Control method and device of grid-connected inverter, controller, grid-connected system and medium

The invention provides a control method and device of a grid-connected inverter, a controller, a grid-connected system and a medium. The control method of the grid-connected inverter comprises the following steps: when the grid-connected inverter is in an overcurrent protection state, monitoring an inversion output current of the grid-connected inverter; when the inversion output current of the grid-connected inverter is smaller than or equal to a preset current return difference value, the grid-connected inverter is controlled to be switched from an overcurrent protection state to a normal working state; wherein the preset current return difference value is smaller than or equal to the rated output current of the grid-connected inverter, and the preset current return difference value is larger than zero. According to the invention, during the high voltage ride-through period, when the grid-connected inverter is in the overcurrent protection state, and the inversion output current of the grid-connected invert