Adaptive coordinated droop control for multi-battery storage

DC distribution grids are more and more considered an attractive solution to integrate renewable energy sources because of good matching with dc output voltage such as photovoltaic (PV) array systems, electric vehicles and distributed battery energy storage systems (BESS). To overcome the control problems involving coordination control schemes of multi-BESSs in real-time as well as optimized operation strategies of dc grids in long-term, this paper presents the adaptive coordinated droop control of multi-distributed battery energy storage systems in DC distribution grids. The adaptive coordinated droop is proposed to force real-time state of charge of BESS to track on the optimized scheduled state of charge (SOC) in long-term. Furthermore, in this approach, the energy storage units (ESUs) with higher SOC dispatch more power, while the ones with lower SOC dispatch less power. The SOC difference among ESUs exponentially reduces and finally the exchange power is equally shared between the distributed ESUs. Meanwhile, the exchange power share speed can be adjusted by changing the exponent of SOC in the adaptive coordinated droop control.