Probabilistic power system security analysis considering protection failures

This paper proposes a method of probabilistic security analysis of power systems including protection system failures. Protection system failure is the main cause of cascading outages. A protection system reliability model including two major protection failure modes is adopted to demonstrate the effects of different protection failure modes on power system reliability. The mechanism and scheme of protection system have been analyzed for their contribution to cascading outages as well as system stability after a fault occurs. All contingencies and responses in the power system are depicted in their inherent stochastic manner. Therefore, all simulations in this paper contain the features of a real power system. Non‐sequential Monte Carlo simulation approach is used to implement the stochastic properties of component contingencies and protection system failures. The WSCC‐9 bus system is used as the security test system. The security index “probability of stability” is calculated to quantify the vulnerability of a power system under cascading outages.