Software Patches

February 2, 2022

Features and Improvements

  • Difference Case Tool: Added a Verify Computers button to each distributed computation tool dialog box.
  • Transient Stability: Modified the hydro governor models HYGOV, HYGOVD, HYGOVR, HYPID, HYG3, and HYGOV4 models when initial state limit violations occur because the Pmech output is higher than the combination of the inputs of Hdam (or H0), qnl, At, and the nonlinear Gate to Pgv block are able to achieve. When using the initial limit violation option to "Modify Limits and Run", PowerWorld will now calculate a the higher value of Hdam necessary to achieve the Pmech output. Previously PowerWorld would change the At (turbine gain), but discussions with customers indicate it is more appropriate to modify Hdam instead.
  • Bug Fixes

    • Auxiliary Files (SCRIPT and DATA Sections): Fixed bug in RestoreState script command that would not allow the WhichState parameter to be enclosed in double quotes.
    • Case Information Displays: Fixed error with Area, Zone, BalancingAuthority, and Substation objects. General fields like Custom Strings, Integers, Selected, and field associated with specifying what to store in transient stability simulations were not showing properly in case information displays. This error was introduced in an early January 2022 patch, but is now fixed. Not that old files would have functioned fine, just showing these values in case information displays or writing them to AUX files would have resulted in the fields appearing as blank even when they were populated with data.
    • Oneline Diagrams: Fixed contouring bug in which the code could hang when contouring multiple points at the same location (like with generator data).
    • Transient Stability: Fixed bug in CSTCNT switched shunt model which was preventing it from regulating the voltage at a remote bus. The model was instead always regulating the local terminal bus voltage.
    • Transient Stability: When performing a validation check for most values in transient stability against a minimum limit PowerWorld had a 0.000001 tolerance we checked against. For some situation this tolerance was too small. For example a user may run auto-correction against time constants the are required to be 4 times the 0.25 cycle times timestep which we would calculated as 1/240 * 4 = 0.0166666667 seconds. If a time constant was smaller than this we would round it up to exactly that time constant. However if the user then changed the contingency to use a timestep of 0.004167 seconds (we store timestep in second out to microsecond precision), then the required minimum timestep was 4*0.004167 = 0.016668 seconds. That means that the previously auto-corrected timestep was no "too small" because 0.0166666667 < 0.016668. Thus the value is too low by 0.0000013333 seconds which is just slighly above the old tolerance we have. This has been changed so the tolerance is now 0.05% of the limit, so in this case the tolerance if 0.0166666667*0.0005 = 0.0000083333 (so just over 8 microseconds). This slightly larger tolerance will scale appropriately for all situations.