the ability to monitor the dV/dP sensitivity while running the PV Curve tool. This will calculate the sensitivity of the bus voltage with respect to a change in the transfer amount.

Bug Fixes

• File Formats - Simulator 11.0 no longer supports the old load variation schedules. These may now be implemented using the time step simulation. However, when reading in an old PWB or AUX file which had the load variation schedule, Simulator 11.0 was including these. The user had no way to see them or remove them however. This has been fixed now so that load variation schedules are now longer kept when read from an old case.
• File Formats - Simulator 11.0 sped up the reading of 3-winding transformer data form all file formats. Previously it was very slow because of a slow search routine. In the original release of 11, however, when reading in a PWB file which contained a 3-winding transformer that had one terminal connected to a DC transmission line, this would result in an error and a failed file read. This occurred with some cases in ERCOT. This has been fixed.
• File Formats - When saving a oneline diagram in an older PWD file format, all display objects were showing up with a color of black. This has been fixed so that Version 11 will now properly save older PWD version files.
• Auxiliary Files - The deletion of MW transactions was not possible using the Delete SCRIPT command. This has now been enabled.
• User Interface Dialogs - When creating or viewing a Model Filter via the Model Filter dialog, access violation bugs could occur. These have been fixed.
• User Interface Dialogs - When clicking the box "Use Another Filter" on the Advanced Filter dialog, Simulator was not properly registering that you had chosen a value for the field. This has been fixed.
• Oneline Diagrams - The saving/loading of Keyboard Shortcuts to an auxiliary file format was not working correctly. This has been fixed.
• Oneline Diagrams - Fixed bug with contouring the percent flow on an interface. It was showing the MVA percent instead of the MW percent.
• Oneline Diagrams - When dragging line vertices or moving a bus to which a line was anchored, the movement of circuit breakers, line fields, or pie charts could occur incorrectly for lines. This was caused by the CB, field, or pie thinking it was anchored to the wrong segment of the line. This has been fixed.
• Oneline Diagrams - When specify the pie chart color and scalar options by percentage, values above 100% were not allowed. This has been fixed so that values above 100% are now allowed.
• Oneline Diagrams - When zooming out on a diagram with pie charts shown, in some situations, it was possible for a divide by zero error to occur for pie charts showing text. This has been fixed.
• Oneline Diagrams - Printing oneline diagrams and copying them to the windows clipboard was limited by the resolution of the monitor on the computer from which printing was done. This has been fixed so that the resolution is not limited in this way for either printing or copying.
• Oneline Diagrams - When deleting a display object that had been added to the oneline since that oneline had been opened, an access violation would occur. This has been fixed.
• Oneline Diagrams - When right-clicking on a bus and choosing Insert Connected Buses, the new buses are inserted in a radius around the bus. This radius was a function of the size of the bus which for horizontal buses was only checking the height. This made is so that the normal action for this feature would be to put the buses right on top of one another. This has been fixed so that the radius is now based on the maximum of the height and width.
• Oneline Diagrams - Fixed bug when right-clicking on a line and choosing the Open action. Previously it would update the display to show zero flow on the line, but would not cause Simulator to resolve the power flow. This has been fixed.
• Bus View and Substation View Onelines - Normally, bus view onelines will not prompt the user to save them as a oneline diagram. Under some situations this was still occurring which could cause some confusion. This has been removed so that you will never be prompted to save a bus view.
• Bus View and Substation View Onelines - For the bus view onelines, the other end bus link objects height was not being properly set. This has been fixed.
• Power Flow Solution - When using the merit-order dispatch for injection groups in the PVQV or Contingency analysis tools, if the enforcement of generator MW limits was turned off for the case, then all the change in dispatch would come from the generator with the highest merit. This has been fixed so that generator limits are always enforced for merit-order dispatch.
• Power Flow Solution - Simulator was not properly handling the outage of a multi-terminal line DC converter outage which was caused by the loss of the AC system at the converter. This has been fixed.
• Power Flow Solution - Simulator will now handle the status of a DC converter separately from the loss of the AC system bus. Previously, the DC converter status was not used.
• Contingency Analysis Tool - Fixed writing out the contingency analysis AUX file so that it does not write out the label name of the contingency twice.
• OPF and SCOPF Tool - Removed limitation of modeling 500 line constraints as simultaneously binding in the linear program solution. No limitation is now enforced.
• Memory - Fixed memory leak when deleting a Model Condition
• Memory - Fixed memory leak when reading an auxiliary file with MW Transactions in it
• Memory - Fixed memory leak associated with copying data to the windows clipboard.
• Memory - Fixed memory leak when deleting an Advanced Filter 
• Memory - Fixed memory leak in creation of Select by Criteria settings.

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May 13, 2005

New Features/Minor Improvements

• PVQV Tool - Added the ability to track voltage-control devices hitting limits during the PV and QV curve tool.

Bug Fixes

• File Formats - Added support for reading/writing various PSS/E sequence data file formats from Version 24-30.
• Case Information Displays - The column for interfaces labeled # of Monitored elements was showing the number of contingent elements instead. This has been fixed.
• User Interface Dialogs - Fixed bug created by May 10 patch which removed old load variation schedules. This bug removed the ability to use a multiplier in the area/zone records to increase all loads in the area/zone by the multiplier.
• User Interface Dialogs - When choosing to bring up the on-line help documentation if the help file location was set wrong then nothing would happen. It will now bring up a dialog asking you to locate the help file.
• Oneline Diagrams - When auto-inserting a list of bus display objects from a text file list of locations, consecutive buses with the same x/y coordinate are places in a circle around the location. The radius of this circle was previous being set to the height of the bus. It is now being set to the larger of either the height or width.
• PVQV Tool - Modified the plotting tools in the PV and QV curve plots so that enough significant digits are always available on the plots.

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May 17, 2005

New Features/Minor Improvements

• Case Information Displays - Modified the "Send to Excel" commands so that the cell format is changed to "Text" for all string fields sent out from PowerWorld. This will correct problems related to Excel automatically converting strings into some other format, such as a date string. An example: "MAR 2551" might become "March 2551".
• PVQV Tool - Added the ability in the devices hitting limits lists so that you can filter out all devices that never change. For example: a generator which is always at its maximum VAR output will not be listed.

Bug Fixes

•  File Formats -In the installation files for Simulator 11.0, the file type registration with Windows for PWB and PWP files was not correctly configured to open a file when it was double-clicked upon. This patch will automatically correct this problem if it exists.
• File Formats - Fixed bug which could sometimes result in buses not being written out as part of the RAW file format. This occurred because Simulator was incorrectly treating a bus as the star bus of a three-winding transformer when it was not. These buses were then not written to some RAW file formats.
• Oneline Diagrams - Add check to ensure that right-click options work correctly when right-clicking on a vertex handle. Previously some of the options line split background line were not working correctly.
• PVQV Tool - Modified previous bug fix regarding increasing the number of significant digits on PVQV plots so that too many digits were not used.

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May 26, 2005

New Features/Minor Improvements

• Case Information Displays - Modified so that case info displays that they can be released after they are embedded on a oneline.
• Case Information Displays - Added a right-click option to create an interface from a selection of lines/transformers in a case info display.
• Case Information Displays - Added a right-click option to create an injection group from a selection of generator or loads in a case info display.
• User Interface Dialogs - Added a button on the Interface dialog to allow you to copy elements from one interface into another interface.
• Contingency Analysis Tool - Modified the display of the percent column for bus voltage contingency violations so that it is only displayed when the violation represents a "change violation" relative to the reference case.
• Contingency Analysis Tool - Added the ability to "clone" a contingency. This will make a contingency that is an identical copy of another with the work "copy" appended to the name.
• ATC Tool - Added a new option on how the ATC Solution Method "(IL) the Full CTG Solution" is processed called "Force all transfer ramping to occur in pre-contingency states and repeat full CTG Solutions". Prior to this new option, the Full CTG solution would only occur once and extra ramping would occur after that.
• ATC Tool - Added a new option to specify whether to include phase-shifters in the determination of the post-contingency sensitivity values when performing ATC calculations.

Bug Fixes

• File Formats - When reading Multi-Section lines from a PTI RAW file adjustments were being made to the area/zone assignments of the dummy buses similar to those made when reading a GE EPC file. These adjustments are needed when reading GE because the multi-section line itself maintains where the meter is. This is not done in PTI, but we were still adjusting area/zone definitions incorrectly.
• Case Information Displays - Modified so that case info displays can not be embedded once they have already been embedded in a oneline.
• Oneline Diagrams - Modified transformer display objects so that their symbol size can be edited using the size value on the generic format dialog.
• Oneline Diagrams - Fixed an error with reading in line flow arrow objects. Previously the angle-orientation of the arrow was not being read in correctly and was defaulting to zero always.
• Contingency Analysis Tool - Fixed an error when performing a comparison of two lists of contingency results which could sometimes result in an access violation.
• OPF and SCOPF Tool - When using the script command SolveFullSCOPF(OPF, success.aux, failure.aux), if the SCOPF ran out of LP iterations it was incorrectly executing the success.aux Auxiliary file anyway.  This has been fixed.

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June 6, 2005

New Features/Minor Improvements

• User Interface Dialogs - Modified to allow series capacitor objects to be tapped the same as a transmission branch.
• Oneline Diagrams -  Add a right-click option on a selection of display objects that allows you to "snap selection to grid".  This will align the objects you have selected to the drawing grid.
• Oneline Diagrams -  Added a new option so that the font color of a Pie Chart can be specified on the oneline display options dialog.
• Oneline Diagrams -  Generally cleaned up some of the local menu (right-click drop-downs) that appear on a oneline diagram so that options related to all objects appear in a consistent manner.
• Oneline Diagrams -  Fixed font name alignment on substation display objects.  Previously the fonts were shifted downwards a small amount.
• ATC Tool - Added a script command which would perform the same action as done on the ATC multi-scenario results tab for Write to Excel.

Bug Fixes

• File Formats - Modified the read/write routines for GE EPC file so that they utilize only a period (.) as the decimal place separator.  The read/write routines for PTI files had previously been changed to behave this way.
• Auxiliary Files - When using regional settings in Windows, which set the comma as the decimal place separator, you could not read in numeric values correctly in the auxiliary files.  PowerWorld was incorrectly treating the text entered as though it were not the right format.  This has been fixed.
• Case Information Displays - When using regional settings in Windows, which set the comma as the decimal place separator, you could not edit numeric values correctly in the case information display.  PowerWorld was incorrectly treating the text entered as though it were not the right format.  This has been fixed.
• Contingency Analysis Tool - Fixed bug that would occur when the first contingency the list did not contain any elements, or the elements did nothing (such as opening a line that was already open).  In these situations when using the DC approximation for the power flow, or when using one of the linearized contingency calculation methods, the contingency results could be calculated wrong.  The results would be very strange (100,000% overloads and such).
• Memory - When deleting a bus that was also an island slack bus and then trying to save the case, an access violation error would occur this has been fixed.
• Memory - When deleting a bus that was a terminal or the star bus of a three winding transformer, you would get errors because the three winding transformer was not getting properly deleted along with the bus.  Now if one of the terminals or the star bus is deleted, the entire three winding transformer record and all three equivalent transformers are removed as well.
• Memory - Fixed memory leak in clearing of the time step simulation results

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June 8, 2005

New Features/Minor Improvements

• No new features added. 

Bug Fixes

• Memory - When defining more than one label, it was possible that an infinite loop would occur if none of the labels were assigned as primary labels.  This has been fixed.
• Memory - For older Pentium III processors, the emphasis filtering on a oneline diagram or the OPF algorithm may fail giving an "External Exception C0000001D".  This was related to some speed enhancements done in Version 11 which were improperly calling some assembly code instructions.  The error has been fixed.

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June 14, 2005

New Features/Minor Improvements

• Power Flow Solution - At the end of a power flow solution, Simulator looks at the voltage angles in each island and if the angles are outside of the +/- 160 degrees, then Simulator automatically rotates all the angles by an equal amount to center the range around zero.  This is done to prevent angles from spanning across +180/-180 degrees.  This isn't really a problem generally and rotating the angles has no effect on the system solution, but PowerWorld considered the situation very strange.  If you would like to disable this feature, a new option has been added to the solution options called "Disable Angle Rotation Processing".
• Power Flow Solution - Added ability to specify that a discrete switched shunt be available for switching during the inner power flow loop.  This option is specified with each switched shunt record by changing the "Inner PF Loop Switching" field to YES.  By default these are all NO.  This is accomplished by setting any discrete shunts allowed to switch in the inner power flow loop to continuous shunts, solving the inner power flow loop, setting the selected shunts back to discrete and rounding the nominal Mvar up to the nearest block, and then solving the inner power flow loop again.
• Oneline Diagrams - Added options to specify whether to show flow arrows on branches, generator, shunts, or loads separately.  This allows you to disable flows on specific types of objects while keeping the flow on other types.
• Oneline Diagrams - Added options on whether to show circuit breakers for particular types of objects.

Bug Fixes

• Oneline Diagrams - When auto-inserting buses and substations, if a bus/substation does not exist in the case, under some situations an error could occur.  This has been fixed.
• Oneline Diagrams - Fixed some errors with using the Dynamic Formatting dialog to specify formatting for different kinds of Case Information Fields.
• File Formats - When reading in PWB files containing the old "Scheduled MW Transactions" Simulator will now convert these into the newer MW Transaction records.
• Memory - Added checks throughout to ensure that users are not able to add more buses than the maximum number allowed.  Previously when performing actions like "tap transmission line" or "split bus", Simulator would attempt to add the extra bus needed but this would result in access violations because too many buses were being created.

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June 15, 2005

New Features/Minor Improvements

• File Formats - Modified the reading of PTI *.sub files so that when a PARTICIPATE block is encountered inside a SUBSYSTEM without any previous definition of subsystem buses, then PowerWorld will assume that all buses listed in the PARTICIPATE block should be used.  Previously we would not create the injection group which is represented by the subsystem.
• File Formats - Added better error messaging to alert if the incorrect number of ENDs are encountered in a *.sub file.

Bug Fixes

• Oneline Diagrams - An access violation error could occur when merging buses together or when auto-inserting generators on a oneline.  This has been fixed.
• Oneline Diagrams - When pressing the A and B keys, the oneline diagram would toggle between 2D and 3D mode.  This has been removed and switching between 2D and 3D mode can now be done only through the main menu.
• ATC Tool - When using injection groups in conjunction with the iterated ATC solution methods, the method for ramping the transfer could sometimes result in not achieving the correct amount of transfer.  This was related to the slack bus picking up part of the losses when Simulator is designed to assign all losses to the buyer injection group. 

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June 28, 2005

New Features/Minor Improvements

• Auxiliary Files - Added script action “SetCurrentDirectory” which sets the present directory path.
• Auxiliary Files - Modified calls the all script actions which might change the current directory path so that they do not do so. All current directory changes must now be handled using the script command SetCurrentDirectory. This included the actions RenameFile, CopyFile, DeleteFile, LoadAux, LoadScript, LoadData, SaveData, OpenCase, SaveCase, LogSave, and others.
• Oneline Diagrams - Modified the dynamic formatting for transmission lines so that setting the fill color dynamically will change the color of the flow arrows.
• Contingency Analysis - Add options for specifying post-contingency high and low voltage limits which are different than the normal voltage limits. Note that Version 11 patch, these options are not stored with the PWB file because these would change the file format. These options can only be saved/loaded with the AUX file format. In Version 12, these will be added to the PWB file format.
• ATC Tool - For multiple ATC scenarios, now have the option of changing line rating A and B.
• Power Flow Solution - For switched shunts which are controlling the Mvar output of generation, a modification was made to the power flow which allows the generation to ignore its Var limits during the direct inner power flow loop solution. This switched shunt will then bring it back into limits, otherwise a subsequent run through the inner loop will bring it back.

Bug Fixes

• Auxiliary Files - Modified writing out auxiliary files so that when a numeric field contains a text which includes the field delimiter (spaces) it will always uses quotes.
• Auxiliary Files - Writing out the LPVariable information to an auxiliary file or passing it out via SimAuto was not working correctly. This has been fixed.
• Case Information Displays - Fixed the super area fields for showing the total production cost and profit for the super area. These were only showing the values of the last area in the super area instead of the sum.
• Oneline Diagrams - Modified the area fields which show transaction-related values to work properly. Simulator now allows multiple transactions between two areas which was not properly supported by these area fields.
• Oneline Diagrams - When editing a text box memo on a oneline diagram, keyboard shortcuts such as the arrow keys were being passed through to the oneline. As a result you couldn’t use the arrow keys on the memo because this would pan the oneline. This has been fixed.
• Oneline Diagrams - The scalar size for normal pie charts was being applied in Edit Mode. Pie chart scaling is only supposed to be applied in Run Mode so this has been modified to behave correctly.
• Oneline Diagrams - Mvar flow arrows were appearing in Edit Mode. This has been removed.
• Oneline Diagrams - When using the toolbar buttons to zoom on a oneline diagram, under some situations an access violation could occur. These have been fixed.
• PV and QV Tool - On the PV analysis dialog, the option for how reactive power load should change as real power load is ramped did not behave consistently. This has been fixed to not allow a specified power factor entry when the option to keep the ratio constant is checked.
• PV and QV Tool - When performing the PV tool runs, Simulator modifies the unspecified MW transactions for areas to keep area transfer in balance. This doesn’t affect the PV tool results at all, but is convenient if you perform studies on cases generated by the PV tool. A bug was found in the accounting for these transfers which has now been fixed.
• Contingency Analysis - When loading two contingencies files for comparison, errors could occur when refreshing the contingency result displays. This has been fixed.

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July 5, 2005

New Features/Minor Improvements

• User Interface Dialogs - Added memo tabs to the Line Dialogs, Super Area Dialog, Load Dialog, and Zone Dialog.
• User Interface Dialogs - Added an option to automatically set the case as a base case after the case is loaded.
• Oneline Diagrams - Added option to local menu for background rectangles and ellipses to convert them to buses or substations.

