Control Strategy of Grid-connected Inverter Based on Multistage Hysteresis Regulator Under Asymmetrical Grid Conditions

The effective control of a grid-connected inverter under asymmetrical grid condition is able to enhance the grid-connected operation capability of the inverter. This paper studies a control scheme of 3-phase grid-connected inverter with multistage hysteresis current regulators on the alpha beta reference frame. Under the condition of asymmetrical grid, the celerity of the multistage hysteresis is fully taken advantage of to control both positive and negative current component directly without any decomposition and grid -connected current requirements are satisfied by controlling negative sequence current of the grid to zero, suppressing active or reactive power second pulsations. Three control targets are respectively achieved through simulation.Simulation results demonstrate the effectiveness and correctness of the method.