SOC Balancing Scheme of Microgrid Lithium Battery Energy Storage System Considering SOH

The existing state of charge (SOC) balancing scheme of the lithium battery energy storage system (LBESS) does not consider the state of health (SOH) of LBESS in the process of energy distribution, which results in an inability to reduce SOH balancing errors and increases maintenance costs for LBESS. To solve this problem, an SOC balancing scheme for LBESS of microgrids considering SOH is proposed. In this scheme, SOC equalization factor and health status factor (HSF) are introduced into droop control, and the power output of LBESS inverter is adjusted according to SOC and SOH status so as to achieve SOC balancing and reduce SOH imbalance errors. Simulation and experimental results demonstrate that the proposed SOC balancing factor and HSF can maintain SOC balancing and reduce SOH balancing difference even under load fluctuations by adjusting the output active power of LBESS. With the implementation of SOC balancing, its SOC balancing factor becomes zero, thereby achieving a frequency stabilization effect. In addition, the proposed solution has good effects in multiple LBESS scenarios and LBESS charging processes.