Open Access

ARTICLE

SOC-Constrained Virtual Inertia Control of Hybrid Energy Storage Systems for Frequency Stability Enhancement

Qing Zhi¹, Jin Guan¹, Ruopeng Zhang¹, Lixia Wu¹, Shuhui Zhang¹, Xinyu Xue², Caifeng Wen^2,*, Yunlong Zhao²
1 Inner Mongolia Power (Group) Corporation Limited–Inner Mongolia Power Research Institute Branch, Hohhot, China
2 School of Energy and Power Engineering, Inner Mongolia University of Technology, Hohhot, China
* Corresponding Author: Caifeng Wen. Email:

Energy Engineering https://doi.org/10.32604/ee.2026.082562

Received 18 March 2026; Accepted 01 May 2026; Published online 02 June 2026

Abstract

With the increasing integration of renewable energy sources, grid frequency stability has become a major concern, placing higher demands on the dynamic response capabilities of frequency regulation resources. Energy storage systems, with fast response and bidirectional regulation capabilities, demonstrate significant value in frequency control. To address insufficient regulation of the state of charge (SOC) in existing methods, this study proposes a novel frequency regulation control approach for grid-side standalone energy storage stations. The system integrates a supercapacitor with a lithium-ion battery, allocates power hierarchically through low-pass filtering, and implements a virtual synchronous generator (VSG) control mechanism on the grid-connected side to enhance system inertia support. Furthermore, the mapping between charging/discharging coefficients and SOC is refined and embedded into an adaptive virtual inertia control framework, enabling coordinated SOC regulation and enhancing system dynamic performance. Simulation studies are performed using MATLAB/Simulink. The results show that the method significantly improves frequency response, enables more balanced power sharing in hybrid energy storage systems, and mitigates overcharging and over-discharging, thereby enhancing overall operational safety.

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Keywords

Independent energy storage power station; virtual synchronous generator; hybrid energy storage system; virtual inertia support

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