Distributed Balanced Grouping Power Control for Battery Energy Storage Systems to Mitigate Adjustable Capacity Discrepancy

Conventional grouping control strategies for battery energy storage systems (BESS) often face issues concerning adjustable capacity discrepancy (ACD), along with reduced operational speed and accuracy, especially in delay environments. To address these challenges, this paper proposes a distributed grouping power control strategy based on bipartite grouping for BESS. First, the causes of ACD in battery groups (BGs) within BESS are analyzed. An ACD evaluation model is developed to examine the limited competition among BGs, and a new BESS grouping allocation mechanism is introduced. Next, a bipartite consensus algorithm (BCA) is adapted for power control using a normalized transformation matrix. Enhancements to the Laplacian matrix are proposed to compress delays and improve iteration speed and accuracy, resulting in an improved BCA (IBCA). Finally, the lBCA is implemented to achieve balanced power control according to the proposed grouping allocation mechanism. Both simulations and experimental results demonstrate that the lBCA provides faster iteration speed, higher accuracy, and effectively mitigates ACD, resulting in better state-of-charge balance and precise control.