Study on Improving Output Current Waveform of Photovoltaic Grid-Connected System

Residential photovoltaic grid-connected systems are distributed power generation devices that convert the dc energy from the solar arrays to high-quality ac power at the utility grid interface. In this paper, the strategy, which based on repetitive control and feedforward control of utility grid, is applied to improve the output current waveform. First, it is shown that the commonly used photovoltaic grid-connected inverter topology, based on the SPWM modulated full-bridge converter. Then, the operational principle of system is analyzed, and the repetitive control is presented. Finally, the validity of the proposed strategy and its effect on the improvement of the quality of the output current waveform are verified through simulation and experiment