Arc　extinguishing　of　grounding　faults　is　a　problem　for　neutral　non-effective　grounding　distribution　networks.　In　consideration　of　line　parameters　and　load,　a　flexible　arc-suppression　optimization　method　under　the　single-phase-to-ground　fault　in　the　distribution　network　is　proposed.　When　a　single-phase-to-ground　fault　occurs,　the　compensation　current　is　injected　by　a　cascaded　H-bridge　converter.　By　measuring　the　zero　sequence　voltage　of　the　bus,　the　grounding　resistance　can　be　calculated.　For　the　higher　grounding　resistance,　the　fault　phase　is　selected　according　to　the　variation　trend　determined　of　the　three-phase　voltage　on　the　bus　after　compensation　current　injection.　Then　the　voltage　in　the　fault　phase　is　controlled　to　be　zero　by　adjusting　the　injection　current　according　to　the　result　of　fault　phase　selection,　which　means　to　adopt　the　voltage-based　arc-suppression　method.　Otherwise,　the　compensation　current　will　be　injected　continuously,　which　means　to　adopt　the　current-based　arc-suppression　method.　The　simulation　result　has　proved　that　the　proposed　method　is　able　to　suppress　the　arc　flexibly　and　effectively　and　overcome　the　shortages　of　current-based　and　voltage-based　arc-suppression　methods　due　to　line　parameters　and　load.　©　2017　Automation　of　Electric　Power　Systems　Press.