Design and Analysis of the Distributed Controller for the Modular Multilevel Cascaded Converter

The modular multilevel cascaded converter (MMCC) has in recent years drawn interest for applying in the utility-scale photovoltaic (PV) and the battery energy storage (BES) systems. However, the large numbers of the cascaded modules lead to the difficulty of the implementation with a centralized control architecture. The paper [1] has proposed a distributed control strategy which significantly reduces the complexity and increases the flexibility to expand the system. This paper continues the research which analyzes the operation range of each module and its fault tolerant capability. The analysis provides a guideline to design the MMCC controller based on the distributed control approach. Simulation and experimental results are carried out on a star-connected cascaded converter to validate the analysis.