Design of a Grid-Tie Photovoltaic System With a Controlled Total Harmonic Distortion and Tri Maximum Power Point Tracking

This article proposes an adaptive grid-tie photovoltaic system that maximizes the power injected to the grid while maintaining a predetermined power quality level. The proposed algorithm tracks the maximum power generated by the photovoltaic source, the maximum efficiency of the dc–dc converter, and the maximum efficiency of the inverter operating within a predefined total harmonic distortion limit. The tracked parameters that comprise the operating voltage of the photovoltaic source, the switching frequency of the dc–dc converter, and the switching frequency of the sinusoidal pulsewidth modulation inverter are updated, continuously, according to the generated photovoltaic power. The proposed method is fully adaptive, fast, and has a 100% convergence rate. Derivation of the proposed technique followed by the experimental verification and discussion are presented.