Improving relay reach and speed through a hybrid algorithm

A standard distance relay is usually set to operate for a fault within 80% of the length of the line being protected. The paper describes how the reach of such a relay can be increased without an end-to-end communication channel and the zone 2 element of an impedance relay can be utilized to improve fault detection speed. The proposed method is not only reliable, but also capable of detecting faults quickly. An added advantage is the ability of the relay to accurately calculate the distance to the fault from the relay location. The algorithm was tested for different fault conditions through simulations using PSCAD and the results for a few cases are presented in the paper.