SOC-balancing droop control strategy using secondary voltage compensation for distributed energy storage units in islanded DC microgrids

doi:10.19799/j.cnki.2095-4239.2025.0047

Abstract

Abstract:

A distributed energy storage unit state-of-charge (SOC)-balancing droop control strategy based on secondary voltage compensation is proposed for islanded direct current microgrids to address issues of inaccurate power allocation and SOC imbalance in energy storage units, which can reduce battery lifespan. The control structure used to implement this strategy consists of two layers: a primary control layer and a secondary control layer. The primary layer ensures voltage stability through traditional droop control, while the secondary layer introduces a voltage compensation term derived from an arctangent function with balanced regulation. This strategy aims to achieve accurate current sharing based on each battery's SOC and capacity. Ultimately, the SOC of all batteries gradually converges to an average value, while the average output voltage remains consistent with the nominal voltage of the microgrid. The simulation and experimental results demonstrate that the strategy features a simple control structure, low communication burden, and improves the SOC balancing accuracy and efficiency of the energy storage units. In addition, it effectively protects batteries from overcharging and overdischarging under varying charge and discharge currents. The simulation and experimental results confirm the validity and effectiveness of the proposed control strategy.

Key words: DC microgrid, distributed energy storage, sag control, voltage compensation, state of charge

CLC Number:

TP 273.4

Xiaolan WU, Yongzhi YANG, Zhifeng BAI, Haichang GUO, Guifang GUO, Jinhua ZHANG. SOC-balancing droop control strategy using secondary voltage compensation for distributed energy storage units in islanded DC microgrids[J]. Energy Storage Science and Technology, 2025, 14(8): 3160-3169.

Figures/Tables 13

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