Research On The Location Of The Short-circuit Fault Section Of The Distribution Network

With the continuous progress of distribution network automation construction,it has been able to determine the location of distribution network fault section by analyzing and processing the fault current information reported by the field measuring equipment installed in the distribution line after the short-circuit fault occurs at this stage.However,field measurement equipment such as feeder terminal unit(FTU)is mostly installed in outdoor environment with unsatisfactory conditions,and even there may be other electromagnetic interference,which may distort the fault current information reported by FTU.In addition,distributed generation has been integrated into the power grid.The access of DG not only changes the distribution of fault current in the distribution line,but also makes the corresponding topology structure of the distribution network more complex,which will affect the fault current information reported by FTU in the line.The above disadvantages will ultimately affect the accuracy of fault section location of distribution network based on FTU fault reporting information.In order to solve the above problems,the fault-tolerant ability of fault section location of distribution network must be improved.This paper analyzes the principle of fault section location in distribution network at present.On this basis,considering the distortion of fault current information reported by FTU and the influence of DG access on fault section location information reported by FTU,this paper studies fault section location algorithm that is applicable to accurate and rapid fault section location in distribution network and has high fault tolerance.The main research content of this paper includes the following three aspects:(1)Build a distribution network model through simulation software,simulate and analyze the impact of DG access on the distribution network current protection,and analyze its impact on the location of distribution network fault sections based on FTU reported fault information.(2)This paper uses the firefly algorithm to locate the faulty section of the distribution network.This paper studies an immune binary firefly optimization algorithm,introduces the idea of memory pool and immune algorithm,and stores and updates the optimal of each generation through the memory pool solution,draw on the information entropy idea of the locus in the immune algorithm,calculate the affinity between the individuals in the population,and screen out marginal individuals with low affinity with a certain probability during the evolution process,using good individuals in the memory pool replaces the screened individuals,improves the algorithm's global optimization ability and accelerates the convergence speed.The switch function and evaluation function models of distribution network fault section location are constructed,and the IEEE-33 node distribution network simulation model is built.Under the condition that the fault information reported by FTU is complete and the fault information is distorted,the single point and multi-point fault section location of distribution network is realized based on the algorithm.At the same time,the binary firefly algorithm and binary particle swarm optimization algorithm are used for comparative test.The results show that the optimization ability and convergence of the algorithm are better than the other two algorithms,and the algorithm has a certain fault tolerance ability.(3)In order to locate the fault section of the distribution network with DG,this paper first defines the positive direction of the distribution network with DG,and recodes the information reported by the FTU,it also constructs a switching function that can adapt to the structure of the distribution network with DG;then the immune binary firefly algorithm is applied to the IEEE-33 node distribution network with three DGs,in the case of complete and distorted fault information,the algorithm is used to carry out single point and multi-point fault location simulation experiments,the results show that the algorithm has high fault tolerance and fast convergence.