The　frequency　of　power　system　and　the　rotational　speed　of　generator　are　the　derivative　of　generator　rotor　angle,　so　they　can　be　controlled　by　the　generator　rotor　angle.　This　paper　describes　the　mechanism　that,　after　rotor　angle　droop　control　is　implemented,　generators　can　autonomously　adjust　the　power　output　to　share　load　variations　and　restore　frequency　without　dispatching　center　intervention.　Then　the　relationship　between　the　power　output　variation　and　the　rotor　angle　variation　after　the　transient　process　(caused　by　load　change)　ends　is　provided.　Further,　the　power　flow　calculation　method　that　can　be　used　after　the　implementation　of　rotor　angle　droop　control　is　given.　The　analysis　shows　that,　after　slight　modification,　the　Newton-Raphson　method　can　also　be　used　as　a　power　flow　calculation　method　under　the　rotor　angle　droop　control.　The　calculation　results　can　be　well　matched　with　the　simulation　results.　The　method　can　be　used　for　static　safety　analysis　or　state　estimation　calculation　after　implementing　the　rotor　angle　droop　control.　©　2018　Automation　of　Electric　Power　Systems　Press.