Control of single-phase photovoltaic H6 inverter in grid-connected and stand-alone modes of operation

This paper proposes a control strategy for single-phase transformerless photovoltaic H6 inverter with capability of operation in both grid connected and stand-alone modes. This control strategy enables seamless transition between two modes without any reconfiguration of control structure and need of any external communication. A multi-loop control structure including an inner voltage and current control with PR controller and outer power control with droop controller is utilised to make the inverter operate in both modes. In grid-connected mode, the power control loop regulates reference voltage and frequency for voltage control loop, to adjust power flow of inverter to the main grid while in islanded mode, reference voltage and frequency are determined according to droop characteristic of inverter to supply local load demand. The simulation and experimental result are used to verify the performance of the proposed control. © 2022 Inderscience Enterprises Ltd.