交流变电站细节设计指南.docx

1、ACsubstationdetaileddesignquidelines:Bestpractice,dosanddonts交流变电站详细设计指南：最佳实践、注意事项ByEdvardSubstationDesignComplexity变电站设计的复杂性Substationdesignisaverycomplexprocessthatinvolvesmanyprofessionalengineersinmanydifferentareas.However,therearealwaysfewpeoplewhoareleadingthewholedesignprocessbothfromthetech

2、nicalandeconomicalaspects.Thistechnicalarticlecoverstheselectionofsubstationtype(GISorAir-insulated)andthedetaileddesignofAir-insulatedSubstation.变电站设计是一个非常复杂的过程，涉及许多不同领域的专业工程师。然而，从技术和经济两个方面领导整个设计过程的人总是很少的。本技术文章涵盖了变电站类型(GIS或空气绝缘)的选择以及空气绝缘变电站的详细设计。Figure4一Arrangementsofcircuitbreakers(a)Withcircuitbr

3、eakersatonesideofthesubstation;(b)Withcircuitbreakersatbothsidesofthesubstation图4断路器(a)的布置，断路器位于变电站的一侧；(b)在变电站两侧安装断路器Lineandtransformerbayssequenceshould,ifpossible,befixedminimisingthepossibilityofoverloadingbusbarsorconnectionconductors.Itisnecessarytoconsiderinthelayoutdesign,thepossibilityofexte

4、nsionofthesubstation.Thistopicismoreimportantinthecaseofsubstationswithringschemebusbars.Aparticulardesignallowsforaneasytransformationfromaringschemetoadoublebusbarwitha1%circuit-breakerscheme.SeeFigure5.如果可能，线路和变压器间隔序列应固定，以尽量减少母线或连接导线过载的可能性。在布局设计中，有必要考虑变电站扩建的可能性。对于带有环形母线的变电站，该主题更为重要。一种特殊的设计可以方便地从环

5、形方案转换为带有1%断路器方案的双母线。参见图5oFigure5Figure5一Mesharrangement图5网格布置DLJc/ur/口Figure5一Mesharrangement0.图5网格布置Lightningprotectionisnecessarytoprotectasubstationagainstdirectlightningstrokes.Thisprotectioncanbearrangedineitheroverheadearthwiresorlightningrods.Itiseasiertogetanefficientprotectionbayusingearthw

6、ires.Specialattentionhastobepaidtotheeliminationoftheriskofearthwirefalldownontheswitchgear.为防止变电站遭受直接雷击，必须进行防雷保护。这种保护可以安装在架空地线或避雷针中。使用接地线更容易获得有效的保护间隔。必须特别注意消除接地线掉落在开关设备上的风险。22SecondaryCircuit22二次电路Inordertominimisetheelectromagneticinterferencebetweenprimarycircuitandcontrolequipmentandforeconomicr

7、easons(especiallywhencablesareemployed),analternativeistodecentralisethecontrol,protectionandautomationapparatus.Followingthiswaykioskscontainingsecondaryequipmentshouldbeinstalledasnearaspossibletotheswitchingequipment.Inhardclimateconditions,(verycold/hot),thissolutionmaynotbeeconomic.InFigure6,ad

8、ispositionexampleofsecondarycircuitsconcerningcontrolandprotectionsystemsisillustrated,takingintoaccountthetechnologytrendsregardingenergymanagementsystems.为了将主电路和控制设备之间的电磁干扰降至最低，并出于经济原因(尤其是在使用电缆时)，另一种选择是分散控制、保护和自动化设备O按照这种方式，包含二次设备的信息亭应尽可能靠近开关设备安装。在恶劣气候条件下（非常冷/热），这种解决方案可能不经济。在图6中，考虑到能源管理系统的技术趋势，说明了与

