Mixed cells modular multilevel converter

This paper uses a scaled down version of the mixed cells modular multilevel converter (MMC) to discuss its modulation and capacitor voltage balancing method, and investigates its AC and DC fault ride-through capability. It has been found that the mixed MMC is resilient to both AC and DC network faults, which are necessary for next generations of highly meshed multi-terminal HVDC grids. The power losses comparison conducted in this paper has shown that the mixed cells MMC and three-level cells MMC achieve DC fault reverse blocking capability at reduced on-state losses than full-bridge MMC and alternative arm MMC.