An Accelerated Single-Pole Trip Scheme for Zone-2 Faults of Distance Relays

This study presents a new accelerated single-pole trip scheme for distance relays zone-2 single-phase-to-ground faults. A novel nonpilot scheme for detecting the remote-end circuit breaker (CB) operation based on measured signals of unfaulted phases is presented. The proposed method is founded on mutual coupling characteristics of different fault stages between faulted and unfaulted phases. Single-pole tripping of the remote-end CB causes variation of induced voltage on unfaulted phases. The current signals due to this variation are utilized as indicators to issue the accelerated single-pole trip command. The algorithm proficiency in various conditions is tested and impacts of different elements, such as fault resistance, fault location, tower configuration, etc., on its performance are analyzed. Implementation of the new accelerated trip method results in dependability improvement, while it has no adverse effect on the protection security. Extensive simulation results confirm that the proposed method is well capable of protecting internal faults and provides a fast, accurate, and reliable protection technique.