Supervised Tripping and Blocking of Distance Relays

This paper introduces a new scheme for supervised tripping and blocking of distance relays using the data from phasor measurement units (PMUs). The proposed scheme utilizes fault detection, double ended fault location algorithm and expert system rule sets to arrive at a decision whether to trip or block the backup protection. Conventional distance relays encounter challenges in the form of parallel line operation, mutual coupling effect, fault resistance etc. These issues are well addressed by the proposed scheme in a reliable manner and the concept is supported by the case studies.