Seamless Transfer Control Strategy for Grid-Interactive Inverters.

Abstract—Single-phase microgrids are widely used in residential houses. The energy storage system with grid-interactive inverters in these microgrids should operate in both grid-tied and standalone modes. In this article, proportional resonant controller for the single-phase grid-interactive inverter with LCL-filter is designed and implimented in the both operation modes. Also, a novel seamless transfer strategy based on hysteresis current control is proposed when off-grid transfer operation is needed. With the proposed method, the inverter is able to provide voltage support to the local critical loads during the whole transfer process when the grid fails. For the grid-tied transfer process, a phase difference eliminating method based on inverter frequency regulation is introduced in this article to eliminate the phase difference between the grid voltage and the inverter voltage when the grid recovers. Simulation and experiments are carried out and the results verify the effectiveness of the proposed control method. [ABSTRACT FROM PUBLISHER]