Vulnerability Assessment For Distribution Networks Based On Complex Network Theory

Vulnerability assessment of distribution network is to dig out the key nodes and lines,based on the role links play in the network.Failure events of distribution network will have a great impact on the reliability,safety and stability of distribution network.However,the current research on distribution network's vulnerability is still at the initial stage and the research results are few.This paper studies the vulnerability assessment method of distribution network,according to the structure and operation characteristics,and the roles nodes and lines play in distribution network.The complex network model of distribution network is constructed.This model considers the difference of network structure,voltage level and components between distribution and transmission network.The simulation results show that the modeling method is simple,whose results can reflect the topological features of distribution network,and calculated characteristic parameters are in line with the structure of actual distribution network.In this paper,a node vulnerability assessment method combining technique for order preference by similarity to ideal solution and gray correlation degree is proposed.This method constructs vulnerability indexes of nodes from several different perspectives,such as degree,betweenness,agglomeration and closeness,and uses entropy weight and AHP to empower indexes in both objective and subjective ways.What's more,this method assesses vulnerability with technique for order preference by similarity to ideal solution improved by gray correlation and makes the assessment results more accurate.The simulation results show that the proposed method can evaluate the vulnerability of distribution network well,and multi-index comprehensive evaluation can compensate the shortcomings of single index.For distribution network with distributed generations,a vulnerability assessing method considering risk theory is proposed.This method takes into account the restoration strategy of distributed generations and tie lines,considering the influences they have on distribution network's vulnerability.What's more,this method considers the severity of fault consequences and probability based on the fuzzy comprehensive evaluation and makes the assessment results more accurate.The simulation results show that the proposed method overcomes the shortcomings of the evaluation method which considers the failure consequence only.The results prove that the method proposed is effective for analyzing the vulnerability of distribution network with distributed generations.