Analysis Of Cascading Failures In Power Grids Based On Complex Network Theory

In recent years, Large-scaled interconnection of power grids makes the power system become more and more complicated, the cascading failures can lead to Large-scale blackouts, and then cause great economic losses and social influence. Traditional power system analysis methods have already confronted the limitations in comprehending the mechanism of cascading failure. The theory of complex network provides a new perspective for cascading failure analysis.This paper introduces the complex network theory basics and the software Netw orkX which are used to build network models, comments the models for cascading f ailures based on the complex theory, the topological model of power grids is establis hed by defining the reactance as connection weights, and the calculation method of b etweenness in weighted power grids is proposed; in weighted power grids models, w e assure that the power is transmitted through the shortest paths, then takes IEEE-30bus system and IEEE-118bus system for example, analyze the difference of topolog y characteristic parameter, come to a conclusion that it cannot change the scale-free property of power grids when it weighted; presents supply efficiency index and consi ders the situation that the load may balance in subsystems, makes the simulations res ults close to real power grids; studies the cascading failure and its critical characteris tic, presents the calculation method of critical tolerance parameters; Finally, edges sw apping method in weighted power grids was adopted, which can improve the robustn ess against intentional attacks, this method can keep invariant the number of links an d the degree of each node.In weighted power grids models, takes IEEE-30bus system and IEEE-118bus s ystem for example, both the static analysis and dynamic analysis are adopted to stud y the vulnerability of power grids. In the static analysis, based on structure vulnerabi lity index, it is concluded that the power grids are robust to random failures and hig hly vulnerable to intentional attacks on components with high betweenness and degre e. The nodes which have high betweenness and degree in power grids play an impor tant role for stability of power grids. Using dynamic analysis method, weighted betw eenness was introduced into the Motter-Lai model, the node weighted betweenness is used to define the load carried by the nodes, furthermore support the above conclus ion. Finally, take real power grids for example, both the static analysis and dynamic analysis are adopted to study the vulnerability of power grids, and edges swapping m ethod used to improve the robustness against intentional attacks.