State‑of‑charge adaptive balancing strategy for distributed energy storage units with line impedance compensation

The charge/discharge of distributed energy storage units (ESU) is adopted in a DC microgrid to eliminate unbalanced power, which is caused by the random output of distributed energy and load fluctuation. However, the difference of line impedance causes diversity in the state-of-charge (SoC) between ESUs, which can lead to overcharging or overdischarging. Thus, this study proposed an adaptive SoC balancing strategy under weak communication by associating the droop coefficient, the output current, and the SoC of ESU. The integral of the local output current was introduced in the iteration of the line impedance compensation, while the local iteration signal was updated synchronously. With low bandwidth communication, the consistency algorithm considered the iteration signal of neighboring ESUs and was used to judge the finished compensation. Moreover, the compensated line impedance and the SoC were introduced into the adaptive droop law. Hence, the current sharing and SoC balancing of ESUs were guaranteed. The convergence proof of the iteration and the stability of the control system were presented in detail. Finally, an experimental prototype with several ESUs was built to verify the feasibility and effectiveness of the proposed strategy.

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Cite this article

[IEEE Style]

W. Fang, M. Zhou, L. Wang, Q. Shi, X. Liu, Q. Zhang, "State‑of‑charge adaptive balancing strategy for distributed energy storage units with line impedance compensation," Journal of Power Electronics, vol. 25, no. 11, pp. 2103-2113, 2025. DOI: 10.1007/s43236-025-01041-1.

[ACM Style]

Wei Fang, Mi Zhou, Leiyu Wang, Qingping Shi, Xiaodong Liu, and Qianjin Zhang. 2025. State‑of‑charge adaptive balancing strategy for distributed energy storage units with line impedance compensation. Journal of Power Electronics, 25, 11, (2025), 2103-2113. DOI: 10.1007/s43236-025-01041-1.