The AC Line Current Regulation Strategy for the Grid-Connected PV System

The ac line current regulation strategy for the grid-connected photovoltaic (GCPV) system is proposed in this paper. The power flow of the GCPV system and the operational principles of different ac line current regulation strategies are presented. In this paper, the optimal ac line current regulation is defined to be able to achieve dc-link voltage regulation in one 60 Hz ac mains cycle while minimizing the injected ac line current variation. The mathematical equations for the proposed optimal ac line current regulation strategy are derived thoroughly. The derived equations also explain the behavior of the dc-link voltage responding to the power variation of the GCPV system. As a result, the selection criteria of the dc-link capacitor can be established. Hardware experimental results have been presented to verify the validity of the proposed optimal ac line current regulation strategy.