The characteristics of microgrid inverter to compensate the voltage sags are theoretically analyzed. Microgrid inverter is influenced by system voltage distortions and harmonics when it is connected into the grid normally. In order to solve the problems, based on an analysis of the performance of the VPI controller, a PVPI control method is proposed which adds an independent proportional term and then applies it in energy storage grid-connected inverter control. Furthermore, a double mode control strategy is presented which makes the inverter realize grid-connected generation control and based on the practical situation converts to PCC voltage sag compensation. Positive sequence and negative sequence PVPI controllers are used to make closed-loop feedback control on positive sequence components and negative ones respectively. Simulation results verify the validity of the proposed control strategy.