Design Considerations of Modular Multilevel Converters in Bidirectional Energy-Storage Systems

Bidirectional energy-storage systems have become important elements in many renewable-energy applications to control power fluctuations between the energy source and the power grid. Recently, modular multilevel converters (MMCs) integrated with energy storage have become attractive solutions in such applications. They exhibit low harmonic distortion, improved fault tolerance, and faster response compared to traditional solutions. These qualities make MMCs well-suited for grid-connected applications, where maintaining stable and high-quality power is required. This work presents a novel approach to design and optimize the operation of a MMC connected to energy-storage. In the work, the energy-storage type, semiconductor devices, and control strategy are selected so that an efficient system operation is guaranteed. Simulation results are shown and used to demonstrate the effectiveness of the proposed methods.