地鐵供電系統(tǒng)設(shè)計

地鐵供電系統(tǒng)設(shè)計地鐵供電系統(tǒng)設(shè)計TheDesignofSubwayPowerSupplySystem目錄TOC\o"1-3"\h\u966第1章緒論 ③出口短路時，可取1.3；9.3.3直流短路計算的方法這里采用電路圖法，按照實際供電網(wǎng)絡(luò)，畫出等效電路圖，進(jìn)行網(wǎng)絡(luò)變換，在供電網(wǎng)絡(luò)中只包括電阻。再按網(wǎng)絡(luò)變換后的電路圖利用歐姆定律、基爾霍夫定律進(jìn)行計算。用電路圖法進(jìn)行短路電流計算，需要以下兩個假設(shè)條件：(1)牽引網(wǎng)供電網(wǎng)絡(luò)中，電源電壓相同；(2)牽引變電所為電壓源，其內(nèi)阻因不同的短路點而有不同的數(shù)值。用電路圖法進(jìn)行短路電流計算，需要已知以下三個條件：牽引變電所直流母線電壓U，V；牽引變電所內(nèi)阻，；牽引網(wǎng)(接觸網(wǎng)，走行軌)電阻，。用電路圖法進(jìn)行短路電流計算，按下列方法和步驟進(jìn)行：(1)按實際供電網(wǎng)絡(luò)畫等效電路圖；(2)進(jìn)行網(wǎng)絡(luò)變換；(3)分清網(wǎng)孔數(shù)目及其自阻和互阻；(4)按等效電路圖的網(wǎng)孔數(shù)列回路方程式；(5)解聯(lián)立方程組，求出未知數(shù)；(6)應(yīng)用歐姆定律、基爾霍夫電流定律(KCL)、基爾霍夫電壓定律(KVL)三條基本定律，進(jìn)行數(shù)學(xué)推導(dǎo)，求出相應(yīng)的計算公式。地鐵牽引供電系統(tǒng)有單邊供電和雙邊供電兩種方式，當(dāng)牽引網(wǎng)為雙邊供電時，某一點短路，不只是短路點處的牽引變電所向短路點供電，而是全線的牽引變電所都向短路點供電。全線的牽引變電所，是通過牽引變電所直流母線和牽引網(wǎng)進(jìn)行電聯(lián)結(jié)的[13]。下面分析相鄰兩側(cè)牽引變電所影響的正常雙邊供電(考慮對側(cè)接觸網(wǎng)的影響)(1)其等效電路圖可表示為9-3所示、網(wǎng)絡(luò)變換如圖9-4所示。圖9-3考慮相鄰兩側(cè)牽引變電所影響等效電路圖圖9-4網(wǎng)絡(luò)變換等效電路圖(2)根據(jù)KVL定律，按圖9-3網(wǎng)孔①②③④列四個獨立回路方程：回路1(9-11)回路2(9-12)回路3(9-13)回路4(9-14)對以上方程求解得到：(9-15)(9-16)(9-17)(9-18)(3)根據(jù)星—角變換，可得各饋電線短路電路如下：(9-19)(9-20)(9-21)(4)總短路電流(9-22)(5)各變電所短路電流(9-23)(9-24)(9-25)(9-26)式中U——牽引變電所母線電壓，V；——牽引變電所內(nèi)阻，；——接觸網(wǎng)電阻，；——走行軌(上下行并聯(lián))，；；；；。9.3.4中山廣場牽引降壓混合所直流短路計算示例已知：牽引變電所雙機(jī)組并聯(lián)運(yùn)行，1500V低碳鋼接觸網(wǎng)正常雙邊供電，短路時考慮對側(cè)接觸網(wǎng)及相鄰牽引變電所的影響，供電距離均為2.6km，在距變電所800m處發(fā)生短路，求短路電流和各牽引變電所供出的短路電流。解：通過已知條件可得各參數(shù)如下：接觸網(wǎng)電阻0.02；走行軌電阻：0.01(上下行并聯(lián))；牽引變電所內(nèi)阻：(雙機(jī)組并聯(lián))。利用以上參數(shù)及給定條件計算等效電路圖中的電阻值：計算等效電路圖中的計算各饋線電流計算短路點的總電流計算各變電所的短路電流第10章結(jié)論地下鐵道工程是一項復(fù)雜的、多專業(yè)的綜合性工程。隨著我國現(xiàn)代化步伐的加快，各大城市建設(shè)地鐵的熱情日益高漲。本設(shè)計主要針對目前我國地鐵的發(fā)展水平，以線地鐵3號線一期工程為背景，對地鐵供電系統(tǒng)的設(shè)計進(jìn)行分析研究。本設(shè)計中從地鐵供電系統(tǒng)設(shè)計的主要問題入手，詳細(xì)分析了地鐵3號線供電系統(tǒng)的組成和功能，結(jié)合實際工程案例給出了完整的設(shè)計方案?？偟膩碚f，本設(shè)計在地鐵供電系統(tǒng)的工程設(shè)計中完成了如下工作：(1)地鐵外部電源方案形式。分別列出了三種可行的供電方式，集中式供電、分散式供電和混合式供電，經(jīng)分析比較選擇了集中式供電方案，并給出具體理由。(2)地鐵主變電所設(shè)計。涉及的內(nèi)容主要有主變電所選址、電氣主接線、主變壓器選擇、主變壓器中性點接地等，并給出了相應(yīng)的具體設(shè)計方案和主接線CAD圖。(3)中壓網(wǎng)絡(luò)設(shè)計。對中壓網(wǎng)絡(luò)有兩大屬性即電壓等級和構(gòu)成形式進(jìn)行了論述，給出了設(shè)計方案即牽引降壓混合網(wǎng)絡(luò)，采用同一電壓等級。(4)牽引供電系統(tǒng)設(shè)計。主要分為牽引變電所設(shè)置和主接線兩個部分，對牽引變電所的設(shè)置、牽引變電所的中壓主接線和直流主接線的形式及其運(yùn)行方式進(jìn)行分析，給出直流牽引系統(tǒng)保護(hù)方案，并作出牽引供電系統(tǒng)主接線的CAD圖。(5)供配電系統(tǒng)設(shè)計。主要分為中壓接線和低壓側(cè)接線設(shè)計兩個部分，對降壓變電所的設(shè)置、牽引變電所的中壓主接線和低壓主接線的形式及其運(yùn)行方式進(jìn)行分析，并作出降壓變電所供電系統(tǒng)主接線的CAD圖。(6)地鐵供電系統(tǒng)容量計算。主要包括牽引變壓器供電計算，降壓變壓器容量計算，以及主變壓器容量計算。并分別給出了計算結(jié)果。(7)雜散電流防護(hù)與接地。主要分為雜散電流與接地方案兩個部分。對于雜散電流給出了相應(yīng)的防護(hù)措施，同時也確定了合理的接地方案，即利用地下結(jié)構(gòu)鋼筋構(gòu)成的等電位法拉第籠作為地鐵電氣設(shè)備的自然接地體。