Distributed Control Architecture for a Low-Voltage Modular Multilevel Converter with Partial Energy Storage Integration

This paper discusses the design of a low-voltage multilevel converter used for validation of energy storage integration topologies. The impact of control architecture on design complexity, common-mode noise immunity, and protections is discussed. In this implementation the converter operates on distributed control – a main control unit communicates with six distributed control units each performing functions related to the local stack. The submodules are connected via galvanically isolated components with their local control unit, and each of the local control units is connected with the main control unit over fibre optical interface. The hardware design, control and protections are presented. The setup is easy to reconfigure for different topologies, especially important in the case of partial energy storage integration. The paper is concluded by experimental results of the converter in standard MMC mode, and topologies involving partial energy storage integration.