A hybrid control strategy based on modified repetitive control for single-phase photovoltaic inverter in stand-alone mode

In this paper, a hybrid control strategy based on modified repetitive control (MRC) and multi-loop control are presented for single-phase photovoltaic (PV) inverter in stand-alone mode. Multi-loop controller are adopted to gain good dynamic performance, while a plug-in modified repetitive controller is proposed to achieve zero steady-state error for sinusoidal reference. In addition, in order to solve the contradiction between stability and control performance of the repetitive controller, the relationship between control performance and robustness is elaborated, and the optimization method of repetitive controller is presented, which increased the freedom to design the compensator. The stability of overall system has been analyzed and the explicit optimization procedures of repetitive controller have been proposed. Simulation and experimental results confirm that the proposed strategy offers good-quality sinusoidal voltage with nearly zero-steady state and low total harmonic distortion (THD) under different load conditions.