Vulnerability Analysis Of Power System With Distributed Generation Based On Complex Network Theory

In recent years, it has become an inevitable trend that large-scaled interconnection of power grid among various areas and the interconnection between distributed generation and power grid, which makes the power grid become more and more complicated, and the traditional power system analysis method has more and more limitations. The complex network theory provides a new perspective for the power system vulnerability analysis, it makes contributions to the stable operation of power system and strengthens the combination among power system, mathematics and system science, which has important theoretical value and practical significance.This paper summarizes several applications of the complex network theory to power system, introduces the complex network theory basics and the software NetworkX which are used to build network models, and proposes a kind of failure strategy based on high node importance degree. It is proved that this failure strategy can simulate the deliberate node attack well by applying it to vulnerability evaluation of power grid. Then this paper not only introduces static analysis method and dynamic analysis method, but also sums up several common vulnerability indexes.Based on the highest connectivity index and several kinds of failure strategy, the network vulnerability evaluation of IEEE-30bus system and IEEE-57bus system are did to confirm the "robust yet fragile" characteristics, and it is proved that the node failure has a greater influence on network performance than the edge failure. Based on the power supply efficiency index, the power supply efficiency of all load nodes in IEEE-57bus system are estimated. Several distributed generations are designed near some of the worst power supply efficiency nodes, and a new power grid with distributed generation nodes is built, then the vulnerability of the new network is estimated.This paper proposes two kinds of new attack modes named deliberate attack mode and global node(edge)attack mode, which are used to estimate and compare the two power grids with and without distributed generation. In deliberate attack mode, it is concluded that the distributed generation can improve the power supply efficiency of power grid and the ability of resisting failure. In global node attack mode and global edge attack mode, it is also concluded that distributed generation not only can enhance the ability to resist the node failure and edge failure, but also can strengthen the power supply efficiency of power grid. In addition, the simulation results show that the attack vulnerability index can accurately identified the fragile node and fragile edge of power grid, it provides useful theoretical bases for power system maintenance.