Research on the Stability Strategy of Weak Grid of Photovoltaic Grid Connected Inverter based on MPC

Abstract

This paper proposes a model predictive control (MPC) algorithm for the stability control of Photovoltaic grid-connected inverters in weak grid. In the case of weak grid, the stability of inverter is greatly reduced because the grid impedance can not be ignored, and the effect is greatly reduced. Therefore, this paper will study the stability mechanism of three-phase grid connected inverter in weak grid, establish a wide band model, and compare and analyze the stability of traditional PI control and model predictive control under PLL interference in weak grid. The simulation model of three-phase grid connected inverter is built by using MATLAB / Simulink. The simulation and experimental results show that the difference between the output voltage and the given voltage of the proposed algorithm is significantly smaller than that of the traditional PI control algorithm in the case of weak grid, which improves the output voltage quality of the inverter and greatly improves the stability of the output voltage.