Real-time Simulation Study of Switch Open-Circuit Fault Detection and Localization Scheme for MMCs with High Submodule Count

This paper conducts a real-time simulation study of a switch open-circuit fault detection and localization (FDL) scheme for high voltage Modular Multilevel Converters (MMCs) that utilize a high number of submodules (SMs). The scheme under study stands out for high-voltage MMC applications, as it maintains consistently low computational complexity regardless of the number of SMs used per arm. However, to date, the chosen FDL scheme has only been validated by scaled-down simulation models and low-power experimental prototypes that use a limited number of SMs. This work addresses this gap by confirming the practical efficacy of the selected FDL scheme through real-time simulation testing on a 100 SMs/arm MMC model—a scenario not tested in most published FDL methods, showcasing significantly low computation cost for practical high SM count MMCs. The presented results verify the chosen scheme’s capability for accurate FDL, alongside its robustness to load variations.