A Novel Control Strategy to Share Power among Dispatchable Battery Sources and Achieve SOC Balancing without a Droop Control in a DC MicroGrid

Abstract

In a DC microgrid, several batteries with their converters are controlled to share the load power among themselves. Battery power management strategies are incorporated to charge and discharge the batteries. The life of the storage system can be maintained properly by avoiding overcharging, limiting current and deep discharging of batteries. Along with the battery management to improve reliability and power sharing, the SOC balancing of all the batteries also needs to be achieved. A novel control strategy is proposed in this paper to share the power among the batteries according to their power ratings and SOC. In the proposed scheme, a common time reference is generated according to the discharging or charging power demand. The proposed strategy does not require sensing of the output current of the converters. This reduces the overall complexity and cost of the system as compared to the droop control system. Low speed communication is adequate to convey the reference time for the controllers of the other batteries. The batteries are charged or discharged at the same time due to the SOC balancing. The simulation and hardware results validate the working of the proposed control scheme.