Adaptive Coefficient-based Power Sharing Scheme for Balanced State of Charge in DC Microgrids

Direct current microgrids (DCMGs) have gained significant attention due to reduced power conversion stages and improved power management opportunities. In DCMGs, battery energy storage systems (BESSs) enhance system reliability through appropriate management of energy in the system. This paper focuses on a system comprising multiple DCMGs, each integrating solar photovoltaic (SPV) generation, BESSs, and load demand. A key challenge in such systems is ensuring balanced state-of-charge (SoC) levels among connected BESSs to prolong their lifespan and improve operational efficiency. This paper proposes a novel adaptive coefficientbased power-sharing scheme (PSS) for connected BESSs in DCMGs. The adaptive coefficient, which is the core novelty of the proposed strategy, is derived using a fuzzy inference system with two inputs: net mismatch power and the SoC of individual BESS. During charging, BESSs with lower SoC receive a higher proportion of the total charging power, while during discharging, BESSs with higher SoC contribute more power to the load demand. The proposed PSS addresses the issues of slow SoC equalization and uneven current sharing across interconnected DCMGs. Simulation studies are carried out on the MATLAB<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup> Simulink platform, considering three distinct scenarios based on varying SoC conditions of BESSs, SPV generation, and load demand. The results validate the effectiveness of the proposed approach in achieving faster SoC balancing, efficient power distribution, and enhanced operational stability in connected DCMGs.