Modular Multilevel Converters for Renewable Energies Interfacing: Comparative review

Recently, utilities impose strict regulations on the quality of power/current/voltage from power electronic circuits that interfacing Renewable Energy Sources (RES). Two-level inverters usually suffer from the inability to follow these standards without compromising efficiency. Moreover, Two-level topologies require expensive solid-state devices with high current/voltage ratings. Therefore, the trend is adopting Modular Multilevel Converters (MMCs) for interfacing RESs. MMCs could cope easily with the quality standards while employing inexpensive switches. This article presents a comprehensive review for different topologies, modulation strategies and control schemes of MMC used for interfacing RESs. Salient features of different MMC configurations are highlighted. Then, objective and illustrative comparison is carried out to identify the most promising MMC topology for interfacing different types of RESs. Finally, the line frequency equivalent circuit for these preferred topologies is derived to facility the performance analysis and control design of these MMC circuits.