Comprehensive protection of medium-voltage microgrids

Traditional protection schemes are not adequate for the protection of microgrids because of bidirectional flow in feeders and reduced fault levels in islanded operations, thus it is needed a new protection scheme. This paper proposes a protection scheme that primarily depends on differential protection. In the event of primary protection failure, a robust backup protection is developed to isolate the fault after a certain time delay. It should be noted that the proposed primary protection scheme is applicable irrespective of the operational mode. Meanwhile, communication system plays a critical role on the protection of microgrid in the proposed protection strategy. This protection scheme is simulated on an 18-bus distribution system containing a high penetration of distributed energy resources and the climes made in this paper are evaluated using simulations.