The　accessing　of　distributed　generation　resources　to　distribution　network　leads　to　a　multi　power　grid　structure.　The　direction　of　power　flow　changes　with　it.　The　photovoltaic　(PV)　generation　contains　a　large　number　of　power　electronic　devices　and　control　links,　which　causes　that　the　output　responses　and　fault　characteristics　are　significantly　different　from　the　synchronous　machine.　In　consideration　of　the　topological　structure　of　the　distributed　distribution　network,　this　paper　analyses　the　differences　of　transient　characteristics　of　AC　distribution　line　with　PV　power　supply　between　internal　and　external　faults.　Then,　a　new　principle　for　constructing　directional　element　using　transfer　and　consumption　characteristics　of　high-frequency　transient　energy　is　proposed.　This　directional　element　only　uses　high-frequency　transient　fault　voltage　and　current　in　early　stage,　which　can　reliably　distinguish　the　fault　direction.　What＇s　more,　the　existence　of　transition　resistance　will　be　conducive　to　the　judgement.　Finally,　corresponding　simulation　cases　were　carried　out　to　verify　the　feasibility　and　superiority　of　the　proposed　directional　element.　©　2019　Institution　of　Engineering　and　Technology.All　right　reserved.