Energy Management Strategy for Supercapacitor in Droop-Controlled DC Microgrid Using Virtual Impedance

With a proper energy management strategy (EMS), supercapacitor can be integrated into droop-controlled dc microgrid as an independent supercapacitor energy storage system (SCESS). The resulted microgrid could supply repeatedly quick bursts of electrical power due to load or source transients and improve power quality and lifetime of other distributed generations (DGs) or distributed energy storages. In this paper, a novel control strategy for SCESS is proposed. The method uses the virtual impedance loop to add a virtual resistor and a virtual capacitor connected in series between the converter and dc bus, which decouples power flow between SCESS and other DGs while ensuring the plug `n' play feature. The results show that the proposed EMS has a competing dynamic performance with excellent flexibility as compared to existing methods.