9、控制和保护系统有关的二次电路的配置示例。Fiqure6-Mesharrangement,Sectiona(seeFigure5)图6网格布置，截面图a(见图5)Figure6-Mesharrangement,Sectiona(seeFigure5)图6网格布置，裁面图a(见图5)2.3.CriteriafortheChoicebetweenRigidorFlexibleConductor2.3.选择刚性导体或柔性导体的标准Atpresent,thesubstationdesignwithvoltagelevelupto500kV,rigidconductorsispreferredasitis

10、moresimpleandeconomic.Inthiscase,aluminiumalloytubesareemployed.Forhighervoltagelevels,itcancausemoredifficultytosetupbytubebundleconductorswithanequivalentdiametersuitabletocontainthecoronaeffecttoanacceptablelimit.Ofcourse,thechoiceofthebestsolutionisinfluencedbytheavailabilityofmaterialsthatchang

11、efromcountrytocountry,andbydifferentcompanyexperiences.Inthefollowingparagraphs,themainadvantagesanddisadvantagesofbothsolutionsarelisted.目前，变电站的设计电压等级高达500kV,刚性导体更简单、更经济，因此是首选。在这种情况下，使用铝合金管。对于更高的电压水平，使用具有适合将电晕效应控制在可接受极限的等效直径的管束导线进行设置可能会造成更大的困难。当然，最佳解决方案的选择受到不同国家的材料可用性以及不同公司经验的影响。在以下段落中，列出了两种解决方案的主要

12、优缺点。2.3.1Rigidconductorssolution2.3.1刚性导体解决方案Advantages优势1. Simplicity,easyreadingofoperationconfigurationPlantdispositionwithonlytwolevels2. Easyaccesstothetransformersortotheswitchyardformaintenance.3. Easyuseofpantographorsemi-pantographdisconnectorsEasysubstationextension4. Easyverificationofele

13、ctrodynamicforceseffectShorterectiontime5. Lowergroundingareaforplantinstallation.操作配置简单易读1 .只有双层布置易于接近变压器或开关站进行维护。3. 易于使用受电弓或半受电弓隔离开关简易变电站扩建4. 电动力效应的简易验证7.安装时间短8.工厂安装的下部接地区域Disadvantages缺点Uneasytemporarybypassofcircuit-breakersonbothsidesofbusbars.1. Possibilityofmechanicalresonancebetweenthetubest

14、ructureandthewindgustfrequency.Canbepreventedbysuitabledampingdevices2. Thedifficultywiththeavailabilityoftubesandthesupportmaterialinsomecountries.1. 母税两侧断路器的不稳定临时旁路。2. 管道结构与阵风频率之间发生机械共振的可能性。可通过适当的阻尼装置防止在某些国家，管子和支撑材料的可用性存在困难。Figure7一Rigidbusbars图7刚性母线Figure7-Rigidbusbars图7刚性母线2.3.2Flexibleconductor

15、ssolution2.3.2软导线连接方案Advantages优点Useofthesamematerialemployedforoverheadlines1. BundleMultipleconductorswithappropriatediametertoreducecoronaeffectinultra-highvoltagesubstationsareeasyfulfilled使用与架空线路相同的材料1. 在超高压变电站中，用合适直径的多导线束来减少电晕效应是很容易实现的Disadvantages缺点1. ThecomplexlayoutalsoforsimplexschemesDiff

16、icultverificationofwithstandingtoelectrodynamicforces.2. BusbarsoverpassesaretobeprovidedConsiderableenvironmentalimpactconsequenttothreelevelsofconductorsinthesubstation3. Considerableconstructioncost.4. DifficultyinemployingpantographandsemipantographdisconnectorsDifficultyinsubstationextension.1.

