Capacitor voltage balance control strategy based on MMC-MTDC

The MMC is composed of a large number sub-modules. operating conditions each sub-module are different, which will inevitably affect the capacitor voltage sub-module, resulting in difference sub-module. problem uneven system unavoidable, and greatly stable operation system. This paper studies multi-terminal flexible DC transmission (MMC-MTDC) based on modular multi-level converters. MMC-MTDC model established through converter station level controller, then according to shutdown process system, several optimal control methods proposed realize energy feedback discharge achieve balance. Finally, effectiveness method verified by building simulation model.