Voltage Collapse Propagation and Protection Assessment

Branches with emergency thermal limit violations and buses with emergency voltage limit violations at the point of non-solution can indicate potential branch and generator outage contingencies that would propagate the voltage instability for contingencies that have no dynamic simulation approximation. Buses with significant voltage decline at the Boundary Case Solution for these CVVS contingencies indicate critical voltage levels that warn of cascading voltage instability, motor protection actions, Under Voltage Load Shedding actions, and generator protection actions. The critical voltages at the point of non-solution are needed for design of protection controls.

  • The critical voltages are determined as they should be by the contingencies that cause voltage instability and not by P-V or V-Q curves after contingencies that do not stress the system or loadpocket in the same manner as the underlying contingency
  • Determines critical voltage at load buses that are used in protection schemes that trigger under voltage load shedding, switchable shunt capacitor insertions, motor protection when voltages are close to the critical level
  • Determines branches that experience emergency overload levels which might be outaged causing propagation of the cascading voltage instability to a larger loadpocket or to other loadpockets
  • Determines generator buses with emergency voltage limit violation which indicate generators that may be tripped and propagate the voltage instability to larger loadpocket or other loadpockets