The Research On Identification Criteria Of Lighting In EHV Transmission Line Based On Wavelet Transform

EHV transmission lines have the characteristics of a transmission capacity, long distance power transmission,low line loss and less take up land,which as an increasingly important task in the power system.But at the same time,it puts forward higher requirements for the reliable operation of EHV transmission lines.In the transient protection of transmission line, lightning interference is the most common interference signals of high-frequency. When lightning interference occurs, it will produce high-frequency interference signals on the line. And if the signals have not be identified, which may cause malfunction of protection.This paper has made a thorough research about the characteristics of lightning directly stroke, lightning interference and short circuit fault on transmission line.And it has made a detailed study with the research about EHV transmission lines transient signal recognition.At last it has proposed a solution based on wavelet transform to solve the problem of signal identification.In this paper,it has built a transmission line model of500kV with Matlab,and made the simulation of lightning stroke fault, lightning interference and common short circuit faults respectively.This article has analyzed the energy distribution and waveform of transient current component signal on different circumstances, found the differences, put forward the criteria about distinguish lightning interference.lightning stroke fault and common short circuit faults. In this way, ultimately the purpose of identifying lightning interference, in order to ensure the protection will not malfunction.A large number of Matlab simulations has verified the correctness and validity of this method.