Average Modeling and Control of Module Multilevel Converter

Modular Multilevel Converter (MMC) has presents great potential in high power quality, low operation loss, scalability and high reliability, which make MMC a good choice for DC transmission, MV drive and other HV or MV applications. This paper describes the average modeling and control of MMC. Firstly, the operation principles of MMC are analyzed, based on which the average MMC model is deduced. Secondly, the control methods for DC voltage control, circulating current suppression, and capacitor voltage balancing, etc are developed. Finally, the effectiveness of the proposed average model is verified by comparing the simulation results of an MVDC distribution system using detailed MMC models. The correctness of the designed control methods also demonstrated through simulation. It is also proven to be feasible of using MMC in MVDC applications.