Accurate Power Sharing and Synthetic Inertia Control for DC Building Microgrids With Guaranteed Performance

Abstract

Direct current (DC) building microgrids allow the integrations of DC distributed energy resources (DERs) and loads with a simpler topology and the elimination of alternating current (AC) system issues, such as frequency transients and harmonics. Because of the domination of power-electronics-interfaced generators, islanded DC microgrids in general present very low inertia, which reveals subtle stability threats to the systems. In addition, the conventional droop-based DER power-sharing mechanisms may suffer from poor power-sharing accuracy and DC bus voltage deviations that require secondary restorations. In this paper, a novel control scheme for building-scale islanded DC microgrids is proposed based on finite control set model predictive control (FCS-MPC). A new DER power-sharing mechanism is devised by introducing a current-sharing vector in the controller formulation, which eliminates bus voltage deviation during load/DER fluctuation and offers plug-and-play capabilities. Moreover, for the first time, virtual capacitance control for DC microgrids is implemented in an FCS-MPC manner to enhance the adaptive synthetic inertia of DC bus. Both the simulation and experimental case studies are carried out to provide verification for the promising performance of the proposed method.