Bug Fixes

• File Formats - Removed the memo field from the DC Line and Multi-Terminal DC Line records. These were available for entry, but the values were not included in the Version 11 PWB format, so for now they have been removed. Starting with Version 12 these will be included again.
• File Formats - When reading a PWB file, Simulator was not correctly setting which end of a multi-section line was metered. This has been fixed.
• Auxiliary Files - Fix so that unlinked elements of interfaces are saved to an auxiliary file when the user chooses this option.
• Auxiliary Files - When calling the SaveData() script action using SubData sections, Simulator was not properly recognizing the subdata section names. This has been fixed.
• Oneline Diagrams - Pie Charts were modified to show a different graphic when the line was out-of-service. This was not working correctly when using the difference flows feature to show the base case system. It has been fixed to properly show the out-of-service graphic when displaying the base case.

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July 10, 2005

New Features/Minor Improvements

• Contingency Analysis - Added a right-click option to the contingency-violation case info displays to create contingent-interfaces from the selected violations.
• User Interface Dialogs - Completely overhauled the transformer impedance correction dialog to allow showing more information regarding the transformers that use the table

Bug Fixes

• Oneline Diagrams - When auto-inserting buses and substations from the latitude/longitude information in the case, the substations and buses were not being inserted at exactly correct point. They were being inserted within a radius of the point specified by the width of the object. This has been fixed.
• User Interface Dialogs - Errors could occur when trying to insert new Transformer Impedance Correction tables.  These have been fixed.
• Auxiliary Files - When reading a DATA record, if not enough fields are found on the first line of text, Simulator will read and append fields on the next line of text. This was leading to errors if the next line of text was the start of a SUBDATA section or the termination character "{" of the data section. This would only occur if there was a problem in the AUX file format, but Simulator now detects this problem and just appends some blanks to the last data record.
• Auxiliary Files - The auxiliary script command LoadAux() was resetting the submode to PowerFlow or Edit after it was called. This has been fixed.
• Memory - When deleting an object which had a label assigned to it, Simulator was not properly removing the invalid label. This was leading to memory access violations. This has been fixed.
• Memory - Fixed potential access violations that could occur when saving a case that employs labels for some types of objects but not for others.
• Memory - Very old Simulator cases (Version 8 and earlier) allowed interfaces with the same name. This is no longer allowed, but old PWB cases still exist. Error checking was added to assign a unique name to these.

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July 17, 2005

New Features/Minor Improvements

• Oneline Diagrams - Added ability to export a oneline diagram to a set of Shapefile files (shp/shx/dbf set).  This is available in the Tools, GIS Tools menu.
• Oneline Diagrams - When saving out a list of dynamic formatting or select by criteria descriptions to an auxiliary file, Simulator will now automatically include a data section describing the advanced filters used.
• Case Information - When sending data from a case information to Excel, a dialog may now appear prompting the user to select which instance of Excel and to which sheet name to send the data.
• User Interface Dialogs - Added an option to include a timestamp on every message sent to the message log.

Bug Fixes

• Oneline Diagrams - When zooming in on very large filled lines, the fill color would sometime flip. This has been fixed.
• Oneline Diagrams - A degradation of display performance was introduced between version 10 and 11 so that drawing in Version 11 was about half as fast as in Version 10. The degradation has been corrected.
• Oneline Diagrams - Fixed error in the drawing of transmission lines connected between substations that could result in the flow arrows appearing in the wrong direction.
• OPF Tool - When performing the intial power flow solution to initialize the DC OPF, Simulator would sometimes return an "excessive angle separation higher than 360 degrees" error. This would cause the OPF to abort. Simulator has been changed to ignore this error during the initial power flow solution because the error is normally only a notification that the gen/load balance in the case is wrong and too much power is coming from the slack bus. Because the LP OPF is solved immediately after this initialization, this will be fixed by the LP.
• PV and QV Curve Tool - When writing out the PV Curve options, the tracking settings for Transmission Lines was not being properly saved to the auxiliary file. This has been fixed.
• Memory - When deleting an advanced filter which was used as part of a Dynamic Formatting description, the link from the dynamic formatting was not properly cleaned up in memory. This was causing bugs which have now been fixed.

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July 22, 2005

New Features/Minor Improvements

• Oneline Diagrams - Added new measurement lines which can be added to determine the length of a particular parts of the oneline.
• Oneline Diagrams - Modified the up/down arrows associated with the transformer tap position so that they are always available if the transformer is on manual control.
• Oneline Diagrams - Modified the keyboard shortcut which performs the "Bring to Front" on a oneline so that it will not open a second oneline if the oneline is already open. Previously it would only bring forward a oneline which had been created as a result of a keyboard shortcut.
• Case Information - Modified the Interface Case Information display so that there are now subtabs that show a list of only a specific type of object in the interface. For example, a list of branches can now be brought up which then allows the user to customize the list with all the fields available for a branch.
• Case Information - Modified the Injection Group Information display so that there are now subtabs that show a list of only a specific type of object in the injection group. For example, a list of generators can now be brought up which then allows the user to customize the list with all the fields available for a generator.
• Power Flow - Simulator has handled for a few years the situation when all transmission lines connected to a slack bus are opened by choosing a new slack bus. Simulator did not however handle the situation when generators at the slack bus were opened. This would cause a dialog to appear which said that the slack bus must have generation. Simulator has now been changed so that a new slack bus will automatically be selected with appropriate messages sent to the message log.

Bug Fixes

• Oneline Diagrams - ATC Tool - Modified the generator scenarios so that negative generator values are allowed. 
• Auxiliary File - The auxiliary script command Move() was improperly causing the script to abort. The first Move() command would occur, but then the script would immediately abort. This has been fixed.
• Sensitivity Calculations - When calculated the TLR sensitivity for interfaces that contained elements marked to "meter the far end" of the line, Simulator was calculated the sensitivity incorrectly. The PTDF calculation has always been correct, but a sign error was occuring in the TLR calculation. This has been fixed.
• Contingency Analysis - A bug has been fixed that occurred when reducing the generation in an Injection group using merit order dispatch. This was resulting in not enough generation being dropped.

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July 29, 2005

New Features/Minor Improvements

• Oneline Diagrams -  Modified auto insertion for buses and substations so that the user has the option to not insert buses or substations that are already shown on the diagram
• Oneline Diagrams - Added the ability to change the shape of substation, bus, area, zone and injection group objects using the Format Selected objects dialog.
• Oneline Diagrams - Added an Apply button the oneline display options dialog so that the options can be applied without closing the dialog.
• Oneline Diagrams - Added the ability to select objects touched by the selection window instead of only objects fully contained by the selection window.
• Oneline Diagrams - Modified the writing out of shapefiles to use longitude/latitude coordinates if the user has chosen to "show coordinates in lon/lat"on Oneline Display Options dialog.
• File Formats - Modified the reading of EPC files so that we read in the interface element multipliers and utilize these fields in the calculation of interface flows.
• File Formats - Modified the reading of RAW files when encountering loads that are assigned to a different area than their terminal bus. Most RAW files have been solved so loads like this are not treated as tie-lines. (AREA INT CODE = 1 FOR LINES ONLY). Simulator requires that loads be treated as they are modeled (i.e. as tie-lines) (AREA INT CODE = 2 FOR LINES AND LOADS). To make the area interchange consistent, Simulator now creates new transactions to represent these loads. If the RAW file was solved assuming that loads like this are treated as tie-lines, then you will need to open the MW Transactions table and remove the transactions with ID "RAW_LOAD".
• PVQV Tool - Added the ability to control whether constant power, current, or impedances load is used as part of the transfer of a PV curve.
• Contingency Analysis - Modified the interaction contingency elements that modify individual generators and the post-contingency max/min generator response. Now generators that are modified by individual contingency elements will ignore the max/min generator response option.

Bug Fixes

• Oneline Diagrams - The option on the Oneline Display Options Dialog for Show longitude,latitude coordinates when showing x,y coordinates was not being saved as part of the PWD file. This is now saved with the PWD file. 
• Oneline Diagrams - Modified the Bus View and Substation View oneline so that they no longer inherited any oneline display options from the oneline that invokes them. Previously when you right-clicked on a oneline object and choose Bus View it would inherited the settings from that oneline such as the pie chart sizes, colors, animation settings, etc...
• Power Flow Solution - If the user has specified that all generator Mvar limits should be ignored, Simulator now forces all generators with an AVR status of YES to force their setpoint to be enforced. Previously if a generator was stuck at its min or max limit, it would stay there after checking the ignore limits options.
• Auxiliary Files - When loading in an AUX file that uses labels as the identifier, it was possible to change the primary keys of the objects, thus allowing you for instance to set all the buses in the case to have the same bus number. While obviously a bad thing to attempt, Simulator allowed this. Simulator will no longer allow key fields to be modified via auxiliary files or via copy/paste to/from Excel.
• Auxiliary Files - When loading in default drawing values via an auxilary file, the default fields positions were sometimes being set incorrectly. This has been fixed.
• Contingency Analysis - When bypassing a series capacitor as part of a contingency action, Simulator was sometimes having difficulty solving the power flow due to an error in resetting the system state. This only affected Series Capacitor bypassing and has now been fixed.

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August 1, 2005

Bug Fix

• SimAuto - Modified the commands WriteAuxFile(*), SendToExcel(*), and variations of ListOfDevices(*) so that they will not return error messages of the form "No objects returned for type *** and filter***". Having commands such as ListOfDevices(*) return no objects because none exist in the case should not be considered an error.

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August 2, 2005

Bug Fix

• File Formats - After loading in an AUX file that contains injection group descriptions, Simulator will maintain records for “unlinked” injection group elements representing gens or loads described in the AUX file that do not exist in the case. After loading such an AUX file and then saving the case as a PWB file, Simulator is supposed to ignore these unlinked elements and not save them. There was, however, a bug that was causing these to be saved resulting in a corrupted PWB file that could not be reopened. This has been fixed.

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August 3, 2005

New Features

• Contingency Analysis - Modified the clone contingency tool to insert the contingency right next to the cloned contingency.
• Oneline Diagrams - Added the ability to renumber the areas, zones, and substations on a oneline diagram.  This new feature works in the same manner as the "renumber bus" feature.
• PVQV Curve Tool - Added the ability to scale the Load Mvar as part of a PVQV transfer by a multiple relative to the amount that it would change if the load maintained constant power factor. For example: Assume an initial load of 100 MW and 50 Mvar. If you wanted to increase the load by 50 additional MW and maintain constant power factor, you would increase the Mvar by 25 and end up with 150 MW and 75 Mvar. If instead you said increase it by 0.8 of what it would increase for constant power factor, then you increase by 20 Mvar and end up at 150 MW and 70 Mvar.

Bug Fix

• Optimal Power Flow (OPF) - Simulator previously contained both Cost of Energy and Cost of Losses Reference fields.  There should only be one reference that applies to Energy, Losses and Congestion. The feature has been changed so that only one reference is specified as the "Cost of Energy, Losses, and Congestion Reference." Backward Compatibility:  When reading PWB and AUX files containing the now obsolete Cost of Energy and Cost of Losses references, the Cost of Energy Reference value will be used. The Cost of Losses Reference will be ignored.

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August 8, 2005

New Features

• User Interface Dialogs - Added diagrams and equations to the transformer dialog to better explain how transformer base values are converted to system base values.
• User Interface Dialogs - Added support to Model Filters for showing columns that represent the number of Model Conditions and the number of unlinked Model Conditions.

Bug Fixes

• One-Line Diagrams - In run mode, the user can toggle the AGC status of an area by placing an Area AGC Status field on the one-line.  Fixed a problem where toggling the AGC status would not immediately update the one-line field.
• One-Line Diagrams - An object with the dashed line format option set would not always be drawn with a dashed line as expected. This has been fixed.
• One-Line Diagrams - Fixed bug with graphical Interface objects not correctly linking to Interface data.
• Case Information Displays - Fixed bug when displaying Advanced Filters in Case Information Display.  Only those filters that are associated with a power system element will be displayed.
• Auxilary Files - Fixed bug with reading in transformer records from auxiliary files when the transformer type is something other than fixed.

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August 19, 2005

New Features

• Oneline Diagrams: Modified the showing of MW and MVar arrows simultaneously so that the initial locations for the arrows were offset from each other. This makes the initial locations so that the MVar arrows are not hidden by the MW arrows.
• Oneline Diagrams: Modified the oneline link dialog so that when you click browse you can choose an auxiliary file to link to as well.

Bug Fixes

• Oneline Diagrams: When using Select by Criteria to find substations, if a substation was empty it was not being selected. This has been fixed.
• Oneline Diagrams: When marking a line field or pie chart as immobile, the object would then no longer follow its anchor when a bus was moved that was connect to its line. This has been fixed.
• Oneline Diagrams: Unselecting objects using a Shift-Click on a presently selected object was not properly working. This has been fixed.
• Oneline Diagrams: When unselecteding a single text object, the handle squares were not properly erased making it appear that the object was unselected. This has been fixed.
• Oneline Diagrams: When checking the box "Use the default font size for new text fields (Ignore object-specific sizes)", all new text and fields were being inserted with a negative font size making it so that you could not see them. This has been fixed.
• AUX Case Info: Modified so that secondary key fields can be editted using an auxiliary file. Simulator does not require their uniqueness so this is not a problem.
• Power Flow: Setting the status of a multi-terminal DC transmission line to OPEN was not being properly handled by Simulator. Simulator now properly handles this and treats it the same as setting the mode to BLOCKED.
• Contingency Analysis: Fixed bug which resulted in the contingency records not properly linking to the model criteria when read from a PWB file. This worked fine when read from an AUX file however.
• OPF: When committing and decommitting generation in the OPF it was possible for an infinite loop to occur under some circumstances. This has been fixed.
• PVQV: When plotting our the points in the PV Curve plots, the order of the points near the nose would sometimes be switched. This was caused by the plotting program sorting the points by the x-axis dimension. This sorting has been removed.
• PVQV: Fixed the coordination of the default step size and max/min voltage and the values specified with each bus. Previously they were not properly coordinated.
• PVQV: Fixed bug that occurred when the temporary directory name was specified without a path. Simulator will now use the current directory. Without the path, users coudl not save the QV results or plot them.
• PVQV: Fixed bug when using the QV curve script command. The output filename was not being correctly set and thus the results not properly saved.
• PVQV: When running a QV curve at a bus that is remotely regulated by other generators, Simulator will now set the AVR status of the remotely regulating generators to NO while running the QV Curve. This was a mistake which was causing two different generators to be controlling the same bus to different voltages.
• PVQV: When reading an AUX file which contained tracking information for MVar values of switched shunts, the tracking of MW and MVar values for switched shunts were conflicting. This resulted in the MVar value never being set for tracking. This has been fixed.

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August 31, 2005

New Features

• Oneline Diagrams: Added the ability for formatting of color, font color, etc... of substation fields to be determined by the dynamic formatting specified with buses that make up the substation. For instance, this allows the "min kv of max nom kv" substation field to be formatting based on dynamic formatting related to a bus voltage.
• Oneline Diagrams: Cleaned up interaction with the Dynamic Formatting dialog.
• Case Information Displays: Modified the Search for Text... right-click feature of the case information displays so that it can optionally "Search Ignoring Filtering". When searching with "Search Ignore Filters" chosen, then the search will look through all possible records regardless of what the filtering is. If text is found which is not presently displayed due to filtering, then all filtering will be removed for the case information display and the text shown.
• Case Information Displays: Modified the Search for Text... right-click feature of the case information displays so that it can optionally "Search All Fields". When searching with "Search All Fields" chosen, then the search will look through all possible columns regardless of how the present Display/Column options are set. If text is found in a column that is not presently displayed, then this column will be added to the end of the case information display and the text shown.
• OPF: Added new script command InitializePrimalLP;

Bug Fixes

• Bus View Onelines: When right-click on a bus link object to bring up the bus dialog, the delete button was available on the dialog. It should not have been and has been removed. Deleting a bus in this manner would cause access violations.
• OPF: The LP OPF, OPF Transactions case information display showed each transaction twice. This has been fixed.
• PVQV: The user had to press "ok" twice after changing the name of the output file, but that has been corrected so that the user has to confirm his choice only once.
• Oneline Diagrams: Circuit Breaker and Pie Chart objects had their stack level changed to top regardless of what had been saved in the PWD file. This made it so that the user could not change their stack level.
• Oneline Diagrams: Fixed bug which was causing the flow arrows for DC transmission lines to flow backwards in some instances.
• Case Information Displays: Modified the manner in which labels are defined and the interaction with primary labels. The column "primary label" is no longer available and only the "Labels (All)" column may be used to define labels. The primary label is only significant in that it is the first label listed when there are multiple labels.
• Case Information Displays: The columns showing Bus CTG voltage per unit limits were erroneously added in a patch of Simulator. There are only 4 high and 4 low per unit limits specified with each bus. The contingency limit is specified by choose which rating set A, B, C or D to use during the contingency.

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September 11, 2005

New Features

• User Interface Dialogs - Added messages to the log when bus load is reduced because the bus voltages are dropping below the minimum voltage for constant power load. Also changed the default value for the minimum voltage for constant power load from 0.8 to 0.7.
• Oneline Diagram - Added an Simulator Environment option that allows the user to specify not to show the dialog asking the user if they would like to create a new oneline after opening a case.

Bug Fixes

• Oneline Diagrams - Made changes to the Select by Criteria so that unlinked objects can be selected as long as selecting by all areas, zones, and voltages.
• Oneline Diagrams - Fixed bug occurring when objects that were set to a fixed screen locations were displayed along with the Thumb Nail View. This was resulting in erratic movement of the objects.
• Oneline Diagrams - Fixed the storage of Dynamic Formatting Definitions to an AUX file. Previously we were not writing out all the necessary fields for the file.
• OPF - When using the DC approximations and choosing the DC Solution Option "Use bus MW loss sensitivities in OPF and ED dispatch algorithms, if the ...", Simulator was correctly utilize the loss sensitivities in calculating the MW Marginal Cost at each bus. However, when performing the post-processing to split the Marginal Cost into a cost of Energy, Losses and Congestion, Simulator was not using the sensitivities correctly resulting in an incorrect allocation.
• File Format - Fixed a problem when reading in a Promod file that would terminate prematurely if it was trying to read a contingency element that was not found in the case
• File Format - Modified the storage of the jumper threshold and Minimum Voltage for Constant Current Load in the GE EPC file.
• Format - Corrected bug when writing out he branch records to a GE EPC file. .

