Secondary Control of Battery Energy Storages in Hybrid Microgrids

Interests in hybrid DC plus ac microgrids is surging due to the combination of renewable DC power sources, and dc and ac loads in commercial, industrial and residential applications. The dc section of the hybrid microgrid can be used to integrate various distributed dc sources like battery energy storage (BES), solar generation etc. Voltage in a dc microgrid needs to be maintained at a nominal value with a small margin of variation for smooth operation. The DC/DC converters of the BESs in the DC microgrid can be controlled by the microgrid secondary controller to maintain this voltage. This research proposes a secondary controller for DC/DC converters of BESs to maintain voltage at DC microgrid and share the loads among the energy storages based on their capacities in a distributed manner. Simulation results show that the proposed control strategy maintains DC voltage in the DC microgrid when there is a sudden change of load in the microgrid.