Cooperative Control between the Distributed Energy Resources in AC/DC Hybrid Microgrid

Increase of renewable energy resource (RES) and development of energy storage system (ESS) encourage a lot of researches in DC microgrid system. AC system is used in almost power system and it is not easy to change from AC system to DC system at once. Therefore, it is necessary for DC microgrid to be connected to existing AC microgrid or power system unless it is only operated in island mode. In this paper, a strategy on improving stability and reliability of AC/DC hybrid microgrid is proposed. Battery Energy Storage Systems (BESSs) are interfaced with both AC and DC microgrids to improve the system stability by P-f, Q-v, P-v(2) droop control. The AC/DC converters connected to DC microgrid maintain the DC voltage constant and balances the energy of whole system. The simulation results by PSCAD /EMTDC are analyzed in grid connected mode and island mode on a peak season of one small island.