17、 复杂布局也适用于单纯形方案2. 难以验证是否能承受电动力。2 .应提供母线天桥3. 变电站内二层导线对环境造成的重大影响5.相当可观的建筑成本。6.使用受电弓和半受电弓隔离开关的困难7.变电站扩建困难。Figure8一Flexibleconductors图8-柔性导体Figure8一Flexibleconductors图8-柔性导体3,GeneralCriteriaandRules3.一般标准和规则SafetyRules:Definitions3.1安全规则：定义StepVoltaqeStepVoltaqe- Thedifferenceinsurfacepotentialexperience

18、dbyapersonbridgingthedistanceofahumanstepwithoutcontactinganyotherconductivepartIEEE80.HSIEiWSin-ThemaximumpotentialdifferencebetweentheaccessibleearthsurfaceandthedeadpartwhichcanbetouchedbyahandofapersonstandingonthesurfacejIEEE81.- Thecurrentwhichcanflowthroughthehumanbodywithoutthreattothelifean

19、dhealthoftheexposedpersonIEC60479-1,-2.Maximumstepandtouchvoltagesaresettolevelsthatwilllimitthecurrentflowingthroughanexposedpersontothesafecurrentlevel.ouchVoltaqeSafeCurrenlTheproposedmethodsofserviceandrepairworkmustbeconsideredinthedesignofasubstation.Inmostcountries,theminimumclearancebetweenl

20、ivepartsandpersonnelisstandardised.跨步电压-一个人在不接触任何其他导电部件的情况下跨越人的阶跃距离所经历的表面电位差IEEE80o接触电压-可接近的地球表面和站在表面上的人的手可以接触到的死区之间的最大电位差IEEE81。安全电流能够在不威胁接触者生命和健康的情况下流过人体的电流IEC60479-1,-2o最大阶跃电压和接触电压设置为将流经暴露人员的电流限制在安全电流水平的水平。在设计变电站时，必须考虑拟定的服务和维修工作方法。在大多数国家，带电部件和人员之间的最小间隙是标准化的。Thefollowingparametersareusuallydefined

21、:通常定义以下参数：1. Minimumheightoflivepartsabovetheaccessiblesurface.2. Minimumheightofthelowestpartsofinsulatorsabovetheaccessiblesurface.3. Minimumhorizontaldistancebetweenalivepartandprotectiverails,fences,etc.4. Minimumdistancebetweenalivepartandahumanbody(orconductivetools)duringtheworkinthesubstatio

22、n.1. 带电部件在可触及表面上方的最小高度。2. 可接近表面上方绝缘子最低部分的最小高度。3. 带电部件与防护栏杆、围栏等之间的最小水平距离。4. 变电站工作期间带电部件与人体(或导电工具)之间的最小距离。Themaincircuit,onceisolated,mustbeconsideredalivepartuntilitisearthed.Itisgenerallyrequiredtocheckforvoltageontheconductorbeforeapplyingtheearthingdevice.Asitisnoteasytotestvoltagebyanindependentd

23、eviceinEHVandUHVsubstations,aremotelycontrolledearthingswitchisusedtoearththecircuitaftervisuallycheckingthedisconnectorsintheopenposition.主回路一旦隔离，在接地之前必须视为带电部件。在使用接地装置之前，通常需要检查导线上的电压。由于在超高压和超高压变电站中不容易用独立设备测试电压，在目视检查断路器处于打开位置后，使用远程控制接地开关将电路接地。Itisalsodangeroustohandlealongrodwithaportableearthingcon

24、ductorinthevicinityofliveparts.Thereforeearthingswitchesarepreferableinsubstationsabove145kV.Ptectionagainstinducedvoltageonlongbusbars.在带电部件附近搬运带有便携式接地导体的长杆也是危险的。因此，145kV以上变电站最好使用接地开关。便携式接地装置仅用于附加接地，例如保护长母线上的感应电压。3.1 OvervoltageandInsulat

25、ionLevels3.2过电压和绝缘水平Allequipmentinstalledinasubstationmustbedesignedbytakingtheratedpowerfrequencyvoltageofthenetworkintoaccount.Thetemporaryovervoltagesatpowerfrequencyareoftencausedbythesuddenlossofloadorearthfaults,switchingovervoltagesandlightningovervoltages.变电站中安装的所有设备的设计必须考虑电网的额定工频电压。工频临时过电压通

