Cross-current control method for parallel inverters in digital grid

In Digital Grid which has been proposed as a new electric power grid, multi-inverters are operated in parallel and it may cause the cross-current among those inverters, since inverters do not have synchronizing mechanism. In this study, the authors propose a method to control the cross-current caused by the difference in switching frequencies of multi-inverters in parallel operation. An indirect hysteresis voltage digital control method is used to control the output of each inverter. The cross-current is controlled by considering the delay of the output voltage comparing with reference voltage, which depends on the switching frequency of each inverter. The simulation results show good performances of the proposed control method.