Model Predictive Voltage and Power Control of Islanded PV-Battery Microgrids with Washout Filter Based Power Sharing Strategy

This paper proposes a new control strategy of microgrids for the improved voltage quality. In the existing control techniques, the droop control is commonly adopted as a decentralized power sharing method at the cost of voltage deviations. Besides, the conventional cascaded control featuring relatively slow dynamic response shows difficulties in handling the fluctuation of renewable energy outputs, leading to further voltage quality deterioration. In this paper, an advanced model predictive power control strategy by considering the battery constraints is proposed for the bidirectional dc-dc converters to smooth the solar photovoltaic (PV) outputs and stabilize the dc-bus voltages. A model predictive voltage control scheme taking into account the voltage changing trend is then developed to control the distributed inverters to improve the output ac voltages. Furthermore, a washout-filter-based power sharing approach with the plug-and-play capability is adopted to achieve a proper load sharing among parallel inverters and mitigate the voltage deviation. The proposed control strategy is numerically simulated in MATLAB/Simulink and experimentally verified by hardware-in-the-loop tests under the condition of fluctuating PV outputs and variable power demands. (This paper is accompanied by a video showing the hardware-in-the-loop test.)