The Fault Line Selection Of Non-Effective Ground Based On Improved HHT

35kV power distribution network and lower mostly use small current grounding way,which includes non-ground neutral system and the coil of arc extinction grounding system.For the main distribution network is radiation nets of bare wire as aerial, as to the smallcurrent grounding system, one-phase ground fault has the highest probability, up to80%ofthe power distribution network fault. In order to improve the power supply continuity, ensurethe safety and stability of power systems operation, fast and accurate detect the fault line hasespecially important implications to power distribution automation system.As to the problem of small current grounding system fault location, the principle ofdomestic and foreign existing fault location methods and its advantages and disadvantages areanalyzed in this paper. The steady and transient state fault characteristics are deeply analyzed,especially for utilization of fault transient information, when one-phase ground occurred tonon-ground and the coil of arc extinction neutral grounding system.Fault transient signal is mixed with the noise of the singularity and the non-stationaryhigh frequency signals. The emerging Hilbert-Huang Transform (Hilbert-Huang Transform,HHT) theory, which analysis the non-stationary signal is superior to the traditional methods,for its good localization characteristics in time-frequency. The theory often used in the kindof signal singularity detection. EMD decomposition is very important in using HHT method.But the original EMD (Empirical Mode Decomposition) of HHT method existing endpointeffect in decomposed process, which makes the intrinsic mode function (IMF) seriousdistortion. The distortion greatly affects the accuracy of the fault location. By extending theendpoint could suppress endpoint effect. This paper compared several different endpointcontinuation comparison methods, applied the adaptive waveform match endpointcontinuation to improve HHT.In order to make lots of simulation about non-effective ground system, correspondingsimulation model is established by MATLAB software in this thesis. In the simulation experiments, through set the different parameters values of the grounding position, angle offault voltage, grounding resistance, line length equal to analysis the effect of improved HHTmethod in fault location. Simulation results show the improved methods HHT not onlyeffectively suppress the endpoint effect, but also improve accuracy of phase-to-ground faultlocation.