Grid-connected PV power plant LCL filter based on PI and PR control strategy

The grid-connected inverter is important power electronic implements, used to transfer the power from the DPGS to the public grid, and the quality of its output power has been studied a lot. The repetitive control technique based on the internal model principle, can achieve low steady-state tracking error and total harmonic distortion (THD) in AC systems, so it is widely adopted in the inverter systems. However in the practical applications, there are still some issues needs solving when using the repetitive control technique. To suppress the current distortion, a control strategy of fundamental current and harmonics controlled separately is adopted. Proportion-integral (PI) values above which can achieved output controller and proportion resonant (PR) controller are adopted to control the power adjustment and zero error control of harmonic restrain.