Power Reversal of Hybrid HVDC System

Hybrid HVDC combines the advantages of line commutated converter (LCC) and modular multilevel converter (MMC). In this paper the topology and basic control strategy of hybrid HVDC are described. Then the power reversal of hybrid HVDC is analysed. For LCC-HMMC (MMC adopting half bridge sub-module), the sequence of power reversal after stopping operation is proposed while for LCC-FMMC (MMC adopting full bridge sub-module), a new modulation strategy is proposed to maintain the sub-module voltage during the power reversal without blocking the converters. Simulation results are presented to verify the feasibility of power reversal of hybrid HVDC.