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September 13, 2005

New Features

• PV and QV Curve: Modified the layout of the PV Curve tool to make the new features regarding scaling components of constant power, current, and impedance load more easily understood.
• Power Flow Solution: Modified so that the generator setpoint voltage can not be set to zero. Now, when the user tries to change the voltage to zero Simulator will not change the voltage.

Bug Fixes

• Oneline Diagram: Fixed an error with the pie-chart option for "Min Pie Chart Font Size for Warning/Limit" setting. This was not working properly when zooming out on a large display. This has been fixed.
• Power Flow Solution: Fixed a bug which might occur when a very low impedance branch connects a generator's terminal bus to a bus that it remotely regulated. This bug would cause the generator to not control its voltage and report a warning to the log saying the generator could not regulate because "there is no path between them that doesn't go over another regulated bus". This has been fixed.
• Power Flow Solution: After reading in a generator which had it's minimum and maximum VAR output equal Simulator disables VAR control at the generator internally. A bug existed however that would not allow the generator to regulate even after changing the min or max VAR output. This has been fixed.

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September 15, 2005

New Features

• PVQV Curve: Modified the QV Curve tool so that when viewing the results of the QV Curve runs, you may right-click and choose Display/Columns Options and add all field related buses.
• Oneline Diagrams: Added a feature to convert the selected AC tranmsission lines into background lines. To use this feature, the user must customize the toolbars and added the new command available under the Insert category called "Convert AC Line to BackgroundLine"
• Available Transfer Capability: Added a better indication of when the "(IL) then full CTG" solution method encounters an unsolvable power flow when ramping out the pre-contingent state. A new gray-highlighted transfer limitation will appear showing the final state at which a successful contingency solution was achieved. Additional fuchsia-highlight transfer limitations then show the pre-contingent state at which the power flow solution failed.

Bug Fixes

• Available Transfer Capability: When using "(IL) then Full CTG" solution method and forcing all ramping to occur in the pre-continency states, if a failed power flow solution occurs in the pre-contingency ramping, then Simulator would not continue to iterate on multiple limitations. This has been fixed.

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September 19, 2005

New Features

• Oneline Diagrams: Added the option to specify with a Screen Layer whether display objects in the layer are "Selectable in Edit Mode". Setting this value to NO makes it impossible to select the display object at all. You will still see the display object but will not be able to edit, move, or select the display object while in Edit Mode. The Run Mode behavior of the display object will not change.
• Sensitivity Calculations: Modified the error messages that report invalid transfer directions to better describe why a sensitivity calculation fails (for instance the buyer and seller are in different electrical islands).

Bug Fixes

• Case Information Displays: When editing the latitude/longitude via a string of the format "DD:HH:SS.SSS N/W" including trailing spaces on the string would cause the modification of the value to fail. This has been fixed.
• Sensitivity Calculations: Modified the calculation of sensitivities based on Injection Groups so that off-line generation is never included in the calculation. Previously, off-line generation was included.

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September 26, 2005

New Features

• Auxiliary File: Added a new script command WriteTextToFile("filename", "text to write"); The file will be created if it doesn't presently exist. If the file exists, the "text to write" will be appended to the file. When using the command to add comments to an AUX file, be sure to include the // characters.

Bug Fixes

• Case Information: When editing the fixed transformer taps on the From or To side, previously Simulator would keep the impedances and taps on the SYSTEM base constant instead of modifying them. This has been changed so that the impedances and taps on the TRANSFORMER base are held constant instead and the values on the SYSTEM base change instead.
• User Interface Dialogs: On the Model Condition dialog, when choosing an element type of Transformers, the list of elements would show a list of buses instead of a list of transformer branches. This has been fixed.
• File Formats: Fixed a problem in the parsing a text file such as a RAW file which would cause it to fail if a value NOT inside quotes had trailing spaces before a comma delimiter, AND both spaces and commas were considered delimiters for the file (this is how RAW files are ready because the delimiters are sometimes mixed)
• File Formats: When reading the status of a transformer from an EPC which was greater than 1, Simulator now treats this as an 1. This appears to be an error in the file. Previously, Simulator would treat a status of "8" for instance as though it were open.
• File Formats: When reading in a RAW or EPC file, warning messages are added regarding transformers that are outside the control limits. Previously these warning messages were even added for transformers that were set to be off control. This has been changed so that messages are only generated for generators which are on control.

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October 4, 2005

New Features

• Oneline Diagrams: Previously the generators at the slack bus did not display a circuit breaker symbol on the oneline diagram.  This has been changed so that slack bus generators can now be opened on the oneline diagram.  Simulator can dynamically choose a new slack bus anyway.
• Oneline Diagrams: When drawing large JPEGs on a diagram and zooming into these JPEGs the drawing speed of the oneline diagram was greatly diminished.  A change has been made to speed this up greatly.

Bug Fixes

• Auxiliary Files: When choose to save an entire case as an auxiliary file, the Model Conditions, Model Filters, and Model Expressions were be written out near the top of the auxiliary file.  When later reading the case back into Simulator the specific objects referenced by the Model Conditions/ Filters/ Expressions would not yet be read in.  This resulted in all the Model Conditions/ Filters/ Expressions being invalid.
• Oneline Diagrams: On dialogs which specified the size of generator, bus, load, or shunt a maximum size of 256 was being enforced.  This was incorrect and no size limitation is enforced anymore.
• PVQV Curve: Added the ability to save the extra tracking information from the QV Curve tool to an auxiliary file.

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October 11, 2005

New Features

• SimAuto: Added new procedure call ChangeParametersMultipleElement(objecttype, ParamList, ValueList) so that multiple objects may have their parameters changed using one function call. Also added ChangeParametersSingleElements, which calls ChangeParameters. This was done to be consistent with GetParameters.

Bug Fixes

• Case Information: The field "Interface MW Flow Offset" for an interface was showing the value divided by the System Base. This has been fixed so that the value is properly scaled to the units of MW.
• Oneline Displays: Fixed an access violation which would occur in Dynamic Formatting when there were unlinked display objects on a oneline diagram.
• User Interface Dialogs: Fixed the Edit Mode Bus Dialog so that zero or negative nominal voltages can not be specified.
• User Interface Dialogs: When defining a filter which "uses another filter" on the Filter Dialog, the list of other filters to choose from was not being properly populated. This has been fixed.

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October 18, 2005

New Features

• File Formats: Made changes to allow EPC files to be used as change files for appending data to a case.
• Case Information Displays: Added special feature when entering data into a case information display, or reading data from an AUX file. If a field is entered as "@variablename", then Simulator will attempt to change the field to the value contained in the respective variablename. For instance, for generators entering the string "@BusPUVolt" in the column for the voltage setpoint will change the generator voltage setpoint to be equal to the present terminal bus voltage.
• User Interface Dialogs: Added support for multi-directional MW-mile calculations.

Bug Fixes

• File Formats: Fixed bug in ReadOwnerDataBinary where read would get corrupted if you were appending from a PWB file and an owner in the appending file did not already exist in the original file.
• Oneline Diagrams: When using Advanced Filters inside of Custom Display Detail or Emphasis Highlighting on the oneline display options, the oneline was not properly updated as the data changed. The check of the advanced filtering only occurred when you changed the settings, or when you switched between modes. This has been fixed so that the display detail and emphasis highlighted are updated as needed.
• Oneline Diagrams: The pie chart option Max. Zoom Percentage for Full Resizing was not working for normal sized pie charts. This has been fixed.
• Fault Analysis: When a fault to ground impedance was given, it was being incorrectly multiplied by 3 when applied to a three phase fault. It should be multiplied by 3 only for single line to ground and double line to ground faults.
• Fault Analysis: The fault impedance was being internally stored multiplied by 3, and was again multiplied by 3 each time the fault dialog was opened and a fault calculated, resulting in the fault impedance growing by a factor of 3 each time. This has been corrected.

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October 20, 2005

New Features

• User Interface Dialogs: Added the ability to specify through the registry if customization of the toolbars is allowed. The only way to set this option is to specify a value of zero for the registry key
  HKEY_LOCAL_MACHINE/PowerWorld/Simulator 11/dxToolbar11/ Allow_Customization_Of_Toolbars

Bug Fixes

• User Interface Dialogs: Fixed the positioning of the Area Information Dialog so that it always appears in the center of the Simulator form.
• User Interface Dialogs: When renumbering the buses in a case, the multi-terminal DC line converter buses were not being properly renumbered. This has been fixed.
• User Interface Dialogs: Fixed a bug in the new area/zone renumbering feature so that the area of generators, loads, and switched shunts are properly updated.
• Optimal Power Flow: Fixed a bug with Super Areas when determining the cost of energy, losses, and congestion.
• Fault Analysis: Fixed a bug where the grounding code was not being passed to generators when the short circuit generator objects were being created.

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October 31, 2005

New Features

• User Interface Dialogs: On the "Present Topological Differences from Base Case" dialog, the ability to save out the list of topology differences in the case which only meet the area/zone filters has been added.

Bug Fixes

• Case Information Displays: The Spinning Reserve (Pos) and (Neg) column for an area or zone were only showing the amount of reserve for generations that was both online AND set to AGC=YES. This column has been changed to only check if the generation is online and not check the AGC status.
• File Formats: Fixed a few problems with writing out DC Line records to EPC files
• Oneline Diagrams: When writing out shapefiles which represented points (such as buses or substations), the file format was being written a incorrectly. This has been fixed.
• PV and QV Curve Tool: Modified the PV and QV curve tools so that the minimum voltage for constant power load solution option is ignored. When running the PV or QV Curve tool, the minimum voltage for constant power load is always treated as zero.

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November 7, 2005

New Features

• Case Information Displays: Added fields for buses, substations, areas, and zones which show net MW, MVar, and MVA injection.

Bug Fixes

• Contingency Analysis: The calculation of the total amount of load islanded during a contingency was being improperly calculated thus values always showed zero. This has been fixed.
• Memory: Fixed a few memory leaks which could occur during a time-step simulation.
• Memory: Fixed memory leak which could occur in an advanced filter when doing a field-to-field comparison that involved a numeric field that was showing a blank value.

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November 11, 2005

New Features

• User Interface Dialogs: Modified all dialogs so that Read-Only edit boxes always appear with a gray background. This better highlights what is read-only and what is no read-only
• Auxiliary Files: Added a new case information options which allows you to specify whether to write SUBDATA sections of AUX files using primary or secondary keys. This allows you to write AUX files using the "name/nominal kv" keys instead of the number keys.
• SimAuto: Added a new case information options which allows you to specify whether to write SUBDATA sections of AUX files using primary or secondary keys. This allows you to write AUX files using the "name/nominal kv" keys instead of the number keys.

Bug Fixes

• File Formats: For PWB files written before August 2, 2005 if injection groups contains unlinked participation points, then the file may not be read back in properly to a Simulator patch after August 2, 2005. This has been fixed so that all PWB files are properly read in.
• File Formats: When reading an EPC file, an access violation would occur if one of the terminals of a two-terminal DC line record did not exist. This has been fixed.
• User Interface Dialogs: On the Nomogram Dialog, an access violation was fixed that could occur when clicking on the limit graph.
• User Interface Dialogs: Fixed an improper coloring of some dialogs which would occur in Windows 2000.
• Oneline Diagrams: When using the 3D View and drawing filled in background lines, lines with greater than 4096 points were not being filled properly. This has been fixed so that all lines are now filled properly.
• PV and QV Curve Tool: The added feature for tracking "devices at limits" was not working properly for lines and interfaces. The dialogs in thye PV and QV curve tool have been fixed to properly select the filter for the lines and interfaces

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November 14, 2005

Bug Fixes

• User Interface Dialogs: The new feature added on November 11, 2005 which made the background color of read-only edit boxes appear gray was causing problems with edit boxes that displayed colors.  This has been fixed.

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November 28, 2005

New Features

• Case Information Displays: Modified custom expression evaluation so that invalid user-specified expressions will report errors to the message log.
• Contingency Analysis: Now include the nominal kV in the contingency description strings

Bug Fixes

• Case Information Displays: Fixed a potential problem for users with a very large number of custom expressions which could result in invalid expression evaluation.
• Optimal Power Flow: Fixed bug which resulted in phase-shifting transformers set to be on OPF control to be reset to Off control when restoring the contingency reference state.
• Oneline Diagrams: Fixed inconsistency when inserting a DC transmission line display object that represents an existing DC line. This was causing some confusion resulting in new DC line additions.
• Memory: Fixed memory leak in the deletion of Model Expressions.
• Memory: Fixed memory leak in the deletion of Model Filters that contained unlinked elements.

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November 30, 2005

New Features

• Oneline Diagrams: Modified the Substation object so that clicking on a substation now allows invoking commands and opening URLs in a web browser.

Bug Fixes

• Optimal Power Flow: When running the OPF using the DC approximation, angles were being rotated so that they were between +/- 360 degrees. This should not be done in the DC approximation and was causing incorrect interaction between the DC power flow and OPF solution.
• Power Flow Solution: When performing a Set to Flat Start, the voltage at a generator bus was not begin properly set.
• Power Flow Solution: When performing the Robust Power Flow Solution, sometimes the Jacobian was setup and factored in the wrong coordinates (rectangular instead of polar) and this was causing the decoupled power flow solution to fail. This is now fixed.
• Memory: Fixed bug related to fix with Model Filters on Nov 28.

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December 7, 2005

Bug Fixes

• Contingency Analysis: When running contingency analysis with the check to not dynamically assign new slack buses for new islands, the restoration of the system state was not working properly. This has been fixed.
• Oneline Diagrams: Fixed bug which could occur with Screen Layers when converting background lines that did not belong to the default layer to the into ac transmission lines. If after doing this conversion, the original layer was deleted, this bug would make it impossible to save the oneline diagram.
• PV and QV Curve Tool: Correctly potential bug when creating several PV Curve plots in the same Simulator session. An error would occur when closing the case in this situation.

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December 14, 2005

New Features

• Fault Analysis: Modified so that fault current and angle can be displayed for the fault bus on a case information display. This then allows you to export the value via SimAuto for via an Auxiliary file.
• Power Flow Solution: When a tap-changing transformer has a tap min to tap max range larger than 0.9 per unit, Simulator always ignores these as controllers. The program now notifies the user in the message log that this change is being made.

Bug Fixes

• Case Information Displays: For multi-section line object, the field which shows the list of intermediate buses is also showing the from and to bus of the multi-section line. This has been fixed so that only intermediate buses are shown.
• File Formats: When reading an EPC file which contained bus records marked as type "-1", Simulator was not properly assigning these buses as load buses. Files in the future will treat these as a "1" instead. This was causing very strange behavior with the power flow solution. A change was also made so the PWB files which had already been created by reading these strange EPC files will be automatically fixed when they are read in.
• Fault Analysis: Fixed a problem with solving an in-line fault and then solving a bus fault immediately after this.
• Optimal Power Flow: The area information column for "Hourly Cost ($/hr)" is supposed to show the combination of the production cost along with revenues or expenses related to MW Transactions. These were not working properly and have now been fixed.
• PV and QV Curve Tool: Fixed nuisnance bug when running the QV tool and choosing to not "process each of the current defined contingencies". Previously Simulator would end up running a power flow solution repeatedly for each contingency defined in the case. The solution itself wouldn't take must time because nothing had changed, but even 0.5 second time 3000 contingencies will take a long time.

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December 22, 2005

New Features

• Contingency Analysis: Added the ability to read PTI *.con files which using name/kv as identifiers instead of bus numbers as identifiers.
• User Interface Dialogs: Modified the Auto Insertion of Injection Groups so that grouping can be done by Custom String as well as CUstom Floating points. Also made sure that all 5 custom strings and floats were available.

Bug Fixes

• Oneline Diagrams: For some contour fields, hard-coded limits were included for the specification of the minimum, nominal, and maximum values. This limitation has been removed.
• Bus View and Substation View Oneline: Fixed the coloring of substation objects so that the symbols and text use the correct coloring.
• Power Flow Solution: Fixed a potential oscillation which might occur with a DC transmission line that was oscillating between two different tap and firing angle settings that meet the power requirements of the converter equally well.
• Power Flow Solution: When opening a RAW or GE file, the initial starting point of a continuous switch shunt is now noted so that an estimate of whether the bus is a PV or PQ bus can be made immediately. This helps ensure with solution speed when you first open a text file case.
• Memory: Fixed a memory leak when destroying an injection group
• Memory: Fixed a memory leak when reading in an AUX file that contained information on an existing three-winding transformer.

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January 9, 2006

New Features

• Case Information Displays: Modified the graying out of the Limit Set and Monitored fields to reflect whether the field is active or not.

Bug Fixes

• File Formats: When reading PTI Contingency (*.con) files, if the name of a contingency contained a slash "/", then Simulator would now read the file correctly. This has been fixed.
• File Formats: When reading PTI Monitor (*.mon) files, an error existed in assigning lines, interfaces, and buses to the default limit group. This has been fixed.
• File Formats: Added reading of SBase from IEEE common format files.
• Oneline Diagrams: Changed how substation objects are drawn so that the text for the number of buses shown on the substation object is formatted with the same font, style and color as the identifier text.
• PV and QV Curve Tool: In the PV Curve tool, if the user specifies a results csv file, then the log file now uses the results filename with the string "_log.txt" appended to it.

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January 11, 2006

New Features

• None

Bug Fixes

• File Formats: Fixed bug caused in January 9 patch which resulted in the improper reading of GE EPC text files.  The error resulting the skipping of interfaces, DC lines, and ownership records when reading, but displayed no error message to the user.

