An adaptive overcurrent protection scheme for microgrids based on real time digital simulation

A microgrid can operate in grid-connected as well as islanded mode using the power available from distributed generation (DG) sources. As the mode of operation changes for the microgrid, the protection settings, i.e. current settings and time settings, for the relays need to be altered according to the change in the direction and fault current level. Moreover, the protection settings should also be updated considering the stochastic nature of the power available from the DGs. Hence, in this paper, an adaptive overcurrent protection relay scheme is proposed for microgrid protection. The proposed scheme is tested on a modified CIGRE test micro-grid simulated in real-time digital simulator (RTDS) for various case studies. Results obtained show that the proposed adaptive protection scheme can operate fast and accurately according to the changes in the network.