VSC HVDC control strategy based on burst mode operation for low voltage ride through

Low voltage ride through ability is necessary for HVDC links based on modular multilevel converter (MMC). However, there is not enough communication between inverter side MMC and rectifier MMC on the AC voltage fault information in some HVDC projects. This paper analyzes how the loss of communication could cause failure in low voltage ride through for VSC HVDC system. An active power control strategy based on burst mode operation is proposed. This control strategy is able to maintain the normal operation of MMC on both sides and eliminates the risk of over voltage both for MMC sub-modules and DC line. The mathematical calculations are presented and PSCAD/EMTDC simulation results verify the effectiveness of the proposed control strategy.