See Also
The Options page of the Time Step Simulation dialog contains options to control how input data is applied and how output results are presented and stored.
Area and Zone Load Scaling
In many practical studies, data of individual MW loads may not be available for all the loads in a control area for each time point. In order to simulate load variations, Simulator allows you to specify the Area or Zone Total MW Load values for each time point in the Area Loads and Zone Loads pages of the Input page. Thus, the Time Step Simulation load data may be a combination of:
- Areas or zones where each individual load is specified
- Areas or zones where only the total MW load is known
- Areas or zones where some individual loads and the total area load are known
If you have specified individual load values for a load within an area or zone that is also set to be scaled to a total MW value, Simulator will adjust the individual load to the individual value first, and then the load will be scaled with the rest of the loads in the area or zone to achieve the total MW value desired for the time point. The final load will be the total value specified for the area or zone.
When time point values are specified for areas and zones within the same time step input, only one or the other can be used. This can be set in the Use Time Point Values of option.
You can also specify in the Reactive Power Scaling option how the reactive power is treated when the load is scaled. You can choose to have the reactive power scaled to keep the power factor constant, or for the reactive power to remain fixed at its original value.
Solution Options
These options control the solution process.
Pause if Power Flow Does Not Solve
The simulation is stopped at the time point where a power flow solution cannot be obtained. This is an indication of wrong data or a system brought to its loadability or transfer capability limit.
Enable Power Flow Area Interchange Control
This option ensures that the area interchange control, if possible, is enforced in the case.
Turn generators off AGC when output changes
At each time point, generators can be adjusted by specifying Gen Actual MW values on the Input page or as part of Injection Groups that have their injection changed on the Input page. If area interchange is enabled for the case and associated area or super area where generation changes have been made, this may cause the generators to move away from their values specified on the Input pages. To prevent this, use this option to disable AGC for these generators so that they will not move because of automatic MW control schemes.
Pricing Options
These options are available only in the OPF/SCOPF add on.
Solve Unconstrained Case
Select this option when you want an unconstrained solution to be obtained before an OPF or SCOPF solution for each time point.
Price Hydro Generation at Marginal Cost
During OPF and SCOPF simulations, hydro generation may experience large changes in output due to its low marginal cost. However, hydro generation is often not as cheap if limited water levels and dam restrictions are observed. These considerations are usually taken care of in the hydro-thermal coordination solution, outside of Simulator. In the OPF and SCOPF solutions it is important to assign a reasonable price to hydro generation to avoid large generation output deviations. A common mechanism to do that is to first obtain the system marginal cost, and then assign this cost to the hydro units.
Reset Hydro Gen Price at the End of Time Period
Choose this option to make the hydro generation price be reset for the next time point solution.
Save Binding Constraints
The binding constraints determined in the OPF/SCOPF are stored.
This is an informational message about how injection group options can be set to scale injection groups as part of the time step tool.
There are no options that can be set with the time step simulation tool as to how injection groups are scaled. By default all loads and generators in an injection group will have their MW injection changed in proportion to their participation factor specified with the injection group to meet the specified MW injection. By default generators will have their minimum and maximum MW limits enforced. (Injection groups have their own set of options that can override the default options on this dialog if they are in use. See the Injection Group Specific Scaling Options topic for more information.) By default Mvar injections will not be modified as part of this input. If a zero injection value is specified for a time point, no modifications will be made to the injection group for that time point. To zero out the injection, change the value to a very small number, e.g. 0.01.
If the Injection Group Specific Scaling Options specify that Merit Order Dispatch is selected, both generators and loads in the injection group will be adjusted in order of highest relative participation factor to lowest with each generator and load in the list being adjusted until it hits either its maximum or minimum MW limit before moving on to the next element. This process continues until the desired injection is met. Mvar load will be adjusted by keeping a constant power factor. Loads that have both their minimum and maximum MW limits set to zero will not be allowed to increase. They can only decrease to 0 MW.
If the Injection Group Specific Scaling Options specify that Economic Merit Order Dispatch be used, only generators will be adjusted. Details about how economic merit order dispatch is performed can be found under the Generator Economic Merit Order Dispatch topic.
Time Step Simulation Options
The Time Step Simulation can be performed in two ways:
Continuous
With this option time points are solved one after another as soon as one time point finishes. The purpose of the simulation is to obtain the solutions for all time points as quickly as possible.
