Facing　serious　environment　problem　and　unbalanced　distribution　of　energy　resources,　power　grid　interconnection　is　thought　to　be　a　significant　way　to　the　effective　utilisation　of　renewable　energy.　High　penetration　of　renewable　energy　brings　a　lot　of　problems　to　the　planning　and　operation　of　power　system.　Considering　seasonal　and　diurnal　scales,　wind　and　solar　energy　are　complementary.　In　this　study,　a　power　gird　interconnection　model　using　linear　programming　techniques　to　minimise　overall　system　costs　was　proposed,　using　high-voltage　direct　current　(HVDC)　to　link　the　power　systems　in　Northeast　Asia　in　view　of　the　difference　in　the　countries＇　power　system.　The　model　not　only　considers　generation　and　transmission　extensions,　but　also　sets　the　cross　border　power　flows.　To　carbon　emission　reduction　and　fuel　cost　saving,　four　power　grid　interconnection　programmes　in　Northeast　Asia　have　been　setup.　The　results　show　that　power　grid　interconnection　can　bring　environment　and　economic　benefits.　©　2019　Institution　of　Engineering　and　Technology.All　right　reserved.