Journal of Power Electronics

The Korean Institute of Power Electronics (전력전자학회)
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State‑of‑charge adaptive balancing strategy for distributed energy storage units with line impedance compensation

  • Wei Fang (School of Electrical & Information Engineering, Anhui University of Technology) ;
  • Mi Zhou (School of Electrical & Information Engineering, Anhui University of Technology) ;
  • Leiyu Wang (School of Electrical & Information Engineering, Anhui University of Technology) ;
  • Qingping Shi (School of Electrical & Information Engineering, Anhui University of Technology) ;
  • Xiaodong Liu (School of Electrical & Information Engineering, Anhui University of Technology) ;
  • Qianjin Zhang (School of Electrical & Information Engineering, Anhui University of Technology)
  • Received : 2024.11.14
  • Accepted : 2025.03.17
  • Published : 2025.11.20
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Abstract

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.

Keywords

Acknowledgement

This work was supported in part by the National Natural Science Foundation of China (52277169). The authors also wish to thank the Key Lab of Power Electronics & Motion Control Anhui University of Technology for their support.

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