See Also
Simulator can estimate MW * Distance quantities for the system’s areas and zones that result from a specified transaction. Given a transaction from a specified source to a specified sink, Simulator uses
Because the MW * Distance calculations use PTDFs, you must access the MW * Distance functionality from the PTDF Dialog. Once you have calculated PTDFs for a particular transaction by pressing the Calculate PTDFs button, click the Calculate MW * Distance button to bring up the MW * Distance Calculations Dialog.
The top portion of the MW * Distance Calculations Dialog is used to set the lengths of the lines in the case. Although line length is represented as a data element in the power flow case, it often is left blank. However, Simulator needs line length information if it is to calculate MW * Distance indices. Simulator offers a few options regarding the source of line length information. If you do not have access to line lengths, either from the existing case or an external text file, Simulator can estimate line lengths for you. It does this by using the Ohms/Length values you specify in the table for lines of various kV. Simply indicate the voltage levels in the first row of the table, and the corresponding ohms or reactance per length in the second column. You do not need to differentiate here between English and metric units, because the calculation is independent of the measurement system. If you want the length estimates calculated using this table to overwrite any line lengths that may already be present in the case, be sure to check the Always Estimate Length checkbox; otherwise, the new estimates will set the lengths only of lines whose pre-defined length isn’t greater than zero. If you want the estimates to populate the lengths of lines in the model so that, when you save the model, the estimated lengths are saved as part of the model, check the Save Estimates With Case. (This provides a handy way to set line lengths for a case that might not have any defined.) Note that, in performing these estimates, transformers are defined as having zero length. If you do not want Simulator to estimate line lengths but instead want to use the line lengths that are currently stored in memory, check the Do Not Use Length Estimates box. Finally, if you want to load line lengths from a text file, click the Load Line Lengths from File button. This file can be either comma- or space-delimited, and each line must have the following fields in the order specified:
From_Bus_Number To_Bus_Number Circuit_ID Length
Once Simulator knows how to calculate line lengths, it can calculate MW*distance indices for each area and zone. Specify the amount of MW that will be transacted in the Size of Transaction textbox. You may use the arrows to increase or decrease the size of the transaction. Simulator assumes that the transaction is to occur between the source and sink groups for which you just calculated PTDFs. Press the button labeled Calculate to compute the indices. Two tables are populated with the results of the calculation, one for areas, and another for zones. Use the tabs to switch between the two tables. These tables are Case Information Displays and thus sharecharacteristics and controls common to all case information displays. Thus, you can sort the tables, add or delete columns, access the area and zone dialogs, print the tables, and save their content as HTML.
Several options can be set to customize the calculation of MW*Distance. These options are reached from the MW*Distance Options Dialog.