The modulation method for sub-modules(SMs)of modular multilevel converter(MMC)is one of the most important issues in practical engineering. In traditional strategy

the capacitor voltages of SMs need to be detected in real time and ranked in total order. If the number of SMs increases

the requirement of calculating time rises accordingly and the safe and stable operation of converter may be influenced. Hence

a modulation method based on dual queues for MMC is proposed. The on-state queue and off-state queue are established at the initial time and adjusted according to the direction of arm current and the maximum voltage margin during the operation. The capacitor voltages of SMs need not to be sorted in this method and the calculating time can be reduced. The simulation model is developed in PSCAD/EMTDC

and the simulation results prove the validity and the feasibility of the proposed method.