Key Nodes Identification And Cascade Fault Control Strategy Based On Complex Network Theory

The safe and stable operation of the power system is an important support for maintaining the safety of the national science and technology industry and the steady operation of the social economy.In order to further study the structure and operation characteristics of power grid and maintain the stable operation of power system,complex network theory provides a new way to study the above problems by abstracting the grid bus and transmission lines as nodes and links in the network.Therefore,the rational use of complex network theory is of great significance to the prevention and control of large-scale power outages.On the basis of previous research,the following research work is completed in this thesis.1.A method of identifying key nodes of power grid based on improved K＿shell algorithm is proposed.This method comprehensively considers the network topology characteristics and electrical operating characteristics of the power system,and constructs multi-dimensional indicators such as node degree,node centrality,node electrical betweenness centrality,and node comprehensive contribution degree.At the same time,it combines analytic hierarchy process and entropy weight method from both subjective and objective perspectives to give the comprehensive weights of the above indicators,and uses the interval division method to improve the traditional K＿shell decomposition algorithm,find the key node set of the power grid.Finally,the IEEE-39 node system is adopted as a simulation example.Compared with the other approaches,the correctness and effectiveness of the proposed method is confirmed by analyzing the impact of removing key nodes on the network load loss and system operation.2.A cascaded fault control strategy based on load redistribution is proposed.Based on the overload mechanism and the principle of propensity distribution,the core of the strategy is considering the power information provided by the node and its neighbor nodes to establish a new load redistribution model of failed nodes.The IEEE-118 and IEEE-300 node systems are taken as simulation examples to compare and analyze the changes in nodes capacity thresholds with load parameters under different strategies.Then the quantitative analysis of the scale of cascading failures in the node system verifies that the strategy proposed in this thesis effectively improve the robustness of the power grid,so as to achieve the aim of controlling the scale of cascading faults.The research work of the thesis shows that,the comprehensive consideration of the structural characteristics and electrical characteristics of the power grid,and the establishment of multi-dimensional indicators achieve the more accurate identification of key nodes.Moreover,the comprehensive consideration of the electrical information of the grid node itself and its neighboring nodes is helpful to formulate a reasonable load redistribution strategy for faulty nodes,which control the scale of grid cascading faults effectively.