Research On The Power Grid Vulnerability Based On The Theory Of Complex Network

A secure and stable power grid matters a great deal to people's life.The recent years have witnessed frequent occurrence of major blackouts at home and abroad,brought to the close attention of professionals and researchers.As researches indicate,cascade rendered ineffective from power grid failure should be held most accountable for large-size blackout accident,and the vulnerable part of power grid is closely linked with failure in power grid.Therefore,the research of vulnerability in power grid aims at discovering a reliable,safe short slab for the operation of power grid,laying solid foundation for the defense of power grid safety.This paper is based on complex network theory.At first,the admittance value of power transmission line is selected to act as the weight,establishing weighted topological model for power grid and analyzing complicated network trait of power system.Secondly,by combining impact model with Markov Chain presents the evolution from a state of power grid to dynamic model,which covers the main feature of power grid.According to impact model,the odd that system causes cascade incident due to the failure in initial timing point represents the principle that the impact system has on matrix corresponds with the element value in vector quantity of left eigenvalue of eigenvalue 1,from which an approach to assessing the vulnerability of power grid is derived.In view of the matching relation and interaction between generator bus and load bus(Topological factor and electrical factor),an evolutionary model is established that fits more with actual system state in power grid.The proposed approach applies to standard test system for IEEE-39 nodes,which,compared with existing method,shows that it takes into account the evolution process of system state.It proves more reasonable and effective than existing model,favorable for the system to provide guidance to analyze the online safety.Finally,three vulnerability indicators that describe the degree to which power grid is vulnerable are put forward in accordance with the research approach to vulnerability of power grid structure from complex network theory applied to actual power grid.Based on that different attack strategies simulate the process of ineffective power grid,a combination of DC flow model and disabled cascade model can analyze the structure vulnerability of transmission network and its existing parts of fragility.