Research On Transmission Line Faults Location Based On Wavelet Analysis

Transmission line's fault occurs regularly in power system. Accurate fault location can reduce the time to find out the fault point and the cost of power transmission line's cut.This paper analyzes the transient state processing of the power system, the cause of the fault traveling wave, and the equivalent model of fault traveling wave. With the distributing parameter model of the transmission line, the spread character of the fault traveling wave along the transmission line has been theoretically analyzed. The branches of traveling wave protection have been discussed and the theories have been given. According to the coupling of the three-phase traveling wave signals, a new method is given by phase-module transform.This paper summarizes the methods of fault location of the transmission lines at present. Aimed at the key problem of traveling wave location--accurate extraction of fault times, a new method using the wavelet transform is brought out which can detect and analyze the transient fault signals. The basic concept and character of wavelet transform are introduced, and the discrete fast wavelet wave transform algorithm has been deduced by the theory of multi-resolution analysis. The practical problems in the fault detection and fault location using the wavelet transform, such as the wavelet basis function, the initial data, the velocity of traveling wave are studied.This paper introduces the traveling wave signal source selection principles and the traveling wave signal extraction methods, and gives the maximum value of the wavelet transform modulus coefficient method to determine the signal singular point. According to the model of practical power system transmission line, simulation results show that the wavelet analysis is availability and accurate in the traveling wave fault times extraction. The simulation results of the single terminal method and the double terminals method have been analyzed, and the advantage and disadvantage of both methods are pointed out, and the practical way of using both methods are given.This subject matter is very meaningful to improve the detection of transmission line's fault and to perfect the safety and reliability of power transmission system. In addition, it helps the research of application of wavelet theory in transmission line's fault location in the future.