Small-Signal Modeling and Stability Analysis of Hybrid AC/DC Microgrids

The deployment of hybrid ac/dc microgrids is a promising alternative for using local distributed energy resources to serve both ac and dc loads. Hybrid ac/dc microgrids, like other types of microgrids, are subjected to dynamic instability when operated in island mode. This paper analyzes the small-signal stability of islanded hybrid ac/dc microgrids and proposes a droop-based control mechanism to coordinate the operation of ac and dc sections. A general approach is presented which uses a linearized state-space model of microgrids for establishing adequate stability margins in hybrid ac/dc microgrid operations. The proposed case studies are conducted to investigate the small-signal behavior of a hybrid ac/dc microgrid based on time-domain simulations and frequency-domain analyses.