This chapter explores submodule capacitor voltage control strategies across four typical MMC operating modes. The discussion covers several key topics: complete sorting and overall participation capacitor voltage balancing strategy, status-based sorting with incremental switching capacitor voltage balancing strategy, retention factor-based sorting with overall participation capacitor voltage balancing strategy, and the effects of varying capacitance values on submodule capacitor voltage balancing control. Additionally, it examines basic concepts of design and operational redundancy, MMC dynamic redundancy and fault-tolerant operation control strategies, and both startup and shutdown control of MMC-HVDC systems.