DC Microgrids: Economic Operation and Enhancement of Resilience by Hierarchical Control

The additional deployment of distributed energy resources (DERs) has attracted further attention to dc microgrid applications. The objective of the study is to discuss the possibilities and the merits of adopting a dc control system for enhancing the economics and the resilient operation of a dc microgrid, and to test the proposed hierarchical control strategy that applies to a dc microgrid. This paper provides case studies in which an existing microgrid at the Illinois Institute of Technology (IIT) is operated as a dc microgrid and the results for each case are compared with the ac model. The structure, components, and control strategies of IIT dc microgrids are discussed and the economic operation of a grid-connected dc microgrid through tertiary control, as well as islanding, load restoration, and resynchronization of the dc microgrid are simulated. The dc microgrid simulation results are compared with those of an ac microgrid, which demonstrate that the proposed coordinated dc strategy for the optimal operation of DERs is an effective way of ensuring the resilient response of dc microgrid to emergencies and its economic operation at steady state.