Research On Single - Phase Earth Fault Detection And Location Of Distribution Network Based On Signal Source Method

The distribution network is the end of the power system, It has the characteristics of wide coverage, more branches, complex wiring, which can easily cause failures. In distribution network fault, the single-phase grounding fault is 60%-85%of all total failures. For the single-phase earth fault of the distribution network, there is no perfect method of detection. Although science and technology personnel conducted in-depth research on detection and location of small current grounding system fault, and achieved good results. But the detection and location technology of the single-phase grounding fault is no great breakthrough, which has not a comprehensive detection and location method, a variety of methods are flawed. In many detection and location methods, the signal source of "median resistance input method"has high detection and location accuracy. In order to improve the application effect of the median resistance input method, This article main research content is as follows:(1)In order to avoid must be approved by the grounding transformer neutral point to access resistance signal source switching device, the improved method is to be directly to the lOkV bus in transformer substation or lOkV line.(2)In order to improve the detection sensitivity, increases the strength of resistance switching test signals, the improved method is switching the advance phase switch of the grounding phase.(3)In order to further improve the detection sensitivity, inhibit the detection signal amplitude, so as to avoid adverse effects on power system, the amplitude of the current amplitude control is appropriate for the 40A, when input resistance, the improved method is the resistance design will be switching of 50～25Ω and the switching position can be adjusted.(4)It is using Matlab/Simulik power system simulation and dynamic physical simulation model of distribution network, combining with improved median resistance device of signal power, to do the supply bureau of Kunming Chenggong Luoyang 110kV substation lOkV Shilong lake line and Qujing 110kV substation lOkV line along the river south of the city, "lOkV distribution line artificial single-phase earth fault test". Comparative study of simulation and field measured data shows that the improved median method of resistance for detection sensitivity as a whole increased by 10%-30%; Fault detection time is half of the conventional methods, the detection time is less than 10s.