Grid-connected Inverter Control Strategy Based On Capacitor Reference Voltage Feedforward

Abstract

In view of the disadvantage that grid-connected power is not high and the phase margin of the grid-connected current is greatly reduced with the increase of impedance of many grid voltage feedforward control strategies. A grid-connected inverter control strategy based on capacitor reference voltage feedforward is proposed. In this control, the error between the filter capacitor voltage and its reference voltage is combined with the proportional controller as the inner loop control, the error between the inverter side current and its reference current is combined with the current controller as the outer loop control to improve the robustness of the system. The phase difference between grid-connected current and grid voltage is reduced by using capacitor reference voltage feedforward. In addition, by using the grid voltage resonance feedforward, the system can not only retains the ability to suppress harmonics, but also prevents the system’s phase margin from decreasing greatly under weak power grid. The proposed strategy has good dynamic performance, it can obtain good grid-connected current quality and high grid-connected power, and it has strong robustness to the change of LCL parameters and the fluctuation of grid voltag. At the same time, it has better adaptability to weak power grid.