Single-Phase Grid-Tied Modular Multilevel Converter for Various Renewable Energy Sources

We investigate a single-phase grid-tied modular multilevel converter (MMC) for various renewable energy sources. The single-phase MMC consists of series-connected full-bridge cells, and each cell is connected to a power conversion system for power generation system such as photovoltaic, wind, and micro-hydroelectric power generation systems. The MMC can be connected to the distribution feeder directly without a passive filter and a transformer. In the proposed system, the generated power of each renewable source can be caluclated without DC-side sensors. The source current is controlled with a unity power factor by power flow control. A computer simulation is implemented to verify the validity of the proposed system using PLECS. The simulation result demonstrates that the generated power from various renewable energy sources can regenerate to the single-phase distribution feeder with a unity power factor by the proposed system.