Supervising distance relay during power swing using synchrophasor measurements

Abstract

Power swing blocking (PSB) is essential for distance relay to avoid unintended tripping of transmission lines. Conventional PSB techniques, which use local information, may not be able to distinguish power swing from fault for all system conditions. An accurate PSB algorithm is proposed in this study, which uses synchrophasor measurements to distinguish power swing from fault. During power swing, the impedance trajectory is predicted for next ten cycles to block the distance relay operation reliably. The prediction approach overcomes the latency issue with synchrophasor data in order to initiate the blocking decision for zone 1/zone 2 of distance relay well in advance. The proposed method is tested for two-area four-machine and ten-machine 39-bus systems under different conditions simulated in power systems computer-aided design/electro-magnetic transient design and control software and compared with conventional method. Execution time of the proposed method including latencies in data arrival are considered in the test results.