影响电力系统运行的因素

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1、HazardstoPowerSystemOperation⑴Theoperationofelectricpowersystemsmaybedisturbedastheresultofanumberofcauses.Thetroublesontheelectriccircuitsareusuallyintheformofbrokenconductorsorcircumstancesinwhichconductorsaretemporarily(orpermanent)connectedtoeachotherortoground.R

2、egardlessofthecauseofthedisturbances,suchtroublesseriouslyinterferewiththeflowofpowerandrequirecorrectiveaction.⑵Overheadlinesarevulnerabletotroublescausedbylightning.Whenlightningstrikesalineoranearbyobject,atransientvoltageiscreatedontheline,Hihg-voltagecircuitshav

3、elargespacingbetweenconductorsandfromconductorstogroundedobjects,suchastowers.Directstrokestosuchlinesareusuallydivertedtogroundthroughoverheadgroundwiresandmaycausenointerferencewithoperation.Occasionallystrokesterminatedirectlyonthepowerconductorsandintroduceontoth

4、emtransienttransientvoltagesofsuchmagnitudethatarcheracrossinsulatorstringsmayresult.Onceanarcisestablished,powercurrentflowsthroughituntilthecircuitisdeenergized.Lightningvoltagesmaybeofhighmagnitudebutareofveryshortduration;theirtimeismeasuredinmicroseconds.Asaresu

5、lt,theireffectsaremostnoticeableatthepointwherethestrokeoccurs.Distributionlines,whichoperateatperhaps12kVorless,aremountedonrelativelysmallinsulators,whichmaybeflashedoverbythevoltageinducedinalineeventhoughthelightningstrokedoesnotcontacttheline.Suchresultingarcsin

6、terferewithoperationandusuallyareeliminatedbydeenergizingtheline.Whenthelineisdeenergized.Thearcisextinguishedand,verycommonly,thelinemaybereenergizingimmediately.⑶Overheadlinesaresubjectedtowindandsleet. 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

7、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）间均有很大的绝缘距离。当接地线遭受雷击时，雷电可经过架空地线流入大地，不会给运行造成什么影响。但是，有时输电线路会遭受雷击，从而在输电线路上产生倡但很高的暂态电压：这种电压会引起线路绝缘子串的电弧放轨一旦绝缘子串上建立电弧，电流会通过它流动而引起线路断电。雷电过电压具有很高的幅值，但持续时间极短，以微秒计算。由此可见，雷电对系统正常运行影响很大。配电线路

8、的运行电压通常为12千伏或更低，它们由相对较少的绝缘子串悬挂，所以即使雷电不足以击倒输电线路。它也会在线路上引起感应电压，从而导致绝缘子串闪络。这种电弧放电会影响系统运行，通常可通过断电来消除故障。跑路一断，电弧熄灭，此时线路可重新合闸架空线易受到大风和冰雹的侵