Design and analysis of stationary frame PR current controller for performance improvement of grid tied PV inverters

In this paper a single phase grid connected photovoltaic (PV) system has been modeled and simulated using Matlab/Simulink. The PV generator is interfaced with the utility grid by a single phase voltage source inverter (VSI). A maximum power point tracking (MPPT) control algorithm is implemented to extract maximum power from the PV generator irrespective of operating conditions. The DC-DC boost converter placed in between PV generator and VSI performs MPPT and amplifies the output voltage from PV array to desired level. A control strategy to regulate the quality of power injected by the grid connected VSI is proposed. Two controllers are designed for the grid side DC-AC inverter one is the proportional integral (PI) voltage controller which regulates the DC link voltage, the other is the Proportional + Resonant (PR) current controller which maintains the current injected by the inverter into grid in phase with the grid voltage so that unity power factor can be achieved. A harmonic compensator (HC) is cascaded with PR controller to mitigate low order odd harmonic components present in the output current of VSI and minimize the total harmonic distortion (THD). Simulation results validate the effectiveness of the proposed control strategy.