Research On Fault Tolerant Technique Of Fault Section Location In Distribution Network

With the rapid development of automatic construction for distribution network in China,after a short-circuit fault in the distribution network,it's one of the key technologies for automation that the fault area is determined in a timely and accurate manner based on the information reported by the feeder terminal unit(FTU)installed along the feeder section.Due to the complex environment and electromagnetic interference in the field devices of the distribution network,it often leads mis-reporting or failed-reporting of fault information when the FTU uploads fault signals.In addition,the connection of more and more distributed generation(DG)will lead to a change in distribution of fault current and the topology structure of distribution network become more and more complicated,which will affect FTU to upload fault signal.These will affect the result of fault section location in distribution network.Therefore,a high requirement for fault tolerance of fault section location in distribution network is put forward.In order to solve the above problems,this paper analyzes the characteristics of current fault section location's principle and the impact of the connection of DG on traditional distribution network.It comprehensively considers the distortion of FTU information and the impact of DG access on FTU upload information.Under the premise of ensuring that the positioning algorithm meets the requirements of accuracy,rapidity and applicability,the fault-tolerant location technology of the fault section in the distribution network is studied.The specific content includes the following three aspects:(1)Through the simulation of fault characteristics,the influence of the distributed generation connecting to the distribution network bus and the feeder to the FTU upload fault current information is analyzed.In addition,combined with the short-circuit current characteristics of the distributed generation,the applicability of the traditional fault section location for the connection of DG is analyzed.(2)For problem with distortion of FTU upload information,this paper proposes a comprehensive consideration of the correlation between the remote signal acquisition and the remote measurement of the feeder terminal unit(FTU)to correct the fault information sequence.At the same time,a fault localization addressing model is established,and a fault loop is determined by looking up the table using the corrected feeder switch fault information sequence.Then,fault-tolerant Bayesian likelihood ratio fault section discriminant model is proposed to achieve fault-tolerant location of the fault section in distribution network without DG in case of mis-reporting or failed-reporting of fault information.An example is given to verify the superiority of this method compared with the traditional method and it has high fault tolerance.(3)For the impact of the DG access distribution network on the FTU upload information and the distortion of the FTU upload information,this paper constructs a fault current coding method and switch function that adapt to multiple distributed generation,and uses the minimum set theory to improve the evaluation function,thereby improving the fault tolerance of positioning.At the same time,the particle swarm optimization algorithm with fast convergence and directionality is used to optimize the basic harmony algorithm.Finally,the fault-tolerant location of the fault section in distribution networks with DG is realized based on the AHSPSO algorithm.This paper compares the HS and PSO algorithms used in other methods of fault section location in distribution networks with the AHSPSO algorithm in the single and dual faults to verify the performance of the AHSPSO algorithm.In addition,by setting FTU information to a certain degree of distortion,the AHSPSO algorithm is used to perform fault section location simulation experiments,which verifies the superiority of the algorithm and has high fault tolerance.