With the increase in microgrid scale and mixture of single phase and three-phase load

the phenomenon of voltage imbalance of microgrid is becoming more and more serious. In order to solve this problem

a three-phase output interconnection and controllable scheme of grid-tied inverter is proposed by using the characteristic that output voltage and current of the three-phase four-leg inverter can be decoupled and controlled independently. The output power of each phase is adaptively controlled according to the voltage unbalance degree. On the basis of establishing the average equivalent model and the unbalanced state transition model

the grading control strategy of three-phase output current of the inverter is presented to compensate for unbalanced voltage of the microgrid. Simulation and experimental results show that the method presented is effective for voltage compensation. This work is supported by National Natural Science Foundation of China(No. 61374050).