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January 19, 2006

New Features

• Power Flow Solution: Add a new General Solution option which determines how MVar outputs are shared between buses that are remotely regulating a bus together. Previously this was always done using the Remote Reg % assigned by bus. There are now an which share MVars so that all generators at all buses remotely regulating together will be at the same relative position in their [min..max] range. There is also an option that weights a bus to be the SUM of the Remote Reg % values of generation at the bus.
• Power Flow Solution: Added an option with each transformer to specify a Regulation Range Target Type. Previously Simulator would always try to bring the regulated value to the "Middle of the Reg Range". The user may now optionally specify with a transformer to target the edge or "Max/Min of Reg Range".
• Auxiliary Files: Added an optional parameter of the name of the new worksheet to the ATCWriteToExcel(worksheet); script command.
• Auxiliary Files: Modified the reading of solution options from SUBDATA sections for Contingency, PV and QV options so that if a syntax error is found the user is notified in the log.
• Optimal Power Flow: Added ability to allow Area and Super Area constraints to be considered enforceable as long as they are below their tolerance. Previously, even if an area constraint was within 0.01 MW of being enforceable it would result in an unenforceable constraint with very high prices.

Bug Fixes

• Memory: A feature was added in Simulator 11 which caused the deletion of a single branch of a three-winding transformer representation to delete the other two branches, the start bus, and the three-winding record. This feature has been removed because it was not properly cleaning up the links between the objects. The feature will be re-added in Simulator 12.
• User Interface Dialogs: On the Topological Differences from Base Case dialog, when writing out the case differences to an AUX file, the deleted transformers were not handled quite right. This has been fixed.
• Sensitivities: On the TLR/GSF calculation, if the buyer or seller was chosen to be a Super Area, and the last area in this Super Area had no generation, then the calculation would report sensitivities of all zero. This has been fixed.
• File Formats: For interface records, the custom strings and floats were not properly stored in the PWB file. This prevented them from being read back in. This has been fixed.

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January 24, 2006

New Features

• PV and QV Curve Tool: Added the ability to specify the Inadequate voltage to be the same as the limit monitoring settings.

Bug Fixes

• User Interface Dialogs: Fixed an error on the Default Drawing Values form which results in the default color specification sometimes applying to the wrong setting.
• SimAuto: Fixed a memory leak which would occur when running DC OPF studies and saving the DC sensitivities to the PWB file. In this situation, every time you saved a PWB file, a memory leak occurred. This could eventually cause Simulator to run out of memory if running thousands of hours.
• Oneline Diagrams: When specifying a Grid Spacing of 200 or higher, and then saving the PWD file for a oneline, a divide by zero error would occur when trying to read the oneline. This has been fixed so that old files are properly read and future files are not written improperly.
• PV and QV Curve Tool: When choosing to stop when voltage is inadequate, Simulator was stopping properly, however the reported critical reason was showing "Reached Nose". This has been fixed so that it properly reports "Inadequate Voltage"

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February 2, 2006

New Features

• Case Information Displays: Added a column called "Bus Neighbor List (ignore status)" which shows a comma separated list of buses that are connected to the bus.
• Case Information Displays: Modified the Interface Case Information Display so that when looking at the elements the user may choose to only see elements (lines, gens, etc...) which are included as a part of at least one interface.
• User Interface Dialogs: Previously Custom Colors were not managed through Simulator. This has been fixed so that all locations which define colors allow you to specify 16 custom colors that will be available throughout the software.
• User Interface Dialogs: Modified the read routine of the Excel file "NERC Book of Flowgates" so that it does not report successful entries.
• Optimal Power Flow: Further enhancements for considering Area and Super Area constraints that are within tolerance as enforceable.

Bug Fixes

• Auxiliary File Format: When reading in Solution Options from an Auxiliary file, the variable name MinVoltSLoad was not being properly interpreted making it impossible to edit this value through an AUX file. This has been fixed.
• Case Information Displays: Fixed the "# of Neighbors" column for a bus so that it counts each bus only once. Previously it would count parallel lines to the same bus twice, which is what the "# of Connections" column is for.
• User Interface Dialogs: Fixed the editing of Display/Column options on the Area Sensitivities tab of the TLR/GSF Dialog. Previously you could not customize the display.
• Oneline Diagrams: When a line was moved, whether itself or through the movement of a bus, the screen refreshing was incorrect. This resulted in lines temporarily disappearing until a full refresh was done.

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February 10, 2006

New Features

• User Interface Dialogs: Modified so that the Custom Colors are maintained on the Color Dialogs throughout Simulator. This allows you to set a custom color at recall it at a later time.
• Case Information Displays: Modified the Injection Group Case Information Display so that when looking at the elements the user may choose to only see elements (gens, loads, shunts) which are included as part of at least one injection group.
• Oneline Diagrams: Added ability to draw generator symbols without rotors.
• Oneline Diagrams: Added the ability draw the Color Key for discrete color maps using equal spacing for each discrete value.

Bug Fixes

• Power Flow Solution: When choosing to model phase-shifters as discrete phase shift values, if the initial phase shift was not one of the allow phase shifts, an incorrect entry could be added to the Y-bus resulting in a temporary mismatch at the phase-shifter terminals. This has been fixed.
• File Formats: Fixed bug that could occur when appending an EPC file to an existing case.

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February 15, 2006

New Features

• User Interface Dialogs: When exporting a shapefile, we modified the dialog so that the user may choose at that point whether to export using x/y or lat/lon coordinates.

Bug Fixes

• User Interface Dialogs: If your case has line shunts that are connected to an out-of-service transmission line, but the terminals of that transmission line were still energized, then there would be an accounting error on the Case Summary Dialog. These Line Shunt values would be counted in the Shunt totals and the Loss Totals. This has been fixed.
• User Interface Dialogs: When exporting a shapefile, grouped objects were not exported correctly. This has been changed so that all objects in the group are exported individually.
• Case Information Displays: For 2-terminal DC lines, the column for Inverter MW and Mvar flows were showing the Rectifier values. This has been fixed.
• Case Information Displays: On the Custom Case Information Display, once a model field has been defined for a cell, then double-clicking on the cell in "Define Mode" would not bring up the dialog to change the model field. This has been fixed.
• SCOPF: When right-clicking and choosing "Show Control Sensitivities" on the Contingency Violations subtab of the SCOPF results, the dialog would bring up the incorrect contingency violation. This has been fixed.
• Oneline Diagrams: Simulator was not correctly importing oneline fields linked to "Primary Label" anymore because the Primary Label field had been removed. With this patch, the fields will be changed to link to the "Fields (all)" information instead.

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February 20, 2006

New Features

• File Formats: Modified the read routines for PTI RAW files so that Simulator handles text fills that contain ASCII NULL characters. These are normally not allowed in a text file and were causing Simulator to abort the PTI RAW read. Going forward these characters are ignored.
• User Interface Dialogs: For modification made to the Interface Case Information Display on Feb 2, 2006, the routine was very slow for cases with a large number of interfaces.  This has been sped up.

Bug Fixes

• File Formats: Fixed bug from Feb 20, 2006 patch when saving out a PWB file. This would result in a nuisance access violation.

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March 6, 2006

New Features

• Power Flow Solution: A dramatic solution speed improvement was implemented when performing transformer tap switching on a large number of transformers (> 100). This makes the speed of the transformer switching calculation twice as fast as previously seen.
• Power Flow Solution: The performance of the check verifying that the remote regulation of generators is possible was greatly improved. This will result in 1-2 second solution improvement on large systems.
• Power Flow Solution: A modification was made to the Jacobian structure which results in between a 5-10% speed improvement for power flow inner loop iterations.
• Oneline Diagrams: Modified the implementation of the Dynamic Formatting. This change should greatly improve the oneline refresh speed for onelines that use dynamic formatting.

Bug Fixes

• Power Flow Solution: The power flow solution timer for the message log was including the time spent refreshing open onelines and case information displays thus making timings of the power flow solution unreliable. This has been fixed so that the solution time only includes the power flow solution.
• Power Flow Solution: In the economic dispatch algorithm, when using loss penalty factors, the averaging of these factors between power flow solution has been updated to ensure convergence of the ED.
• Case Information Displays: When changing the impedance correction table to zero in a case information display, the impedance correction was not being removed from the transformer. This has been fixed.
• File Formats: The values for the Make Up Power by Area were not being stored in the PWB file. This has been fixed so that the values are now properly stored.
• Oneline Diagrams: Fixed access violation error that could occur if the bus view oneline was opened to a remotely regulating generator if Run Mode had not been entered at least once since opening the case.

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March 14, 2006

New Features

• None

Bug Fixes

• Power Flow Solution: Fixed bug in the new feature added on March 6 which dramatically sped up the remote regulation check for generators.
• Case Information Displays: Modified the Enforce Gen MW Limits columns so that they only show the setting for the individual generator. Previously they would show NO if the Solution Options was unchecked also.
• Oneline Diagrams: Line Flow Display Objects were inherited some of their display properties from the Line Flow Pie Charts, such as whether they are visible. This has been removed.
• Fault Analysis: When adding a graphical bus to represent an in-line fault location, the bus orientation was up instead of down. This has been fixed.

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March 21, 2006

New Features

• Optimal Power Flow: More enhancements with considering unenforceable area/Superarea constraints. A possible problem occurred in the ACE was exactly zero.

Bug Fixes

• Oneline Diagrams: When comparing two different cases using the Difference Flows feature, if the same transmission line existed in both case, but the from and to buses were reversed, the difference would be calculated incorrectly. This has been fixed
• Oneline Diagrams: In Edit Mode, when zoomed in very close to a background line with a very large number of vertices (>10000), the performance of clicking on the oneline diagram became very slow. This has been fixed.
• Oneline Diagrams: Modified Full Screen Oneline diagrams so that they are set to "Stay-on-Top". Previously the oneline would cover up other stay-on-top forms such as the Windows Task Manager. Now the full screen onelines are made normal windows.
• Power Flow Solution: Fixed potential conflict between transformer switching when one of the terminals of the transformer had a swtiched shunt at it. The conflict could result in the phase shifter moving the wrong direction initially.
• Power Flow Solution: Modified the phase-shifter switching so that a phase shifter is not allowed to move more than 10 degrees at a time between each inner power flow loop solution. This prevents divergence in situations that require the phase-shifter to more a large amount.
• Power Flow Solution: Fixed another bug in the new feature added on March 6 which dramatically sped up the remote regulation check for generators.
• Power Flow Solution: When generation at a single bus had a mix of AVR = YES and AVR = NO, the power flow solution would solve correctly, but the VAR outputs from the generators was not consistent. This has been fixed.

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April 5, 2006

New Features

• User Interface Dialogs: Modified the Time Step Simulation so that time can be specified with a precision of seconds. Previously all precision was to minutes only.
• Case Information Displays: Modified to make the Custom Expression name a value which can be editted via AUX files and Case Information grids.
• Case Information Displays: Added a bus column to display the bus neighbor list for only in service buses.

Bug Fixes

• Auxiliary File Formats: Ensured that when looking for a branch, that the uppercase/lowercase of the circuit id is not used.
• Auxiliary File Formats: Modified to refresh all open case information displays after executing an auxiliary file.
• Power Flow Solution: Fixed a potential error in the DC approximation power flow solution which occurred with radial phase-shifting transformers on control. It's not possible to control the flow on these transformers so they are now properly ignored.
• Power Flow Solution: Modified to prevent problems when line drop compensation is specified against a very large impedance. These situations are likely bad data, but floating point errors could occur with the bad data.
• Optimal Power Flow: Fixed potential floating point error which could occur in the OPF if a binding constraint suddenly became insensitive to all available controls. This was a rare situation but could occur when a phase-shifting transformer on power flow control backed off an angle limit during the OPF solution.
• Optimal Power Flow: Fixed access violation in showing the SCOPF sensitivities after loading in a saved PWB case but not resolving the power flow.
• Optimal Power Flow: Fixed incorrect LMP values that could occur under rare situations when there were interfaces using the limit cost curves specified in limit monitoring settings.

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April 12, 2006

New Features

• File Formats: When reading in a GE EPC file, Simualator will now assume that the GE paramater for "Generator Var Limit Dead Band" is equal to 2.0 MVar. This parameter is used in GE to signify which generators to not act on AVR. Simulator will assume all generators with a [min..max] var range of 2.0 MVar or less are set to AVR = NO..

Bug Fixes

• Oneline Diagrams: Fixed access violation which would occur after closing the Contour Options Dialog. This bug was added in the previous patch and presents only a nuisance.
• Oneline Diagrams: When using dynamic formatting on a transformer display object, the color of the second half of the transformer was not properly updated. It will now draw both halfs the same color.

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April 17, 2006

New Features

• None.

Bug Fixes

• Optimal Power Flow: In situation with conflicting controls, it was possible for the value of a control variable to become extremely large resulting in a fatal error.  This has been fixed and the program will more graceful fail with a message about a control variable approaching an infinite value.
• Contingency Analysis: Fixed bug that would occur when placing a SOLVEPOWERFLOW contingency action that was followed by only POSTCHECK actions. The POSTCHECK actions would be skipped in this situation.
• User Interface Dialogs: The time step resolution of seconds made it possible for time points to overlap if the time needed to process a point exceeded the time between that point and the next one. Simulator would get stuck looping back to the earlier time point if this occurred.  It has been fixed by changing the time processing between points to be calculated from the time the previous point finished to the time the next point begins, making sure that time points cannot overlap.

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April 18, 2006

New Features

• None.

Bug Fixes

• File Formats: When reading in an EPC file, a tap control on/off flag of 0 or 1 is expected. Some EPC files were appearing with values of -1 instead. Simulator reading this as 255 instead and then writing this back out to EPC files. Simulator does not use this field, but values of 255 resulted in problems in the GE software. Simulator will now read all non-zero values and assume them to be a 1.
• Power Flow Solution: The fix on April 5 to prevent errors resulting from very large line drop compensation values was causing a large memory leak if any generators were on line drop control. This has been fixed.

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May 8, 2006

New Features

• None.

Bug Fixes

• File Formats: Fixed error with reading in OPF result information from the PWB file for phase-shifting transformers which were binding at their regulation range.
• Oneline Diagrams: Fixed access violation that occurred with unlinked Load Fields.
• Available Transfer Capability: Fixed error that was limiting the number of scenarios to 50 in the ATC tool. The proper limitation is 1024..

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May 13, 2006

New Features

• None.

Bug Fixes

• File Formats: In EPC files, when a line shunt belongs to a line that is part of a multi-section line, write the circuit id that belongs to the multi-section line rather than the line segment since the shunt is identified by the from and to bus of the multi-section line. This fixes a bug that prevents line shunts from being read in correctly.
• Available Transfer Capability: When using an iterated solution method, with injection groups as the buyer/seller, and if generators ended up hitting limits, then the reported ATC values could be incorrect. This has been fixed.

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May 19, 2006

New Features

• None.

Bug Fixes

• Available Transfer Capability: Fixed error in May 13 ATC patch which was causing the results to be off by a factor of SBase.
• Optimal Power Flow: Modified so that the DC-OPF initialization includes the estimation of generation by area to prevent a large change in the slack bus generation.
• Optimal Power Flow: Cleaned up more bugs related to the check which allows a small unenforceable ACE value.

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May 23, 2006

New Features

• File Formats: Added data correction when reading IEEE Common Format files that included bus nominal voltages of zero (assume 138 instead) or transformer tap ratios of 0 (assume 1.0 instead).

Bug Fixes

• File Formats: Fixed bug which could occur when performing the following sequence: (1) be in Run Mode, (2) save case as EPC file, (3) Solve the power flow
• User Interface Dialogs: Fixed infinite loop which might occur when inserting a new three winding transformer from the three-winding transformer dialog.
• Optimal Power Flow: Increased the number of iterations of the linear program which must occur before turning on the anti-cycling code. Anti-cycling prevents an infinite loop, but also increases solution time so must only be done when needed.

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June 6, 2006

New Features

• File Formats: Modified the reading of PTI SUB files so that generators or loads that area off-line are not excluded.
• Oneline Diagrams: Enhanced the speed of reading in a oneline diagram.

Bug Fixes

• Contingency Analysis: Fixed error in the interaction of Post-Power Flow Actions with the Global Contingency Actions. The Post Power Flow Actions were also calling the Global Contingency Actions.
• Fault Analysis: Modified the calculation of faults to greatly speed up the solution speed when large amounts of fault sequence data is included.
• Oneline Diagrams: Fixed error in the writing of a PWD file when the grid spacing has been set to zero. Also modified to prevent the grid spacing from ever being set to zero going forward.

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June 12, 2006

New Features

• None

Bug Fixes

• PV and QV Curves: Fixed access violation when plotting in PV or QV Curves.  This bug was introduced in the June 6 patch.

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June 26, 2006

New Features

• File Formats: Modified to allow non-series capacitor branches to be read from a GE EPC file as bypassed.

Bug Fixes

• Oneline Diagrams: PowerWorld internally limits the number of vertices on a graphical line to 32,767.  When reading in very detailed GIS Shapefiles however it's possible to come across a line with more points than this.  This is now properly handled.
• User Interface Dialogs: When using the PTDF dialog to "toggle the flow visualization", errors could occur if the initial flow visualization was not set to MW values only.  This has been fixed.
• Case Information Displays: The value for OPF Transmission Charge associated with a DC Transmission line was always displayed as a zero in the case info display.  This has been fixed.

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July 7, 2006

New Features

• None

Bug Fixes

• Optimal Power Flow: Fixed potential external error which could occur on a Pentium III processor.

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July 18, 2006

New Features

• None

Bug Fixes

• Oneline Diagrams: Fixed minor display error of the generator AVR status on a oneline diagrams.  It was possible for a generator to show that it was at a VAR limit when it was actually not.  This could only happen if there were multiple generators at the bus and you had recently changed the status of one of them.

