According　to　the　wind　farm　technical　rule　and　considering　the　maximum　output　voltage　and　the　current　capacity　of　double-fed　induction　generator　(DFIG)　rotor-side　converter,　this　paper　discussed　the　DFIG　low-voltage　ride　through　(LVRT)　control　strategy.　On　this　basis,　three　characteristics　of　the　DFIG　fault　current　were　analyzed.　This　paper　also　analyzed　the　applicability　of　directional　element　in　the　collection　line　of　doubly　fed　wind　farm,　and　pointed　out　that　the　directional　element　may　misoperate　when　the　phase-phase　fault　occurs　on　the　opposite　direction.　The　accuracy　of　the　proposed　conclusion　was　proved　by　the　digital-analog　hybrid　simulation.　©　2018　Chin.　Soc.　for　Elec.　Eng.