電氣工程及其自動(dòng)化專業(yè)英語(yǔ) 課件 -Chapter 2 Transmission system

目錄Introduction2.1TransmissionLines2.2Transformers2.3ExtraHighVoltage(EHV)Transmission2.4Chapter2Transmissionsystemeactivepower無(wú)功功率

overheadline架空線leakagecurrent泄漏電流alternatingvoltages交流電壓capacitance[k?'p?sit?ns]n.電容，電流容量parameter[p?'r?mit?]n.參數(shù)，系數(shù)，參量insulate['insjuleit,'ins?-]vt.隔離，使絕緣impregnate['impreɡneit,im'preɡ-,im'preɡnit,-neit]adj.浸漬的，浸染的sinusoidal[,sin?'s?idl]adj.正弦曲線的shuntadmittance并聯(lián)導(dǎo)納propagationconstant傳播常數(shù)Shunt（）mayincreasethesettlingtime.capacitancereducesinductorelectricreactorABCD提交單選題1分attenuationconstant衰減常數(shù)incidentvoltage入射電壓exponential[,eksp?u'nen??l]adj.指數(shù)的tap[t?p]n.抽頭compensate['k?mpenseit]vt.補(bǔ)償tap-changing['t?p't?eind?i?]n.抽頭切換distributiontransformers輸電變壓器autotransformer[,?:t?utr?ns'f?:m?]n.自耦變壓器magneticcoupling磁力耦合transformationratio變比overload[,?uv?'l?ud,'?uv?l?ud]n.過(guò)載，超負(fù)荷()facetocustomersdirectly,itsoperationstateistheimportantcomponentofsafeeconomicaloperationofthewholedistributionnetwork.ACtransformerammeterDistribution

transformersVoltmeterABCD提交單選題1分saturation[,s?t??'rei??n]n.飽和，磁化飽和turnsratio匝數(shù)比deviation[,di:vi'ei??n]n.偏差，誤差irrespectiveof不考慮fictitious[fik'ti??s]adj.虛構(gòu)的，假想的transient['tr?nzi?nt]adj.暫態(tài)的symmetrical[si'metrik?l]adj.勻稱的，對(duì)稱的transferadmittance轉(zhuǎn)移導(dǎo)納tremendous[tri'mend?s]adj.巨大的infrastructure['infr?,str?kt??]n.基礎(chǔ)設(shè)施transmissiongrid輸電網(wǎng)Impedancewillreflectbackasthesquareofthe（）.acceleratedspeedArmatureWindingnumberofturnsturnsratioABCD提交單選題1分generatingplants發(fā)電廠optimize['?ptimaiz]vt.使最優(yōu)化reliability[ri,lai?'bil?ti]n.可靠性coordinate[k?u'?:dinit,k?u'?:dineit]vi.協(xié)調(diào)alleviate[?'li:vieit]vt.減輕，緩和complementary[,k?mpli'ment?ri]adj.補(bǔ)足的，補(bǔ)償?shù)膇nnovation[,in?u'vei??n]n.創(chuàng)新commissioned[k?'mi??nd]adj.受委任的，被任命的synchronize['si?kr?naiz]vt.使同步backbonegrids主干網(wǎng)demonstration[,dem?n'strei??n]n.示范，證明Duringthesameperiod,theworldwasthrustintothenuclearerawithbothitsdestructivedevicesanditspower-（）.hydropowerstationgeneratingplantsnuclearpowerstationdynamoABCD提交單選題1分geographic[d?i?'gr?fik]adj.地理的，地理學(xué)的substation['s?bstei??n]n.變電站feasibility[,fi:z?'biliti]n.可行性preliminary[pri'limin?ri]adj.初步的，預(yù)備的facilitate[f?'siliteit]vt.促進(jìn)，幫助（）locatingisanimportantpartofpowersystemplanning.transformerconvertorstationSubstationcontrolcenterABCD提交單選題1分目錄Introduction2.1TransmissionLines2.2Transformers2.3ExtraHighVoltage(EHV)Transmission2.4Electricalpoweristransmittedfromgeneratingstationstoconsumersthroughoverheadlinesandcables.電能通過(guò)架空線路和電纜從發(fā)電廠輸送給電力用戶。2.1IntroductionOverheadlinesareusedforlongdistancesinopencountryandruralareas.Whereascablesareusedforundergroundtransmissioninurbanareasandforunderwatercrossings.Forthesamerating,cablesare10to15timesmoreexpensivethanoverheadlinesandtheyarethereforeonlyusedinspecialsituationswhereoverheadlinescannotbeused;thedistancesinsuchapplicationareshort.

