Lines may be added, deleted, or given impedance changes through the use of convenient dialog boxes, without actually altering the underlying (necessarily very large and cumbersome) data base. A list of all such changes that the user has made is available from the main menu, and any change may be readily "undone," or if desired, changed further.
In addition, there are four network alterations which can be made immediately, do not appear in the list of changes, and are automatically reversed when subsequent faults are requested:
There are two methods provided to fault lines anywhere along their lengths while each end remains normally connected:
The program's user interface screen is divided into a graphics section, which shows network connectivity, and a control-results dialog box containing standard Windows input and output controls. (Selected segments of an actual screen are currently being displayed at left.)
Fault currents can be displayed in the graphics section for all lines up to two buses away from any bus, for a fault on any bus. These currents can be suppressed to decrease clutter if the network configuration is of primary concern.
The program uses the Philadelphia Electric Version 2 data base format
with a couple of new fields for phase-shifter angles, and additional
mutual coupling information (optional).
Solutions are obtained using sparse admittance matrix, optimal bus ordering, and upper-lower triangular factorization techniques. While several data files are used by the program, the user is only responsible for the Philadelphia Electric data base, and the rest of the files are generated automatically.