A User Defined Characteristics Based Optimal Coordination Of Directional Overcurrent Relay for Microgrids

The integration of distributed generations (DGs) in the microgrids creates numerous diificulties to the present protection schemes. The magnitude and direction of fault current changes significantly in a microgrid upon DG allocation, that may lead to loss of coordination among the protective relays. This paper proposes a user-defined characteristics-based optimal relay coordination scheme for AC microgrids. The user defined characteristics involve constants that adjusts the nature of the relay characteristics as variable controllable parameter that are optimally decided along with time multiplier setting (TMS) by chaotic cuckoo search (CCS) algorithm. The performance of the CCS algorithm is tested on IEC 61850 microgrid model penetrated with and without DGs. The proposed scheme is tested and also compared with existing standard relay characteristics-based scheme. Extensive case studies are carried out in the microgrid interfaced with mixed type of DGs such as inverter-based and induction-based DGs to demonstrate the efficiency of the proposed CCS algorithm-oriented relay coordination technique for designing a good protection method suitable for AC microgrids.