A　HVDC　grid　based　on　voltage　source　converter　(VSC)　is　an　attractive　solution　for　the　grid　integration　of　offshore　renewable　energy,　interconnection　of　ac　grids,　facilitation　of　power　markets,　and　energy　emergency　support.　However,　the　power　flow　within　the　dc　grids　is　determined　by　the　line　resistance　and　cannot　be　fully　controlled　by　the　VSCs　only.　Thus,　power　flow　control　of　dc　grids　are　needed　not　only　to　realize　the　economic　operation　and　power　markets,　but　also　to　prevent　overload　of　dc　lines　in　post-fault　conditions.　Four　types　of　control　devices,　dc　transformer,　the　variable　resistor,　series　voltage　source　and　interline　dc　power　flow　controller　(IDCPFC)　are　presented　to　achieve　the　goal　of　power　flow　controlling.　This　paper　presents　a　dc　power　flow　controller　(DCPFC)　based　on　dc　converter.　This　DCPFC　can　be　extended　to　multi-terminal　power　flow　control　in　dc　power　grids.　The　operation　principle　of　the　proposed　DCPFC　is　analyzed.　And　the　theoretical　analysis　is　validated　by　a　full-scaled　simulation.　©　2020　IEEE.