With　the　increasing　penetration　of　wind　power　into　electric　power　grid,　large　scale　integration　of　the　doubly　fed　induction　generator　(DFIG)　in　wind　farm　and　its　low　voltage　ride-through　(LVRT)　capability　stipulated　stringently　in　the　revised　grid　code　have　led　to　extensive　researches　on　the　detailed　theoretical　analysis　of　the　DFIG　dynamic　characteristics　and　its　LVRT　enhancement　capability.　However,　no　matter　whether　mathematical　analysis　or　simulation　calculation　was　used　in　previous　investigations,　different　kinds　of　negligence　and　assumptions　have　emerged,　such　as　neglecting　stator　resistance　or　assuming　the　same　leakage　inductance　between　stator　and　rotor　sides,　which　will　result　in　different　influences　on　the　accuracy　and　validity　of　the　dynamic　characteristics　analysis　and　the　LVRT　control　design.　In　order　to　overcome　these　drawbacks,　a　completely　accurate　mathematical　dynamic　DFIG　model　is　developed　during　the　three-phase　voltage　dips　without　any　negligence,　and　different　interactivities　between　the　generator＇s　rotor　parameters　and　the　damping　speed　and　degree　of　the　generator＇s　electro-magnetic　variables　have　been　derived.　Based　on　the　proposed　calculation　and　analysis,　the　improved　Crowbar　circuit　prototype　and　the　optimal　parameters　design　of　the　Crowbar　are　given.　The　simulation　results　in　MATLAB/　SimuLink　have　totally　verified　the　validity　and　efficiency　of　the　theoretical　calculation　and　the　proposed　scheme.　©　2014　State　Grid　Electric　Power　Research　Institute　Press