A Fully Decentralized Control Approach for Hybrid Energy Storage System in DC Microgrids Based on Fractional Order Voltage Compensation

Recently, power networks are observing high-level integration of renewable energy, direct current (DC) loads, and energy storage devices. As a result of more power electronic-based components integration, the conventional alternating current (AC) microgrid is gradually transforming to DC microgrid. However, DC bus voltage control and power-sharing among energy storage devices are challenging tasks. This study proposes a new voltage compensation control strategy for DC microgrids based on fractional-order differential-integral (FODI) controller. In the proposed approach, a voltage compensation term which is processed by the FODI controller is added to the droop control loop. The advantages of the proposed controller are manyfold such as autonomous bus voltage restoration, power split between battery and supercapacitor, and autonomous state of charge (SOC) control. The DC microgrid consisting of battery, supercapacitor, and DC loads is simulated in MATLAB Simulink. The results show that the proposed controller is superior to the conventional controller in controlling DC bus voltage, active power, and SOC.