Cascading Failure Risk Assessment Considering Protection System Hidden Failures

Cascading failure plays an important role in blackouts. Complex network theory, with the disadvantage of ignoring some of physical features of the power systems, is often utilized to model the cascading failure evolution processes. In this paper, a new risk assessment method based on evolution procedure and dynamic fault trees (DFTs), is proposed to model cascading failures in power systems. DFTs, which extend standard fault tree by allowing the modeling of complex system components’ behaviors and interactions, are introduced to describe the cascading failure mathematical model. The power grid topologies affected by protective relays, circuit breakers and transmission lines are taken into consideration to overcome the disadvantages of complex network theory. The evolution of cascading failures of power system, which is modeled based on the DFT, is significantly closer to the actual physical system behavior. The effectiveness of the proposed risk assessment method is discussed using two test cases.