In order to solve the problems of grid current impact and output power overshoot caused by the switching between the two working modes of remote island and grid connection of the microgrid inverter

an improved dual- mode unified control strategy was designed on the basis of droop control

drawing on the control of virtual synchronous machine

adding an inertia adjustment unit in the active droop control

and adding an integral link in the active and reactive droop control at the same time. While suppressing the impact of the incoming current

the system power is stably output at the rated value

and combined with the active pre- synchronization control of the grid

the smooth switching of the inverter's off/on- grid mode is realized. The simulation results verify the effectiveness of the control strategy proposed in this paper

and the inverter can achieve stable control of output power in both off- grid and grid- connected modes

and there is no voltage and current impulse when the mode is switched.