Study On The Fault Location Of Transmission Line Based On Wavelet Analysis

Fast and accurate faults location of transmission line is an important research topic in power system analysis, and it is important to insure power system work normally again. This dissertation focuses on applying wavelet analysis to detect the time faults occurred and to calculate faults'distance of the transmission line.This thesis contains four parts. Firstly, based on the introduction of the wave course of transmission, the effect of coupling among three phase lines can be solved by phase-mode transform. Then the echo and refraction of traveling waves at the discontinuous spot of impedance, such as fault point or bus bar, are analyzed and the corresponding methods of eliminating disturbance are proposed. Secondly, the singularity detection theories of wavelet analysis are applied to the study of transient traveling wave fault characters. Through modulus maxima of the wavelet transform, the fault phase can be selected and fault traveling wave can be extracted. Thirdly, the mathematical morphology theories are introduced to noise reduction of fault traveling wave and morphology wavelet arithmetic is proposed. Morphology wavelet is more effectively compared with wavelet arithmetic on pulse noises. Lastly, traveling wave fault location arithmetic avoiding wave speed influence is presented. Transmission line models are constructed with Matlab/Simulink and the simulation results suggest that the arithmetic was valid to improve the fault location precision.