Disclosed in the present invention are a grid-connect control method and apparatus for a grid-connect
inverter. The method comprises: on the basis of a control structure of a grid-connect
inverter in a dp domain, passing a deviation
signal of a power outer loop through power outer loop controllers, so as to generate reference values of a current
inner loop, and comparing the reference values of the current
inner loop with an actual output current, so as to obtain error signals, wherein the control structure comprises a PQ
power control outer loop and a current control
inner loop, and the actual output current is obtained by means of performing phase tracking, on the basis of a synchronous
reference frame phase-locked loop, on the
voltage of a
point of common coupling; and adjusting the error signals by means of a current inner loop controller, so as to generate modulation signals, performing
pulse width modulation (PWM) on the modulation signals, so as to generate an on-off
signal of an
inverter bridge
power semiconductor device, and controlling the state of connection and disconnection between the grid-connect inverter and a
power grid on the basis of the on-off
signal. In the present embodiment, the connection and disconnection between a grid-connect inverter and a
power grid are controlled, so as to improve the stability of the grid-connect inverter in weak power grids.