Design and control of Proportional-Resonant controller based Photovoltaic power conditioning system

This paper presents a current control technique for a single-phase grid-connected DC/AC inverter which is used in photovoltaic power conditioning system (PV PCS). A proportional-resonant (PR) controller is used for replacing the conventional proportional-integral (PI) controller in this system. By comparison with the conventional PI control method, the PR control can introduce an infinite gain at the fundamental frequency and hence can achieve zero steady-state error. A theoretical analysis of the PR controller is presented and verified by experiment. Furthermore, a pseudo synchronous d-q transformation is employed in current control scheme and an all-pass filter based single-phase digital phase-locked loop (PLL) is introduced to detect the phase of grid voltage. Based on the theoretical analysis, the control strategy is implemented on a 32-bit fixed-point TMS320F2812 DSP and tested in a 3 kW prototype PV PCS. Simulation and experimental verify the high performance of the implemented control scheme.