DC microgrid with variable generations and energy storage

DC microgrid operation with variable sources is studied in this paper. A 3-level hierarchical DC voltage control is proposed which corresponds to grid connected operation, islanding operation, and load shedding/generation curtailment operation. The system operational status is verified according to voltage levels and corresponding control strategies are used according to voltage levels to secure system stability. A 4-terminal prototype microgrid comprising a grid connected VSC, a wind generator, an energy storage system, and DC loads is established to demonstrate the excellent operation performance of the proposed control system during various operating conditions such as load step, islanding, grid reconnection, and load shedding.