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---

New Features/Minor Improvements:

Select the desired item to view all New Features and Improvements since the release of Simulator 11.0

• File Formats
• Auxiliary Files (SCRIPT and DATA Sections)
• Simulator Automation Server (SimAuto)
• Case Information Displays 
• User Interface Dialogs
• Oneline Diagrams
• Bus View and Substation View Onelines
• Power Flow Solution
• Sensitivity Calculations
• Contingency Analysis Tool
• PV and QV Curve (PVQV) Tool
• Available Transfer Capability (ATC) Tool
• Optimal Power Flow (OPF) and Security Constrained OPF (SCOPF) Tool
• Fault Analysis
• Help

  Top

File Formats

• (June 15, 2005) Modified the reading of PTI *.sub files so that when a PARTICIPATE block is encountered inside a SUBSYSTEM without any previous definition of subsystem buses, then PowerWorld will assume that all buses listed in the PARTICIPATE block should be used.  Previously we would not create the injection group  represented by the subsystem.
• (June 15, 2005) Added better error messaging to alert if the incorrect number of ENDs are encountered in a *.sub file.
• (July 29, 2005) Modified the reading of EPC files so that we read in the interface element multipliers and utilize these fields in the calculation of interface flows. 
• (July 29, 2005) Modified the reading of RAW files when encountering loads that are assigned to a different area than their terminal bus. Most RAW files have been solved so loads like this are not treated as tie-lines. (AREA INT CODE = 1 FOR LINES ONLY). Simulator requires that loads be treated as they are modeled (i.e. as tie-lines) (AREA INT CODE = 2 FOR LINES AND LOADS). To make the area interchange consistent, Simulator now creates new transactions to represent these loads. If the RAW file was solved assuming that loads like this are treated as tie-lines, then you will need to open the MW Transactions table and remove the transactions with ID "RAW_LOAD".
• (October 18, 2005) Made changes to allow EPC files to be used as change files for appending data to a case.
• (February 20, 2006) Modified the read routines for PTI RAW files so that Simulator handles text fills that contain ASCII NULL characters. These are normally not allowed in a text file and were causing Simulator to abort the PTI RAW read. Going forward these characters are ignored.
• (April 12, 2006) When reading in a GE EPC file, Simualator will now assume that the GE paramater for "Generator Var Limit Dead Band" is equal to 2.0 MVar. This parameter is used in GE to signify which generators to not act on AVR. Simulator will assume all generators with a [min..max] var range of 2.0 MVar or less are set to AVR = NO.
• (April 18, 2006) When reading in an EPC file, a tap control on/off flag of 0 or 1 is expected. Some EPC files were appearing with values of -1 instead. Simulator reading this as 255 instead and then writing this back out to EPC files. Simulator does not use this field, but values of 255 resulted in problems in the GE software. Simulator will now read all non-zero values and assume them to be a 1.
• (May 23, 2006) Added data correction when reading IEEE Common Format files that included bus nominal voltages of zero (assume 138 instead) or transformer tap ratios of 0 (assume 1.0 instead).
• (June 6, 2006) Modified the reading of PTI SUB files so that generators or loads that area off-line are not excluded.
• (JUne 26, 2006) Modified to allow non-series capacitor branches to be read from a GE EPC file as bypassed.

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Auxiliary Files (SCRIPT and DATA Sections)

• (May 10, 2005) When using the LoadScript(filename, ScriptName) and LoadData(filename, DataName) script commands to load a particular SCRIPT or DATA section, previously we would read all the sections that had the ScriptName or DataName specified. This has been left that way for the LoadData() command. For the LoadScript command however, if multiple SCRIPT sections with the same ScriptName exist, only the first one is read.
• (May 10, 2005) Added new script command: ZeroOutMismatches;
• (May 10, 2005) Added new script command: CalculateVoltSelfSense(filter);
• (May 10, 2005) Added new script command: CalculateVoltToTransferSense([transactor seller],[transactor buyer],TransferType,TurnOffAVR);
• (June 28, 2005) Added script action “SetCurrentDirectory” which sets the present directory path.
• (June 28, 2005) Modified calls the all script actions which might change the current directory path so that they do not do so. All current directory changes must now be handled using the script command SetCurrentDirectory. This included the actions RenameFile, CopyFile, DeleteFile, LoadAux, LoadScript, LoadData, SaveData, OpenCase, SaveCase, LogSave, and others.
• (August 31, 2005) Added new script command InitializePrimalLP;
• (September 26, 2005) Added a new script command WriteTextToFile("filename", "text to write"); The file will be created if it doesn't presently exist. If the file exists, the "text to write" will be appended to the file. When using the command to add comments to an AUX file, be sure to include the // characters.
• (November 11, 2005) Added a new case information options which allows you to specify whether to write SUBDATA sections of AUX files using primary or secondary keys. This allows you to write AUX files using the "name/nominal kv" keys instead of the number keys.
• (January 19, 2006) Added an optional parameter of the name of the new worksheet to the ATCWriteToExcel(worksheet); script command.
• (January 19, 2006) Modified the reading of solution options from SUBDATA sections for Contingency, PV and QV options so that if a syntax error is found the user is notified in the log.

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Simulator Automation Server (SimAuto)

• (October 11, 2005) Added new procedure call ChangeParametersMultipleElement(objecttype, ParamList, ValueList) so that multiple objects may have their parameters changed using one function call.
• (November 11, 2005) Added a new case information options which allows you to specify whether to write SUBDATA sections of AUX files using primary or secondary keys. This allows you to write AUX files using the "name/nominal kv" keys instead of the number keys.

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Case Information Displays 

• (May 10, 2005) When pasting in data from the clipboard into a case information display, the column headers are now trimmed of leading and trailing spaces. Previously we did not do this, so " Num " would not be interpreted as "Num" thus preventing a paste from occurring.
• (May 17, 2005) Modified the "Send to Excel" commands so that the cell format is changed to "Text" for all string fields sent out from PowerWorld. This will correct problems related to Excel automatically converting strings into some other format, such as a date string. An example: "MAR 2551" might become "March 2551".
• (May 26, 2005) Modified so that case info displays that they can be released after they are embedded on a oneline.
• (May 26, 2005) Added a right-click option to create an interface from a selection of lines/transformers in a case info display.
• (May 26, 2005) Added a right-click option to create an injection group from a selection of generator or loads in a case info display.
• (July 17, 2005) When sending data from a case information to Excel, a dialog may now appear prompting the user to select which instance of Excel and to which sheet name to send the data.
• ( July 22, 2005 ) Modified the Interface Case Information display so that there are now subtabs that show a list of only a specific type of object in the interface.  For example, a list of branches can now be brought up which then allows the user to customize the list with all the fields available for a branch.  
• ( July 22, 2005 ) Modified the Injection Group Information display so that there are now subtabs that show a list of only a specific type of object in the injection group.  For example, a list of generators can now be brought up which then allows the user to customize the list with all the fields available for a generator.
• (August 31, 2005) Modified the Search for Text... right-click feature of the case information displays so that it can optionally "Search Ignoring Filtering". When searching with "Search Ignore Filters" chosen, then the search will look through all possible records regardless of what the filtering is. If text is found which is not presently displayed due to filtering, then all filtering will be removed for the case information display and the text shown.
• (August 31, 2005) Modified the Search for Text... right-click feature of the case information displays so that it can optionally "Search All Fields". When searching with "Search All Fields" chosen, then the search will look through all possible columns regardless of how the present Display/Column options are set. If text is found in a column that is not presently displayed, then this column will be added to the end of the case information display and the text shown.
• (October 18, 2005) Added special feature when entering data into a case information display, or reading data from an AUX file. If a field is entered as "@variablename", then Simulator will attempt to change the field to the value contained in the respective variablename. For instance, for generators entering the string "@BusPUVolt" in the column for the voltage setpoint will change the generator voltage setpoint to be equal to the present terminal bus voltage.
• (November 7, 2005) Added fields for buses, substations, areas, and zones which show net MW, MVar, and MVA injection.
• (November 28, 2005) Modified custom expression evaluation so that invalid user-specified expressions will report errors to the message log.
• (January 9, 2006) Modified the graying out of the Limit Set and Monitored fields to reflect whether the field is active or not.
• (February 2, 2006) Added a column called "Bus Neighbor List (ignore status)" which shows a comma separated list of buses that are connected to the bus.
• (February 2, 2006) Modified the Interface Case Information Display so that when looking at the elements the user may choose to only see elements (lines, gens, etc...) which are included as a part of at least one interface.
• (February 10, 2006) Modified the Injection Group Case Information Display so that when looking at the elements the user may choose to only see elements (gens, loads, shunts) which are included as part of at least one injection group.
• (April 5, 2006) Modified to make the Custom Expression name a value which can be editted via AUX files and Case Information grids.
• (April 5, 2006) Added a bus column to display the bus neighbor list for only in service buses.

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User Interface Dialogs

• (May 26, 2005) Added a button on the Interface dialog to allow you to copy elements from one interface into another interface.
• (June 6, 2005) Modified to allow series capacitor objects to be tapped the same as a transmission branch.
• (July 5, 2005) Added memo tabs to the Line Dialogs, Super Area Dialog, Load Dialog, and Zone Dialog. 
• (July 5, 2005) Added an option to automatically set the case as a base case after the case is loaded.
• (July 10, 2005) Completely overhauled the transformer impedance correction dialog to allow showing more information regarding the transformers that use the table.
• (July 17, 2005) Added an option to include a timestamp on every message sent to the message log.
• (August 8, 2005) - Added diagrams and equations to the transformer dialog to better explain how transformer base values are converted to system base values.
• (August 8, 2005)- Added support to Model Filters for showing columns that represent the number of Model Conditions and the number of unlinked Model Conditions.
• (October 18, 2005) Added support for multi-directional MW-mile calculations.
• (October 20, 2005) Added the ability to specify through the registry if customization of the toolbars is allowed. The only way to set this option is to specify a value of zero for the registry key HKEY_LOCAL_MACHINE/PowerWorld/Simulator 11/dxToolbar11/ Allow_Customization_Of_Toolbars
• (October 31, 2005) On the "Present Topological Differences from Base Case" dialog, the ability to save out the list of topology differences in the case which only meet the area/zone filters has been added.
• (November 11, 2005) Modified all dialogs so that Read-Only edit boxes always appear with a gray background. This better highlights what is read-only and what is no read-only
• (December 22, 2005) Modified the Auto Insertion of Injection Groups so that grouping can be done by Custom String as well as Custom Floating points. Also made sure that all 5 custom strings and floats were available.
• (February 2, 2006) Previously Custom Colors were not managed through Simulator. This has been fixed so that all locations which define colors allow you to specify 16 custom colors that will be available throughout the software.
• (February 2, 2006) Modified the read routine of the Excel file "NERC Book of Flowgates" so that it does not report successful entries.
• (February 10, 2006) Modified so that the Custom Colors are maintained on the Color Dialogs throughout Simulator. This allows you to set a custom color at recall it at a later time.
• (February 15, 2006) When exporting a shapefile, we modified the dialog so that the user may choose at that point whether to export using x/y or lat/lon coordinates.
• (February 20, 2006) For modification made to the Interface Case Information Display on Feb 2, 2006, the routine was very slow for cases with a large number of interfaces. This has been sped up.
• (April 5, 2006) Modified the Time Step Simulation so that time can be specified with a precision of seconds. Previously all precision was to minutes only.

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Oneline Diagrams

• (May 10, 2005) Added support for reading comments from a PTI Draw (*.drw) file.
• (May 10, 2005) Modified how the underlying drawing on oneline diagrams occurs so that the memory footprint of PowerWorld will remain consistent while you are resizing and moving around a set of open onelines. While this results in a larger memory footprint on average it will not change over time and result in memory fragmentation.
• (May 10, 2005) Modified so that when setting the Undo Memory Limit Per Oneline to zero MB, this has the same effect as disabling the undo feature.
• (May 10, 2005) Modified the oneline link so that it can also be used to open an Auxiliary File from the oneline diagram.
• (June 6, 2005) Add a right-click option on a selection of display objects that allows you to "snap selection to grid".  This will align the objects you have selected to the drawing grid.
• (June 6, 2005) Added a new option so that the font color of a Pie Chart can be specified on the oneline display options dialog.
• (June 6, 2005) Generally cleaned up some of the local menu (right-click drop-downs) that appear on a oneline diagram so that options related to all objects appear in a consistent manner.
• (June 6, 2005) Fixed font name alignment on substation display objects.  Previously the fonts were shifted downwards a small amount.
• (June 14, 2005) Added options to specify whether to show flow arrows on branches, generator, shunts, or loads separately.  This allows you to disable flows on specific types of objects while keeping the flow on other types.
• (June 14, 2005) Added options on whether to show circuit breakers for particular types of objects.
• (June 28, 2005) Modified the dynamic formatting for transmission lines so that setting the fill color dynamically will change the color of the flow arrows.
• (July 5, 2005) Added option to local menu for background rectangles and ellipses to convert them to buses or substations.
• (July 17, 2005) Added ability to export a oneline diagram to a set of Shapefile files (shp/shx/dbf set). This is available in the Tools, GIS Tools menu.
• (July 17, 2005) When saving out a list of dynamic formatting or select by criteria descriptions to an auxiliary file, Simulator will now automatically include a data section describing the advanced filters used.
• ( July 22, 2005 ) Added new measurement lines which can be added to determine the length of a particular parts of the oneline.
• ( July 22, 2005 ) Modified the up/down arrows associated with the transformer tap position so that they are always available if the transformer is on manual control.
• ( July 22, 2005 ) Modified the keyboard shortcut which performs the "Bring to Front" on a oneline so that it will not open a second oneline if the oneline is already open.  Previously it would only bring forward a oneline which had been created as a result of a keyboard shortcut.
• (July 29, 2005) Modified auto insertion of buses and substations so that the user has an option to not insert buses or substations that are already drawn on the diagram.
• (July 29, 2005) Added the ability to change the shape of substation, bus, area, zone and injection group objects using the Format Selected objects dialog.
• (July 29, 2005) Added an Apply button the oneline display options dialog so that the options can be applied without closing the dialog.
• (July 29, 2005) Added the ability to select objects touched by the selection window instead of only objects fully contained by the selection window.
• (July 29, 2005) Modified the writing out of shapefiles so that it uses longitude/latitude coordinates if the user has chosen the Oneline Display Option that says to show coordinates in lon/lat.
• (August 3, 2005) Added the ability to renumber the areas, zones, and substations on a oneline diagram.  This new feature works in the same manner as the "renumber bus" feature.
• (August 19, 2005) Modified the showing of MW and MVar arrows simultaneously so that the initial locations for the arrows were offset from each other. This makes the initial locations so that the MVar arrows are not hidden by the MW arrows.
• (August 19, 2005) Modified the oneline link dialog so that when you click browse you can choose an auxiliary file to link to as well.
• (August 31, 2005) Added the ability for formatting of color, font color, etc... of substation fields to be determined by the dynamic formatting specified with buses that make up the substation. For instance, this allows the "min kv of max nom kv" substation field to be formatting based on dynamic formatting related to a bus voltage.
• (August 31, 2005) Cleaned up interaction with the Dynamic Formatting dialog.
• (September 11, 2005) Added an Simulator Environment option that allows the user to specify not to show the dialog asking the user if they would like to create a new oneline after opening a case.
• (September 15, 2005) Added a feature to convert the selected AC tranmsission lines into background lines. To use this feature, the user must customize the toolbars and added the new command available under the Insert category called "Convert AC Line to BackgroundLine"
• (September 19, 2005) Added the option to specify with a Screen Layer whether display objects in the layer are "Selectable in Edit Mode". Setting this value to NO makes it impossible to select the display object at all. You will still see the display object but will not be able to edit, move, or select the display object while in Edit Mode. The Run Mode behavior of the display object will not change.
• (October 4, 2005) Previously the generators at the slack bus did not display a circuit breaker symbol on the oneline diagram. This has been changed so that slack bus generators can now be opened on the oneline diagram. Simulator can dynamically choose a new slack bus anyway.
• (October 4, 2005) When drawing large JPEGs on a diagram and zooming into these JPEGs the drawing speed of the oneline diagram was greatly diminished. A change has been made to speed this up greatly.
• (November 30, 2005) Modified the Substation object so that clicking on a substation now allows invoking commands and opening URLs in a web browser.
• (February 10, 2006) Added ability to draw generator symbols without rotors.
• (February 10, 2006) Added the ability draw the Color Key for discrete color maps using equal spacing for each discrete value.
• (March 6, 2006) Modified the implementation of the Dynamic Formatting. This change should greatly improve the oneline refresh speed for onelines that use dynamic formatting.
• (April 12, 2006) Fixed access violation which would occur after closing the Contour Options Dialog. This bug was added in the previous patch and presents only a nuisance.
• (April 12, 2006) When using dynamic formatting on a transformer display object, the color of the second half of the transformer was not properly updated. It will now draw both halfs the same color.
• (June 6, 2006) Enhanced the speed of reading in a oneline diagram.

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Bus View and Substation View Onelines

• No new features yet

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Power Flow Solution

• (June 14, 2005) At the end of a power flow solution, Simulator looks at the voltage angles in each island and if the angles are outside of the +/- 160 degrees, then Simulator automatically rotates all the angles by an equal amount to center the range around zero.  This is done to prevent angles from spanning across +180/-180 degrees.  This isn't really a problem generally and rotating the angles has no effect on the system solution, but PowerWorld considered the situation very strange.  If you would like to disable this feature, a new option has been added to the solution options called "Disable Angle Rotation Processing".
• (June 14, 2005) Added ability to specify that a discrete switched shunt be available for switching during the inner power flow loop.  This option is specified with each switched shunt record by changing the "Inner PF Loop Switching" field to YES.  By default these are all NO.  This is accomplished by setting any discrete shunts allowed to switch in the inner power flow loop to continuous shunts, solving the inner power flow loop, setting the selected shunts back to discrete and rounding the nominal Mvar up to the nearest block, and then solving the inner power flow loop again.
• (June 28, 2005) For switched shunts which are controlling the Mvar output of generation, a modification was made to the power flow which allows the generation to ignore its Var limits during the direct inner power flow loop solution. This switched shunt will then bring it back into limits, otherwise a subsequent run through the inner loop will bring it back.
• (July 22, 2005) Simulator has handled for a few years the situation when all transmission lines connected to a slack bus are opened by choosing a new slack bus.  Simulator did not however handle the situation when generators at the slack bus were opened.  This would cause a dialog to appear which said that the slack bus must have generation.  Simulator has now been changed so that a new slack bus will automatically be selected with appropriate messages sent to the message log.
• (September 11, 2005) Added messages to the log when bus load is reduced because the bus voltages are dropping below the minimum voltage for constant power load. Also changed the default value for the minimum voltage for constant power load from 0.8 to 0.7.
• (September 13, 2005) Modified so that the generator setpoint voltage can not be set to zero. Now, when the user tries to change the voltage to zero Simulator will not change the voltage.
• (December 14, 2005) When a tap-changing transformer has a tap min to tap max range larger than 0.9 per unit, Simulator always ignores these as controllers. The program now notifies the user in the message log that this change is being made.
• (January 19, 2006) Add a new General Solution option which determines how MVar outputs are shared between buses that are remotely regulating a bus together. Previously this was always done using the Remote Reg % assigned by bus. There are now an which share MVars so that all generators at all buses remotely regulating together will be at the same relative position in their [min..max] range. There is also an option that weights a bus to be the SUM of the Remote Reg % values of generation at the bus.
• (January 19, 2006) Added an option with each transformer to specify a Regulation Range Target Type. Previously Simulator would always try to bring the regulated value to the "Middle of the Reg Range". The user may now optionally specify with a transformer to target the edge or "Max/Min of Reg Range".
• (March 6, 2006) A dramatic solution speed improvement was implemented when performing transformer tap switching on a large number of transformers (> 100). This makes the speed of the transformer switching calculation twice as fast as previously seen.
• (March 6, 2006) The performance of the check verifying that the remote regulation of generators is possible was greatly improved. This will result in 1-2 second solution improvement on large systems.
• (March 6, 2006) A modification was made to the Jacobian structure which results in between a 5-10% speed improvement for power flow inner loop iterations.
• (April 18, 2006) The fix on April 5 to prevent errors resulting from very large line drop compensation values was causing a large memory leak if any generators were on line drop control. This has been fixed.

