Mitigating the impact of distributed generation on directional overcurrent relay coordination by adaptive protection scheme

Distributed Generation (DG) brought new challenges for protection engineers since standard relay settings of traditional system may no longer function correctly under the new conditions of DG. The extreme case is coordination loss between primary and backup relays. The directional overcurrent relay (DOCR) which is the most implemented protection device in the electrical network also suffers performance degradation in presence of DG. Therefore, the paper proposes the mitigation of DG impact on DOCR coordination employing adaptive protection scheme (APS) using differential evolution algorithm (DE). The impacts of DG prior and after the application of APS are presented and a new mitigation scheme is proposed.