Walsh digital filters applied to distance protection

Distance relays must estimate accurately and quickly the distance to the fault even in presence of highly distorted input signals. Several digital filtering algorithms for distance relays have been proposed and some of them are used in practical applications. However nonlinear loads are becoming more and more common in electric power systems and that increases the corruption level of signals. For this reason, the study of digital filtering techniques for the extraction of fundamental components from highly corrupt voltage and current waveforms is of vital importance for the development of algorithms applied to the digital protection of transmission lines. The studied technique, proposed in this paper, is based on Walsh functions.