26、常由突然失去负载或接地故障、操作过电压和雷电过电压引起。Inordertodetermineitscapabilityitissubjecttovoltagetestsasfollows:为了确定其性能，需要进行如下电压测试：1. LightningImpulseWithstandVoltage.(1.2/50)SwitchingImpulsewithstandvoltage(250/2500)2. Powerfrequency(50or60Hz)(wetand/ordry).1. 雷电冲击耐受电压。(1.2/50)操作冲击耐受电压(250/2500)2. 电源频率(50或60Hz)(湿和/或

27、干)。Additionally,anoscillatingvoltageorchoppedwavetestmayberequired.Thesetoftestvoltagevaluesdeterminestheinsulatinglevel.StandardinsulatinglevelsaredefinedinIECStandard71althoughthenetworkparametersmaydictateothervaluesIEC60071-1,-2.此外，可能需要进行振荡电压或斩波测试。测试电压值的设置决定了绝缘ACsubstationdetaileddesignguideline

28、s:Bestpractice,dosanddonts交流变电站详细设计指南：最佳实践、注意事项Manynationshavetheirownsafetyrulesand,becauseoftheirimportanceandlegalityasconsideredatthebeginningofthisarticle.Thethreecomponentpartsofthesubstationaredefinedasfollows:Primary,Secondary,andAuxiliarySystem.许多国家都有自己的安全规则，因为它们的重要性和合法性，正如本文开头所考虑的那样。变电站的三个

29、组成部分定义如下：一次系统、二次系统和辅助系统。Letsremindourselvesofthesethreebasicsubstationsystems:让我们提醒自己这三个基本的变电站系统：1. PrimarySystem:Theprimarysystemcomprisesallequipmentthat,inwholeorinpart,isinserviceatthehighestoperatingvoltageofthesystem.2. SecondarySystem:Thesecondarysystemcomprisesallequipmentthatisusedforthecon

30、trol(localandremote),protection,monitoringautomationandmeasurementoftheprimarysystem.水平。标准绝缘水平在IEC标准71中定义，尽管网络参数可能规定其他值IEC60071-1,-2oThenecessaryinsulationleveldependsontheinsulationco-ordination,i.e.onthepropertiesofdifferentpartsofthenetwork(mainlylines),theprotectionusedagainstovervoltages(surgea

31、rrestersZnOareveryeffective),onaltitudeandalsoontherequiredreliabilityofthesubstation(permissibleprobabilityofflashover)andmayvaryindifferentpartsofthesamesubstation.必要的绝缘水平取决于绝缘协调，即取决于网络不同部分(主要是线路)的性能、用于过压的保护(电涌放电器非常有效)，海拔高度和变电站所需的可靠性(允许的闪络概率)，在同一变电站的不同部分可能有所不同。3,3 CurrentRatingandOvercurrents3.3额定

32、电流和过电流Theinstantaneousloadflowwithinasubstationdependsonthestateoftheentireelectricalnetwork.Usually,acompletenetworkanalysisincludingthedevelopmentofthenetworkinfutureisrequiredtodeterminethenominalvaluesofcurrentsflowinginanindividualsubstationcircuit.变电站内的瞬时负荷流量取决于整个电网的状态。通常，需要进行完整的网络分析，包括未来网络的开发

33、，以确定单个变电站电路中流动电流的标称值。Itistheoreticallypossibleformaximumcurrentflowtooccurwitharelativelylowtotalproductionofelectricityinthenetwork,e.g.thesupplytoapumpedstoragepowerstationorwhenutilisingtheby-passfacilitywithinasubstation.理论上，在电网总发电量相对较低的情况下，最大电流是可能的。e、g抽水蓄能电站的供电或使用变电站内的旁路设施时。Whiledesigningasubst

