Reserch on Model Predictive Control-Based Single-Stage Photovoltaic System During Grid

The single-stage grid-connected photovoltaic (PV) system receives widely attention due to the higher efficiency and lower cost comparing to two-stage system. The control strategy of the single-stage system combines model predictive control (MPC) and maximum power point tracking (MPPT) control to maintain the DC voltage and extract maximum possible power from PV array. However, the conventional setting method is unsuited to single-stage system and fails to reflect the over-modulation risk during grid voltage swell. To find out the reasons, the relationship between PV voltage, grid voltage and output power will be analysed. Hence a new calculation method to evaluating the minimum required DC voltage. And the operating mode of the MPPT control will be discussed under different conditions. Finally, several simulations are carried out to test the performance of the MPC-based single-stage system and verify the correctness of the proposed theoretical analysis.