Converter energy balancing in MMC system energy sharing using master controller

Modular Multilevel Converters (MMC) are power-electronics systems built with number of submodules connected in series/parallel manner to increase voltage and current range of the converter in comparison with single component rating what allows to use low-voltage low-power products in MVDC and HVDC applications. For increase of voltage or power multiple MMCs can be connected in series or parallel. This paper introduces a new energy balancing algorithm for such multi-converter systems. The problem of equal energy sharing is highlighted. Control algorithms are presented. Finally, simulation test results are shown from system comprising two MMCs in configurable parallel and series connection.