The Grid’s Fault Location Based On The Traveling Wave

When a fault happens on the transmission lines, it can produce the traveling wave spread to the ends of the lines. With deep analysis of the traveling wave principle, this article gives the wave equation. And thus, it obtains the principle of traveling wave reflection and refraction, and deduces the reflection and refraction coefficient, and provides a theoretical basis for the following traveling wave measurements. The fault location principle based on single-ended traveling wave and double-ended traveling wave were analyzed in detail. The single-ended traveling wave method has the advantages of high accuracy, but it has the problems about the algorithms immature and auto-ranging less reliable. Though the double-ended traveling wave has the advantage of high reliability of the automatic ranging, the accuracy is relatively low because of the line length and the time synchronization.This paper describes the advantage of wavelet transform on the traveling wave fault location, and the selection of wavelet base. The fast algorithm of wavelet transform was given to facilitate the automatic calculation of traveling wave fault location based on the wavelet transform modulus maxima value theory. It can find the exact time when the traveling waves arrive, thus it is able to be used for the fault location.How to obtain the traveling wave become the key of the traveling wave fault location. There are two types:one is using current transformer to obtain the current signal, the other is using a specially designed transformer to obtain the voltage signal. Getting the head of the traveling wave, the determination of the wave velocity, and the GPS time synchronization device are the factors affecting the traveling wave signal extraction, and based on which the solution can be obtained.Based on the wavelet transform modulus maxima theory, this article designs the ranging models of the fault traveling wave, and simulates with Matlab in ATPDraw software. The simulation of single-ended and double-ended traveling wave fault location model, and calculating the fault location using the voltage and current traveling wave, the results show that the single-ended traveling wave fault location devices can achieve high accuracy. Actually, single-ended traveling wave fault location and double-ended traveling wave distance measuring device used in combination, will give the traveling wave fault location higher accuracy and reliability.