Adaptive protection schemes for the microgrid in a Smart Grid scenario: Technical challenges

Microgrids are gaining attention as an important part of the smart grid, due to their numerous benefits and their ability to operate both in the island mode as well as in the grid connected mode. However, a protection scheme which suits to a microgrid both in the island mode and the grid connected mode of operation is a challenge. The conventional overcurrent protection scheme faces selectivity and sensitivity issues during the grid faults and the microgrid faults, since the fault current level is different in both the cases for the same relay. Various approaches have been implemented in the past to deal with this problem yet the most promising ones are the adaptive protection techniques. The feasibility, reliability and cost benefit issues are some major concerns which are associated with the implementation of the adaptive microgrid protection schemes. This paper presents a critical review of the existing adaptive protection schemes, the technical challenges, if any, and the recent advancement concerning to their suitability to operate in a smart grid scenario.