Research On Cascading Failure Of Blackout Based On Complex System Theory

A few key links in the grid play an important role in cascading failure of power system. Identify the key link, the cascading failure causes and its process of development, is of great significance to the safe and stable operation of power system.This paper makes a research on power system cascading failure based on complex system theory. First the paper presents a critical branch recognition method based on coupling branch betweenness. On the basis of topology, identify the branch that can cause the split of power grid when it is disconnected. Then respectively calculate the coupling branch betweenness of other branches and choose the betweenness bigger branch as the critical branch. Coupling branch betweenness evaluator indicator not only considers the influence of load level and transport margin the branch itself, but also considers maximum relevance branch which obtained through shortest path method. The method considers the influence of the current transfer factor and maximum relevance branch, so it can implement the accurate recognition of critical branch. Then, based on the coupling branch betweenness, convert the calculation of critical node to the calculation of critical branch and puts forward the coupling node betweenness evaluation index which is used to identify critical node. Finally, the paper makes the maximum relevance branch of the fault branch as the next level failure and predicts the sequence of cascading failure. When the maximum relevance branch is not exist, select the next level failure according to coupling branch betweenness under the current topology. Based on Ningxia 750 k V/330 k V/220 k V power grid, the paper identifies the critical branch and critical node under a particular operation mode and also predicts the sequence of cascading failure. The result of PSD-BPA transient stability calculation verifies the effectiveness and adaptability of large power grid of the method.