A　novel　approach　with　active　grounding　is　proposed　to　solve　the　problems　of　ground　fault　arc　extinguishing　and　line　detection　for　distribution　networks.　The　single-phase　cascaded　H-bridge　multi-level　converter　is　connected　to　the　neutral　point　in　distribution　networks　directly.　When　the　single　phase　ground　fault　occurs,　a　compensating　current　is　injected　to　neutral　point　by　multi-level　converter,　fully　compensating　the　fault　current　and　controlling　the　fault　phase　voltage　to　zero,　thus　extinguishing　the　fault　arc.　After　a　certain　delay,　the　ground　fault　judgment　is　executed　when　the　compensating　current　is　reduced　to　zero.　If　permanent　ground　fault　is　determined,　the　line　detection　is　carried　out　to　identify　fault　line　according　to　changes　of　compensating　current　and　zero-sequence　current　before　and　after　the　multi-level　converter　exiting.　The　theoretical　analysis　and　simulation　results　show　that　this　method　has　the　advantages　of　clear　principle,　easy　implementation　and　good　feasibility.　©,　2015,　Power　System　Technology　Press.　All　right　reserved.