架空線路用于曠野和農(nóng)村地區(qū)的長(zhǎng)距離線路。而電纜則用于城市地區(qū)的地下和從水下敷設(shè)。相同輸送容量下，電纜的投資比架空線路貴10到15倍，因此它們只用于不能使用架空線路的特殊情況;這些應(yīng)用中的距離都很短。Introduction2.1TransmissionLines2.2Transformers2.3ExtraHighVoltage(EHV)Transmission2.4目錄2.2.1OverheadlinesAtransmissionlineischaracterizedbyfourparameters:seriesresistanceRduetotheconductorresistivety,shuntconductanceGduetoleakagecurrentsbetweenthephaseandground,seriesinductanceLduetomagneticfieldsurroundingtheconductor,andshuntcapacitanceCduetotheelectricfieldbetweenconductors.傳輸線的特征有四個(gè)參數(shù):導(dǎo)體電阻率引起的串聯(lián)電阻R，相與地之間漏電流引起的并聯(lián)電導(dǎo)G，導(dǎo)體周圍磁場(chǎng)引起的串聯(lián)電感L，導(dǎo)體之間電場(chǎng)引起的并聯(lián)電容C。2.2.1OverheadlinesDetailedderivationsfromfirstprinciplesforthelineparameterscanbefoundinstandardbooksonpowersystems.Here,wewillbrieflysummarizesalientpointsrelatingtolineparameters.線路參數(shù)的詳細(xì)推導(dǎo)的原理可以在電力系統(tǒng)的標(biāo)準(zhǔn)書籍中找到。在這里，我們將簡(jiǎn)要總結(jié)與線路參數(shù)有關(guān)的要點(diǎn)。2.2.1OverheadlinesSeriesresistanceR.Theresistancesoflinesaccountingforstandingandskineffectaredeterminedfrommanufacturers’tables.ShuntconductanceG.Theshuntconductancerepresentslossesduetoleakagecurrentsalonginsulatorstringsandcorona.Inpowerlines,itseffectissmallandusuallyneglected.串聯(lián)電阻R：線路的電阻根據(jù)制造商的目錄確定。并聯(lián)電導(dǎo)G：并聯(lián)電導(dǎo)表示由于絕緣子串和電暈上的泄漏電流而造成的損耗。在輸電線中，它的影響很小，通常被忽略。2.2.1OverheadlinesSeriesinductanceL.Thelineinductancedependsonthepartialfluxlinkageswithintheconductorcrosssectionandexternalfluxlinkages.Foroverheadlines,theinductancesofthethreephasesaredifferentfromeachotherunlesstheconductorshaveequilateralspacing,ageometrynotusuallyadoptedinpractice.串聯(lián)電感L：線路電感取決于導(dǎo)體截面內(nèi)的部分磁鏈和外部磁鏈。對(duì)于架空線路，除非導(dǎo)體間距相等，否則三相間電感互不相同，但在實(shí)際中通常不采用這種（等邊三角形）結(jié)構(gòu)。2.2.1OverheadlinesTheinductancesofthethreephaseswithnon-equilateralspacingcanbeequalizedbytransposingthelinesinsuchawaythateachphaseoccupiessuccessivelyallthreepossiblepositions.通過(guò)調(diào)換線路，使每個(gè)相位依次占據(jù)所有三個(gè)可能的位置，可以使具有非等邊間距的三個(gè)相位的電感相等。2.2.1OverheadlinesForatransposedthree-phaseline,theinductanceperphaseis

Intheaboveequation，Dsistheselfgeometricmeandistance,takingintoaccounttheconductorcomposition,stranding,andbundling;itisalsocalledthegeometricmeanradius.AndDeqisthegeometricmeanofthedistancesbetweentheconductorsofthethreea,b,andc:對(duì)于轉(zhuǎn)置的三相線路，每相電感為上式中，Ds為自身幾何平均距離，考慮到導(dǎo)體的組成、絞合和捆扎;它也被稱為幾何平均半徑。Deq是abc三個(gè)導(dǎo)體之間距離的幾何平均值2.2.1OverheadlinesThepotentialdifferencebetweentheconductorsofatransmissionlinecausestheconductorstobecharged;thechargeperunitofpotentialdifferenceisthecapacitancebetweenconductors.Whenalternatingvoltagesareappliedtothecapacitances.當(dāng)對(duì)電容施加交流電壓時(shí)，傳輸線導(dǎo)體之間的電位差使導(dǎo)體帶電;單位電勢(shì)差的電荷就是導(dǎo)體間的電容。備注：電容是電荷與電勢(shì)差之間的比值,用來(lái)衡量電路存儲(chǔ)電荷的能力。2.2.2UndergroundcablesUndergroundcableshavethesamebasicparametersasoverheadlines:seriesresistanceandinductance;shuntcapacitanceandconductance.However,thevaluesoftheparametersandhencethecharacteristicofcablesdiffersignificantlyformthoseofoverheadlinesforthefollowingreasons:地下電纜具有與架空線路相同的基本參數(shù):串聯(lián)電阻和電感,并聯(lián)電容和電導(dǎo)。但由于以下原因，電纜的參數(shù)值和特性與架空線路有很大的不同:2.2.2Undergroundcables（1） Theconductorsinacablearemuchclosertoeachotherthantheconductorsofoverheadlines.