A Smooth Grid-connected Strategy for Photovoltaic-storage Virtual Synchronous Generator Based on Adaptive Model Predictive Control

The photovoltaic-storage unit based on virtual synchronous generator (VSG) control can work in two modes: islanding and grid-connected. When the island is transferred to the grid, there is a voltage and current impact problem due to the poor traditional control accuracy, and due to the mutual coupling between the frequency and the phase angle, a large frequency fluctuation will occur during the pre-synchronization process. Therefore, this paper pro-poses an adaptive-model predictive control (A-MPC) method for the optical-storage virtual synchronous generator unit in the above-mentioned mode switching process. On the basis of adopting a more accurate model predictive control (MPC) strategy, the frequency variation during the switching process is introduced to adjust the weighting coefficient of the MPC adaptively. A-MPC can improve the dynamic response of VSG-controlled converters in the pre-synchronization process and the operation mode switching process. Finally, the effectiveness and superiority of the control strategy proposed in this paper are verified by building a controller-level hardware-in-the-loop simulation experiment.