Muhammad Cahyo Bagaskoro, Aripriharta, Muhammad Afnan Habibi, Gabrielley Ferdhiansyah Riyadi

State of Charge Balancing Analysis Using Droop Control on Energy Storage System

Introduction

State of charge balancing analysis using droop control on energy storage system. Dynamic droop control balances State of Charge (SOC) in BESS for DC microgrids. Ensures uniform SOC, optimizes energy distribution, and enhances renewable energy integration reliability.

Abstract

The growing energy crisis has driven the global shift toward renewable energy development. Governments are taking significant steps by promoting diverse sources such as photovoltaic (PV), wind turbines, and battery systems. Among these, Battery Energy Storage Systems (BESS) play a crucial role in decentralized energy generation, especially in DC microgrids. Within BESS, Battery Energy Storage Units (BESUs) are vital components, where monitoring the State of Charge (SOC) is essential. The Coulomb Counter (CC) method is widely used due to its reliability in SOC estimation. This study introduces a dynamic SOC balancing strategy using droop control, aiming to maintain uniform SOC across multiple BESUs. The proposed method regulates BESU discharge behaviour to achieve SOC parity and optimize energy distribution throughout the microgrid. Simulations under various operating scenarios charging and discharging modes with different SOC levels were conducted using the MATLAB/SIMULINK® environment. The results show that the control approach effectively equalizes SOC levels under non-uniform initial conditions. The balancing duration varied according to the initial SOC difference, highlighting the controller's adaptability. Although the study did not directly measure battery lifespan or energy efficiency, enhanced SOC uniformity is expected to reduce current imbalances and operating stress, potentially improving long-term system reliability. This research offers valuable insights into the control and management of BESS, supporting the stable integration of renewable energy in modern microgrid applications.

Review

This paper addresses a critical challenge in Battery Energy Storage Systems (BESS) within DC microgrids: maintaining uniform State of Charge (SOC) across multiple Battery Energy Storage Units (BESUs). In the context of growing renewable energy integration and the global energy crisis, efficient and reliable BESS management is paramount. The authors propose a novel dynamic SOC balancing strategy that leverages droop control to regulate the discharge behavior of individual BESUs. The primary objective is to achieve SOC parity and optimize energy distribution, thereby enhancing the overall stability and performance of the microgrid system. The study highlights the importance of robust SOC monitoring, for which the Coulomb Counter method is utilized for estimation. A significant strength of this research lies in its clear demonstration of the proposed droop control strategy's effectiveness. Through comprehensive simulations conducted in MATLAB/SIMULINK® under various operational scenarios, including diverse charging and discharging modes and non-uniform initial SOC levels, the authors effectively show that their control approach successfully equalizes SOC levels. The results particularly emphasize the adaptability of the controller, as the balancing duration was shown to vary appropriately with the initial SOC difference. While direct measurements of battery lifespan or energy efficiency were not performed, the paper logically posits that enhanced SOC uniformity is expected to lead to reduced current imbalances and operational stress, which are crucial factors in improving long-term system reliability and battery longevity. Despite its valuable contributions, the study presents an opportunity for further empirical validation and deeper analysis. The absence of direct measurements for battery lifespan and energy efficiency, while acknowledged, represents a limitation that future work could address through more extensive experimental setups or advanced modeling. Incorporating these metrics would provide a more holistic understanding of the control strategy's long-term practical benefits and potential trade-offs. Nevertheless, this research offers valuable theoretical and simulation-based insights into the intelligent control and management of BESS. Its findings are highly relevant for advancing the stable and efficient integration of renewable energy sources within modern microgrid applications, laying a solid foundation for future development in this critical area.

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