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Sensitivity Calculations

• (May 10, 2005) Under Tools, Other Sensitivities, previously all the sensitivities were used to calculate the sensitivity at a single metered point to multiple transfers (transfer from each bus to the slack bus). New tabs have been added for calculating the voltage sensitivity at all the buses for transfer of real or reactive power, and a tab the self sensitivity of voltage with respect to P and Q injection at each individual bus.
• (September 19, 2005) Modified the error messages that report invalid transfer directions to better describe why a sensitivity calculation fails (for instance the buyer and seller are in different electrical islands).

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Contingency Analysis Tool

• (May 10, 2005) Added ability to report contingency analysis violations based on the relative change in the dV/dQ self-sensitivity at a bus. The user specifies a list of buses to look at dV/dQ and will then report a violation if the dV/dQ changes by a specified multiple.
• (May 10, 2005) Add the ability to "merge contingencies". This is done by selecting a set of contingencies on the Contingency Dialog and then creating all possible combinations of two of the selected contingencies.
• (May 26, 2005) Modified the display of the percent column for bus voltage contingency violations so that it is only displayed when the violation represents a "change violation" relative to the reference case.
• (May 26, 2005) Added the ability to "clone" a contingency. This will make a contingency that is an identical copy of another with the work "copy" appended to the name.
• (June 28, 2005) Add options for specifying post-contingency high and low voltage limits which are different than the normal voltage limits. Note that Version 11 patch, these options are not stored with the PWB file because these would change the file format. These options can only be saved/loaded with the AUX file format. In Version 12, these will be added to the PWB file format.
• (July 10, 2005) Added a right-click option to the contingency-violation case info displays to create contingent-interfaces from the selected violations.
• (July 29, 2005) Modified the interaction contingency elements that modify individual generators and the post-contingency max/min generator response. Now generators that are modified by individual contingency elements will ignore the max/min generator response option.
• (August 3, 2005) Modified the clone contingency tool to insert the contingency right next to the cloned contingency.
• (November 28, 2005) Now include the nominal kV in the contingency description strings
• (December 22, 2005) Added the ability to read PTI *.con files which using name/kv as identifiers instead of bus numbers as identifiers.

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PV and QV Curve (PVQV) Tool

• (May 10, 2005) Added the ability to monitor the dV/dP sensitivity while running the PV Curve tool. This will calculate the sensitivity of the bus voltage with respect to a change in the transfer amount.
• (May 13, 2005) Added the ability to track voltage-control devices hitting limits during the PV and QV curve tool.
• (May 17, 2005) Added the ability in the devices hitting limits lists so that you can filter out all devices that never change. For example: a generator which is always at its maximum VAR output will not be listed.
• (July 29, 2005) Added the ability to control whether constant power, current, or impedances load is used as part of the transfer of a PV curve.
• (August 3, 2005) Added the ability to scale the Load Mvar as part of a PVQV transfer by a multiple relative to the amount that it would change if the load maintained constant power factor. For example: Assume an initial load of 100 MW and 50 Mvar. If you wanted to increase the load by 50 additional MW and maintain constant power factor, you would increase the Mvar by 25 and end up with 150 MW and 75 Mvar. If instead you said increase it by 0.8 of what it would increase for constant power factor, then you increase by 20 Mvar and end up at 150 MW and 70 Mvar.
• (September 13, 2005) Modified the layout of the PV Curve tool to make the new features regarding scaling components of constant power, current, and impedance load more easily understood.
• (September 15, 2005) Modified the QV Curve tool so that when viewing the results of the QV Curve runs, you may right-click and choose Display/Columns Options and add all field related buses.
• (January 24, 2006) Added the ability to specify the Inadequate voltage to be the same as the limit monitoring settings.

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Available Transfer Capability (ATC) Tool

• (May 26, 2005) Added a new option on how the ATC Solution Method "(IL) the Full CTG Solution" is processed called "Force all transfer ramping to occur in pre-contingency states and repeat full CTG Solutions". Prior to this new option, the Full CTG solution would only occur once and extra ramping would occur after that.
• (May 26, 2005) Added a new option to specify whether to include phase-shifters in the determination of the post-contingency sensitivity values when performing ATC calculations.
• (June 6, 2005) Added a script command which would perform the same action as done on the ATC multi-scenario results tab for Write to Excel.
• (June 28, 2005) For multiple ATC scenarios, now have the option of changing line rating A and B.
• (September 15, 2005) Added a better indication of when the "(IL) then full CTG" solution method encounters an unsolvable power flow when ramping out the pre-contingent state. A new gray-highlighted transfer limitation will appear showing the final state at which a successful contingency solution was achieved. Additional fuchsia-highlight transfer limitations then show the pre-contingent state at which the power flow solution failed.

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Optimal Power Flow (OPF) and Security Constrained OPF (SCOPF) Tool

• (August 31, 2005) Added new script command InitializePrimalLP;
• (January 19, 2006) Added ability to allow Area and Super Area constraints to be considered enforceable as long as they are below their tolerance. Previously, even if an area constraint was within 0.01 MW of being enforceable it would result in an unenforceable constraint with very high prices.
• (February 2, 2006) Further enhancements for considering Area and Super Area constraints that are within tolerance as enforceable.
• (March 21, 2006) More enhancements with considering unenforceable area/Superarea constraints. A possible problem occurred in the ACE was exactly zero.

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Fault Analysis

• (December 14, 2005) Modified so that fault current and angle can be displayed for the fault bus on a case information display. This then allows you to export the value via SimAuto for via an Auxiliary file.

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Help

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Bug Fixes:

• File Formats
• Auxiliary Files (SCRIPT and DATA Sections)
• Simulator Automation Server (SimAuto)
• Case Information Displays 
• User Interface Dialogs
• Oneline Diagrams
• Bus View and Substation View Onelines
• Power Flow Solution
• Sensitivity Calculations
• Contingency Analysis Tool
• PV and QV Curve (PVQV) Tool
• Available Transfer Capability (ATC) Tool
• Optimal Power Flow (OPF) and Security Constrained OPF (SCOPF) Tool
• Fault Analysis
• Memory

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File Formats

• (May 10, 2005) Simulator 11.0 no longer supports the old load variation schedules. These may now be implemented using the time step simulation. However, when reading in an old PWB or AUX file which had the load variation schedule, Simulator 11.0 was including these. The user had no way to see them or remove them however. This has been fixed now so that load variation schedules are now longer kept when read from an old case.
• (May 10, 2005) Simulator 11.0 sped up the reading of 3-winding transformer data form all file formats. Previously it was very slow because of a slow search routine. In the original release of 11, however, when reading in a PWB file which contained a 3-winding transformer that had one terminal connected to a DC transmission line, this would result in an error and a failed file read. This occurred with some cases in ERCOT. This has been fixed.
• (May 10, 2005) When saving a oneline diagram in an older PWD file format, all display objects were showing up with a color of black. This has been fixed so that Version 11 will now properly save older PWD version files.
• (May 13, 2005) Added support for reading/writing various PSS/E sequence data file formats from Version 24-30.
• (May 17, 2005) In the installation files for Simulator 11.0, the file type registration with Windows for PWB and PWP files was not correctly configured to open a file when it was double-clicked upon. This patch will automatically correct this problem if it exists.
• (May 17, 2005) Fixed bug which could sometimes result in buses not being written out as part of the RAW file format. This occurred because Simulator was incorrectly treating a bus as the star bus of a three-winding transformer when it was not. These buses were then not written to some RAW file formats.
• (May 26, 2005) When reading Multi-Section lines from a PTI RAW file adjustments were being made to the area/zone assignments of the dummy buses similar to those made when reading a GE EPC file. These adjustments are needed when reading GE because the multi-section line itself maintains where the meter is. This is not done in PTI, but we were still adjusting area/zone definitions incorrectly.
• (June 6, 2005) Modified the read/write routines for GE EPC file so that they utilize only a period (.) as the decimal place separator.  The read/write routines for PTI files had previously been changed to behave this way.
• (June 14, 2005) When reading in PWB files which contained the old "Scheduled MW Transactions" Simulator will now convert these into the newer MW Transaction records.
• (July 5, 2005) Removed the memo field from the DC Line and Multi-Terminal DC Line records. These were available for entry, but the values were not included in the Version 11 PWB format, so for now they have been removed. Starting with Version 12 these will be included again. 
• (July 5, 2005) When reading a PWB file, Simulator was not correctly setting which end of a multi-section line was metered. This has been fixed.
• (August 2, 2005) After loading in an AUX file that contains injection group descriptions, Simulator will maintain records for “unlinked” injection group elements representing gens or loads described in the AUX file that do not exist in the case. After loading such an AUX file and then saving the case as a PWB file, Simulator is supposed to ignore these unlinked elements and not save them. There was, however, a bug that was causing these to be saved resulting in a corrupted PWB file that could not be reopened. This has been fixed.
• (September 11, 2005) Fixed a problem when reading in a Promod file that would terminate prematurely if it was trying to read a contingency element that was not found in the case
• (September 11, 2005) Modified the storage of the jumper threshold and Minimum Voltage for Constant Current Load in the GE EPC file.
• (September 11, 2005) Corrected bug when writing out he branch records to a GE EPC file.
• (September 26, 2005) Fixed a problem in the parsing a text file such as a RAW file which would cause it to fail if a value NOT inside quotes had trailing spaces before a comma delimiter, AND both spaces and commas were considered delimiters for the file (this is how RAW files are ready because the delimiters are sometimes mixed)
• (September 26, 2005) When reading the status of a transformer from an EPC which was greater than 1, Simulator now treats this as an 1. This appears to be an error in the file. Previously, Simulator would treat a status of "8" for instance as though it were open.
• (September 26, 2005) When reading in a RAW or EPC file, warning messages are added regarding transformers that are outside the control limits. Previously these warning messages were even added for transformers that were set to be off control. This has been changed so that messages are only generated for generators which are on control. 
• (October 18, 2005) Fixed bug in ReadOwnerDataBinary where read would get corrupted if you were appending from a PWB file and an owner in the appending file did not already exist in the original file.
• (October 31, 2005) Fixed a few problems with writing out DC Line records to EPC files.
• (November 11, 2005) For PWB files written before August 2, 2005 if injection groups contains unlinked participation points, then the file may not be read back in properly to a Simulator patch after August 2, 2005. This has been fixed so that all PWB files are properly read in.
• (November 11, 2005) When reading an EPC file, an access violation would occur if one of the terminals of a two-terminal DC line record did not exist. This has been fixed.
• (December 14, 2005) When reading an EPC file which contained bus records marked as type "-1", Simulator was not properly assigning these buses as load buses. Files in the future will treat these as a "1" instead. This was causing very strange behavior with the power flow solution. A change was also made so the PWB files which had already been created by reading these strange EPC files will be automatically fixed when they are read in.
• (January 9, 2006) When reading PTI Contingency (*.con) files, if the name of a contingency contained a slash "/", then Simulator would now read the file correctly. This has been fixed.
• (January 9, 2006) When reading PTI Monitor (*.mon) files, an error existed in assigning lines, interfaces, and buses to the default limit group. This has been fixed.
• (January 9, 2006) Added reading of SBase from IEEE common format files.
• (January 11, 2006) Fixed bug caused in January 9 patch which resulted in the improper reading of GE EPC text files.  The error resulting the skipping of interfaces, DC lines, and ownership records when reading, but displayed no error message to the user.
• (January 19, 2006) For interface records, the custom strings and floats were not properly stored in the PWB file. This prevented them from being read back in. This has been fixed.
• (February 10, 2006) Fixed bug that could occur when appending an EPC file to an existing case.
• (February 20, 2006) Fixed bug from Feb 20, 2006 patch when saving out a PWB file. This would result in a nuisance access violation.
• (March 6, 2006) The values for the Make Up Power by Area were not being stored in the PWB file. This has been fixed so that the values are now properly stored.
• (May 8, 2006) Fixed error with reading in OPF result information from the PWB file for phase-shifting transformers which were binding at their regulation range.
• (May 13, 2006) In GE files, when a line shunt belongs to a line that is part of a multi-section line, write the circuit id that belongs to the multi-section line rather than the line segment since the shunt is identified by the from and to bus of the multi-section line. This fixes a bug that prevents line shunts from being read in correctly.
• (May 23, 2006) Fixed bug which could occur when performing the following sequence: (1) be in Run Mode, (2) save case as EPC file, (3) Solve the power flow.

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Auxiliary Files (SCRIPT and DATA Sections)

• (May 10, 2005) The deletion of MW transactions was not possible using the Delete SCRIPT command. This has now been enabled.
• (June 6, 2005) When using regional settings in Windows, which set the comma as the decimal place separator, you could not read in numeric values correctly in the auxiliary files.  PowerWorld was incorrectly treating the text entered as though it were not the right format.  This has been fixed.
• (June 28, 2005) Modified writing out auxiliary files so that when a numeric field contains a text which includes the field delimiter (spaces) it will always uses quotes.
• (June 28, 2005) Writing out the LPVariable information to an auxiliary file or passing it out via SimAuto was not working correctly. This has been fixed.
• (July 5, 2005) Fix so that unlinked elements of interfaces are saved to an auxiliary file when the user chooses this option.
• (July 5, 2005) When calling the SaveData() script action using SubData sections, Simulator was not properly recognizing the subdata section names. This has been fixed.
• (July 10, 2005) When reading a DATA record, if not enough fields are found on the first line of text, Simulator will read and append fields on the next line of text. This was leading to errors if the next line of text was the start of a SUBDATA section or the termination character "{" of the data section. This would only occur if there was a problem in the AUX file format, but Simulator now detects this problem and just appends some blanks to the last data record.
• (July 10, 2005) The auxiliary script command LoadAux() was resetting the submode to PowerFlow or Edit after it was called. This has been fixed.
• (July 22, 2005) The auxiliary script command Move() was improperly causing the script to abort.  The first Move() command would occur, but then the script would immediately abort.  This has been fixed.
• (July 29, 2005) When loading in an AUX file that uses labels as the identifier, it was possible to change the primary keys of the objects, thus allowing you for instance to set all the buses in the case to have the same bus number. While obviously a bad thing to attempt, Simulator allowed this. Simulator will no longer allow key fields to be modified via auxiliary files or via copy/paste to/from Excel.
• (July 29, 2005) When loading in default drawing values via an auxilary file, the default fields positions were sometimes being set incorrectly. This has been fixed.
• (August 8, 2005) Fixed bug with reading in transformer records from auxiliary files when the transformer type is something other than fixed.
• (August 19, 2005) Modified so that secondary key fields can be editted using an auxiliary file. Simulator does not require their uniqueness so this is not a problem.
• (September 11, 2005) Fixed the storage of Dynamic Formatting Definitions to an AUX file. Previously we were not writing out all the necessary fields for the file.
• (October 4, 2005) When choose to save an entire case as an auxiliary file, the Model Conditions, Model Filters, and Model Expressions were be written out near the top of the auxiliary file. When later reading the case back into Simulator the specific objects referenced by the Model Conditions/ Filters/ Expressions would not yet be read in. This resulted in all the Model Conditions/ Filters/ Expressions being invalid.
• (February 2, 2006) When reading in Solution Options from an Auxiliary file, the variable name MinVoltSLoad was not being properly interpreted making it impossible to edit this value through an AUX file. This has been fixed.
• (April 5, 2006) Ensured that when looking for a branch, that the uppercase/lowercase of the circuit id is not used.
• (April 5, 2006) Modified to refresh all open case information displays after executing an auxiliary file.

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Simulator Automation Server (SimAuto)

• (August 1, 2005) Modified the commands WriteAuxFile(*), SendToExcel(*), and variations of ListOfDevices(*) so that they will not return error messages of the form "No objects returned for type *** and filter***". Having commands such as ListOfDevices(*) return no objects because none exist in the case should not be considered an error.
• (January 24, 2006) Fixed a memory leak which would occur when running DC OPF studies and saving the DC sensitivities to the PWB file. In this situation, every time you saved a PWB file, a memory leak occurred. This could eventually cause Simulator to run out of memory if running thousands of hours.

