For the parallel multi-terminal hybrid HVDC transmission system

the discrimination of DC line fault area is of great significance to minimize the isolation of fault and improve the availability of DC system. In view of the unique structure of parallel connection of converter stations in the parallel multi-terminal HVDC transmission systems

the influence on transient traveling waves is analyzed. The research shows that the parallel connection converter has greatly reduced the fault traveling wave in the middle and low frequency band. Therefore

the wavelet transform is used to analyze the transient current

and the fault direction discrimination principle based on the energy difference of transient current on both sides of the T zone is proposed

and the fault area is determined by the fault direction information of each converter station. Finally

the PSCAD/EMTDC simulation model of four-terminal hybrid HVDC transmission system is established to verify the correctness and effectiveness of the proposed method.