Enhanced real time coordination of distance and user defined over current relays

In this research article, zone -2 setting of distance relays are made adaptive, so that minimum coordination time margin is maintained for complete reach of distance relays. User defined time inverse over current relays are proposed in conjugation with flexible feature of zone-2 setting of distance for improving the operating time of backup DOCRs. The performance of the proposed algorithm is validated in real time simulation with hardware in loop testing of numerical distance and user defined DOCR. From hardware in loop simulation results, it is observed that the performance of the proposed combined distance & DOCR coordination algorithm is in close concurrence with simulated results. The sensitivity of proposed algorithm is checked for different phase as well as ground faults with different fault resistance and it is also observed that the proposed algorithm is highly robust for different fault conditions.