Hybrid　HVDC　is　a　novel　topology　which　combines　advantages　of　both　line　commuted　converter　(LCC)　and　the　voltage　source　converter　(VSC).　In　this　paper,　the　power　flow　model　of　hybrid　HVDC,　which　contains　mathematical　models　of　LCC　and　VSC　stations,　is　built　first,　concerning　the　control　modes　of　hybrid　HVDC　and　converter　transformers　ratios.　Based　on　that,　the　unified　iterative　power　flow　calculation　algorithm　of　hybrid　AC/DC　networks　incorporating　hybrid　HVDC　is　proposed.　The　algorithm　is　suitable　for　hybrid　HVDC　embedded　in　an　AC　grid　or　connecting　different　asynchronous　AC　grids.　Finally,　the　accuracy　of　the　mathematical　model　and　the　validity　of　the　proposed　algorithm　are　verified　by　a　case　study.　©　2016　IEEE.