Research On Fault Location Method Of Distribution Network

Reliability is an important quality to be satisfied in power system operation.To ensure the reliable operation of power system,it must have relay protection devices which can react and remove faults in time and accurately.If the relay protection device operates in the instantaneous fault,the power supply of the system can be restored under the action of reclosing.However,if the relay protection device operates in a permanent fault,the reclosure will not succeed.At this time,it is necessary to locate the fault area,to remove the fault quickly and restore the power supply,so as to shorten the blackout time and ensure the continuous power supply to the user.At present,the research on fault location for long-distance transmission lines is relatively mature.However,due to the short line and complex line structure of distribution network,this method cannot be directly applied.Moreover,the distribution network is an important bridge connecting the transmission network and the user,and timely troubleshooting plays an important auxiliary role in the continuous transmission of electric energy.Therefore,the research on fault location of distribution network has important theoretical and practical significance.Distribution network fault location can generally be divided into three categories:fault line selection,fault area location and fault location.The former two have made great progress.This paper proposed a new algorithm for distribution network fault location.Firstly,this paper summarized the development background and significance of fault location,and focused on the research of distribution network fault location.Then impedance method,injection method and traveling wave method have been analyzed in this paper.Impedance method and injection method cannot achieve better results in distribution network,or even cannot be used.Therefore,the traveling wave method was taken as the fault location method used in this paper.In this paper,the principle of traveling wave fault location method was analyzed,which laid the foundation for its application in distribution network fault location,and the difficult problems faced when traveling wave fault location method is applied in distribution network fault location were put forward.For traveling wave processing,this paper used the mathematical method of wavelet transform,briefly introduced its basic principle,multi-resolution analysis and Mallat algorithm,and simulated the modulus maximum method of wavelet transform applied to traveling wave analysis.Then,according to the characteristics of the distribution network itself,combined the above principles and methods,a new fault location algorithm for distribution network which can greatly reduce the cost of equipment was proposed in this paper.Finally,the PSCAD simulation software was used to model and simulate the distribution line,and the traveling wave collected was analyzed by the software of Matlab.It is verified that the algorithm is not affected by the structure of distribution network,the number of branches and the size of transition resistance.When grounding fault occurs,the fault can be accurately located.When other fault types occur,the fault can be positioned in fault area locations.The positioning error is within the reasonable range of engineering.