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Case Information Displays

• (May 13, 2005) The column for interfaces labeled # of Monitored elements was showing the number of contingent elements instead. This has been fixed.
• (May 26, 2005) Modified so that case info displays can not be embedded once they have already been embedded in a oneline.
• (June 6, 2005) When using regional settings in Windows, which set the comma as the decimal place separator, you could not edit numeric values correctly in the case information display.  PowerWorld was incorrectly treating the text entered as though it were not the right format.  This has been fixed.
• (June 28, 2005) Fixed the super area fields for showing the total production cost and profit for the super area. These were only showing the values of the last area in the super area instead of the sum.
• (August 8, 2005) Fixed bug when displaying Advanced Filters in Case Information Display.  Only those filters that are associated with a power system element will be displayed.
• (August 31, 2005) Modified the manner in which labels are defined and the interaction with primary labels. The column "primary label" is no longer available and only the "Labels (All)" column may be used to define labels. The primary label is only significant in that it is the first label listed when there are multiple labels.
• (August 31, 2005) The columns showing Bus CTG voltage per unit limits were erroneously added in a patch of Simulator. There are only 4 high and 4 low per unit limits specified with each bus. The contingency limit is specified by choose which rating set A, B, C or D to use during the contingency.
• (September 19, 2005) When editing the latitude/longitude via a string of the format "DD:HH:SS.SSS N/W" including trailing spaces on the string would cause the modification of the value to fail. This has been fixed.
• (September 26, 2005) When editing the fixed transformer taps on the From or To side, previously Simulator would keep the impedances and taps on the SYSTEM base constant instead of modifying them. This has been changed so that the impedances and taps on the TRANSFORMER base are held constant instead and the values on the SYSTEM base change instead.
• (October 11, 2005) The field "Interface MW Flow Offset" for an interface was showing the value divided by the System Base. This has been fixed so that the value is properly scaled to the units of MW.
• (October 31, 2005) The Spinning Reserve (Pos) and (Neg) column for an area or zone were only showing the amount of reserve for generations that was both online AND set to AGC=YES. This column has been changed to only check if the generation is online and not check the AGC status.
• (November 28, 2005) Fixed a potential problem for users with a very large number of custom expressions which could result in invalid expression evaluation.
• (December 14, 2005) For multi-section line object, the field which shows the list of intermediate buses is also showing the from and to bus of the multi-section line. This has been fixed so that only intermediate buses are shown.
• (February 2, 2006) Fixed the "# of Neighbors" column for a bus so that it counts each bus only once. Previously it would count parallel lines to the same bus twice, which is what the "# of Connections" column is for.
• (February 15, 2006) For 2-terminal DC lines, the column for Inverter MW and Mvar flows were showing the Rectifier values. This has been fixed.
• (February 15, 2006) On the Custom Case Information Display, once a model field has been defined for a cell, then double-clicking on the cell in "Define Mode" would not bring up the dialog to change the model field. This has been fixed.
• (March 6, 2006) When changing the impedance correction table to zero in a case information display, the impedance correction was not being removed from the transformer. This has been fixed.
• (March 14, 2006) Modified the Enforce Gen MW Limits columns so that they only show the setting for the individual generator. Previously they would show NO if the Solution Options was unchecked also.
• (June 26, 2006) The value for OPF Transmission Charge associated with a DC Transmission line was always displayed as a zero in the case info display. This has been fixed.

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User Interface Dialogs

• (May 10, 2005) When creating or viewing a Model Filter via the Model Filter dialog, access violation bugs could occur. These have been fixed.
• (May 10, 2005) When clicking the box "Use Another Filter" on the Advanced Filter dialog, Simulator was not properly registering that you had chosen a value for the field. This has been fixed.
• (May 13, 2005) Fixed bug created by May 10 patch which removed old load variation schedules. This bug removed the ability to use a multiplier in the area/zone records to increase all loads in the area/zone by the multiplier.
• (May 13, 2005) When choosing to bring up the on-line help documentation if the help file location was set wrong then nothing would happen. It will now bring up a dialog asking you to locate the help file.
• (July 10, 2005)  Errors could occur when trying to insert new Transformer Impedance Correction tables.  These have been fixed.
• (September 26, 2005) On the Model Condition dialog, when choosing an element type of Transformers, the list of elements would show a list of buses instead of a list of transformer branches. This has been fixed.
• (October 11, 2005) Fixed the Edit Mode Bus Dialog so that zero or negative nominal voltages can not be specified.
• (October 11, 2005) When defining a filter which "uses another filter" on the Filter Dialog, the list of other filters to choose from was not being properly populated. This has been fixed.
• (October 20, 2005) Fixed the positioning of the Area Information Dialog so that it always appears in the center of the Simulator form.
• (October 20, 2005) When renumbering the buses in a case, the multi-terminal DC line converter buses were not being properly renumbered. This has been fixed.
• (October 20, 2005) Fixed a bug in the new area/zone renumbering feature so that the area of generators, loads, and switched shunts are properly updated.
• (November 11, 2005) On the Nomogram Dialog, an access violation was fixed that could occur when clicking on the limit graph.
• (November 11, 2005) Fixed an improper coloring of some dialogs which would occur in Windows 2000.
• (November 14, 2005) The new feature added on November 11, 2005 which made the background color of read-only edit boxes appear gray was causing problems with edit boxes that displayed colors. This has been fixed.
• (January 19, 2006) On the Topological Differences from Base Case dialog, when writing out the case differences to an AUX file, the deleted transformers were not handled quite right. This has been fixed.
• (January 24, 2006) Fixed an error on the Default Drawing Values form which results in the default color specification sometimes applying to the wrong setting.
• (February 2, 2006) Fixed the editing of Display/Column options on the Area Sensitivities tab of the TLR/GSF Dialog. Previously you could not customize the display.
• (February 15, 2006) If your case has line shunts that are connected to an out-of-service transmission line, but the terminals of that transmission line were still energized, then there would be an accounting error on the Case Summary Dialog. These Line Shunt values would be counted in the Shunt totals and the Loss Totals. This has been fixed.
• (February 15, 2006) When exporting a shapefile, grouped objects were not exported correctly. This has been changed so that all objects in the group are exported individually.
• (April 17, 2006)  The time step resolution of seconds made it possible for time points to overlap if the time needed to process a point exceeded the time between that point and the next one. Simulator would get stuck looping back to the earlier time point if this occurred.  It has been fixed by changing the time processing between points to be calculated from the time the previous point finished to the time the next point begins, making sure that time points cannot overlap.
• (May 23, 2006) Fixed infinite loop which might occur when inserting a new three winding transformer from the three-winding transformer dialog.
• (June 26, 2006) When using the PTDF dialog to "toggle the flow visualization", errors could occur if the initial flow visualization was not set to MW values only. This has been fixed.

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Oneline Diagrams

• (May 10, 2005) The saving/loading of Keyboard Shortcuts to an auxiliary file format was not working correctly. This has been fixed.
• (May 10, 2005) Fixed bug with contouring the percent flow on an interface. It was showing the MVA percent instead of the MW percent.
• (May 10, 2005) When dragging line vertices or moving a bus to which a line was anchored, the movement of circuit breakers, line fields, or pie charts could occur incorrectly for lines. This was caused by the CB, field, or pie thinking it was anchored to the wrong segment of the line. This has been fixed.
• (May 10, 2005) When specify the pie chart color and scalar options by percentage, values above 100% were not allowed. This has been fixed so that values above 100% are now allowed.
• (May 10, 2005) When zooming out on a diagram with pie charts shown, in some situations, it was possible for a divide by zero error to occur for pie charts showing text. This has been fixed.
• (May 10, 2005) Printing oneline diagrams and copying them to the windows clipboard was limited by the resolution of the monitor on the computer from which printing was done. This has been fixed so that the resolution is not limited in this way for either printing or copying.
• (May 10, 2005) When deleting a display object that had been added to the oneline since that oneline had been opened, an access violation would occur. This has been fixed.
• (May 10, 2005) When right-clicking on a bus and choosing Insert Connected Buses, the new buses are inserted in a radius around the bus. This radius was a function of the size of the bus which for horizontal buses was only checking the height. This made is so that the normal action for this feature would be to put the buses right on top of one another. This has been fixed so that the radius is now based on the maximum of the height and width.
• (May 10, 2005) Fixed bug when right-clicking on a line and choosing the Open action. Previously it would update the display to show zero flow on the line, but would not cause Simulator to resolve the power flow. This has been fixed.
• (May 13, 2005) When auto-inserting a list of bus display objects from a text file list of locations, consecutive buses with the same x/y coordinate are places in a circle around the location. The radius of this circle was previous being set to the height of the bus. It is now being set to the larger of either the height or width.
• (May 17, 2005) Add check to ensure that right-click options work correctly when right-clicking on a vertex handle. Previously some of the options line split background line were not working correctly.
• (May 26, 2005) Modified transformer display objects so that their symbol size can be edited using the size value on the generic format dialog.
• (May 26, 2005) Fixed an error with reading in line flow arrow objects. Previously the angle-orientation of the arrow was not being read in correctly and was defaulting to zero always.
• (June 14, 2005) When auto-inserting buses and substations, if a bus/substation does not exist in the case, under some situations an error could occur.  This has been fixed.
• (June 14, 2004) Fixed some errors with using the Dynamic Formatting dialog to specify formatting for different kinds of Case Information Fields.
• (June 15, 2005) An access violation error could occur when merging buses together or when auto-inserting generators on a oneline.  This has been fixed.
• (June 15, 2005) When pressing the A and B keys, the oneline diagram would toggle between 2D and 3D mode.  This has been removed and switching between 2D and 3D mode can now be done only through the main menu.
• (June 28, 2005) Modified the area fields which show transaction-related values to work properly. Simulator now allows multiple transactions between two areas which was not properly supported by these area fields.
• (June 28, 2005) When editing a text box memo on a oneline diagram, keyboard shortcuts such as the arrow keys were being passed through to the oneline. As a result you couldn’t use the arrow keys on the memo because this would pan the oneline. This has been fixed.
• (June 28, 2005) The scalar size for normal pie charts was being applied in Edit Mode. Pie chart scaling is only supposed to be applied in Run Mode so this has been modified to behave correctly.
• (June 28, 2005) Mvar flow arrows were appearing in Edit Mode. This has been removed.
• (June 28, 2005) When using the toolbar buttons to zoom on a oneline diagram, under some situations an access violation could occur. These have been fixed.
• (July 5, 2005) Pie Charts were modified to show a different graphic when the line was out-of-service. This was not working correctly when using the difference flows feature to show the base case system. It has been fixed to properly show the out-of-service graphic when displaying the base case.
• (July 10, 2005) When auto-inserting buses and substations from the latitude/longitude information in the case, the substations and buses were not being inserted at exactly correct point. They were being inserted within a radius of the point specified by the width of the object. This has been fixed.
• (July 17, 2005) When zooming in on very large filled lines, the fill color would sometime flip. This has been fixed.
• (July 17, 2005) A degradation of display performance was introduced between version 10 and 11 so that drawing in Version 11 was about half as fast as in Version 10. The degradation has been corrected.
• (July 17, 2005) Fixed error in the drawing of transmission lines connected between substations that could result in the flow arrows appearing in the wrong direction.
• (July 29, 2005) The option on the Oneline Display Options Dialog for Show longitude,latitude coordinates when showing x,y coordinates was not being saved as part of the PWD file. This is now saved with the PWD file.
• (July 29, 2005) Modified the Bus View and Substation View oneline so that they no longer inherited any oneline display options from the oneline that invokes them. Previously when you right-clicked on a oneline object and choose Bus View it would inherited the settings from that oneline such as the pie chart sizes, colors, animation settings, etc...
• (August 8, 2005) In run mode, the user can toggle the AGC status of an area by placing an Area AGC Status field on the one-line.  Fixed a problem where toggling the AGC status would not immediately update the one-line field.
• (August 8, 2005) An object with the dashed line format option set would not always be drawn with a dashed line as expected. This has been fixed.
• (August 8, 2005) Fixed bug with graphical Interface objects not correctly linking to Interface data.
  (August 19, 2005) When using Select by Criteria to find substations, if a substation was empty it was not being selected. This has been fixed.
• (August 19, 2005) When marking a line field or pie chart as immobile, the object would then no longer follow its anchor when a bus was moved that was connect to its line. This has been fixed.
• (August 19, 2005) Unselecting objects using a Shift-Click on a presently selected object was not properly working. This has been fixed.
• (August 19, 2005) When unselecting a single text object, the handle squares were not properly erased making it appear that the object was unselected. This has been fixed.
• (August 19, 2005) When checking the box "Use the default font size for new text fields (Ignore object-specific sizes)", all new text and fields were being inserted with a negative font size making it so that you could not see them. This has been fixed.
• (August 31, 2005) Circuit Breaker and Pie Chart objects had their stack level changed to top regardless of what had been saved in the PWD file. This made it so that the user could not change their stack level.
• (August 31, 2005) Fixed bug which was causing the flow arrows for DC transmission lines to flow backwards in some instances.
• (September 11, 2005) Made changes to the Select by Criteria so that unlinked objects can be selected as long as selecting by all areas, zones, and voltages.
• (September 11, 2005) Fixed bug occurring when objects that were set to a fixed screen locations were displayed along with the Thumb Nail View. This was resulting in erratic movement of the objects.
• (September 11, 2005) Fixed the storage of Dynamic Formatting Definitions to an AUX file. Previously we were not writing out all the necessary fields for the file.
• (September 13, 2005) Fixed an error with the pie-chart option for "Min Pie Chart Font Size for Warning/Limit" setting. This was not working properly when zooming out on a large display. This has been fixed.
• (October 4, 2005) On dialogs which specified the size of generator, bus, load, or shunt a maximum size of 256 was being enforced. This was incorrect and no size limitation is enforced anymore.
• (October 11, 2005) Fixed an access violation which would occur in Dynamic Formatting when there were unlinked display objects on a oneline diagram.
• (October 18, 2005) When using Advanced Filters inside of Custom Display Detail or Emphasis Highlighting on the oneline display options, the oneline was not properly updated as the data changed. The check of the advanced filtering only occurred when you changed the settings, or when you switched between modes. This has been fixed so that the display detail and emphasis highlighted are updated as needed.
• (October 18, 2005) The pie chart option Max. Zoom Percentage for Full Resizing was not working for normal sized pie charts. This has been fixed.
• (October 31, 2005) When writing out shapefiles which represented points (such as buses or substations), the file format was being written a incorrectly. This has been fixed.
• (November 11, 2005) When using the 3D View and drawing filled in background lines, lines with greater than 4096 points were not being filled properly. This has been fixed so that all lines are now filled properly.
• (November 28, 2005) Fixed inconsistency when inserting a DC transmission line display object that represents an existing DC line. This was causing some confusion resulting in new DC line additions.
• (December 7, 2005) Fixed bug which could occur with Screen Layers when converting background lines that did not belong to the default layer to the into ac transmission lines. If after doing this conversion, the original layer was deleted, this bug would make it impossible to save the oneline diagram.
• (December 22, 2005) For some contour fields, hard-coded limits were included for the specification of the minimum, nominal, and maximum values. This limitation has been removed.
• (January 9, 2006) Changed how substation objects are drawn so that the text for the number of buses shown on the substation object is formatted with the same font, style and color as the identifier text.
• (January 24, 2006) When specifying a Grid Spacing of 200 or higher, and then saving the PWD file for a oneline, a divide by zero error would occur when trying to read the oneline. This has been fixed so that old files are properly read and future files are not written improperly.
• (February 2, 2006) When a line was moved, whether itself or through the movement of a bus, the screen refreshing was incorrect. This resulted in lines temporarily disappearing until a full refresh was done.
• (February 15, 2006) Simulator was not correctly importing oneline fields linked to "Primary Label" anymore because the Primary Label field had been removed. With this patch, the fields will be changed to link to the "Fields (all)" information instead.
• (March 6, 2006) Fixed access violation error that could occur if the bus view oneline was opened to a remotely regulating generator if Run Mode had not been entered at least once since opening the case.
• (March 14, 2006) Line Flow Display Objects were inherited some of their display properties from the Line Flow Pie Charts, such as whether they are visible. This has been removed.
• (March 21, 2006) When comparing two different cases using the Difference Flows feature, if the same transmission line existed in both case, but the from and to buses were reversed, the difference would be calculated incorrectly. This has been fixed
• (March 21, 2006) In Edit Mode, when zoomed in very close to a background line with a very large number of vertices (>10000), the performance of clicking on the oneline diagram became very slow. This has been fixed.
• (March 21, 2006) Modified Full Screen Oneline diagrams so that they are set to "Stay-on-Top". Previously the oneline would cover up other stay-on-top forms such as the Windows Task Manager. Now the full screen onelines are made normal windows.
• (May 8, 2006) Fixed access violation that occurred with unlinked Load Fields.
• (June 6, 2006) Fixed error in the writing of a PWD file when the grid spacing has been set to zero. Also modified to prevent the grid spacing from ever being set to zero going forward.
• (June 26, 2006) PowerWorld internally limits the number of vertices on a graphical line to 32,767. When reading in very detailed GIS Shapefiles however it's possible to come across a line with more points than this. This is now properly handled.
• (July 18, 2006) Fixed minor display error of the generator AVR status on a oneline diagrams.  It was possible for a generator to show that it was at a VAR limit when it was actually not.  This could only happen if there were multiple generators at the bus and you had recently changed the status of one of them.

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Bus View and Substation View Onelines

• (May 10, 2005) Normally, bus view onelines will not prompt the user to save them as a oneline diagram. Under some situations this was still occurring which could cause some confusion. This has been removed so that you will never be prompted to save a bus view.
• (May 10, 2005) For the bus view onelines, the other end bus link objects height was not being properly set. This has been fixed.
• (August 31, 2005) When right-click on a bus link object to bring up the bus dialog, the delete button was available on the dialog. It should not have been and has been removed. Deleting a bus in this manner would cause access violations.
• (December 22, 2005) Fixed the coloring of substation objects so that the symbols and text use the correct coloring.

