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.