(8)短路計算。主要包括交流中壓側(cè)短路計算、牽引網(wǎng)直流短路計算。并結(jié)合實例分別進(jìn)行了具體計算。以上設(shè)計成果對地鐵供電系統(tǒng)的設(shè)計與施工，并提高其可靠性、安全性、經(jīng)濟(jì)性，具有一定的參考意義。參考文獻(xiàn)[1]高滿茹．建筑配電與設(shè)計[M]．第二版．中國電力出版社，2010．[2]劉介才．工廠供電[M]．第四版．機(jī)械工業(yè)出版社，2007．[3]黃德勝．地下鐵道供電M]．第一版.中國電力出版社，2010．[4]于松偉．城市軌道交通供電系統(tǒng)設(shè)計原理與應(yīng)用[M]．第一版．西南交通大學(xué)出版社，2008．[5]賀威俊．軌道交通牽引供變電技術(shù)[M]．第一版.西南交通大學(xué)出版社，2011．[6]王曉麗．建筑供配電與照明[M]．第一版．人民交通出版社，2008．[7]孫萍．建筑智能安全系統(tǒng)[M]．第一版．機(jī)械工業(yè)出版社，2010．[8]陳小川．鐵路供電繼電保護(hù)與自動化[M]．第一版.中國鐵道出版社，2010．[9]劉寶林．建筑電氣設(shè)計圖集[M]．中國建筑工業(yè)出版社，2002．[10]劉寶林．現(xiàn)代建筑電氣設(shè)計[M]．機(jī)械工業(yè)出版社，2003．[11]孫成群．建筑電氣設(shè)計實例圖冊[M]．中國建筑工業(yè)出版社，2003．[12]LiuXiao-dong.ResearchonTC-SCdynamicsystemsimulationsteadyimpendancecharacteristics.AutomationofElectricpowersystem,1999,23(5)14-17[13]F.W.H.Yik,J.Burnett,I.Prescott,Predictingair-conditioningenergyconsumptionofagroupofbuildingsusingdifferentheatrejectionmethods[J]．EnergyandBuildings33(2001)151–166．附錄附錄A外文資料PowerSystemModelingforUrbanMassiveTransportationSystems1.IntroductionUrbanMassiveTransportationSystems(UMTS),likemetro,tramway,lighttrain;requiresthesupplyofelectricpowerwithhighstandardsofreliability.So,animportantstepinthedevelopmentofthesetransportationsystemsistheelectricpowersupplysystemplanninganddesign.Normally,thetrainsofaUMTSrequiresaDCpowersupplybymeansofrectifierAC/DCsubstations,knowastractionsubstations(TS);thatareconnectedtotheelectricHV/MVdistributionsystemofacity.TheDCsystemfeedscatenariesoftramwaysorthethirdrailofmetros,forexample.TheDCvoltageisselectedaccordingtothesystemtakingintoaccountpowerdemandandlengthoftherailway’slines.Typically,a600Vdc–750Vdcisusedintramways;while1500Vdcisusedinametrosystem.Someinterurban-urbansystemsusea3000Vdcsupplytothetrains.Fig.1presentsanelectricschemeofatypicaltractionsubstation(TS)withitsmaincomponents:ACbreakersatMV,MV/LVtransformers,AC/DCrectifiers,DCbreakers,tractionDCbreakers.As,itisshown,aredundantsupplysystemisplacedateachtractionsubstationinordertoimprovereliability.Inaddition,someelectricschemesallowthepowersupplyofthecatenariesconnectedtoaspecifictractionsubstation(A)sincetheneighbourtractionsubstation(B)byclosingthetractionsectioningbetweenAandBandopeningthetractionDCbreakers.Inthisway,thereliabilitysupplyisimprovedandallowsflexibilityformaintenanceofTS.So,animportantaspectfortheplanninganddesignofthiselectricpowersupplyisagoodestimationofpowerdemandrequiredbythetractionsystemthatwilldeterminetherequirednumber,sizeandcapacityofAC/DCrectifiersubstations.Ontheotherhand,thedesignofthesystemrequiresstudyingimpactsofthetractionsystemontheperformanceofthedistributionsystemandviceversa.Powerqualitydisturbancesarepresentintheoperationofthesesystemsthatcouldaffecttheperformanceofthetractionsystem.Thischapterpresentsusefultoolsformodeling,analysisandsystemdesignofElectricMassiveRailwayTransportationSystems(EMRTS)andpowersupplyfromDistributionCompaniesorElectricPowerUtilities.Firstly,asectiondepictingthemodelingandsimulationofthepowerdemandisdeveloped.Then,asectionaboutthecomputationoftheplacementandsizingofTSforurbanrailwaysystemsispresentedwherethemodelingisbasedonthepowerdemandmodeloftheprevioussection.Afterthat,twosectionsaboutthepowerquality(PQ)impactofEMRTSondistributionsystemsandgroundingdesignarepresented.Bothsubjectsmakeuseoftheloaddemandmodelpresentedpreviously.Fig.1.ATypicalTractionSubstation(TS)2.PowerdemandcomputationofelectrictransportationsystemsThissectionpresentsamathematicalmodelusefultosimulateurbanrailwaysystemsandtocomputetheinstantaneouspoweroftheElectricMassiveRailwayTransportationSystems(EMRTS)suchasametro,lighttrainortramway,bymeansofcomputingmodelsthattakeintoaccountparameterssuchasthegridsize,acceleration,velocityvariation,EMRTSbraking,numberofwagons,numberofpassengersperwagon,numberofrectifiersubstations,andpassengerstations,amongotherfactors,whichpermittosimulatethephysicalandelectriccharacteristicsofthesesystemsinamoreaccuratewayofarealsystem.Thismodelconnectsthephysicalanddynamicvariablesofthetractionbehaviourwithelectricalcharacteristicstodeterminethepowerconsumption.Theparametricconstructionofthetractionandbrakingeffortcurvesisbasedonthetractiontheoryalreadyimplementedinlocomotivesandurbanrails.Generally,therearethreefactorsthatlimitthetractioneffortversusvelocity:themaximumtractioneffort(Fmax)conditionedbythenumberofpassengersthatareinthewagons,themaximumvelocityofthetrain(orrail),andthemaximumpowerconsumption.Basedonthesefactors,asimulationmodelisformulatedforcomputingtheacceleration,speedandplacementofeachtrainintherailwaylineforeachtimestep(1second,forexample).So,thepowerconsumptionorre-generationiscomputedalsoforeachtimestepandknowingtheplacementofeachtrainintheline,thepowerdemandforeachelectricTSiscalculated.2.1PowerconsumptionmodelofanurbantrainThepowerconsumedbyonerailwayvehicledependsonthevelocityandaccelerationthatithasateachinstantoftime.Itscomputationisbasedonthetractioneffortcharacteristic(suppliedbythemanufacturerofthemotors),thenumberofpassengersandthedistancesbetweenthepassengers’stations(Vukan,2007),(Chenetal.,1999),(Perrin&Vernard,1991).Thedutycycleofanurbantrainbetweentwopassengers’stationsiscomposedbyfouroperationstates:acceleration,balancingspeed,constantspeedanddeceleration.Fig.2showsthebehaviorofthespeed,tractioneffortandpowerconsumptionofatractionvehicleduringeachoperationstateelapsedeithertimeorspace(Hsiang