（2） Theconductorsinacablearesurroundedbymetallicbodiessuchasshield,leadoraluminumsheets,andsteelpipes.（3） Theinsulatingmaterialbetweenconductorsinacableisusuallyimpregnatedpaper,low-viscosityoil,oraninertgas.(1)電纜導(dǎo)體之間的距離比架空線路的導(dǎo)體之間的距離要近得多。(2)電纜導(dǎo)體周圍有金屬體，如屏蔽板、鉛板或鋁板、鋼管等。(3)電纜導(dǎo)體之間的絕緣材料通常是浸漬紙、低粘度油或惰性氣體。2.2.2UndergroundcablesIntheprevioussection,weidentifiedtheparametersofatransmissionlineperunitlength.Thesearedistributedparameters;thatis,theeffectsrepresentedbytheparametersaredistributedthroughoutthelengthoftheline.在上一節(jié)中，我們確定了單位長(zhǎng)度傳輸線的參數(shù)。這些是分布參數(shù);也就是說(shuō)，由參數(shù)表現(xiàn)的效應(yīng)分布在整個(gè)線的長(zhǎng)度上。2.2.2UndergroundcablesIfthelineisassumedtransposed,wecananalyzethelineperformanceonaper-phasebasis.Fig.2.1showstherelationshipbetweencurrentandvoltagealongonephaseofthelineintermsofthedistributedparameters,with如果假設(shè)線路經(jīng)過(guò)完整的換位，我們可以按相分析線路的性能。圖2.1給出了沿線路某相電流與電壓的分布參數(shù)關(guān)系，其中……Fig.2.1Voltageandcurrentrelationshipofadistributedparameterline2.Undergroundcableshavethesamebasicparametersasoverheadlines:seriesresistanceandinductance;shuntcapacitanceandconductance.地下電纜具有與架空線路相同的基本參數(shù):串聯(lián)電阻和電感,并聯(lián)電容和電導(dǎo)。Introduction2.1TransmissionLines2.2Transformers2.3ExtraHighVoltage(EHV)Transmission2.4目錄2.3.1IntroductionAtransformerisadeviceusedtoconvertvoltagelevelsinanACcircuit.Theyhavenumeroususesinpowersystems.Tobegin,itismoreefficienttotransmitpowerathighvoltagesandlowcurrentthanlowvoltageandhighcurrent.Conversely,lowervoltagesaresaferandmoreeconomicforenduse.變壓器是一種在交流電路中用來(lái)轉(zhuǎn)換電壓等級(jí)的裝置。它們?cè)陔娏ο到y(tǒng)中有許多用途。首先，在高電壓和小電流下傳輸功率比在低電壓和大電流下傳輸功率更有效。反過(guò)來(lái)說(shuō)，較低的電壓更安全，更經(jīng)濟(jì)的最終用途。2.3.1IntroductionThus,transformersareusedtostep-upvoltagesfromthegeneratorsandthenusedtostep-downthevoltageforenduse.Anotherwideuseoftransformersisforinstrumentationsothatsensitiveequipmentcanbeisolatedfromthehighvoltagesandcurrentsofthetransmissionsystem.Transformersmayalsobeusedasmeansofcontrollingrealpowerflowbyphase-shifting.因此，變壓器用于從發(fā)電機(jī)升壓電壓，然后用于降壓電壓，以供最終使用。變壓器的另一個(gè)廣泛用途是用于儀器儀表，以便將靈敏的設(shè)備與傳輸系統(tǒng)的高壓和高壓電流隔離開(kāi)來(lái)。變壓器也可用作通過(guò)移相控制實(shí)際功率流的手段。2.3.1IntroductionTransformersenableutilizationofdifferentvoltagelevelsacrossthesystem.Fromtheviewpointsofefficiencyandpower-transfercapability,thetransmissionvoltageshavetobehigh,butitisnotpracticallyfeasibletogenerateandconsumepoweratthesevoltages.變壓器使在系統(tǒng)中利用不同的電壓等級(jí)成為可能。從效率和輸電能力的角度考慮，輸電電壓必須高，但在這樣的電壓下發(fā)電和用電是不現(xiàn)實(shí)的。2.3.1IntroductionInmodernelectricpowersystems,thetransmittedpowerundergoesfourtofivevoltagetransformationsbetweenthegeneratorsandtheultimateconsumers.Consequently,thetotalMVAratingofallthetransformersinapowersystemisaboutfivetimesthetotalMVAratingofallthegenerators.在現(xiàn)代電力系統(tǒng)中，傳輸?shù)碾娏υ诎l(fā)電機(jī)和最終用戶之間要經(jīng)歷4到5次電壓轉(zhuǎn)換。因此，電力系統(tǒng)中所有變壓器的總額定值視在功率大約是所有發(fā)電機(jī)的總額定視在功率的5倍。2.3.1IntroductionInadditiontovoltagetransformation,transformersareoftenusedforcontrolofvoltageandreactivepowerflow.Therefore,practicallyalltransformersusedforbulkpowertransmissionandmanydistributiontransformershavetapsinoneormorewindingsforchangingtheturnsratio.