Wavelet transform approach to distance protection of transmission lines

An application of wavelet transform to digital distance protection for transmission lines is presented in this paper. Fault simulation is carried out using the Power System Computer Aided Design program (PSCAD). The simulation results are used as an input to the proposed wavelet transform protection-relaying technique. The technique is based on decomposing the voltage and current signals at the relay location using wavelet filter banks (WFB). From the decomposed signals, faults can be detected and classified. Also the fundamental voltage and current phasors, which are needed to calculate the impedance to the fault point can be estimated. Results demonstrate that wavelets have high potential in distance relaying.