The Modular Multilevel Converter (MMC) has become one of the most promising topologies for high-voltage applications. Although the MMC has a modular and redundant structure, which can significantly enhance its reliability and faulttolerance, its fault handling capability can be further improved by adopting a post-fault strategy. In this paper, a post-fault strategy based on the neutral-shift method is proposed, which, subsequent to bypassing the faulty SM(s), aims at improving the maximum attainable line-to-line voltages of the MMC. Based on a newly developed internal variable analysis method, the impact of the neutral-shift strategy on the operation of the MMC is analyzed. In conjunction with the proposed post-fault strategy, a modified circulating current suppression (CCS) method is used to mitigate the double-frequency component of the circulating currents. Performance and effectiveness of the proposed neutralshift strategy with and without the CCS method is evaluated based on time-domain simulation studies in the PSCAD/EMTDC software environment.
- Modular Multilevel Converter (MMC)
- Post- Fault Strategy
ASJC Scopus subject areas
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering