Abstract:A protection scheme based on the ratio of energies of direction traveling waves is presented in this paper.Firstly,the propagation characteristic of fault traveling waves in a star-connected VSC-HVDC system is analyzed,and the different propagation law between fault and non-fault lines is studied.Then modal voltage and current are transformed in discrete wavelet transform (DWT),and wavelet energies of direction traveling waves are calculated.Finally,the fault line is determined by the ratio of positive and negative direction traveling waves.Simulation results of PSCAD/EMTDC show that the proposed method can identify the fault line quickly in the star-connected VSC-HVDC system.The proposed method is insensitive to different fault lines,fault distance,fault types and fault resistance,and has good robustness.