Fast state-of-charge balancing control strategies for battery energy storage systems to maximize capacity utilization

Abstract

To improve the carrying capacity of the distributed energy storage system, fast state of charge (SOC) balancing control strategies based on reference voltage scheduling (RVSF) function and power command iterative calculation (PIC) are proposed in this paper, respectively. First, as an improvement to the traditional droop SOC balancing control, the working principle and parameters design of the RVSF-based method is introduced, which can realize the energy interaction among the storage units during the balancing process. The PIC-based fast SOC balancing strategy is then proposed for a system with a current bus sensor. The PIC strategy realizes the fastest SOC equalization speed by ensuring there is always at least one storage unit operating in the maximum power flow during the SOC balancing process. In addition, the proposed strategy is extended to the system with inconsistent energy storage unit capacity. Finally, circuit-based simulation and code-based models for a plan with different energy storage units are constructed in PLECS and MATLAB simulation software, respectively. The hardware in the loop simulation results validate the correctness and feasibility of the proposed strategies and show that the proposed techniques can significantly improve the load capacity and duration of the system under many operating conditions.