Research On The Location Method Of Single Phase Grounding Fault For City Distribution Line

City distribution network in China is mainly composed of10kV and35kV distribution lines, most of which use neutral non-effective grounding mode, or called small current neutral grounding system. Many branches in a distribution line,high grounding resistance at the fault point and low current signal are the difficulties of locating fault.Based on this satuation, C-type of traveling wave is available to determine the fault distance.In order to improve the accuracy of traveling wave fault location, a new method for accurate fault location on a distribution line with branches using wavelet packet analysis and neural network is presented. This composite method has two steps. The first step is determining the fault distance by C-type of traveling wave location method and wavelet packet analysis; the second one is locating the fault branch by artificial neural network. The effect of the different source and different resistance is analyzed,and current traveling wave signal is adopted to determine the fault distance.Because of excellent symmetry and applicability to high-frequency transient analysis, coif5wavelet packet is choosed to analyse the traveing wave signal as well.Both theoretical analyses and simulation show that this composite location method can be used to determine the single-phase-to-earth fault location accurately in the distribution network.