Software Patches

March 26, 2020

Bug Fixes

  • GIC: An access violation could result when going from Edit to Run mode after moving the terminals of branches to different buses. This would occur even when not doing a GIC solution. This has been fixed.
  • Power Flow Solution: When generators remotely regulate a bus that can not be reached without crossing buses that have SVCs of type svsmo1 or svsmo3, then it is impossible for these generators to perform remote regulation. This data input error had been captured between generators in the past, but was not being captured for a combination of gens/SVCs. It is now properly captured and an appropriate warning message is written to the log and the generator control is not enforced.
  • PV and QV Curve (PVQV) Tool: Fixed an access violation that could result when running PV analysis. This could result if the step size could not be reduced from the Initial Step Size because the Minimum Step Size is greater than the reduced step size, i.e. (Initial Step Size/reduction factor) < Minimum Step Size.
  • Simulator Automation Server (SimAuto): Bug fix in error message management -- message indicating that required fields were missing when attempting to add a new object through SimAuto was being overwritten by a generic "Object not found".
  • Transient Stability: Added three changes to help with solving MMWG transient stability cases: 1) check on GENTPF/J XL <= xdpp, 2) check on ST6B exciter Tda small, 3) added subinterval to handle large negative eigenvalues on AC7B when Kpa*Kf1*inv(Te) is high.
  • Transient Stability: Added initial limit adjustment of the temperature limit value for the GAST2A and GASTWD turbines.
  • Transient Stability: ST6B correction of low Tda values.
  • Transient Stability: For the REPC_B model if a user does not specify any Control Device to which the output is connected, Simulator will assume that Control Device 1 is the generator to which the REPC_B model is assigned.
  • Transient Stability: Fixed initialization of Pmech for HYGOVR and IEEEG3 governor models.
  • Transient Stability: Modified the REEC_A, REEC_B, REEC_C, and REEC_D models. We will now consider the following as an initial limit violation: the Vref0 input parameter creates an initialization that results in the output of the deadband dbd1/dbd2 being non-zero. If auto-correcting initial limit violations, then the value of Vref0 will be modified to either Vinit+dbd1 or Vinit+dbd2 so that the output is at the edge of the deadband.
  • Transient Stability: Modified all machine models that use the Lvpnt1 and Lvpnt0 "low voltage power management" block that manages the current source interface to the network equations. When the Lvpnt1 input parameter is higher than the initial terminal voltage then this is now treated as initial limit violation and we always automatically decrease Lvpnt1 to be equal to the initial terminal voltage. This effects models such as WT3G, WT4G, PV1G, PVD1, REGC_A. This low voltage block should never been active in the initial condition.
  • Transient Stability: When Ke=0 for some types of Exciter models, the value of Ke is automatically calculated based on the initial Field Voltage to achieve a particular value of Vr. This automated routine is handle differently in different software tools and PowerWorld has an option called "Exciter Automatic Parameters" which is set appropriate depending on whether you have loaded a DYR or DYD file. In cases where folks merge two data sets from two different software tools however this option may be more nuanced. This patch modifies this option so that particular Exciter models that are only supported by one other software tool will always use the approach used by that software tool.