Power system reliability analysis considering protection failures

This paper describes power system reliability evaluation including protection system failures. A modified protection system reliability model including two major protection failure modes is established. Protection system failure is the main cause of cascading outages. The mechanism and scheme of protection system have been analyzed on their contribution to the cascading outages after a fault occurs. A nonsequential Monte Carlo simulation approach is used to implement the stochastic properties of component contingency and protection system failure. The whole procedure is verified in the WSCC-9 bus system. BIP (bus isolation probability), LOLP (loss of load probability), and newly introduced EPL (expected power loss) are calculated to demonstrate the vulnerability of a power system under cascading outages.