Research On Fault Line Selection Method For Resonant Grounding Based On Transient Characteristics

In medium voltage distribution network in China, with the running of small current ground, it’s fault in single-phase grounding accounted for about 80%. Over the years, domestic and foreign has never stopped research for single phase to ground fault, but limited to grounding, outside interference and other factors, has’ t been able to effective fault diagnosis, affected the reliable operation of the power distribution network seriously.Advantage, comparative study the situation, therefore, in reading a lot of literature on the basis of single-phase grounding fault of the in-depth study. Firstly, it analyzes the current domestic and foreign for single-phase grounding fault line selection method of principle and advantages and disadvantages, summed up the current in the field of difficulty; then, the resonant grounding system single-phase grounding fault steady-state and transient characteristics of a detailed analysis, through comparative analysis, summed up the transient process in signal strength is compared to the steady state, and taking the opportunity of the object of study, focusing on the wavelet and wavelet packet analysis principle and signal processing in the application of in-depth study to determine the wavelet packet analysis to deal with a provisional State signal and select the Sym6 mother wavelet function as a signal processing tool; correlation analysis method as a single-phase ground fault of line selection method is widely used, focusing on the based on correlation analysis theory of fault selection line application, through modeling and simulation, to verify its reliability; limitations based on correlation analysis method is used, the proposed signal by using wavelet packet preprocessing, re-election line method. Finally, summing up the results of previous studies proposed based on the transient characteristics of fault signal, using wavelet packet analysis method as a signal processing tool, combined analysis principle of selected lines improved line selection scheme.Now, establish a simulation model based on Simulink. A 10 kV, 4 to qualify for the resonant earthed system model, through changing of module fault fault time, transition resistance and initial phase of parameters, simulation of various grounding fault. Through the analysis of the simulation results verified based on transient characteristics, single-phase grounding fault line selection is feasible by using wavelet packet and the method of correlation analysis and the method is easy to implement, can greatly improve the speed and accuracy of line selection.