Research On Vulnerability Assessment Method Of Distribution Network

With the construction of smart grid and energy Internet,the scale and shape of distribution network are becoming larger and larger,which makes its security problems increasingly prominent.Therefore,it is necessary to assess the vulnerability of distribution network before sudden failures or natural disasters occur,identify the weak links and reinforce them,so as to improve the safe operation level and disaster prevention ability of distribution network.Based on this,this paper deeply studies the vulnerability assessment method of distribution network from three aspects: the construction of distribution network vulnerability analysis model,the vulnerability assessment of distribution network based on cluster analysis,and the comprehensive assessment of vulnerable lines of distribution network under typhoon disaster.In order to intuitively reflect the network characteristics of distribution network,and realize the research of distribution network vulnerability assessment method more quickly and effectively,this paper puts forward a method of constructing distribution network vulnerability analysis model based on complex network theory.In view of the mature modeling method of transmission network,this paper comprehensively considers the differences between transmission and distribution networks in network structure,equipment parameters,node types and voltage levels,improves the modeling method of transmission network,and puts forward a complex network modeling method suitable for distribution network.Example results show that this method accords with the actual network structure of distribution network,can reflect the network characteristics of distribution network,and is beneficial to the exploration of vulnerability assessment methods of distribution network.In order to enrich and improve the vulnerability assessment method of distribution network,this paper proposes a vulnerability assessment method of distribution network based on cluster analysis.This method comprehensively considers the topological structure and operation state of distribution network,puts forward the structural vulnerability evaluation index and state vulnerability evaluation index,and weights each index by the combined weighting method which combines AHP and entropy weight method.On the basis of obtaining the vulnerability evaluation index and its weight,the number of clusters is determined by contour function,and the K-means clustering analysis method is used to cluster the system and divide the vulnerability levels of nodes and lines.Example results show that the proposed method can better evaluate the vulnerability of nodes and lines in distribution network and identify the vulnerable links in distribution network.Recently,typhoon disasters frequently affect the power grid seriously,the vulnerability assessment in disaster scenarios is different from that in general scenarios,and the line failure rate under typhoon disasters is high.This paper puts forward a comprehensive assessment method of vulnerable lines in distribution network under typhoon disasters.Based on the Batts model,the line failure rate model of distribution network under typhoon disaster is constructed.Because it is intuitive and more in line with the actual disaster scene,it is regarded as the index with the highest influence factor in comprehensive evaluation.In addition,failure loss index and structural vulnerability index are also selected as vulnerability assessment indexes under typhoon disaster,and AHP and entropy weight method are used to weight each evaluation index,and the final comprehensive vulnerability index is obtained,and the evaluation system of vulnerable lines in distribution network under typhoon disaster is constructed.Example results show that this method can better reflect the vulnerability of distribution network lines under typhoon disaster and identify its weak links.To sum up,the construction of distribution network vulnerability analysis model can provide a model basis for the exploration of distribution network vulnerability assessment methods.The effective vulnerability assessment method of distribution network is of great significance for reasonably arranging power resources to reinforce the distribution network and improving the power supply capacity and disaster prevention capacity of the distribution network.