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Power Flow Solution

• (May 10, 2005) When using the merit-order dispatch for injection groups in the PVQV or Contingency analysis tools, if the enforcement of generator MW limits was turned off for the case, then all the change in dispatch would come from the generator with the highest merit. This has been fixed so that generator limits are always enforced for merit-order dispatch.
• (May 10, 2005) Simulator was not properly handling the outage of a multi-terminal line DC converter outage which was caused by the loss of the AC system at the converter. This has been fixed.
• (May 10, 2005) Simulator will now handle the status of a DC converter separately from the loss of the AC system bus. Previously, the DC converter status was not used.
• (July 29, 2005) If the user has specified that all generator Mvar limits should be ignored, Simulator now forces all generators with an AVR status of YES to force their setpoint to be enforced. Previously if a generator was stuck at its min or max limit, it would stay there after checking the ignore limits options
• (August 19, 2005) Setting the status of a multi-terminal DC transmission line to OPEN was not being properly handled by Simulator. Simulator now properly handles this and treats it the same as setting the mode to BLOCKED.
• (September 13, 2005) Fixed a bug which might occur when a very low impedance branch connects a generator's terminal bus to a bus that it remotely regulated. This bug would cause the generator to not control its voltage and report a warning to the log saying the generator could not regulate because "there is no path between them that doesn't go over another regulated bus". This has been fixed.
• (September 13, 2005) After reading in a generator which had it's minimum and maximum VAR output equal Simulator disables VAR control at the generator internally. A bug existed however that would not allow the generator to regulate even after changing the min or max VAR output. This has been fixed.
• (November 30, 2005) When performing a Set to Flat Start, the voltage at a generator bus was not begin properly set.
• (November 30, 2005) When performing the Robust Power Flow Solution, sometimes the Jacobian was setup and factored in the wrong coordinates (rectangular instead of polar) and this was causing the decoupled power flow solution to fail. This is now fixed.
• (December 22, 2005) Fixed a potential oscillation which might occur with a DC transmission line that was oscillating between two different tap and firing angle settings that meet the power requirements of the converter equally well.
• (December 22, 2005) When opening a RAW or GE file, the initial starting point of a continuous switch shunt is now noted so that an estimate of whether the bus is a PV or PQ bus can be made immediately. This helps ensure with solution speed when you first open a text file case.
• (February 10, 2006) When choosing to model phase-shifters as discrete phase shift values, if the initial phase shift was not one of the allow phase shifts, an incorrect entry could be added to the Y-bus resulting in a temporary mismatch at the phase-shifter terminals. This has been fixed.
• (March 6, 2006) The power flow solution timer for the message log was including the time spent refreshing open onelines and case information displays thus making timings of the power flow solution unreliable. This has been fixed so that the solution time only includes the power flow solution.
• (March 6, 2006) In the economic dispatch algorithm, when using loss penalty factors, the averaging of these factors between power flow solution has been updated to ensure convergence of the ED.
• (March 14, 2006) Fixed bug in the new feature added on March 6 which dramatically sped up the remote regulation check for generators.
• (March 21, 2006) Fixed another bug in the new feature added on March 6 which dramatically sped up the remote regulation check for generators.
• (March 21, 2006) Fixed potential conflict between transformer switching when one of the terminals of the transformer had a swtiched shunt at it. The conflict could result in the phase shifter moving the wrong direction initially.
• (March 21, 2006) Modified the phase-shifter switching so that a phase shifter is not allowed to move more than 10 degrees at a time between each inner power flow loop solution. This prevents divergence in situations that require the phase-shifter to more a large amount.
• (March 21, 2006) When generation at a single bus had a mix of AVR = YES and AVR = NO, the power flow solution would solve correctly, but the VAR outputs from the generators was not consistent. This has been fixed.
• (April 5, 2006) Fixed a potential error in the DC approximation power flow solution which occurred with radial phase-shifting transformers on control. It's not possible to control the flow on these transformers so they are now properly ignored.
• (April 5, 2006) Modified to prevent problems when line drop compensation is specified against a very large impedance. These situations are likely bad data, but floating point errors could occur with the bad data.

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Sensitivity Calculations

• (July 22, 2005) When calculated the TLR sensitivity for interfaces that contained elements marked to "meter the far end" of the line, Simulator was calculated the sensitivity incorrectly. The PTDF calculation has always been correct, but a sign error was occuring in the TLR calculation. This has been fixed.
• (September 19, 2005) Modified the calculation of sensitivities based on Injection Groups so that off-line generation is never included in the calculation. Previously, off-line generation was included.
• (January 19, 2006) On the TLR/GSF calculation, if the buyer or seller was chosen to be a Super Area, and the last area in this Super Area had no generation, then the calculation would report sensitivities of all zero. This has been fixed.

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Contingency Analysis Tool

• (May 10, 2005) Fixed writing out the contingency analysis AUX file so that it does not write out the label name of the contingency twice.
• (May 26, 2005) Fixed an error when performing a comparison of two lists of contingency results which could sometimes result in an access violation.
• (June 6, 2005) Fixed bug that would occur when the first contingency the list did not contain any elements, or the elements did nothing (such as opening a line that was already open).  In these situations when using the DC approximation for the power flow, or when using one of the linearized contingency calculation methods, the contingency results could be calculated wrong.  The results would be very strange (100,000% overloads and such).
• (June 28, 2005) When loading two contingencies files for comparison, errors could occur when refreshing the contingency result displays. This has been fixed.
• ( July 22, 2005 ) A bug has been fixed that occurred when reducing the generation in an Injection group using merit order dispatch.  This was resulting in not enough generation being dropped.
• (July 29, 2005) When bypassing a series capacitor as part of a contingency action, Simulator was sometimes having difficulty solving the power flow due to an error in resetting the system state. This only effected Series Capacitor bypassing and has now been fixed.
• (August 19, 2005) Fixed bug which resulted in the contingency records not properly linking to the model criteria when read from a PWB file. This worked fine when read from an AUX file however.
• (November 7, 2005) The calculation of the total amount of load islanded during a contingency was being improperly calculated thus values always showed zero. This has been fixed.
• (December 7, 2005) When running contingency analysis with the check to not dynamically assign new slack buses for new islands, the restoration of the system state was not working properly. This has been fixed.
• (April 17, 2005) Fixed bug that would occur when placing a SOLVEPOWERFLOW contingency action that was followed by only POSTCHECK actions. The POSTCHECK actions would be skipped in this situation.
• (June 6, 2006) Fixed error in the interaction of Post-Power Flow Actions with the Global Contingency Actions. The Post Power Flow Actions were also calling the Global Contingency Actions.

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PV and QV Curve (PVQV) Tool

• (May 13, 2005) Modified the plotting tools in the PV and QV curve plots so that enough significant digits are always available on the plots.
• (May 17, 2005) Modified previous bug fix regarding increasing the number of significant digits on PVQV plots so that too many digits were not used.
• (June 28, 2005) On the PV analysis dialog, the option for how reactive power load should change as real power load is ramped did not behave consistently. This has been fixed to not allow a specified power factor entry when the option to keep the ratio constant is checked.
• (June 28, 2005) When performing the PV tool runs, Simulator modifies the unspecified MW transactions for areas to keep area transfer in balance. This doesn’t affect the PV tool results at all, but is convenient if you perform studies on cases generated by the PV tool. A bug was found in the accounting for these transfers which has now been fixed.
• (July 17, 2005) When writing out the PV Curve options, the tracking settings for Transmission Lines was not being properly saved to the auxiliary file. This has been fixed.
• (August 19, 2005) When plotting our the points in the PV Curve plots, the order of the points near the nose would sometimes be switched. This was caused by the plotting program sorting the points by the x-axis dimension. This sorting has been removed.
• (August 19, 2005) Fixed the coordination of the default step size and max/min voltage and the values specified with each bus. Previously they were not properly coordinated.
• (August 19, 2005) Fixed bug that occurred when the temporary directory name was specified without a path. Simulator will now use the current directory. Without the path, users coudl not save the QV results or plot them.
• (August 19, 2005) Fixed bug when using the QV curve script command. The output filename was not being correctly set and thus the results not properly saved.
• (August 19, 2005) When running a QV curve at a bus that is remotely regulated by other generators, Simulator will now set the AVR status of the remotely regulating generators to NO while running the QV Curve. This was a mistake which was causing two different generators to be controlling the same bus to different voltages.
• (August 19, 2005) When reading an AUX file which contained tracking information for MVar values of switched shunts, the tracking of MW and MVar values for switched shunts were conflicting. This resulted in the MVar value never being set for tracking. This has been fixed.
• (August 31, 2005) The user had to press "ok" twice after changing the name of the output file, but that has been corrected so that the user has to confirm his choice only once.
• (October 4, 2005) Added the ability to save the extra tracking information from the QV Curve tool to an auxiliary file.
• (October 31, 2005) Modified the PV and QV curve tools so that the minimum voltage for constant power load solution option is ignored. When running the PV or QV Curve tool, the minimum voltage for constant power load is always treated as zero.
• (November 11, 2005) The added feature for tracking "devices at limits" was not working properly for lines and interfaces. The dialogs in thye PV and QV curve tool have been fixed to properly select the filter for the lines and interfaces
• (December 7, 2005) Correctly potential bug when creating several PV Curve plots in the same Simulator session. An error would occur when closing the case in this situation.
• (December 14, 2005) Fixed nuisnance bug when running the QV tool and choosing to not "process each of the current defined contingencies". Previously Simulator would end up running a power flow solution repeatedly for each contingency defined in the case. The solution itself wouldn't take must time because nothing had changed, but even 0.5 second time 3000 contingencies will take a long time.
• (January 9, 2006) In the PV Curve tool, if the user specifies a results csv file, then the log file now uses the results filename with the string "_log.txt" appended to it.
• (January 24, 2006) When choosing to stop when voltage is inadequate, Simulator was stopping properly, however the reported critical reason was showing "Reached Nose". This has been fixed so that it properly reports "Inadequate Voltage"
• (June 12, 2006)  Fixed access violation when plotting in PV or QV Curves.  This bug was introduced in the June 6 patch.

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Available Transfer Capability (ATC) Tool

• (June 15, 2005) When using injection groups in conjunction with the iterated ATC solution methods, the method for ramping the transfer could sometimes result in not achieving the correct amount of transfer.  This was related to the slack bus picking up part of the losses when Simulator is designed to assign all losses to the buyer injection group.
• (July 22, 2005) Modified the generator scenarios so that negative generator values are allowed. 
• (September 15, 2005) When using "(IL) then Full CTG" solution method and forcing all ramping to occur in the pre-continency states, if a failed power flow solution occurs in the pre-contingency ramping, then Simulator would not continue to iterate on multiple limitations. This has been fixed.
• (May 8, 2006) Fixed error that was limiting the number of scenarios to 50 in the ATC tool. The proper limitation is 1024.
• (May 13, 2006) When using an iterated solution method, with injection groups as the buyer/seller, and if generators ended up hitting limits, then the reported ATC values could be incorrect. This has been fixed.
• (May 19, 2006) Fixed error in May 13 ATC patch which was causing the results to be off by a factor of SBase.

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Optimal Power Flow (OPF) and Security Constrained OPF (SCOPF) Tool

• (May 10, 2005) Removed limitation of modeling 500 line constraints as simultaneously binding in the linear program solution. No limitation is now enforced.
• (May 26, 2005) When using the script command SolveFullSCOPF(OPF, success.aux, failure.aux), if the SCOPF ran out of LP iterations it was incorrectly executing the success.aux Auxiliary file anyway.  This has been fixed.
• (July 17, 2005) When performing the intial power flow solution to initialize the DC OPF, Simulator would sometimes return an "excessive angle separation higher than 360 degrees" error. This would cause the OPF to abort. Simulator has been changed to ignore this error during the initial power flow solution because the error is normally only a notification that the gen/load balance in the case is wrong and too much power is coming from the slack bus. Because the LP OPF is solved immediately after this initialization, this will be fixed by the LP.
• (August 3, 2005) Simulator previously contained both Cost of Energy and Cost of Losses Reference fields.  There should only be one reference that applies to Energy, Losses and Congestion. The feature has been changed so that only one reference is specified as the "Cost of Energy, Losses, and Congestion Reference." Backward Compatibility:  When reading PWB and AUX files containing the now obsolete Cost of Energy and Cost of Losses references, the Cost of Energy Reference value will be used. The Cost of Losses Reference will be ignored.
• (August 19, 2005) When committing and decommitting generation in the OPF it was possible for an infinite loop to occur under some circumstances. This has been fixed.
• (August 31, 2005) The LP OPF, OPF Transactions case information display showed each transaction twice. This has been fixed.
• (September 11, 2005) When using the DC approximations and choosing the DC Solution Option "Use bus MW loss sensitivities in OPF and ED dispatch algorithms, if the ...", Simulator was correctly utilize the loss sensitivities in calculating the MW Marginal Cost at each bus. However, when performing the post-processing to split the Marginal Cost into a cost of Energy, Losses and Congestion, Simulator was not using the sensitivities correctly resulting in an incorrect allocation.
• (October 20, 2005) Fixed a bug with Super Areas when determining the cost of energy, losses, and congestion.
• (November 28, 2005) Fixed bug which resulted in phase-shifting transformers set to be on OPF control to be reset to Off control when restoring the contingency reference state.
• (November 30, 2005) When running the OPF using the DC approximation, angles were being rotated so that they were between +/- 360 degrees. This should not be done in the DC approximation and was causing incorrect interaction between the DC power flow and OPF solution.
• (December 14, 2005) The area information column for "Hourly Cost ($/hr)" is supposed to show the combination of the production cost along with revenues or expenses related to MW Transactions. These were not working properly and have now been fixed.
• (February 15, 2006) When right-clicking and choosing "Show Control Sensitivities" on the Contingency Violations subtab of the SCOPF results, the dialog would bring up the incorrect contingency violation. This has been fixed.
• (April 5, 2006) Fixed potential floating point error which could occur in the OPF if a binding constraint suddenly became insensitive to all available controls. This was a rare situation but could occur when a phase-shifting transformer on power flow control backed off an angle limit during the OPF solution.
• (April 5, 2006) Fixed access violation in showing the SCOPF sensitivities after loading in a saved PWB case but not resolving the power flow.
• (April 5, 2006) Fixed incorrect LMP values that could occur under rare situations when there were interfaces using the limit cost curves specified in limit monitoring settings.
• (April 17, 2006) In situation with conflicting controls, it was possible for the value of a control variable to become extremely large resulting in a fatal error.  This has been fixed and the program will more graceful fail with a message about a control variable approaching an infinite value.
• (May 19, 2006) Modificed so that the DC-OPF initialization includes the estimation of generation by area to prevent a large change in the slack bus generation.
• (May 19, 2006) Cleaned up more bugs related to the check which allows a small unenforceable ACE value.
• (May 23, 2006) Increased the number of iterations of the linear program which must occur before turning on the anti-cycling code. Anti-cycling prevents an infinite loop, but also increases solution time so must only be done when needed.
• (July 7, 2006) Fixed potential external error which could occur on a Pentium III processor.

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Fault Analysis

• (October 18, 2005) When a fault to ground impedance was given, it was being incorrectly multiplied by 3 when applied to a three phase fault. It should be multiplied by 3 only for single line to ground and double line to ground faults.
• (October 18, 2005) The fault impedance was being internally stored multiplied by 3, and was again multiplied by 3 each time the fault dialog was opened and a fault calculated, resulting in the fault impedance growing by a factor of 3 each time. This has been corrected.
• (October 20, 2005) Fixed a bug where the grounding code was not being passed to generators when the short circuit generator objects were being created.
• (December 14, 2005) Fixed a problem with solving an in-line fault and then solving a bus fault immediately after this.
• (March 14, 2006) When adding a graphical bus to represent an in-line fault location, the bus orientation was up instead of down. This has been fixed.
• (June 6, 2006) Modified the calculation of faults to greatly speed up the solution speed when large amounts of fault sequence data is included.

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Memory

• (May 10, 2005) Fixed memory leak when deleting a Model Condition
• (May 10, 2005) Fixed memory leak when reading an auxiliary file with MW Transactions in it
• (May 10, 2005) Fixed memory leak associated with copying data to the windows clipboard.
• (May 10, 2005) Fixed memory leak when deleting an Advanced Filter (May 10, 2005) Fixed memory leak in creation of Select by Criteria settings.
• (June 6, 2005) When deleting a bus that was also an island slack bus and then trying to save the case, an access violation error would occur this has been fixed.
• (June 6, 2005) When deleting a bus that was a terminal or the star bus of a three winding transformer, you would get errors because the three winding transformer was not getting properly deleted along with the bus.  Now if one of the terminals or the star bus is deleted, the entire three winding transformer record and all three equivalent transformers are removed as well.
• (June 6, 2005) Fixed memory leak in clearing of the time step simulation results
• (June 8, 2005) When defining more than one label, it was possible that an infinite loop would occur if none of the labels were assigned as primary labels.  This has been fixed.
• (June 8, 2005) For older Pentium III processors, the emphasis filtering on a oneline diagram or the OPF algorithm may fail giving an "External Exception C0000001D".  This was related to some speed enhancements done in Version 11 which were improperly calling some assembly code instructions.  The error has been fixed.
• (June 14, 2005) Added checks throughout to ensure that users are not able to add more buses than the maximum number allowed.  Previously when performing actions like "tap transmission line" or "split bus", Simulator would attempt to add the extra bus needed but this would result in access violations because too many buses were being created.
• (July 10, 2005) When deleting an object which had a label assigned to it, Simulator was not properly removing the invalid label. This was leading to memory access violations. This has been fixed.
• (July 10, 2005) Fixed potential access violations that could occur when saving a case that employs labels for some types of objects but not for others.
• (July 10, 2005) Very old Simulator cases (Version 8 and earlier) allowed interfaces with the same name. This is no longer allowed, but old PWB cases still exist. Error checking was added to assign a unique name to these.
• (July 17, 2005) When deleting an advanced filter which was used as part of a Dynamic Formatting description, the link from the dynamic formatting was not properly cleaned up in memory. This was causing bugs which have now been fixed.
• (November 7, 2005) Fixed a few memory leaks which could occur during a time-step simulation.
• (November 7, 2005) Fixed memory leak which could occur in an advanced filter when doing a field-to-field comparison that involved a numeric field that was showing a blank value.
• (November 28, 2005) Fixed memory leak in the deletion of Model Expressions.
  (November 28, 2005) Fixed memory leak in the deletion of Model Filters that contained unlinked elements.
• (November 30, 2005) Fixed bug related to fix with Model Filters on Nov 28.
• (December 22, 2005) Fixed a memory leak when destroying an injection group
• (December 22, 2005) Fixed a memory leak when reading in an AUX file that contained information on an existing three-winding transformer.
• (January 19, 2006) A feature was added in Simulator 11 which caused the deletion of a single branch of a three-winding transformer representation to delete the other two branches, the start bus, and the three-winding record. This feature has been removed because it was not properly cleaning up the links between the objects. The feature will be re-added in Simulator 12.

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