简介：Thispaperusesthegeometricsingularperturbationtheorytoinvestigatedynamicalbehaviorsandsingularitiesinafundamentalpowersystempresentedinasingle-machineinfinite-busformulation.ThepowersystemcanbeapproximatedbytwosimplifiedsystemsSandF,whichcorrespondrespectivelytoslowandfastsubsystems.Thesingularities,includingHopfbifurcation(HB),saddle-nodebifurcation(SNB)andsingularityinducedbifurcation(SIB),arecharacterized.WeshowthatSNBoccursatPTc=3.4382,SIBatPTO=2.8653andHBatPTh=2.802forthesingularperturbationsystem.ItmeansthatthepowersystemwillcollapsenearSIBwhichprecedesSNBandthatthepowersystemwilloscillatenearHBwhichprecedesSIB.Inotherwords,thepowersystemwillloseitsstabilitybymeansofoscillationneartheHBwhichprecedesSIBandSNBasPTisincreasingtoacriticalvalue.Theboundaryofthestabilityregionofthesystemcanbedescribedapproximatelybyacombinationofboundariesofthestabilityregionsofthefastsubsystemandslowsubsystem.