34、ationitisnecessarytoconsiderthefollowingtwoaspectsoftheeffectofcurrent:在设计变电站时，必须考虑以下两个方面电流的影响：1. Thethermaleffect(includinginducedcurrents).2. Themechanicaleffectonconductiveitemsofplantandtheirsupportstructures.1.热效应(包括感应电流)。2.对设备导电部件及其支撑结构的机械影响。Precisethermalmodellingofequipmentisverydifficultasm

35、anyfactorsinfluencetheresultanttemperaturesofconductivepartse.g.previousloading,ambienttemperature,windspeed,andsolarconditions.Thermaldesignisthereforeempiricalandisprovenbytypetestcoveringnominalcurrentratingandshort-circuitcurrentrating.Standardprocedureshavebeendevisedtopredictthethermalbehaviou

36、rofconductors,particularlywithrespecttosag.设备的精确热建模非常困难，因为许多因素会影响导电部件的合成温度,例如之前的负载、环境温度、风速和太阳条件。因此，热设计是经验性的，并通过涵盖标称电流额定值和短路电流额定值的型式试验得到证明。已经设计了标准程序来预测导体的热行为，尤其是关于弧垂。Itmaybepossibletoassignashort-termcurrentratinginexcessofthenominalbuttheanalysisleadingtothismustbetoensurethatno“hotspots”(transforme

37、rs,terminals,busbarsupportpoints)areoverlooked.可能会指定一个超过标称值的短期额定电流，但导致这种情况的分析必须确保没有忽略“热点”(变压器、端子、母线支撑点)。Methodsofcalculatingshort-circuitcurrentvaluesaregiveninIECStandard909andtheeffectsofshortcircuitcurrentcanbeevaluatedinaccordancewithIECStandard865-1.IEC标准909给出了计算短路电流值的方法，短路电流的影响可根据IEC标准865-1进行评

38、估。3.4 ElectricalClearances3.4电气间隙ItisnotpossibletotestthewholeHVinstallationbycorrespondingtestvoltages.Thereforeminimumclearancesintheairbetweenlivepartsorbetweenliveanddeadpartsintheairarestated,toobtaintherequiredinsulationlevelinarrangementsthathavenotbeentested.Astheclearancesarestateduniversal

39、ly,theymustassumetheinsulationintheworstcaseofspark-gapwithsufficientreliability.Smallerclearancesarepermissibleiftheparticulararrangementhasbeentestedbytheprescribedinsulationtest(IEC60071-1).Thevaluesofminimumdistancestolivepartsintheairalsodependuponpracticalexperienceandtherefore,somedifferences

40、canbefoundwhencomparingrulesindifferentcountries.Thespecifiedelectricalclearancesmustbemaintainedunderallnormalconditions.Exceptionallyreducedelectricalclearancesmaybeallowed.Forexample,inthecaseofconductormovementcausedbyshort-circuitcurrentorbyanextremelystrongwind.不可能通过相应的测试电压来测试整个高压装置。因此，规定了带电部件

41、之间或空气中带电部件与非带电部件之间的最小空气间隙，以便在未经测试的布置中获得所需的绝缘水平。由于间隙是普遍规定的，它们必须在火花间隙的最坏情况下具有足够的可靠性。如果特定布置已通过规定的绝缘试验(IEC60071-1)进行试验，则允许较小的间隙。空气中带电部件的最小距离值也取决于实际经验，因此，在比较不同国家的规则时，可以发现一些差异。在所有正常条件下，必须保持规定的电气间隙。允许出现异常减小的电气间隙。例如，在短路电流或极强风导致导体移动的情况下。3.5 MechanicalForces3.5机械力3.5.1 EquipmentWeight3.5.1设备重量Inadditiontothen

42、ormalweightofapparatus,conductors,structuresetc,temporaryloadsmustbeconsidered,especiallytheweightoffrostandice(dependsonlocalclimate)andloadsimposedbymaintenancestaffaccess.Thestrainduringerectionmustalsobeconsidered(liftingofstructures,theasymmetricpullofconductoretc.).除了设备、导线、结构等的正常重量外，还必须考虑临时荷载，

