Risk Assessment Method of Power System N-K Contingencies

All previous blackouts show that cascading failures caused by simple faults can lead to disastrous consequences.Identification and analysis on severe N-K contingency that may lead to large-area blackouts is an absolutely necessary procedure for power system security assessment and establishment of defensive measures.On the basis of analyzing the evolutionary process of blackout,a method to assess the risk of power system N-K contingency is proposed,that is,considering the interaction of failures and the hidden failures of protective relaying as well as taking the impacts of element operation condition variation on its fault probability into account,based on Bayesian network a probability calculation model of N-K contingency is given;then the control measures during cascading failure process in actual power system are simulated in detail and an optimal control model in which the voltage stability constraints are taken into account is built,and a method to determine the severity of N-K failures is put forward;finally,an approach to calculate the risk index of N-K contingency is given.By use of Python language the PSS/E is re-developed,thus the proposed method is realized.Taking IEEE 30-bus system for example,the severe N-K contingency in it is identified and the correctness of the proposed method is validated.