Software Patches

July 17, 2014

Bug Fixes

  • Power Flow Solution: Fixed a very rare error in phase shifter switching which could occur if impedance correction tables had very large values AND you were simultaneously enforcing discrete phase shifter steps. It was possible for the phase shifters to become stuck in this situation because of some internal hueristics to handle impedance corrections with large values. This has been fixed.
  • Transient Stability: Modified the MOTORW model for double-cage motor simulations. Previously, PowerWorld had assumed that MOTORW model dynamic equations were treated the same as MOTOR1, CIM5, CIM6, and CIMW but with the simplification that saturation was ignored and that Xl = 0.8*Xdpp. Customer testing showed that the they were actually slightly different dynamic models which give different results. We have modified the MOTORW to use these special dynamic equations instead.
  • User Interface Dialogs: On the system equivalencing dialog, when choosing to Delete the external system, it was possible for an access violation to occur if a 3-winding transformer had a terminal bus set to be equivalenced but the internal star bus was not set to be equivalenced. This has been fixed.