除了電壓變換，變壓器經(jīng)常用于控制電壓和無(wú)功潮流。因此，幾乎所有用于大功率傳輸?shù)淖儔浩骱驮S多配電變壓器都有一個(gè)或多個(gè)分接頭來(lái)改變?cè)褦?shù)比。2.3.1IntroductionFromthepowersystemviewpoint,changingtheratiooftransformationisrequiredtocompensateforvariationsinsystemvoltages.Twotypesoftap-changingfacilitiesareprovided:off-loadtapchangingandunder-loadtapchanging(ULTC).Theoff-loadtap-changingfacilitiesrequirethetransformertobede-energizedfortapchanging;theyareusedwhentheratiowillneedtobechangedonlytomeetlong-termvariationsduetoloadgrowth,systemexpansion,orseasonalchanges.從電力系統(tǒng)的角度來(lái)看，需要改變變比來(lái)補(bǔ)償系統(tǒng)電壓的變化。提供兩種類型的分接頭轉(zhuǎn)換設(shè)施:無(wú)載調(diào)壓分接頭轉(zhuǎn)換和有載調(diào)壓分接頭轉(zhuǎn)換(ULTC)。無(wú)載分接設(shè)施要求變壓器斷電進(jìn)行分接;只有當(dāng)由于負(fù)荷增長(zhǎng)、系統(tǒng)擴(kuò)展或季節(jié)變化而需要改變比例以滿足長(zhǎng)期變化時(shí)，（才會(huì)）使用它們。2.3.1IntroductionTheULTCisusedwhenthechangesinrationeedtobefrequent;forexample,totakecareofdailyvariationsinsystemconditions.Thetapsnormallyallowtheratiotovaryintherangeof±10%to±15%.當(dāng)變比變化需求頻繁時(shí)，使用ULTC;例如，考慮到系統(tǒng)運(yùn)行條件的日常變化。抽頭通常允許該變比在±10%到±15%的范圍內(nèi)變化。2.3.1IntroductionTransformersmaybeeitherthree-phaseunitsorthreesingle-phaseunits.ThelattertypeofconstructionisnormallyusedforlargeEHVtransformersandfordistributiontransformers.LargeEHVtransformersareofsingle-phasedesignduetothecostofspare,insulationrequirements,andshippingconsiderations.Thedistributionsystemsservesingle-phaseloadsandaresuppliedbysingle-phasetransformers.變壓器可以是一體的三相變壓器或者由三個(gè)單相變壓器組成三相的。后一種結(jié)構(gòu)通常用于大型超高壓變壓器和配電變壓器。由于備件成本、絕緣要求和運(yùn)輸考慮，大型超高壓變壓器采用單相設(shè)計(jì)。配電系統(tǒng)用于單相負(fù)載，由單相變壓器供電。2.3.1IntroductionWhenthevoltagetransformationratioissmall,autotransformersarenormallyused.Theprimaryandsecondarywindingsofautotransformersareinterconnectedsothatthepowertobetransformedbymagneticcouplingisonlyaportionofthetotalpowertransmittedthroughthetransformer.Thereisthusinherentmetallicconnectionbetweentheprimarysideandsecondarysidecircuits;thisisunliketheconventionaltwo-windingtransformerwhichisolatesthetwocircuits.當(dāng)電壓變比較小時(shí)，通常采用自耦變壓器。自耦變壓器的初級(jí)繞組和次級(jí)繞組是相互連接的，因此通過(guò)磁耦合轉(zhuǎn)換的功率只是通過(guò)變壓器傳輸?shù)目偣β实囊徊糠帧Ｒ虼?，在初?jí)側(cè)和次級(jí)側(cè)電路之間存在固有的金屬連接;這與傳統(tǒng)的雙繞組變壓器不同，它的兩個(gè)繞組電路是隔離的。2.3.1IntroductionAutotransformersareusuallyYconnected,withneutralssolidlygroundedtominimizethepropagationofdisturbancesoccurringononesideintotheotherside.Itisacommonpracticetoaddalow-capacitydelta-connectedtertiarywinding.自耦變壓器通常是Y型連接，中性點(diǎn)牢固接地，以盡量減少一側(cè)發(fā)生的干擾傳播到另一側(cè)。通常的做法是增加一個(gè)小容量的三角連接的第三繞組。2.3.1IntroductionThetertiarywindingprovidesapathforthirdharmoniccurrents,therebyreducingtheirflowonthenetwork.Italsoassistsinstabilizingtheneutral.Reactivecompensationisoftenprovidedthroughuseofswitchedreactorsandcapacitorsonatertiarybus.第三繞組為三次諧波電流提供了通道，從而減少了它們?cè)诰W(wǎng)絡(luò)上的流量。它還有助于穩(wěn)定中性點(diǎn)電位。無(wú)功補(bǔ)償通常通過(guò)在第三母線上使用投切電抗器和電容器來(lái)提供。2.3.1IntroductionAscomparedtotheconventionaltwo-windingtransformer,theautotransformerhasadvantagesoflowercost,higherefficiency,andbetterregulation.Theseadvantagesbecomelesssignificantasthetransformationratioincreases;hence,autotransformersareusedforlowtransformationratios(forexample,500/230kV).

