To　solve　the　problems　in　the　existing　protection　for　high　voltage　source　converter　high　voltage　direct　current　(VSC-HVDC)　transmission　lines,　such　as　insufficient　sensitivity　for　main　protection　and　slow　operation　for　backup　protection,　a　novel　pilot　protection　for　VSC-HVDC　transmission　lines　by　identifying　model　parameters　is　proposed.　In　the　principle,　the　external　fault　is　equivalent　to　a　positive　capacitance　model,　while　the　internal　fault　is　equivalent　to　a　negative　capacitance　model.　For　a　±60　kV　VSC-HVDC　simulation　model　of　300　km　cable　lines,　the　identified　capacitance　is　positive　line-to-ground　one,　about　80　μF,　when　an　internal　fault　occurs;　the　identified　capacitance　is　negative　shunt　one,　about　-1000　μF,　when　an　external　fault　occurs.　Internal　faults　and　external　faults　can　be　distinguished　by　judging　whether　the　identified　capacitor　is　positive　or　negative.　The　results　show　that　this　principle,　unaffected　by　transition　resistance,　line　distributed　capacitance　and　control　type,　can　identify　internal　faults　and　external　faults　reliably　within　10　ms　under　various　operating　conditions　with　sufficient　sensitivity.