Voltage　source　converter-based　high　voltage　DC　transmission　raises　high　demand　for　high-speed　operation　of　relay.　The　derivative-based　traveling　wave　protection　method　exposes　the　problem　of　low-sensitivity　when　high-impedance　faults　occur.　In　this　paper,　the　influence　factors　of　the　fault　initial　traveling　wave　are　analysed　and　the　analytic　expressions　of　the　fault　initial　traveling　wave　are　derived.　In　the　expression,　the　physical　meaning　of　the　exponent　coefficients　is　the　distortion　degree　of　the　fault　initial　traveling　wave,　which　is　related　to　the　location　of　the　fault.　The　exponent　coefficients　will　not　be　influenced　by　the　fault　impedance.　According　to　the　formation　of　the　expression,　a　basic　fitting　function　is　selected　to　extract　fault　location　information　from　the　zero-mode　fault　current　initial　traveling　wave　by　Levenberg-Marquart　fitting　method.　Then　a　high-speed　protection　scheme　is　proposed　using　the　obtained　fitting　coefficients.　The　simulation　results　show　that　the　fitting　coefficients　b　can　directly　correspond　to　the　fault　location,　the　proposed　method　can　reliably　and　fast　identify　faults　and　has　high　sensitivity　when　high-impedance　faults　occur.　©　2020　IET　Conference　Publications.