Research Of Traveling Wave Fault Location Of Distribution Network Based On Time-frequency Analysis

Distribution network is an important part of power distribution network in the power grid and the user is directly connected with the final distribution. Once the distribution network fault happened, short or long time power outages will happen, and bring inconvenience to work and life. On the other hand, there are a lot of branches in the distribution network, and artificial line is time-consuming and laborious, so it is of great significance to locate the fault location quickly and accurately.In this paper, the traveling wave ranging method is used, and the key of traveling wave ranging method is the accurate extraction of traveling wave head. In the case of noise, the wave head may be covered by noise. The traditional time-frequency algorithm, such as short-time Fourier transform and wavelet transform, can not accurately identify the traveling wave head in the presence of noise. In this paper, the method of time frequency analysis based on the synchronous compression wavelet transform and an automatic frequency selection for the measured signal is presented.In this paper, a multi terminal distribution line model is built in Matlab, and the short time Fourier transform, wavelet transform, S transform and Synchrosqueezing wavelet transform are compared. Among them, the S transform has the highest accuracy, but the real-time performance is poor, and the Synchrosqueezing wavelet transform is worse than the S transform in suppressing noise. Therefore, this paper adopts the automatic frequency selection S transform to analyze fault traveling wave signal in multiterminal distribution network, the results showed that, automatic frequency selection S transform can quickly and accurately identify the wave front with or without noise, the occurrence of the fault location positioning.