Reducing Losses and Energy Storage Requirements of Modular Multilevel Converters With Optimal Harmonic Injection

Due to the single phase characteristic of individual arms Modular Multilevel Converter (MMC) topology, difference between instantaneous AC and DC side power must be buffered in module capacitors. This results large capacitors compromising density cost MMC. In this paper, a multi-objective optimization scheme is formulated that aims at reducing required capacitance semiconductor losses same time. Further attention paid maximum voltage amplitude or current. The based on injection circulating current common mode harmonics. Unlike most existing schemes it considers actual trajectories capacitor arm output maximize savings losses. For an exemplary medium MMC parameter set, value reductions more than 50% are achieved while decrease by 8- 18%. Based volume estimation for modules, reduction up 45%.