43、尤其是霜和冰的重量(取决于当地气候)以及维护人员施加的荷载。还必须考虑安装期间的应变(结构的提升、导体的不对称拉力等)。3.5.2 Windloading3.5.2风荷载Thewindpressuremaysubstantiallyinfluencethestrainexertedonstructuresandfootingsandmayalsoreducetheclearancesbetweenconductors(inthecaseofturbulentwind)orbetweentheconductorsandgroundedstructures(considerationshouldb

44、egiventoinsulatorsinVformationwhereproblemsoccur).StandardvaluesforwindspeedarerecommendedbyIECbutlocalconditionsmustalwaysbeconsidered.Whencalculatingthewindloadsonbundleconductorsthescreeneffectfromtheothersubconductorsmaybetakenintoconsideration.Theeffectofwindoninsulatorstringsshouldbetakenintoa

45、ccount.Thewindloadscanbetransmittedtotheapparatusthrougheitherrigidorflexibleconnections.Specialcareshouldbetakenagainsttheeffectsofaeolianvibrationinrigidtubes.ThesevibrationsareduetoVonKarmanvortexsheddingandcanbemanaged(damped)usingeitherexternaldampersorinsomecasesbyinstallingaflexiblecableinsid

46、ethetubes.Theflexiblecableactsasanimpactdamper(efficientiftheaccelerationofthemovementisgreaterthanthegravity).风压可能会极大地影响施加在结构和基脚上的应变，也可能会减少导体之间（在紊流风的情况下）或导体与接地结构之间的间隙（出现问题时，应考虑V形结构中的绝缘体）。IEC推荐风速标准值，但必须始终考虑当地条件。计算分裂导线上的风荷载时，可考虑其他次级导线的屏蔽效应。风对绝缘子串的影响应该考虑到这一点。风荷载可通过刚性或柔性连接传递至设备。应特别注意刚性管道中的风振效应。这些振动是由冯卡

47、门漩涡脱落引起的，可以使用外部阻尼器或在某些情况下通过在管道内安装柔性电缆来管理（阻尼）。柔性缆绳起到了减震器的作用（如果运动加速度大于重力，那么减震器会很有效）。Possiblesolution:可能的解决方案:Figure9一Panelsoflayered,fibreglass-reinforcedplastic.Uponimpact,thelayersdelaminate,slowingandabsorbingaspeedingwindimpact.图9分层玻璃纤维增强塑料面板。受到冲击时，各层分层，减缓并吸收加速的风冲击。Figure9一Ballisticwalls图9防弹墙Earth

48、quake3.5.3地震Earthquakesoccurindifferentpartsoftheworld.Substationplannersshouldconsidertheprobabilityandtheexpectedseverityofapossibleearthquake.Becausethehorizontalaccelerationisabout0,3-0,5g(theverticalaccelerationislessthan50%ofthehorizontal)andthefrequencyoftheearthquakeis0,5-10Hz,275一500kVequip

49、mentthatresonatesinthisfrequencybandmaybedamaged.Bussupportinsulatorsareparticularlyvulnerable.Tubularaluminiumconductorsarealsothoughttoresonateduringearthquakesand,ifrequired,“dampers”orslidesupportsmaybefitted.Equipmentinthesubstationisliabletosufferfromdamagewherethegroundconditionsarenotstable.

