Control method and system for grid connected inverter of fault power grid

The invention provides a control method and a system for a grid connected inverter of a fault power grid. The method comprises steps of obtaining a voltage signal of a faulted power grid, converting the voltage signal to an Alpha voltage component and a Beta voltage component in a stationary coordinate, determining a positive sequence voltage component up=uAlphap+juBetap and a negative voltage component un=uAlphan+juBetan, calculating the amplitude and the phase of the positive sequence voltage component and the negative sequence voltage component of the voltage of the faulted power grid according to the positive sequence voltage component and the negative sequence voltage component of the faulted power grid signal, calculating a positive current component and a negative sequence current component of control current according to the positive sequence voltage component amplitude, the phase, the negative sequence voltage component amplitude, the phase and the setting power of the faulted power grid voltage, forming a PWM control signal according to the positive sequence current component and the negative sequence current component of the control current and controlling the grid connected inverter to operate to output the grid connected current. The invention realizes the accurate control of the grid connected inverter of the faulted power grid, greatly simplifies the calculation process and improves the corresponding speed.