Stationary frame voltage controller of single-phase inverter for seamless transition

In this paper, voltage controller for seamless transition of grid connected inverter for ESS is proposed. Single phase inverter is operated as current controller when grid is connected and as voltage controller when grid is disconnected. The proposed voltage controller is operated in this stand-alone mode and has form of dual loop controller with voltage and current command feed-forward terms. In case of grid-recovery, the proposed controller can solve the problem of over-current which is flowing into the system by the reason of mismatch phase between inverter output and grid voltages. The phase delay problems by the low band-width of voltage controller and over current problem are solved by command feed-forward control, when grid voltage is restored. The effects of the control method were simulated through PSIM and the usefulness of the control method was verified through experiments.