It　is　being　increasingly　recognised　that　the　decentralised　secondary　frequency　regulation　(SFR)　is　more　suitable　for　the　expanding　power　systems.　Decentralised　SFR　can　more　rapidly　restore　system　frequency　and　damp　generator　rotor　oscillations,　as　well　as　relieve　the　information-exchange　stress　between　the　control　centre　and　widespread　generators.　Compared　to　other　previously　proposed　methods,　rotor　angle　droop　(RAD)　control　is　simpler　and　more　straightforward.　Similar　to　primary　frequency　control,　the　RAD　controllers　mainly　distribute　load　variance　among　generators　based　on　their　rated　capacity.　However,　they　can　rapidly　and　autonomously　restore　the　system　frequency　without　the　intervention　of　a　dispatching　centre,　which　makes　it　more　convenient　for　distributed　generation　(such　as　photovoltaic)　to　participate　in　frequency　regulation.　This　study　shows　that　the　unbalance　value　between　load　forecast　and　real　demand　can　be　calculated　through　absolute　rotor　angle　deviation.　This　calculated　amount　can　then　be　reallocated　to　achieve　more　economical　results.　By　calculating　the　area　control　error　and　changing　the　generation　in　different　areas,　the　tie-line　power　flow　(PF)　can　be　controlled　similarly.　However,　the　fluctuation　on　the　tie-line　PF　can　be　decreased　since　generators　near　the　loads　bear　slightly　more　burden.　This　is　helpful　for　tie-line　control　in　large　interconnected　power　systems.