Nonlinear controller design for single-phase grid-connected photovoltaic systems using partial feedback linearization

This paper deals with the design of a nonlinear controller for single-phase grid-connected photovoltaic (PV) systems to maintain the current injected into the grid in phase with grid voltage and to regulate the DC link voltage for achieving maximum power point tracking (MPPT). The controller is designed based on the partial feedback linearization which transforms the nonlinear system into a reduced order linear system and an autonomous system whose dynamics are known as internal dynamics of the system. This paper also deals with the stability of internal dynamics of PV systems which is a basic requirement to design partial feedback linearizing controller. The performance of the proposed controller is evaluated in terms of delivering maximum power and synchronization of grid current with voltage under changes in atmospheric conditions