State-of-Charge Balancing and power sharing control method of energy storage system in DC microgrid

Abstract

State of charge (SoC) difference among the battery energy storage units (BEUs) easily causes the overcharge or over-discharge of the batteries. Different line resistances between the BEUs and the point of common connection (PCC) raises the problem of output power and SoC unbalance of the BEUs. This paper proposes a feedback control strategy to achieve both SoC balancing and output power sharing between the BEUs. The average of all the BEUs’ SoC is set as the SoC reference of each BEUs, and the control objectives are achieved by regulating the output voltage of the BEUs. Simulations verified that the proposed control strategy can achieve accurate SoC balancing and output power sharing with capacities.