High-voltage　direct-current　(HVDC)　based　on　modular　multilevel　converter　(MMC)　is　important　in　the　development　of　DC　grid.　Compared　with　cable　transmission,　long-distance　overhead　line　transmission　costs　are　low,　and　DC　fault　isolation　is　an　important　issue　of　applying　HVDC　power　transmission　over　overhead　lines.　This　paper　studied　the　DC　fault　handling　scheme　of　hybrid　HVDC　breakers　and　proposed　three　protection　schemes　based　on　DC　grid,　including　DC　line　protection,　DC　bus　protection　and　backup　protection.　Based　on　the　existing　technologies　in　actual　projects,　the　principle　of　selecting　parameters　was　discussed.　A　multiterminal　DC　power　grid　simulation　platform　with　a　hybrid　DC　circuit　breaker　was　established　by　using　overhead　line　transmission,　and　the　feasibility　and　effectiveness　of　the　proposed　scheme　were　further　verified.　The　results　show　that　the　hybrid　high-voltage　circuit　breaker　can　break　the　fault　current　within　several　milliseconds.　The　three　proposed　protection　schemes　realize　automatic,　rapid　and　selective　faults　isolation,　ensuring　that　other　non-faulty　components　return　to　normal　operation.　©　2020,　Harbin　University　of　Science　and　Technology　Publication.　All　right　reserved.