相比傳統(tǒng)的雙繞組變壓器，自耦變壓器具有成本低、效率高、調(diào)節(jié)性能好等優(yōu)點(diǎn)。這些優(yōu)勢(shì)在高變壓系數(shù)的時(shí)候并不是很明顯，因此，自耦變壓器用于低變換比(例如，500/230kV)。2.3.1IntroductionIninterconnectedsystems,itsometimesbecomesnecessarytomakeelectricalconnectionsthatformloopcircuitsthroughoneormorepowersystems.Tocontrolthecirculationofpowerandpreventoverloadingcertainlines,itisusuallynecessaryinsuchsituationstousephase-angletransformers.在互聯(lián)系統(tǒng)中，有時(shí)需要通過(guò)一個(gè)或多個(gè)電力系統(tǒng)進(jìn)行電氣連接形成環(huán)路。為了控制電力的循環(huán)和防止某些線路過(guò)載，在這種情況下通常需要使用移相變壓器。2.3.1IntroductionOftenitisnecessarytovarytheextentofphaseshifttosuitchangingsystemconditions;thisrequiresprovisionofon-loadphase-shiftingcapability.Voltagetransformationmayalsoberequiredinadditiontophaseshift.通常需要改變相角差以適應(yīng)不斷變化的系統(tǒng)條件;這需要提供有載移相能力。除相移外，還可能需要電壓變換。Introduction2.1TransmissionLines2.2Transformers2.3ExtraHighVoltage(EHV)Transmission2.4目錄2.4.1IntroductionAttheendof2005theinstalledgenerationcapacityof500GWmakesChinathesecondhighestintheelectricityproductionintheworld,AsChinaisbeingtransformedintothemanufacturingcentreoftheworld,andtheincreaseofelectricitydemandistremendous.2005年底，中國(guó)發(fā)電裝機(jī)容量達(dá)到500GW，成為世界發(fā)電量第二大的國(guó)家。中國(guó)正在變成世界制造業(yè)中心并且電力需求迅速增加。2.4.1IntroductionNewelectricenergyinfrastructureisrequiredtotransferbulkelectricityenergyoveraverylongdistance.Althoughthe500kVACand500-kVDCtransmissionsystemsareexisting,suchtransmissionnetworksarestillconsideredtobeinadequateforbulkelectricityenergytransmission.

新的電力能源基礎(chǔ)設(shè)施需要在很遠(yuǎn)的距離上傳輸大量電能。雖然已有500千伏交流和500千伏直流輸電系統(tǒng)，但這種輸電網(wǎng)絡(luò)仍被認(rèn)為不足以滿足大容量電能傳輸?shù)男枰?.4.1IntroductionThecontinuousadvancesinelectricpowertransmissiontechnologymadeitpossibletotransferbulkelectricenergyoverlongerandlongerdistances.Withthedevelopmentoflargescaletransmissionsystems,voltagelevelshavebeenincreasedcontinuouslytoachievegreatereconomiesofscale.電力傳輸技術(shù)的不斷進(jìn)步使越來(lái)越遠(yuǎn)距離的大量電能傳輸成為可能。隨著大型輸電系統(tǒng)的規(guī)模的擴(kuò)展，電壓等級(jí)不斷提高，以實(shí)現(xiàn)更大的規(guī)模經(jīng)濟(jì)。2.4.1IntroductionThehighestvoltagelevelnowinpracticaloperationis765kV.Thenextvoltagelevelis1000kVorover.Basicallyhighvoltage(HV)transmissionlevelsinclude100(110),138,161,230(220)kV,extrahighvoltagelevels(EHV)include345(330),400,500and765(750)kV,andultrahighvoltage(UHV)levelsareACvoltageshigherthan765kVandDCvoltageshigherthan600kV.目前實(shí)際運(yùn)行的最高電壓等級(jí)為765千伏。下一個(gè)電壓等級(jí)是1000千伏或更高。高壓(HV)等級(jí)主要包括100(110)、138、161、230(220)kV，特高壓(EHV)等級(jí)包括345(330)、400、500和765(750)kV，超高壓(UHV)等級(jí)是交流電壓高于765kV和直流電壓高于600kV。2.4.1IntroductionTheultrohighvoltagegridbeingconsideredinChinaisthetransmissiongridwithvoltageshigherthan750kV.Itismainlysuitablefortransferringbulkelectricityenergyoveraverylongdistance.中國(guó)所考慮的特高壓電網(wǎng)是指電壓高于750kV的輸電網(wǎng)。主要適用于遠(yuǎn)距離輸送大量電能。2.4.1IntroductionPowerindustryindevelopedcountrieswasdevelopingveryquicklybetweenthelater1960s'andtheearly1970s',ItwasrecognizedthatahigherVoltagegridshouldbeintroducedwhenthecapacityofpowersystemisdoubled.Forthisreason,theresearchonsuperhighvoltagetransmissiongridbecamemoreimportant.20世紀(jì)60年代末至70年代初，發(fā)達(dá)國(guó)家的電力工業(yè)發(fā)展迅速，人們認(rèn)識(shí)到，當(dāng)電力系統(tǒng)容量增加一倍時(shí)，就應(yīng)該引入高壓電網(wǎng)。因此，對(duì)超高壓輸電網(wǎng)的研究就顯得尤為重要。2.4.1IntroductionManycountries,suchastheUSA,Russia,Italy,France,JapanandSweden,begantomaketheirdesignandplanningofdevelopingultrohighvoltagegridatthattime.Howevertheseprojectswerenotcompletedbecauseofthepoliticalandeconomicfactors.