In this paper

the study based on VSC-HVDC unit of Luxi DC asynchronous interconnection project is conducted. The influence of bridge arm circulation current of converter with modular multilevel structure is analyzed on the basis of basic principle of the converter. It is shown by the analysis that with or without the bridge arm circulating current

the output AC phase voltage of the converter contains 3 rd

5 th and above odd harmonic component with the 3 rd harmonic component as dominant. While the 3 rd harmonic of output AC phase voltage of the converter can be reduced after using the circulating current control

but cannot be eliminated completely. The circulating current control strategy based on PR controller is adopted to suppress the secondary circulating current harmonics of the bridge arm of VSC-HVDC unit of Luxi project. The simulation model of VSC-HVDC unit of Luxi project is established by using PSCAD/EMTDC. The comparison and verification through the simulation calculation data and site recording data of Luxi project to demonstrate the reasonableness of derivation and analysis and the effectiveness of application of circulating current suppression control strategy in the project.