Reconfiguration Of Distribution Network With Distributed Generations Considering Vulnerability

Distribution network reconfiguration is an important mean to realize the reliable and economic operation of the electrical power system,In order to make full use of the potential of the original distribution networks,It can change the topology of the network by changing the combination state of the switch under certain constraint conditions.In recent years,DG has been developing rapidly,and the proportion of access to distribution network is also getting higher and higher,The access of a large number of DGs will change the direction of the distribution network of power flow,which will redistribute the currents of the network,cause node voltage fluctuations and even limit crossings,overload and load loss of the line,thus increasing the vulnerability of the system.How to exert the advantages of DG and reduce the impact of grid connection has become a research focus of scholars in recent years.This paper focuses on the impact of DG on distribution networks,and introduced the vulnerability of DG in distribution network reconfiguration research.Analysis of the impact of DG on access to the distribution network,based on the operating characteristics of DG can be divided into PQ,PV,PI and PQ(V)four kinds of node types and establishes corresponding flow calculation model,proposed an improved forward backward sweep method to deal with the trend of distribution network with DG.The example analysis was used to verify the effect of DG on the distribution network loss and distribution network voltage.A fast reconfiguration method of distribution network based on RVM algorithm is proposed.This method describes distribution network reconfiguration as pattern recognition problem,and takes distribution network load mode as input and network loss optimal switching state as output.For large-scale distribution networks,combining the theory of graph theory to simplify the structure of the distribution network,the status of the simplified branch group of the distribution network is taken as the output,and then the improved optimal flow method is used to find the Contact switch position.In order to improve the accuracy of model recognition,the QPSO algorithm is proposed to optimize the parameters of the RVM kernel function.The example analysis results show that the proposed method can achieve better recognition performance in distribution network reconfiguration.The vulnerability objective function is introduced to reflect the capacity of thesystem when the distribution network is in an accident,and a vulnerability index based on risk analysis theory is constructed.The index takes account of the probability of failure occurrence and the severity of the consequences caused by the fault.The objective function of net loss and the target function of vulnerability are treated with the method of judgment matrix.Improved genetic algorithm is proposed for optimization of distribution network reconfiguration method,according to the operation characteristics of chromosome coding scheme to improve the distribution network,shorten the length coding,reduced the infeasible solution,make the crossover rate and mutation rate based on the genetic changes in algebra and adaptive adjustment.The calculation example shows that this method can find the optimal structure of the distribution network with the unity of vulnerability and economy.