Software Patches

May 4, 2026

Features and Improvements

  • Transient Stability: Added reading the Vpllfrz parameter for REGFM_B1 transient model from a PSLF dyd file.
  • Transient Stability: Added ability to read/write from a DYD file the REGFM_C1 grid-forming model

  • Transient Stability: Added ability to read/write from a DYR file the REPCGFM_C1 grid-forming plant controller model
  • Transient Stability: When loading a DYR file if a generator or object referred to by a stability model did not exist, the log message will now start with the word "Missing" instead of "Error".
  • Transient Stability: Modified to read and write the CCOMP4A model from a DYR file and treat it as a CCOMP4 model
  • Transient Stability: Added ability to read/write the H6E1 and H6E1H governor models from a DYR file and treat it as a H6E model. Also added ability to translate the USRMDL H6E1U to H6E1.
  • Transient Stability: Added ability to read ABBSVC2 as a ABBSVC1 switched shunt models. When reading a DYR file, PowerWorld looks to see if a 2-character id string between single quotes is in the model declaration and reads switched shunts appropriately based on that.
  • Transient Stability: Added ability to read SWSHNT2 as a SWSHNT switched shunt model. When reading a DYR file, PowerWorld looks to see if a 2-character id string between single quotes is in the model declaration and reads switched shunts appropriately based on that.
  • Transient Stability: When reading a REGCAU2 model from a DYR file it is translated to a REGC_A model.
  • Transient Stability: Added ability to read the USRMDL BASOELU1 and BASOELU2 and translate it to a BASOEL2 model.
  • Transient Stability: Added ability to read and write the DERA1 machine model from a DYR file.
  • Transient Stability: Added ability to read various switch shunt models in flexible ways that allow the DYR record to have the ID of the shunt or not. There are 6 standard stability models that come in 2 versions in the DYR Format as follows
    * ABBSVC1 and ABBSVC2
    * CHSVCT and CHSVCT2
    * CSSCST and CSSCST2
    * SVSMO1T2 and SVSMO1T3
    * SVSMO2T2 and SVSMO2T3
    * SWSHNT and SWSHNT2
    All of these model names in PowerWorld Simulator will have the first model name listed for PowerWorld's model name. When reading a DYR file,The following are valid headings
    123456 'SWSHNT2' '1' 0 9 1.04 2 0.1 0.95 1 0.05 /
    123456 'SWSHNT2' 1 0 9 1.04 2 0.1 0.95 1 0.05 /
    123456 'SWSHNT' 0 9 1.04 2 0.1 0.95 1 0.05 /
    PowerWorld will also interpret a few uncorrect syntax as it is clear what the person creating the DYR file intends, and we have seen these in customer DYR files
    123456 'SWSHNT2' 0 9 1.04 2 0.1 0.95 1 0.05 / the ID was incorrectly omitted, but the number of parameters matches, so read anyway
    123456 'SWSHNT' '1' 0 9 1.04 2 0.1 0.95 1 0.05 / the ID is included with quotations so it's clear it is an ID
  • Transient Stability: When reading a DYR, added ability to translate the USRMDL AC11CU1 to a AC11C exciter model
  • Transient Stability: When reading a DYR, added ability to translate the USRMDL AC7CU1 to a AC7C exciter model
  • Transient Stability: When reading a DYR, added ability to translate the USRMDL AC8CU1 to a AC8C exciter model
  • Transient Stability: When reading a DYR, added ability to translate the USRMDL ST6CU1 to a ST6C exciter model
  • Transient Stability: When reading a DYR, added ability to translate the USRMDL ST8CU1 to a ST8C exciter model
  • Transient Stability: When reading a DYR, added ability to translate the USRMDL OEL2CU1 to a OEL2C OEL model
  • Transient Stability: When reading a DYR, added ability to translate the USRMDL UEL2CU1 to a UEL2C UEL model
  • Transient Stability: Modified the OEL5C model to include an extra input parameter IFDdolev which is a drop-out level below which the OEL activation logic set it back to inactive. Previously IFDdolev = IFDpulev always, so the same level was used for activating and deactivating. If IFDdolow <=0 then it defaults back to old behavior.
    Added ability to read and write the OEL5C model form a DYR file.
    Added ability to read a OEL5CU1 USRMDL and treat it as a OEL5C model
  • Bug Fixes

    • Contingency Analysis: Cleaned up the Insert Special right-click drop down menu in the Contingency Analysis dialog. Features on this menu all can be related to a selection that is made in the list of contingencies, except for a few items under a new submenu called "Full Topology Breaker Features"
    • Time Step Simulation: Fixed issue in which time step was not correctly returning the wind chill or heat index values. Also these values and relative humidty are now rounded to integers.
    • Transient Stability: Fixed a bug with the PSS2C that was causing a small initial movement of the stabilizer during initialization