Research On Power Grid Vulnerability Assessment Based On Complex Network Theory

Electricity is the major energy and economic lifeline of the national, Safe and high quality power supply related to people’s livelihood. But natural disasters、man-made accidents、equipment aging and system defects may lead to the occurrence of blackouts, such as "4.24" incident、"5.25" incident at the China Southern Power Grid in1994、"9.25" incident at the Hainan Power Grid in2005、snow disaster in2008and Shenzhen power grid blackout.in2012for a500kV substation failure. The frequency of the grid large-scale blackout and the complexity of the operation modes and structure make domestic and foreign experts and scholars to re-examine the traditional security analysis methods. Found that the traditional analysis methods based on differential equation solver is not well explained the occurrence mechanism of chain failure blackout. The vigorous development and application of network theory, such as in social relations、 the spread of the virus provide new ideas for the study of power system fault propagation and catastrophic process.The paper start from network topology characteristics, such as network graph, average path length, clustering coefficient, degree and degree acumulative distribution, beweeness and beweeness acumulative distribution and so on, and introduced the application of complex network theory in the power system.Analysis the disadvantages of modeling methods in the past, then according to the actual power system operation, build three network topology models and proper evaluation indexs.One of the research purposes about vulnerability of the grid structure is to looking for critical nodes and critical edges. Put forward the indicators of point weights degree and point weights betweenness based on the traditional indicators of degree and betweenness, deliberate attacks on the network to search the key nodes and edges in accordance with network performance. Analysis the network performance under different indicators though deliberately attacks on the networks.Finally, though the undirected-unweighted network and weighted-undirected network models calculate and analyze the topological structure, prove that the China Southern Power Grid is a small-world network and have property of scale-free. Take deliberate attack on the China Southern Power Grid in accordance with a different sort of indicator, analysis the key nodes and edge in the network. But considering the power flow in cascading failures of IEEE39weighted-directed network, take random attacks and intentional attacks to analysis vulnerability of the network according to the established indicators. Analysis the vulnerability of the network based on network performance parameters.