Control strategy of multiple energy storages system for DC microgrid

This paper proposes a power management strategy of multiple energy storages system for DC microgrid. A static power flow regulation between batteries is accomplished by adopting adaptive droop offset voltage. By addition of offset voltage proportional to state-of-charge (SOC) error, the battery with higher SOC provides more load power while the one with lower SOC provides less. In addition, the dynamic power control allocates power demand for transient between the battery and the supercapacitor. With this method, the battery responds to long-term power demand, while the supercapacitor absorbs only short-term power demand. In this way, the energy storages are managed to equivalently extend the expected lifetime of batteries and reduce the size of supercapacitor. Simulation and experimental results for 48V DC microgrid system verify the proposed control method.