Optimization of MMC level number for battery integration in MV grid

The integration of battery energy storage systems in electrical grids is one of the most interesting challenges of the recent years. In this regard, one potential solution is based on a modular multilevel converter (MMC) with batteries directly embedded at each submodule level. This solution allows to reach medium voltage level using low voltage devices avoiding the necessity of complex battery management system to balance the high voltage battery modules. Several studies have been performed on MMC topologies to integrate storages. Nevertheless, there are not dedicated studies to analyse the effect of the number of levels on efficiency and cost of the final solution. This paper focuses on the efficiency evaluation and on the cost analysis of the MMC combined with energy storage systems. After evaluating the total power losses of the converter, the efficiency for different number of submodules is analysed. In addition, cost comparison between different solutions, taking into account several factors such as component price, converter power losses cost and operational & maintenance cost, is discussed.