第1页共99页编号：时间：2021年x月x日书山有路勤为径，学海无涯苦作舟页码：第1页共99页影响电力系统运行的因素HazardstoPowerSystemOperationTheoperationofelectricpowersystemsmaybedisturbedastheresultofanumberofcauses.Thetroubles⑴ontheelectriccircuitsareusuallyintheformofbrokenconductorsorcircumstancesinwhichconductorsaretemporarily(orpermanent)connectedtoeachotherortoground.Regardlessofthecauseofthedisturbances,suchtroublesseriouslyinterferewiththeflowofpowerandrequirecorrectiveaction.Overheadlinesarevulnerabletotroublescausedbylightning.Whenlightningstrikesalineoranearby⑵object,atransientvoltageiscreatedontheline,Hihg-voltagecircuitshavelargespacingbetweenconductorsandfromconductorstogroundedobjects,suchastowers.Directstrokestosuchlinesareusuallydivertedtogroundthroughoverheadgroundwiresandmaycausenointerferencewithoperation.Occasionallystrokesterminatedirectlyonthepowerconductorsandintroduceontothemtransienttransientvoltagesofsuchmagnitudethatarcheracrossinsulatorstringsmayresult.Onceanarcisestablished,powercurrentflowsthroughituntilthecircuitisdeenergized.Lightningvoltagesmaybeofhighmagnitudebutareofveryshortduration;theirtimeismeasuredinmicroseconds.Asaresult,theireffectsaremostnoticeableatthepointwherethestrokeoccurs.Distributionlines,whichoperateatperhaps12kVorless,aremountedonrelativelysmallinsulators,whichmaybeflashedoverbythevoltageinducedinalineeventhoughthelightningstrokedoesnotcontacttheline.Suchresultingarcsinterferewithoperationandusuallyareeliminatedbydeenergizingtheline.Whenthelineisdeenergized.Thearcisextinguishedand,verycommonly,thelinemaybereenergizingimmediately.Overheadlinesaresubjectedtowindandsleet.Althoughdesignedtowithstandordinarystormloading,⑶practicallytheycannotbedesignedfortheextremeconditionofsleetorwindloading.Hence,occasionallinefailuresoccurasaresultofthesecauses.Failurescausedbywindorsleetareusuallyofsuchnaturethatrepairsmustbemadebeforethelinemaybereenergize.Foreignobjectsmaycontactalineandcausedamage,whichnecessitatesremovalofthelinefromservice.⑷Airplanesmayflyintoaline,anautomobilemayknockapole,aconstructionworkermayrunacraneintoaline,oranexcavatormaydigupacable.Birds,squirrels,snakesandotheranimalsoccasionallyshort-circuitlinesandcauseoutages.Generators,transformers,lines,orothercomponentsmaybeswitchedoutofservicefornormalorroutine⑸maintenance.Whenswitchingoperationsoccur,transientsaresetuponthepowersystemwhichsometimesproduceserousovervoltages.Suchovervoltagesinturnmaycauseflashoverofinsulatorsorpunctureofsolidinsulation.Equipmentsometimesfailswithoutanyparticulardirectcause.Failuremaybeduetoinadequatedesign.⑹previousoverloads,ornaturaldeteriorationofequipment.Humanerrorsmayproducepower-systemoutages.Switchesmaybeopenedunintentionally.Cuttingoff⑺loads;temporarygroundingelectrodesmaybeputonenergizedcircuitsbymistake;equipmenthandledbyhotlinedevicesmaybedropped.Suchoccasions,althoughrare,mustbeconsideredashazardpossibilitiesin第2页共99页第1页共99页编号：时间：2021年x月x日书山有路勤为径，学海无涯苦作舟页码：第2页共99页power-systemdesign.影响电力系统运行的因素⑴影响电力系统正常运行的因素很多。电路故障的形式通常是导体断裂。导体暂时（或永久地）相间接地。不管故障的原因是什么，这些故障都严重干扰电流的输送，需要采取补救措施。⑵雷电容易影响架空线路。当雷电击中输电线路或其附近物体时，线路上产生暂态电压。高压电路的相间以及相对接地体．如杆塔）...