與此同時(shí)，美國(guó)、俄羅斯、意大利、法國(guó)、日本、瑞典等國(guó)家也開(kāi)始對(duì)發(fā)展特高壓電網(wǎng)進(jìn)行設(shè)計(jì)和規(guī)劃。然而，由于政治和經(jīng)濟(jì)因素，這些項(xiàng)目沒(méi)有完成。2.4.1IntroductionTheresearchprojectaboutultrohighvoltagegridinChinahasbeenconductedsince1986.Buttherearefewerprojectsonengineeringapplicationoronatrialbasis.中國(guó)特高壓電網(wǎng)的研究項(xiàng)目始于1986年。但在工程應(yīng)用或試驗(yàn)基礎(chǔ)上的項(xiàng)目較少。2.4.1IntroductionAtpresent,withthedevelopmentofnationaleconomy,theelectricitydemandhasincreasedveryquickly.Notingthefactthatthereareverylongdistancesbetweenenergybasesandmajorloadcenters.Therefore,itisnecessarytoconstructthenationalgridtotransferpowerfromtheenergybasestothemajorloadcenters.目前，隨著國(guó)民經(jīng)濟(jì)的發(fā)展，電力需求增長(zhǎng)十分迅速。注意到能源基地和主要負(fù)荷中心之間的距離非常遠(yuǎn)。因此，有必要建設(shè)國(guó)家電網(wǎng)，將電力從能源基地輸送到各大負(fù)荷中心。2.4.1IntroductionInordertomeettheneedofsocietydevelopment,theNationalGridCorporationhasbeenresponsibleforthedesignandplanningofconstructionofthesuperhighvoltagepowergrid.為了適應(yīng)社會(huì)發(fā)展的需要，國(guó)家電網(wǎng)公司負(fù)責(zé)超高壓電網(wǎng)的設(shè)計(jì)和規(guī)劃建設(shè)。2.4.2EHVTransmissioninChinaIn2004,theelectricityshortageoccurredin24provincesinChina,amongwhichZhejiang,JiangsuandFujianaswerethemostseriousones.Theshortagein2004wasestimatedataround35GW.Oneofthereasonsisthattherewereblindinvestmentsinpowerplantswhilethereisalackofinvestmentsintransmissiongrid.2004年，全國(guó)24個(gè)省份發(fā)生了電力短缺，其中浙江、江蘇和福建是最嚴(yán)重的。2004年的短缺估計(jì)約為35吉瓦。原因之一是電廠盲目投資，輸電網(wǎng)投資不足。2.4.2EHVTransmissioninChinaAseriesofenergypoliciesforsolvingtheenergyproblemsinthedevelopmentofcoalandelectricityinChinahavebeenissuedbyChineseGovernment.Chinahasavastterritory.Itisknownthattherearemoreresourcesinhydroandcoal,butlessinoilandgas.HydroresourcesandcoalreservesarethemostimportantenergyresourcesinChina.Howeverthedistributionofelectricityenergysourcesandthatofelectricitydemandareseriouslyunbalanced.為解決中國(guó)煤電發(fā)展中的能源問(wèn)題，中國(guó)政府出臺(tái)了一系列能源政策。中國(guó)幅員遼闊。眾所周知，水力和煤炭資源較多，而石油和天然氣資源較少。水力資源和煤炭?jī)?chǔ)量是中國(guó)最重要的能源資源。然而，電力能源分布與電力需求分布嚴(yán)重不平衡。2.4.2EHVTransmissioninChinaNearlytwothirdsofhydroresourcesaredistributedinthesouthwestandwestofChina,includingSichuan,YunnanandTibetprovinces.TwothirdsofthecoalreservesaredistributedinthenorthwestandnorthofChina,includingShanxi,XinjiangandInnerMongoliaprovinces.中國(guó)近三分之二的水力資源分布在西南和西部，包括四川、云南和西藏等省。三分之二的煤炭?jī)?chǔ)量分布在中國(guó)的西北和北部，包括山西、新疆和內(nèi)蒙古。2.4.2EHVTransmissioninChinaOntheotherhand,twothirdsofelectricityloadsweremainlyintheeastareasofChinawherethereisalackofelectricityenergysources.Thedistancebetweentheareasofenergyresourcesandenergydemandisverylong,say500km-1500km.另一方面，三分之二的電力負(fù)荷主要集中在電力能源匱乏的中國(guó)東部地區(qū)。能源資源區(qū)和能源需求區(qū)之間的距離很遠(yuǎn)，比如500公里到1500公里。2.4.2EHVTransmissioninChinaConsideringthereasonsmentionedabove,ahigherrequirementforthedevelopmentofanelectricitygridisbroughtforward.Accordingtothepresentplanning,about120millionKWcouldbesenttonorthChina,eastChinaandcentralChinafromthecoalbasesinthenorthwestandnorthChina.考慮到上述原因，對(duì)電網(wǎng)的發(fā)展提出了更高的要求。根據(jù)目前的規(guī)劃，西北和華北的煤炭基地可向華北、華東和華中地區(qū)輸送約1.2億千瓦的電力。2.4.2EHVTransmissioninChinaThedistancesbetweenthemareabout500-1500km,whichisevenmorereasonabletransportationdistanceforACsuperhighvoltagegridthanthatfortransportationofenergyresourcesbytrainsincetheresearchresultshaveshownthatitismuchmoreeconomictotransfertheelectricitythantotransportcoalwithin1500km.