An importance sampling application: 179 bus WSCC system under voltage based hidden failures and relay misoperations

Recent studies have shown that power system protection mechanisms have played a major role in propagating disturbances. Out of the last five major Western Systems Coordinating Council (WSCC) events in the USA (the North Ridge earthquake, December 14th 1994, July 2nd and 3rd 1996, and August 10th 1996), the latter three involved false trips with line protection relays and generators. Using an importance sampling-based algorithm on the 179 bus WSCC equivalent system, the authors modeled the sequence of rare events under generator trips and zone three relay misoperations. The resulting sequence of rare events and its corresponding probability are used to detect weak links in the power system