双控专业英语

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1、Voltagestabilityistheabilityofapowersystemtomaintainsteadyacceptablevoltagesatallbusesinthesystemundernormaloperatingconditionsandafterbeingsubjectedtoadisturbance.Asystementersastateofvoltageinstabilitywhenadisturbance,increaseinloaddemand,orchangeinsystemconditioncause

2、saprogressiveanduncontrollabledropinvoltage・Themainfactorcausinginstabilityistheinabilityofapowersystemtomeetthedemandforreactivepowe匚Theheartoftheproblemisusuallythevoltagedropthatoccurswhenactivepowerflowthroughinductivereactancesassociatedwiththetransmissionnetwork・Pr

3、ogressivedropinbusvoltagescanalsobeassociatedwithrotoranglesgoingoutofstep.Forexample,thegraduallossofsynchronismofmachinesasrotoranglesbetweentwogroupsofmachinesapproachorexceed180°wouldresultinverylowvoltagesatintermediatepointsinthenetwork.Incontrast,thetypeofsustaine

4、dfallofvoltagethatisrelatedtovoltageinstabilityoccurswhererotoranglestabilityisnotanissue・Voltageinstabilityisessentiallyalocalphenomenon;however,itsconsequencesmayhaveawidespreadimpact.Voltagecollapseismorecomplexthansimplevoltageinstabilityandisusuallytheresultofaseque

5、nceofeventsaccompanyingvoltageinstabilityleadingtoalow-voltageprofileinasignificantpartofthepowersystem.Voltageinstabilitymayoccurindifferentways・Forpurposeofanalysis,voltagestabilityisusuallyclassifiedintothefollowingtwosubclasses:(1)Large-disturbancevoltagestabilityisc

6、oncernedwithasystemsabilitytocontrolvoltagesfollowinglargedisturbancessuchassystemfaults,lossofgeneration,orcircuitcontingencies・Thisabilityisdeterminedbythesystemloadcharacteristicsandtheinteractionsofbothcontinuousanddiscretecontrolsandprotections.Acriterionforlarge-di

7、sturbancevoltagestabilityisthat,followingagivendisturbanceandfollowingsystem-controlactions,voltagesatallbusesreachacceptablesteady-statelevels・(2)Small-disturbaneevoltagestabilityisconcernedwithasystem'sabilitytocontrolvoltagesfollowingsmallperturbationssuchasincrementa

8、lchangesinsystemload・Thisformofstabilityisdeterminedbythecharacteristicsofload,continuouscontrols,anddi