50、地震发生在世界各地。变电站规划师应考虑可能发生地震的概率和预期严重程度。由于水平加速度约为0.3-0.5g（垂直加速度小于水平加速度的50%）,且地震频率为0.5-10HZ,在该频带内共振的275-500kV设备可能会损坏。母线支撑绝缘子他们尤其脆弱。管状铝导体也被认为在地震期间会产生共振，如果需要，可以安装“阻尼器或“滑动支架”。在地面条件不稳定的情况下，变电站内的设备容易受到损坏。Therefore,particularattentionshouldbepaidtositepreparationtoensuresolidityoftheground.因此,应特别注意现场准备,以确保地面“坚

51、固”。Figure10图10地震后隔离支架上的断路器Figure10-Circuitbreakersonisolatedsupportsaftertheearthquake图10一一地震后隔离支架上的断路器一CircuitbreakersonisolatedsupportsaftertheearthquakeFigure11一Substationdamageduetoearthquake图11地震造成的变电站损坏Figure11-Substationdamageduetoearthquake图11地震造成的变电站损坏Short-circuit3.5.4短路Generally,equipment

52、istypetestedinashotcicuitlaboratorytodetermineitsdynamicbehaviourwiththeexceptionofsupportinsulators.Insulatorsaregenerallytestedtomeetloadsinstaticmode.Theshort-circuitstrengthofthebusbarsisusuallyonlycalculated,thecalculationmethodsbeingverifiedbytestingoftypicalbusbararrangements.IEC865-1canbeuse

53、dbothforrigidandflexibleconnections,thebackgroundtothecalculationmethodsisdetailedinCIGREBrochureN105,publishedin1996.Equationspresentedinthesepublicationsdonottakeintoaccounttheflexibilityofinsulatorsandthismayresultinover-specificationoftherequiredstrengthofinsulators,especiallywheretheapplication

54、isofnon-ceramicinsulators.Advancedmethodscanbeusedforspecificarrangements,tovalidatesimpleevaluations,ortolimitshort-circuitteststotheminimumnumberofconfigurations.Theygiveaccesstomuchmorecomprehensivedatathansimplemethods(forexampledynamiceffects,supportingstructurestressandstrain,spacercompression

55、,connectiontoapparatus,insulatorandsupportingstructureflexibility,etc.)通常，设备在短路实验室进行型式试验，以确定其动态性能，但支撑绝缘子除外。绝缘子通常经过测试，以满足静态模式下的负载。通常只计算母线的短路强度，计算方法通过典型母线布置的测试进行验证。IEC865-1既可用于刚性连接，也可用于柔性连接，计算方法的背景详见1996年出版的CIGRE手册N105o这些出版物中给出的方程式没有考虑绝缘子的柔韧性，这可能导致绝缘子所需强度的规格过高，尤其是在应用非陶瓷绝缘子的情况下。高级方法可用于特定布置、验证简单评估或将短路测试

56、限制在最小配置数。与简单方法相比，它们提供了更全面的数据(例如动态效应、支撑结构应力和应变、垫片压缩、设备连接、绝缘子和支撑结构柔性等)Calculatedelectromagneticforcesshouldneverbeusedtodeterminedirectloadingonsupports.Thisisbecauseofthedynamicinteractionofahighfrequency(50and100Hz)loadwithstructureshavingalowresonantfrequency(0.5HzforflexiblestructuresandafewHzforr

57、igidones).Thateffectistakenintoaccountinadvancedmethodsandisapproximatedinsimplemethodsbyreductionfactors.不得使用计算出的电磁力来确定支架上的直接载荷。这是因为高频(50和100Hz)荷载与具有低共振频率(柔性结构为0.5日乙刚性结构为几Hz)的结构之间的动态相互作用。这种影响在高级方法中得到考虑，在简单方法中通过折减系数进行近似。Inthecaseofinsulatorsupports,apparatusandtransformerbushings,resonancemayoccur.T

58、hisoccursespeciallyinsubstationsdesignedforavoltageofaround150kV,butotherinstallationsmaybeaffected,Theuseofdampingdevicesmaybeconsidered.Alwaysconsiderthetwo-phaseisolatedfaultconditionforclearancesandthetwoorthree-phasefaultconditionformaximuminter-phasestress.Wherebundleconductorsareusedthepincheffectsmustbeconsidered.Asaminimum,reducesub-conductordistancesandavo