Detection of transmission line-fault through CWT based Bewley lattice diagram

Abstract

Any sudden change in power line produces high frequency electromagnetic impulse called travelling wave (TW). Continuous Wavelet Transform (CWT) can detect transmission line abnormalities. CWT has several advantages over Discrete Wavelet Transform (DWT) since CWT is continuous in terms of shifting and it can operate on any scale. Bewley's lattice method, which is a method of detection of fault location from TW, does not consider the noises and interferences. Noises and interferences modify the TW signals. In this paper a novel CWT based Bewley's lattice method of transmission lines-fault detection is presented. The main difference between the conventional CWT method and the method described in this paper is the accumulation of CWT coefficients at all scales. In the proposed method, the coefficients related to transmission line abnormalities are enlarged while the coefficients of noises at different scales counteract one another. The proposed CWT based Bewley's lattice method is more accurate than conventional Bewley's lattice or DWT/CWT based methods.