Fault Line Selection And Location Technology Research On Single Phase Ground Fault Of Small Current Grounding System

Low voltage distribution network uses the grounding system of small current has a highproportion in our country, and the probability of the occurrence of single-phase ground faultfor the grid accounted for80%of the total. So, after single-phase earth fault was happened,using the appropriate selection line and location method, timely and accurately finding thefault line and ruling out the fault has very important significance to the safe and reliableoperation of the grid.This article firstly reviews the development history of the single-phase earth faultselection line and fault location of the small current grounding system,discussing thetheoretical basis and characteristics of the existing various method classify, respectivelyanalyzing the steady state and transient characteristics of the system of neutral pointnon-ground and neutral point by the arc suppression coil grounded that both happened thesingle-phase earth fault. Secondly, introduces the basis principle of the wavelet and itsapplication in power system, and briefly introduces the MATLAB/Simulink simulationplatform.Aiming at the problem of selection line, according to the processing capacity of thewavelet on the transient signal mutation, this article proposes selection line criterion based onwavelet transform modulus maxima singularity detection principle. Through the analysis ofthe small current grounding system happening the single-phase grounding fault waveformunder the condition of neutral point non-ground and neutral point by the arc suppression coilgrounded, we conclude the steady and transient characteristics when the fault happens, usingMATLAB/Simulink platform to build bus bar with three strands of35kv small currentgrounding system simulation model, and carry out simulation experiments on the model of theselection line method to verify the correctness of the criterion.Aiming at the problem of positioning, after the ground fault occurred, firstly, makingcircuit disconnect, and then finding the fault point, so this article puts forward fault locationmethod using C type of traveling wave, this method does not use traveling wave signalproduced when the fault occurs, but injecting the high voltage pulse signal to the fault lineafter the fault occurs, through using the identification method of C type traveling waveranging method and wavelet analysis for the extraction of fault transient information wavehesd, accurately determines the wave velocity of injection of high voltage pulse wave, thenmeasures the fault distance, and carrys out simulation experiments on the positioning methodon the simulation model to prove the accuracy of positioning method.