Power System Risk Assessment Considering Protection Failures

In recent years widespread blackouts at home and abroad showed that protection misoperation,refusing action and load transfer were one of the main reason led to the large power system blackouts.Therefor, to ensure the protection system in perfect condition and operation correct is an important question of power system. It's meaningful to research the protection reaibility impact on the cascading failure.In this paper, based different action logic and configuration of protection, we set up two failure probability models, only cosdering protection itself and considering primary system. And we can solve the failure probability of probability using the Markov method. And the model can exactly describe the protection impact on the power system risk assessment.Based on the power sytem risk assessment model and algorithmic, we can caculate the risk index with Monte Carlo method. And then compare the average and scattered sampling and the tranditional simple sampling.Finally, we use Monte Carlo method to simulate the cascading failure action caused by the protection hidden failure, and propose a set of composite method to research the cascading failure. The test example proves the protection impact on power system risk assessment.This paper research on the protection failure mode, Monte Carlo method, power system risk assessment algorithm and cascading failure risk assessment considering the protection hidden failure. It aims at improving risk assessment more reliable and effect, so that it can prevent the cascading failure and keep the power system safe and stable.