A distance relay algorithm based on the phase comparison principle

Abstract

In this paper we propose a distance relay algorithm based on a time-domain phase comparator with a smaller computational burden than the traditional phasor-domain based algorithms. The phase comparator used in the time-domain algorithm is based on the average power on a half and full-cycle data window. The algorithm includes a filter which mitigates decaying DC-offset in the current as well as the capacitive coupled voltage transformer transients. The algorithm is compared to an algorithm based on the phasor-domain approach with full-cycle DFT. Both algorithms are tested on various fault locations, fault resistances, load directions, inception angles and SIR. This paper also includes analysis of the complex frequency response of the complete time-domain algorithm, and how the protected zone for a chosen operating characteristic depends on the line load and SIR.