它們之間的距離約為500-1500公里，這是交流超高壓電網(wǎng)比火車運(yùn)輸能源更合理的運(yùn)輸距離，因?yàn)檠芯拷Y(jié)果表明，在1500公里內(nèi)轉(zhuǎn)移電力比運(yùn)輸煤炭更經(jīng)濟(jì)。2.4.2EHVTransmissioninChinaAttheendof2005theinstalledgenerationcapacityof500GWmakesChinathesecondhighestintheelectricityproductionintheworld.AsChinaisbeingtransformedintothemanufacturingcentreoftheworld,theincreaseofelectricitydemandistremendous.2005年底，中國(guó)發(fā)電裝機(jī)容量達(dá)500吉瓦，成為世界上發(fā)電量第二高的國(guó)家。隨著中國(guó)轉(zhuǎn)型為世界制造業(yè)中心，電力需求的增長(zhǎng)是巨大的。2.4.2EHVTransmissioninChinaNewelectricenergyinfrastructureisrequiredtotransferbulkelectricityenergyoveraverylongdistance.Althoughthe500kVACand500kVDCtransmissionsystemsareexisting,suchtransmissionnetworksarestillconsideredtobeinadequateforbulkelectricityenergytransmission.新的電力能源基礎(chǔ)設(shè)施需要在很長(zhǎng)的距離上傳輸大量電能。雖然已有500千伏交流和500千伏直流輸電系統(tǒng)，但這種輸電網(wǎng)絡(luò)仍被認(rèn)為不足以滿足大容量電能的傳輸。2.4.2EHVTransmissioninChinaItisestimatedthattheinstalledgenerationcapabilitywillbe1000GWin2020.IthasbeenrecognizedthatlargeamountsofhydroandcoalresourcesaredistributedinthesouthwestandnorthwestofChina.Henceinordertomeettheenergyconsumptionmoregeneratingplantswillbeconstructedintheseregionsby2020.預(yù)計(jì)到2020年裝機(jī)容量將達(dá)到1000吉瓦。中國(guó)的西南和西北地區(qū)分布著大量的水電和煤炭資源。因此，為了滿足能源消耗，到2020年，這些地區(qū)將建設(shè)更多的發(fā)電廠。2.4.2EHVTransmissioninChinaOntheotherhand,loadcentersaresituatedintheeastcostalareasofChina.Accordingtotheexperienceofinternationalpowerindustry,whenthecapacityofpowergridisexpandedby4times,ahighervoltagelevelshouldbeintroduced.Thecurrent500kVpowergridhasahistoryof23yearswhiletheinstalledgenerationcapabilityin2004isaround6timesthatoftheinstalledgenerationcapabilityin1982.另一方面，負(fù)荷中心位于中國(guó)東部沿海地區(qū)。根據(jù)國(guó)際電力行業(yè)的經(jīng)驗(yàn)，當(dāng)電網(wǎng)容量擴(kuò)大4倍時(shí)，應(yīng)引入更高的電壓等級(jí)。目前500kV電網(wǎng)已有23年的歷史，2004年的裝機(jī)容量是1982年裝機(jī)容量的6倍左右。2.4.2EHVTransmissioninChinaPresentlythetransmissionofelectricityacrossprovincialpowernetworksismainlybasedonthe500kVACand±500kVDCtransmissiongrids.Ithasbeenfoundthatsuchtransmissionpowergridscannotmeetthebulkpowertransmissionrequirementsin2020.Clearlyinthissituationpowergridsofhighervoltagelevelsarerequired.目前各省電網(wǎng)的電力傳輸主要以500kv交流和±500kv直流輸電網(wǎng)為主。研究發(fā)現(xiàn)，這樣的輸電電網(wǎng)已不能滿足2020年大容量輸電的要求。顯然，在這種情況下，需要更高電壓水平的電網(wǎng)。2.4.2EHVTransmissioninChinaLongdistancebulkpowertransmissioncansatisfyfuturepowergrowth,secureenergysupply,andoptimizeenergyresourcesallocation.Furthermore,overallsocialbenefitswillbeimprovedbyenhancingpowergridsafetyandreliability,savingright-of-way,coordinatingthedevelopmentofpowerplantsandgrid,alleviatingcoaltransportationpressureandboostingtheharmoniousdevelopmentofregionaleconomy.遠(yuǎn)距離大容量輸電可以滿足未來(lái)電力增長(zhǎng)，保障能源供應(yīng)，優(yōu)化能源配置。提高電網(wǎng)安全可靠性，節(jié)約路權(quán)，促進(jìn)電廠電網(wǎng)協(xié)調(diào)發(fā)展，緩解煤炭運(yùn)輸壓力，促進(jìn)區(qū)域經(jīng)濟(jì)協(xié)調(diào)發(fā)展，從而提高整體社會(huì)效益。2.4.2EHVTransmissioninChina1000kVACand±800kVDCtransmissiongridshavedifferentfeatures.Theyarecomplementary.Thenaturalsinglecircuitcapacityof1000kVACtransmissionlineisabout5GW,andthatof±800kVDCtransmissionlineisatmost6.4GW.1000kV交流輸電網(wǎng)和±800kv直流輸電網(wǎng)具有不同的特點(diǎn)。它們是互補(bǔ)的。1000kV交流輸電線路自然單回路容量約5GW，±800kV直流輸電線路自然單回路容量不超過(guò)6.4GW。