Risk Assessment of Power System Cascading Failure Considering Hidden Failures of Protective Relayings

Cascading failure is one of the main causes of blackout. The authors propose an integrated approach to assess the risk of power system cascading failure considering hidden failures in protection system. Two probability models of protection system hidden failures are used to demonstrate their effects on power system risk. The mechanism and scheme of protection system have been analyzed for their contribution to cascading failures after fault occurs. The risk of power system cascading failure is assessed by bus isolated risk, load isolated risk, grid break-up risk and integrated system risk, on this basis the preventive measures to reduce the risk of power system cascading failure is put forward. By means of Monte Carlo simulation approach the stochastic properties of contingencies, protective devices and protection system hidden failures are procreated, and the software for prevention and assessment of the risk of power system cascading failure is developed. The results of applying the proposed method to IEEE 118-bus test system illustrate the feasibility of this method and effectiveness of the developed software.