Power system key lines identification based on cascading failure and vulnerability evaluation

Critical segments in power system are closely related to cascading failures. Therefore, how to identify and quantify critical segments in a grid has become a hot topic of power system emergency and early warning. According to hidden failure model and power flow transferring, a searching mode of cascading failures was introduced in this paper, based on operational reliability model of lines. Utility theory is introduced to define the severity of the contingency. And a composite risk indicator for cascading failures is obtained by integrating the various risk indicators, which is based on the entropy and the analytic hierarchy process. According to complex network theory, vulnerability indicators are further proposed for the identification of key lines. Taking a district grid in Henan for example, the vulnerable lines in it are identified. The results demonstrate that improving a few key lines identified can make the grid avoid large blackouts.