2.4.2EHVTransmissioninChinaThetransmissioncapacityofDCtransmissionlinedependsonthepowersystemconnection,restrictedbymaximumstabilitylimit.Itscapacityshouldbeupliftedgradually.Incontrast,thetransmissioncapacityofDCtransmissionlinecouldachievethedesignpowercapacitylevelassoonassupplysourceisavailable.直流輸電線路的傳輸能力取決于電力系統(tǒng)的連接方式，受最大穩(wěn)定極限的制約。它的能力應(yīng)該逐步提高。而直流輸電線路只要有供電源，輸電容量就能達(dá)到設(shè)計(jì)功率容量水平。2.4.2EHVTransmissioninChinaThereasonabletransmissiondistanceof1000kVACtransmissionlineis1000-2000km.Ontheotherhand,±800kVDCtransmissionisthemosteconomicwayoflongdistancepowertransmissionwhentransmissiondistanceislargerthan1500km.1000千伏交流輸電線路合理的傳輸距離為1000-2000公里。另一方面，當(dāng)傳輸距離超過(guò)1500公里時(shí)，±800千伏（特高壓）直流輸電系統(tǒng)是長(zhǎng)距離輸電最經(jīng)濟(jì)的方式。2.4.2EHVTransmissioninChina1000kVACtransmissiongrid,whichhasgeneralfeaturesofACtransmissiongrid,canformasuperbackbonegridofanationalpowersystem.±800kVDCtransmission,"directsuperhighway",whichiscomplementarytoACtransmissiongrid,canbeusedtotransmissionbulkpowerfromlargepowergeneratingbasestolargeloadcentresoverlongdistances.1000kV交流輸電網(wǎng)具有交流輸電網(wǎng)的一般特征，可構(gòu)成國(guó)家電力系統(tǒng)的超級(jí)骨干電網(wǎng)?！?00kV直流輸電，與交流輸電網(wǎng)互補(bǔ)的“直達(dá)超高速公路”，可遠(yuǎn)距離將大型發(fā)電基地的大宗電力輸送到大型負(fù)荷中心。2.4.2EHVTransmissioninChinaHowever,±800kVDCtransmissionwillnotbesuitableforforminganationalbackbonehighvoltagepowergridduetothelimitationofinterconnection.但是，±800kV直流輸電由于互聯(lián)的限制，將不適合形成國(guó)家骨干高壓電網(wǎng)。2.4.3FutureofEHVTransmissionGridGridinChinaBasedonthetechnicalinnovationandupgradingofthecurrentgrid,asbeingplanned,theStateGridCorporationislikelytoconstructthenationalsuperhighvoltagegrid,realizingthecoordinateddevelopmentofthegridseparatedintodifferentvoltagelevels,optimizingtheutilizationofenergysourceswithinlargerareas,providingsafety,economicandhighqualityelectricpowerservices,meetingtherequirementsofeconomyandsocietydevelopment.在對(duì)現(xiàn)有電網(wǎng)進(jìn)行技術(shù)創(chuàng)新和升級(jí)改造的基礎(chǔ)上，國(guó)家電網(wǎng)公司有可能按照規(guī)劃建設(shè)國(guó)家超高壓電網(wǎng)，實(shí)現(xiàn)不同電壓等級(jí)電網(wǎng)的協(xié)調(diào)發(fā)展，在更大范圍內(nèi)優(yōu)化能源利用，提供安全、經(jīng)濟(jì)、優(yōu)質(zhì)的電力服務(wù)，滿足經(jīng)濟(jì)社會(huì)發(fā)展的要求。2.4.3FutureofEHVTransmissionGridGridinChinaAccordingtothestrategicplanningofStateGridCo.,thenationalsuperhighvoltagegrid,whichcoversthemajorityareasofChina,shouldbeoperatedanddispatchedthroughaunitednationalcontrolcentre.ThenationalgridismainlybaseduponACinterconnectednetworkswiththeassistanceofDCinterconnectednetworks.根據(jù)現(xiàn)有國(guó)家電網(wǎng)公司的戰(zhàn)略規(guī)劃，覆蓋中國(guó)大部分地區(qū)的國(guó)家超高壓電網(wǎng)應(yīng)通過(guò)一個(gè)國(guó)家統(tǒng)一控制中心進(jìn)行運(yùn)營(yíng)和調(diào)度。國(guó)家電網(wǎng)以交流互聯(lián)為主，輔以直流互聯(lián)。2.4.3FutureofEHVTransmissionGridGridinChinaThebackbonegridwillbeinterconnectedby1000kVACtransmissionwiththeassistanceof±800kVDCtransmission.Thenorthwestpowergridwillbeinterconnectedby750kVACtransmission.Thefirst750kVACtransmissionlinewithatotallengthof140kmwascommissionedinSeptember2005.主干網(wǎng)將通過(guò)1000千伏交流輸電和±800千伏直流輸電相互連接。西北電網(wǎng)將通過(guò)750千伏交流輸電實(shí)現(xiàn)互聯(lián)。首條全長(zhǎng)140公里的750千伏交流輸電線路于2005年9月投運(yùn)。2.4.3FutureofEHVTransmissionGridGridinChinaAccordingtothedesignandplanningofthenationalsuperhighvoltagegrid,twolargecapacitytransmissionchannelsshouldbeconstructed.Oneisthenorth-southchannelfromnorthviamiddletoeast,formingahugeUHVACsynchronizingpowergrid.Theotheristhewest-eastchannelfr