Filtering and processing of harmonic signals using averaging technique in digital relays

This is a fact that Digital Relay systems deal with harmonic signals. Switching convertors are one of the most significant generators of such signals. Filtering and processing of harmonic signals are considered as very important factors in the process of power systems controlling. In this study, typical harmonic signals are processed using Averaging Technique. Also this work considers the A.T's (Averaging Technique) property in modeling the prevailing behaviors and presents a method, that is comparable to low-pass filter (specially type one), for filtering operation that could be used in Digital Relays. In order to evaluate the proper functioning of the mentioned method, we have utilized distortion indexes such as THD, TIHD and TSHD. In fact one the main goals of this paper is that to present a method which can be applied for attaining the most minimal harmonic pollution (in comparison with the low-pass filter)in digital relays. In Averaging Technique, the Averaging Frequency is highly significant yet in low-pass filter, the important factors are gain factor, cutoff frequency and damping factor. Finally, in this paper we compare the efficiency of Averaging Technique with two types of low-pass filter.