电气专业外文翻译

外文资料翻译ReliabilityofLightningResistant

OverheadDistributionLinesLightingcontinuestobethemajorcauseofoutagesonoverheadpowerdistributionlines.Throughlaboratorytestingandfieldobservationsandmeasurements,thepropertiesofalightningstrokeanditseffectsonelectricaldistributionsystemcomponentsarewell-understoodphenomena.Thispaperpresentsacompilationof32yearsofhistoricalrecordsforoutagecauses,duration,andlocationsforeightdistributionfeedersattheOakRidgeNationalLaboratory(ORNL).Distributiontypelightningarrestersareplacedatdead-endandanglestructuresatpolemountedwormerlocationsandathighpointsontheoverheadline.Stationclasslightningarrestersareusedtoprotectundergroundcableruns,padmountedswitchgearandunitsubstationtransformers.Resistancetoearthofeachpolegroundistypically15ohmsorless.Athigherelevationsinthesystem,resistancetoearthissubstantiallygreaterthan15ohms,especiallyduringthedrysummermonths.Atthesehighpoints,groundrodswererivenandbondedtothepolegroundingsystemsinthe1960'sinanattempttodecreaselightningoutages.Theseattemptswereonlypartiallysuccessfulinloweringtheoutagerate.Fromasurgeprotectionstandpointthevarietyofpolestructuresused(in-line,corner,angle,deadend,etc.)andthevarietyofinsulatorsandhardwareuseddoesnotalloweach13.8kVoverheadlinetobecategorizedwithauniformimpulseflashoverrating(170kV,etc.)oranumericalBILvoltageclass(95kVBIL;etc.).Forsimplicitypurposesintheanalysis,eachoverheadlinewascategorizedwithanominalvoltageconstructionclass(15kV,34kV,or69KV).Sixoftheeightoverheadlines(feeders1through6)werebuiltwithtypicalREAStandardhorizontalwoodcrossarmconstructionutilizingsingleANSIClass555porcelainpininsulators(nominal15kVinsulation).Theshieldangleoftheoverheadgroundwiretothephaseconductorsistypically45degrees.Oneoverheadline(feeder7)wasbuiltwithtransmissiontypewoodpoleconstructionbecausethelineextendedtoaresearchfacilitywhichwastohavegeneratedelectricalpowertofeedbackintothegrid.PolestructureofthislineareofdurablewoodcrossaconstructionwhichutilizedoubleANSI52-3porcelainsuspensioninsulatorstosupporttheconductors(nominal34kVinsulation).Theshieldangleoftheoverheadgroundwiretothephaseconductorsforfeeder7istypically30degrees.In1969,anoverheadline(feeder8)wasintentionallybuiltwith"lightningresistant"constructioninanattempttoreducelightningcausedoutages.Polestructuresofthelinehavephaseoverphase24-inchlongfiberglasssuspensionbracketswithdoubleANSI52-3porcelainsuspensioninsulatorstosupporttheconductors(nominal69kVinsulation).Theshieldangleoftheoverheadgroundwiretothephaseconductorsforfeeder8istypically30degrees.Thefailuredatawascompiledforeachoftheeight13.8kVfeedersandispresentedinTable,alongwithpertinentinformationregardingfeederconstruction,elevation,length,andage.Akeyfindingofthefailureanalysisisthatweather-relatedeventsaccountforoverhalf(56%)ofthefeederoutagesrecorded.Fifty-sevenofthe76weather-relatedoutageswereattributedtolightning.Insulationbreakdowndamageduetolightningisalsosuspectedinatleastadozenoftheequipmentfailuresobserved.Thedataindicatesoverheadlineswhichpassoverhighterrainarelessreliablebecauseofthegreaterexposuretolightning.Forexample,feeder3hadthemostrecordedoutages(48),ofwhichtwo-thirdswereduetoweather-relatedevents;thisfeederisalsothehighestlineontheplantsite,risingtoanelevationof450abovethereferencevalleyelevation.Overheadlinesthatarelongerandtowhichmoresubstationsandequipmentareattachedwerealsoobservedtobelessreliable(moreexposuretolightningandmoreequipmenttofail).Theageofthelinedoesnotappeartosignificantlylessenitsreliabilityaslongasadequatemaintenanceisperformed;noneofthelineshavehadanotableincreaseinthefrequencyofoutagesasthelineshaveaged.Aswouldbeexpected,theempiricaldatapresentedinTableIconfirmsthetwooverheadlineswhichhavebeeninsulatedtoahigherlevel(34or69KV)havesignificantlybetterreliabilityrecordsthanthoseutilizing15kVclassconstruction.Feeder7(insulatedto34KV)andfeeder8(insulatedto69kV)havebadonly3outageseachovertheir32and23yearlifespans,respectively.Theselinesfollowsimilarterrainandarecomparableinlengthandagetothe15kVclasslines,yettheyhaveacombinedfailurerateof0.22failuresperyearversus4.32failuresperyearfortheremainingfeeders.Ontypical15kVinsulatedlineconstruction,lightningflashoversoftencause60cyclepowerfollowandfeedertrip.Withthehigherinsulationconstruction,outageratesarereducedbylimitingthenumberofflashoversandtheresultantpowerfollowwhichcausesanovercurrentdevicetotrip.Thisallowslightningarresterstoperformtheirdutyofdissipatinglightningenergytoearth.Thenumberofrecloseractionsandtheirresultantmomentaryoutagesarealsoreduced.Thisisbeneficialforcriticalfacilitiesandprocesseswhichcannottolerateevenmomentaryoutages.Anadditionalbenefitisthatoutagesduetoanimalcontactarealsoreducedbecauseofthegreaterdistancefromphaseconductortogroundonpolestructures.Distributionlineequipmenttoincreaselineinsulationvaluesare"offtheshelf"itemsandproventechnology.Newlightningresistantconstructiontypicalbyutilizeshorizontallineposts,fiberglassstandoffbracketsoranyothermethodwhichworldincreasetheinsulationvalue.Thereplacementofstandardpininsulatorswithlinepostinsulatorsofgreaterflashovervalueisaneffectivemeanstoretrofitexistingwoodcrossarmconstruction.Thedoublingandtriplingofdeadendandsuspensioninsulatorsisalsoameansofincreasingflashovervaluesonexistingangleanddead-endstructures.Currentfiberglass,polymer,andepoxytechnologiesprovideanaffordablemeanstoincreaselineinsulation.Whiletheuseofincreasedinsulationlevelstoreducelightningflashoversandtheresultantoutagesonoverheaddistributionlineshasbeenthoroughlytestedanddemonstratedinlaboratoryandexperimentaltests[5],longtermhistoryfielddatahaspositivelydemonstratedthattheuseof"lightningresistant"constructioncangreatlyreduceoutages.FielduseatORNLhasshownthatinareaswhicharevulnerabletolightning,theuseofincreasedinsulationandasmallershieldingangleisanimpressiveandcosteffectivemeanstoappreciablyincreasethereliabilityofoverheaddistributionlines.Thisreliabilitystudyclearlyillustratesthattheinsulationrequirementsforhigh-reliabilitydistributionfeedersshouldbedeterminednotbythe60Hzoperatingvoltagebutratherbywithstandrequirementsforthelightningtransientsorotherhighvoltagetransientsthatareimpressedupontheline.Electricalequipment(switchgear,insulators,transformers,cables,etc.)haveareserve(BElevelorflashovervalue)tohandlemomentaryovervoltages,andbyincreasingthatreserve,theservicereliabilityisappreciablyincreased.Astheelectricalindustrygraduallymovesawayfromstandardwoodcrossarmconstructionandmovestowardmorefiberglass,polymerandepoxyconstruction,increasedinsulationmethodscanbeappliedaspartofnewconstructionoraspartofanupgradeorreplacementeffort.Inconsideringneworupgradedoverheadlineconstruction,theincrementalincreasedcostofthehigherinsulationequipmentisdinproportiontothetotalcostsofconstruction(labor,capitalequipment,cables,electricpoles,right-of-wayacquisition),Itscosteffectivenessvarieswiththeapplicationandtheconditionstowhichitisbeapplied.Economicbenefitsincludeincreasedelectricalservicereliabilityanditsinherentabilitytokeepmanufacturingprocessesandcriticalloadsinservice.Othermoredirectbenefitsincludelessrepairofoverheaddistributionlines,whichcanhaveasignificantreductioninmaintenancecostduetolessreplacementmaterialsandalargereductioninovertimehoursformaintenancecrews.抗雷击架空配电线路的可靠性闪电仍然是架空配电线路上的中断1的主要原因。通过实验室测试和现场观察和测量，雷击和其对配电系统组件的属性是很好理解的现象。本文提出了一个32年的历史记录，停运的原因，时间，地点，在橡树岭国家实验室的八个配电馈线汇编。配电型避雷器在死胡同和角度的结构被放置在极安装W奥莫尔的位置，并在高点上的架空线。站级避雷器是用来保护地下电缆运行，垫置式开关柜，单位变电站变压器。每个极接地的接地电阻通常是15欧姆或更小。在高海拔系统中，基本上是对地电阻大于15欧姆，尤其是在干燥的夏季。在这些高点，研磨棒极接地系统，在1960年，企图以减少雷击停电驱动和保税。这些尝试只是部分成功地降低停电率。从浪涌保护的角度来看，使用各种不同的杆件结构（列直插式，角，角，死路，等），和绝缘体及使用的硬件的各种不允许每13.8千伏架空线具有均匀的冲击闪络分类评价（170千伏，等）或一个数值的的BIL电压类（95千伏BIL，等等）。在分析中为了简单起见，每个分类的额定电压建筑类（15千伏，34千伏，69千伏）架空线。六七八个架空线（馈线1至6）建立典型的REA标准水平木横担，利用单级的ANSI55-5瓷针式绝缘子（标称15千伏绝缘）。架空地线相导线的屏蔽角通常是45度。一架空线（馈线7）建延长线传输型木杆建设，因为这是已产生的电能反馈到电网的研究设施。这条线极结构耐久的建设的其中利用双ANSI52-3瓷悬式绝缘子支持（标称34千伏绝缘）。馈线7的架空地线的相导体的屏蔽角通常是30度。在1969年，架空线（馈线8）有意建立“抗雷击”试图减少雷电造成的停电。该行的极结构阶段阶段超过24英寸长的玻璃纤维悬挂支架与双ANSI52-3瓷悬式绝缘子，支持标称69千伏绝缘的导体。馈线8架空地线的相导体的屏蔽角通常是30度。编制各八个13.8千伏馈线故障数据列于表I中，沿馈线结构，海拔高度，长度，和年龄的相关信息。故障分析的一个重要发现是，与天气有关的事件占了一半以上（56％）的馈线停电记录。五十七名76天气有关的中断是由于雷击。绝缘击穿损坏，由于雷击还涉嫌至少有十几观察到的设备故障。数据表明架空线路经过地势高，是不可靠的，因为雷击风险更大。例如，馈线3最录制中断（48），其中三分之二是由于与天气有关的事件，这也是最高的馈线线厂区，上升到海拔450英尺以上的参考山谷高度。也观察到架空线更长，更多的变电站和设备连接不可靠（多接触雷击和更多的设备失败）。行的年龄似乎并不显着减轻其只要足够的维护;线中断的频率有一个显着的增加作为线路岁。正如所预料的，实证的数据列于表我确认两架空线路绝缘已到一个更高的水平（34或69千伏），有显着更好的可靠性记录比那些利用15千伏级建设。馈线7（绝缘的34千伏）和馈线8（绝缘的69千伏）每过32年和23年的寿命只有3停电有坏。下面的几行类似的地形，在15千伏级线路长度和年龄相媲美，但他们有一个合并的