A Distributed Power Control of Series-Connected Module-Integrated Inverters for PV Grid-Tied Applications

To enhance the redundancy and reliability for a distributed generation system, a grid-tied photovoltaic (PV) generation system based on series-connected module-integrated inverters (SC-MIIs) is presented in this paper. In the grid-tied SC-MII system, each PV panel is interfaced with an MII with independent maximum power point tracking to harvest maximum solar energy. The outputs of MIIs are at ac line frequency and are connected in series to fulfill the voltage requirement in the utility grid. Since the high step-up power conversion stage in the conventional microinverter is avoided, the grid-tied SC-MII system is easier to implement and features high efficiency. Meanwhile, a distributed control strategy for SC-MIIs is proposed, in which the active power sharing among the MIIs depends on the individual maximum power available from PV panels, while the reactive power of the system can be regulated by any of the MIIs according to the utility grid command. Simulation and experimental results verify the feasibility and effectiveness of the proposed system and its corresponding control strategy.