Comprehensive protection of medium-voltage microgrids

Abstract

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.