A robust predictive dual-loop control strategy for grid-connected photovoltaic generation system

In this paper, a robust predictive dual-loop control strategy is proposed in single-phase grid-connected photovoltaic generation system with LC filter. To stabilize the dc link voltage, the proportional-integrator (PI) controller is applied to the outer voltage loop. For the inner current loop, the deadbeat controller is proposed to realize grid current control. Power feed-forward control is introduced to speed up the system response. Considering the delay and the filtering inductance variation in the conventional deadbeat controller, a delayed z-domain deadbeat control model was analyzed, and the delay and inductance effects on system stability were discussed. The robust predictive current deadbeat control was proposed to enhance the system robustness and reduce the current distortion due to the control delay and inductance deviation, and its design was given. In z-domain, the system transfer function was derived, and the system stability was analyzed, and the control parameters were selected. Simulation and experimental results verified the validity of the proposed control strategy.