Timed
With this option the solutions are simulated as they would occur in actual time. The difference in date/time between two time points in the list defines a delay to start the solution of the next point. A Time Scale is used to set the speed of the simulation with respect to actual time. Suppose that you have 3 time points defined at the following date/times:
1/20/05 1:00 AM
1/20/05 2:00 AM
1/20/05 4:00 AM
Assume also that the Time Scale is 1 hour runs in 10 seconds. If you start the Timed Simulation you would see the conditions of the first time point applied to the power system immediately, the conditions of the second time point applied 10 seconds later, and those of the third point applied 20 seconds after the second point. The delays on the simulation allow you to see how the quantities evolve in actual time. In addition, you can animate the time simulation while each time point is being solved. The visualization of the Timed Simulation is enhanced when you use the Time Step Simulation Toolbar.
Step Type
This section of options allows you to specify if the data for each time point should be applied only, or if the data should be applied and the load flow solved. Use Apply and Solve to apply the input data and actually solve the power flow. Use Just Apply Data to apply the input data and not solve the power flow. Check the Apply Input Data box to apply input data and custom input data. This does not include scheduled data. Check the Apply Schedule Data box to apply scheduled data.
Any pre-script or post-script commands will be applied regardless of how these options are set.
Auto Load TSB File Options (saved in case pwb file)
These are options that relate the power system case (.pwb file) to the time series binary file (.tsb file). These options are saved with the .pwb case.
Automatically Load Default *.tsb File
The .tsb file specified in the Default *.tsb file is loaded automatically when opening the .pwb case. If the file cannot be found, a message will be issued.
Automatically Run Simulation after Loading *.tsb
This option is only relevant if the .tsb file was automatically loaded. This instructs the Time Step Simulation form to start the simulation immediately following loading the .tsb file.
Automatically Set Default *.tsb File to Current *.tsb File
When leaving Simulator, the current time series information is saved in the Default *.tsb file.
Default *.tsb File
Default path and name of the *.tsb file.
Save the Default *.tsb File after Finishing the Run
If this option is checked, immediately upon finishing the simulation run, the settings and results are saved in the Default *.tsb file.
Result Storage Options
These options allow the selection of where the results from the simulation are directed.
Store results in memory
Only store the results in the computer's random access memory (RAM). This option is prone to running out of memory when many fields are stored over many time points.
Only store results in csv file
With this option the results are sent directly to a CSV file without filling up computer memory. Keep in mind that when this option is chosen, the Results grids will not contain any data.
Store in memory and csv file
With this option the results will be stored both in the computer's memory and sent to CSV file.
CSV Object ID Options
When choosing to store results in a CSV file, this option will determine if the objects will be identified by Primary key (number), Secondary key (name), or Label.
CSV File Identifier
This is a label that will be prepended to every generated CSV file if choosing to send results to CSV. Files are generated for each result type. For example if a user is storing bus voltage and angle, the results will be stored in a file named CSV File Identifier_Buses.csv. A separate file will be created for each of the results types to store data of that type.
CSV Output Path
This specifies the computer or mapped network drive where the CSV results will be stored.
Auto Contouring Options
The Time Step Simulation allows you to contour quantities on the oneline diagram using Simulator Contouring at each time point. Optionally, these contour diagrams can be saved in different formats.
No Auto Contouring
Contouring is not used during the Time Step Simulation. Although using the Timed Simulation you can see the quantities change and the animation take place on the diagrams, the contouring is not displayed.
Contour but Do not Save
Contouring takes place at each time point, but the diagrams are not saved.
Save in File as Bitmap
The contouring diagrams generated at each time point are saved in Bitmap format.
Save in File as JPEG
The contouring diagrams generated at each time point are saved in JPEG format.
Contour File Name Format
The Bitmap or JPEG contouring diagrams are saved using the specified format, which includes the time point date/time.
Run Pre-Script Command
This option allows the pre-script command to be run Before Applying Input Data or Right After Applying Input Data. Input data includes any hourly input data and scheduled actions. With either setting, the pre-script command is applied prior to solving the power flow solution for the time point.
Run Post-Script Command
This option allows the post-script command to be run either Before Storing Results or After Storing Results. Running the post-script command before storing the results could be useful in situations in which sensitivity analysis is done based on the solution of the time point and these sensitivities need to be stored as part of the results for that time point. Running the post-script command after storing the results could be useful in situations in which a specific control setting was used for the current time point and needs to be restored to the original setting before moving on to the next time point.
Set Reference Case
The reference case is the case that will be restored when resetting the simulation or starting a simulation run. The reference case is initially set to be the case in memory when Time Step Simulation dialog is first opened. If changes are made to the case in memory while the Time Step Simulation dialog is open and these changes need to be reflected in the reference case, click this button to set the case that is currently in memory to be the reference case.