Research On Risk Assessment Method Of Power Grid Cascading Failure

With economic development, with a sharp increase in electricity demand, largepower grids have emerged. This expands the grid scale, improve the power supplylevel, but also bring new challenges to safe and reliable operation of the power grid.In recent years there have been many big blackout, which allows cascading failureand risk assessment has become a hot research.First, the cascading failure outage probability model based on real-timeoperating state is established. The model consists of two parts, one is the outagemodel considered different factors lines, generators and load. Another is the modelconsidered protective action logic implicit fault. Then sort the importance of theinitial failure to select the initial failure appropriately based on the vulnerability andsensitivity. After that, consider the hidden fault protection, make a pattern searchaccording to the certain termination conditions, simulated power system cascadingfailure. Finally found the path of cascading failures, and find the probability ofoccurrence of different termination conditions cascading failures.On the basis of the path of the cascading failure, considering the severity of thefault, from static security point of view, based on utility entropy principle, definethe operational risk indicators. Next, establish the risk assessment model, and useAHP and PCA conducted a comprehensive assessment of the risk indicators. Makecomparison on the cascading failure comprehensive risk indicators and indicators ofcascading failure probability and the probability of failure of the initial. The resultsshow that the trend is the same of integrated risk evaluation and probabilisticevaluation. This method can compare the consequences quantitatively of the lineswhich bring more serious consequences. There is no necessary connection betweenthe initial failure probability and the risk.In the end, categorization probabilistic indicators and vulnerability indicatorsand risk indicators using cluster analysis method. Establish the membershipfunction of risk indicators based on fuzzy reasoning method. Calculate theclassification results of the comprehensive risk indicators. Considering theprobability indicators and vulnerability indicators and comprehensive riskindicators, early warning of cascading failures is build. This approach examines theimpact on the system of the probability, vulnerability and the risk. Forlow-probability, high-risk failure can make early warning correct andeffective.Calculated and analyzed using IEEE39. This method can carry out riskassessment and make early warning. This shows the effectiveness of the method.This work funded by the State Grid Corporation of science and technology projects of Control Technology Under the State Power Grid Failure.