Mathematical Relationship Between The Topology Characteristics Of Distribution Networks And Reliability

Distribution networks,connecting with Power transmission system and loads,are significant in the suppling and distributing power energy.The constructions of distribution networks are extremely complicate with various devices and running mode so that it is important for power industries to evaluate the reliability of distribution networks.The similarity of network topology was introduced,based on which,an approach was proposed on reliability assessment of distribution network.In this method,the singular value sequence,as goal solving of similarity indexes,was used to construct the quantitative mathematical relationship between similarity of network topology and power supply reliability of distribution network.First,the matrix representation and similarity indexes and its determination methods of network topology were introduced,and then the compression and reconstruction of matrix were analyzed,which ensures topological property of adjacent matrix.Next,based on topology similarity,a novel algorithm was presented for power supply reliability assessment,which used the topology database,and root mean square(RMS)method to decide similarity and modify reliability indexes,in addition,the calculation flow chart was given;the topology of IEEE 33 node distribution network was made a case study,which shows that the calculation efficiency of the proposed method is seven times more than congeneric algorithms while the calculation accuracy is the same,presenting reference and guiding significance for the research of improving the power supply reliability assessment of distribution network.Moreover,this paper presents the theory that reliability of distribution network has a close relationship with topology based on topology similarity to avoid the topology being excluded in reliability evaluation and rationalize the distribution network planning.First,abstract the practical network into a topology.This topology is presented by adjacency matrix with weight and failure degree matrix.Second,propose a similarity function based on vertex/edge sharing(VES).This paper also evaluates the reliability by clustering and extracts key factors to increase the reliability.Besides,branch permutation,network structure and the locations of DGs are introduced as three indices to guide the distribution network planning.Detailed strategies are provided in the analysis of engineering project,verifying the operability of the proposed method.Finally,a distribution network evolution strategy based on node group degree is proposed through the simulation and comparison of the three distribution network evolution methods.This strategy enables the distribution network evolve without violating the actual grid evolution law,maintaining a high level of reliability in the evolution process.