Filter-Based Controller to Improve the Power Quality of Single-Phase Grid-Connected Inverters

In this paper, a filter-based control scheme is developed for a single-phase grid-connected inverter system with local load. Improving the quality of the local load voltage in the grid-connected mode and injecting clean current to the grid at the same time is the main objective of the proposed scheme. Moreover, unity power factor at the grid side for different types of the local load is ensured by the proposed controller. Furthermore, this control approach ensures the seamless transfer between grid-connected and stand-alone operation modes without adjusting the controller structure and without any resynchronization scheme. The proposed scheme is validated by a Lyapunov stability analysis as well as via instantaneous dynamic circuit simulation in PLECS software.