The invention discloses a PR (proportional resonant) controller-based NMC-HVDC (modular multilevel converter-
high voltage direct current)
circulating current suppression method. PR controller-based
circulating current suppression is adopted at the
inverter end to suppress positive-sequence and negative-sequence circulating currents, and meanwhile, a zero-sequence
circulating current controller is used to suppress
DC voltage fluctuation and zero-sequence circulating current; PR controller circulating current suppression is adopted at the
rectifier end; or PR controller circulating current suppression is used at the
rectifier end to suppress positive-sequence and negative-sequence circulating current, meanwhile, the zero-sequence circulating current controller is used to suppress the
DC voltage fluctuation and zero-sequence circulating current, and PR controller circulating current suppression is adopted at the
inverter end; or both the
rectifier end and the
inverter end use PR controller circulating current suppression to suppress positive-sequence and negative-sequence components and both use the zero-sequence circulating current controller to suppress the
DC voltage fluctuation and zero-sequence circulating current. In each AC side
system failure, the positive-sequence, negative-sequence and zero-sequence components of the circulating current can all be completely suppressed; the DC
voltage fluctuation can also be suppressed; fault ride-through ability of an AC
system during a fault can be improved; the problems occurring in the use of the traditional PR control method in NMC-HVDC are solved.