Modular multilevel converter control strategy with fault tolerance

Abstract

The Modular Multilevel Converter (MMC) technology has recently emerged in VSC-HVDC applications where it demonstrated higher efficiency and fault tolerance compared to the classical 2-level topology. Due to the ability of MMC to connect to HV levels, MMC can be also used in transformerless STATCOM and large wind turbines. In this paper, a control and communication strategy have been developed to accommodate tolerant module failure and capacitor voltage unbalance. A downscaled prototype converter has been built in order to validate and investigate the control strategy, and also test the proposed communication infrastructure based on Industrial Ethernet.