Optimum coordination of directional overcurrent relays in presence of distributed generation

Distributed generation (DG) is commonly used to supply the local loads. The penetration of distributed generation leads to violate the relay coordination in distribution network. This paper presents the implementation of a fault current limiter (FCL) to limit the fault current contribution from DG, and thus restore the protection coordination. The restoration of protection coordination is carried out without changing the original relay settings or disconnecting DG from distribution network during fault conditions. Teaching learning based optimization (TLBO) algorithm is used to find optimum settings of overcurrent relays without considering the DG. The impact of DG is observed on protection coordination and FCL is used to restore the original relay settings. The obtained results are presented and discussed.