&Chen,2001).Fig.2.Velocity,TractionEffort,andPowerConsumptionofanUrbanTrainTravelbetweenadjacentPassengerStations(Hsiang&Chen,2001)Duringthefirststate(I),thevehiclemoveswithconstantpositiveacceleration,sothespeedincreases.Whenthevehiclereachesadeterminedspeedlowerthantheconstantspeed,thesecondoperationstatestarts.Inthisstate,theaccelerationdecreases,butthespeedkeepsincreasing.Inthethirdstate(III),thecruisespeedisreachedandtheaccelerationiszero.Inthefourthstate(IV),thebrakingoperationstartswithnegativeaccelerationuntilthemomentitdecelerateswithaconstantrateandfinallyitstopsatthedestinationstation(Vukan,2007),(Chenetal.,1999),(Perrin&Vernard,1991),(Hsiang&Chen,2001).2.2SimulationmodelThemodelpresentedatsection2.1allowsthecomputationofthepowerconsumptionandtraveltimecharacteristics(t,x)foreachtrainiintherailwayline.Naturally,arailwaylinesimulationmustincludeanumbernofpassengers’stationsandktrainstravelintheline(goandreturn).Theintegrationofthesecharacteristicsrequiresmodelingthemobilityofpassengersassociatedateachtrain.Itcanbesimulatedinaprobabilisticway,computingthenumberofpassengerscomingupandleavingthetrain(i)ineachpassenger’sstation(j)andthestoppingtimeofthetrainineachstation.Thisfirstpart,statedhereasModule1,usesthefollowingparameters:thepassengers’upanddownrates,andupanddowntimesperpassenger.3.Placementandsizingtraction(rectifier)substationsinurbanrailwaysystemsInthissection,amethodologyofplacementandsizingoftractionsubstationsunderanelectricconnectionscheme,inwhichhighreliablelevelsareguaranteed,ispresented.Inthisscheme,eachtractionsubstation(TS)isabletosupporttheloadofeachadjacentsubstation.ThatmeansthatinthecasewhenafaultoccursinoneTS,thereisasupportsystembasedonautomaticswitchesnormallyopenedthatcloseandallowthetwoneighboursubstationstosupplythepowertotheassociatedloadwiththefaultedsubstation(eachonewouldfeedhalfoftheloadofthefaultedone).Theinputdatatocalculatethesizingofsubstationisobtainedfromthepowerdemandcomputation,explainedintheprevioussection.Ontheotherhand,theplacementofeachTSisobtainedbyaheuristicoptimizationproblem.Thisproblemminimizesthetotalcostofagivenconfiguration,thatiscomposedofinvestmentcosts(rectifiers,transformers,andprotectionandcontrolcells),thecostofenergylossescomposedbyAClosses(associatedwiththetransformer)andDClosses(associatedtorectifiers)andthefailurecost,thatrepresentsthecostoftheannualexpectedenergynotsupplied(EENS).3.1Tractionsubstation(TS)configurationsAschemeofsupplyofanurbanrailwaysystemmustsatisfyelectricconditions,suchas:operatinglimits,voltagedropsthroughthecatenariesorthirdrail(calledhere,ingeneral,DCsection),andmaximumcapacityoftransformers.Theseconditionsmustbesatisfiedforsupplyingthepowerdemandindependentlyoftheoperatingstateofthesystem,i.e.,normalstateorapost-contingencystateafterafaultofaHV/MVsubstation,orTS,oroneDCsection.So,theTSlocationandconfiguration’sselectionarestronglylinkedproblems.Fig.3showsthreepossibleschemesofconnectionoftheMVnetworktoasetofTS.EachTSisdesignedtosupply(innormaloperationstate)aDCsectoroflengthL.Thewayofbehaveinafaultconditiondeterminesthefollowingthreepossibleconfigurations:1.Onetransformer-rectifierunitwithpossibilityofpowersupplyfromtheadjacentTS.EachTSactsasasupportofitsadjacentTS.Thisimpliesthatthesubstationsmustbeabletosupplyatleast1.5timesthelengthofthenormalDCsectionlength(3L/2).2.Twotransformer-rectifierunitsineachtractionsubstation.ThisconfigurationmeanstheredundancyinthemainequipmentoftheTS.Incaseofafaultinonetransformerand/orrectifier,theparallelunitmustsupplythetotalpowerdemandoftheTS.3.Twotransformer-rectifierunitsineachTSandsupportofadjacentDCsection.Thisisthecombinationofconfigurations1and2.ThismeansthatthereisredundancyineachtractionsubstationandthereisalsopossibilityofsupportofadjacentDCsectionfeeder.Fig.3.ConfigurationsofTractionSubstations’Connection3.2OptimizationproblemAminimizationofthetotalprojectcostissolvedfordeterminingthequantityoftractionsubstations,theirconnectionconfigurations,andtheirlocations.Theoptimizationisaconstrainedproblemthatguaranteestheelectricalrequirements,likevoltagelevelsandhighreliabilityrequirements.ThedistancebetweenTSisassumedtobeequal,andeachTSislocatedatthemiddlepointoftheDCsectionthatitsupplies,asFig.3shows.3.3TechnicalconstraintsThevoltagedropbetweenasupplypointandautilizationpointmustnotbemorethan15%innormaloperationandasmaximum30%inspecialcases(Arriagada&Rudnick,1994).ThesespecialscasesmaybetheoutageofasubstationorthelastDCsectionintheroute.3.4ApplicationtothestudycaseTheunitarycostoffaultwasassumed1074US$/kWh,fromreliabilityanalysis.Simulationsweredoneforthreelevelsofload:high(themaximumnumberofvehiclesinservice),medium(halfofthetotalvehiclesinservice),andlow(withnovehiclesinservice).ThesimulatorallowsthecalculationofpowerlossesinN-0state,andthedemandofeachsubstationforN-0andN-1contingenciesstate.Simplecontingencies(N-1)atthemaximumloadweremadeinordertosizingtheTSwhenconfigurations1and3areused,togivesupportofadjacentTS.While,normalstateoperationwasusedforsizingTSinconfiguration2.4.PowerqualityimpactofurbanrailwaysystemsondistributionsystemsPowerqualityphenomenaoriginatedinpowerdistributionsystemsimpactsontheelectricalpowersupplysystemofUMTSand,atthesametime,powerelectronicsusedinthetractionsystemimpactsonthepowerquality(PQ)serviceofthedistributionsystem.Inaddition,thepowerdemandofUMTSpresentshighandfastvariationsasconsequenceoftheoperationcyclesofeachtrain-vehicleandthenon-coincidenceofoperationalcyclesamongseveralvehicles.So,PQphenomenaaretimevariable(Singhetal.,2006).TheidentificationofPQproblemsinpowersystemsrepresentsanimportantissuetothedistributionutilities.TheharmonicdistortionisoneofthemainPQphenomenaintheelectricalsystemfeedinganEMRTSbecausetheinjectionofharmonicsbyitsnonlinearloadsflowsthroughthenetworkandaffectsotherconsumersconnectedtothedistributionsystem.Inaddition,thecomputationofthetotalharmonicdistortion(THD)intheACsideoftherectifiersubstationattherailwaysystemmusttakeintoaccountthetimeloadvariabilityateachTS.So,theinstantaneouspowerloadmustbecomputedasfunctionoftimeanddistanceasitwasexplainedatsection2.OncethecurrentconsumptionineachTSisobtained,itispossibletoidentifythevariationoftheTHDduringthetime.4.1ProbabilisticmodelGenerally,deterministicmodelshavebeenadoptedfornetworkharmonicanalysis;however,thesemodelscanfailformodellingtheloadvariationinsystemssuchastherailways’electricalsystem(Changetal.,2009).So,aprobabilisticanalysistocharacterizetheharmoniccurrentloadsproperlymustbeusedinordertoobtainanaccuratemodel.AnEMRTSischaracterizedbyfluctuatingloadsduetothedifferentoperationstatesofthetrainsinthetractionsystem.Thus,theharmonicsinjectionfromtherectifiersubstationstotheMVnetworkcausesthatthecurrentharmonicspectrumatthedistributionsystem’sconnectionpoint(PCC)variesovertime.So,eachtractionsubstationcanberepresentedasaharmoniccurrentsourcethatprovidesaprobabilisticspectralcontentatthePCC(Riosetal.,2009).Then,itisnecessarytoperformthevectorsumofseveralharmonicsources(i.e.tractionsubstations)atthedistributionsystem’sconnectionpointtodeterminethetotalharmonicdistortion.Therearetwomethodstoevaluatetheeffectofdifferentnon-linearloads:theanalyticalmethodandMonteCarlosimulationmethod.Thecompleximplementationofanalyticalmethodsforlargepowersystemsstudiesinvolveslittlepracticalapplicationinrealsystems.Bycontrast,MonteCarlosimulationhasprovedtobeapracticaltechnique(Casteren&Groeman,2009)basedonthelowcorrelationbetweendifferentharmonicloads(independenceofthesources).4.2ActivepowerfilterallocationmethodologyTheharmonicdistortionproducedbyrailways’systemsatthedistributionsystem’sconnectionpointcanbereducedusingpassiveoractivepowerfilters(APF).However,duetotherandomandtimevariabilityoftheharmonicdistortionintractionsystems,itisrequiredanactivepowercompensationwiththeabilityofadaptationtodifferentloadconditions.Passivefiltersaredesignedwithfixedparametersandforspecificharmonics,sothistypeoffilterdoesnothavetherequiredability.Bycontrast,APFsbasedonthep-qtheorybecameaneffectivesolutionintractionsystems;normally,theyareusedfordynamicharmonicsuppression(Xu&Chen,2009).Thistypeofcompensationpresentstheadvantageofeliminatingawiderangeofharmonicssimultaneously.Ontheotherhand,thetractionsystemhasseveralrectifiersubstationsandfromtheeconomicpointofviewitisdifficulttoinstallanAPFineachTSduetoitshighcost.Then,itisnecessarytoallocateAPFsinthemostsensitivepositionsintheownpowersystemoftheEMRTSusingtheleastnumberoffiltersandminimizingtheirsize.Animportantfactortobeconsideredinthedecisionofharmoniccompensationintractionsystemisthesuddenfluctuationoftractionloadbecausethisdynamicbehaviorisalsoobservedintheharmonicdistortion,asithasbeenexplainedintheprevioussection.5.GroundinginDCurbanrailwaysystemsAprimaryrequirementtoensuretheappropriateoperationofanyelectricalsystemistoguaranteepersonnelandsystemsafety,eitherundernormalandfaultconditions.So,groundingisthemostimportantcomponenttocontrolelectricalsystemfailures.GroundinginelectrictractionsystemsrequiresadifferenttreatmentthanintypicalACelectricalsystems,becauseoftheexistenceoftractionsubstationsAC/DCofhighcapacity,thehighvariableloadcharacteristicintimeanddistance,thedirectcontactoftherailswiththeearth,thecurrentflowthroughthegroundduringnormaloperatingconditionsthatcancausecorrosionofundergroundmetallicelements,theappearanceofstepandtouchvoltagethatcanjeopardizetheintegrityofpersons.Thegroundingsystemiscomposedbytwosubsystems.Thefirstone(subsystem1)assuresthepersonnelsafetyandtheprotectivedeviceoperation;while,thesecondone(subsystem2)isusedtogroundthenegativepoleintheDCsideoftherailway’stractionsubstation.Thegroundingsubsystem1isusedtogroundallmetallicstructures:boxes,protectivepanels,pipeline,bridges,passengerplatforms,etc.Therearetwowaystoconnectthissubsystem:-HighResistanceGroundingMethod(HRGM):Aconstantvoltageof25VdcisappliedbetweentheTS’shousingandtheground,inordertoenergizearelaytosendtheopeningordertotheprotectionequipment.Whenthevoltageleveldecreases,otherrelayissettosendtheopeningordertotheprotectionifabigcurrentflowsthroughthemodule.-LowResistanceGroundingMethod(LRGM):Aconstantvoltageof1VdcisappliedbetweentheTS’shousingandtheground.Inthiscasenoresistanceisused,butadirectconnectionismadetothegroundsystem.Inaddition,whentherelaysandprotectionsdetectthevoltage’sabsence,theywillsendtheopeningordertotheprotectionsystem.6.ConclusionThischapterhaspresentedusefultoolsforpowersystemsmodeling,analysisandsystemdesignofElectricMassiveRailwayTransportationSystems(EMRTS)andpowersupplyfromDistributionCompaniesorElectricPowerUtilities.Firstly,asectiondepictedtopresentthemodelingandsimulationofthepowerdemandwasdeveloped.Then,asectionaboutthecomputationoftheplacementandsizingoftractionsubstationsforurbanrailwaysystemswaspresentedwherethemodelingisbasedonthepowerdemandmodelofthepreviouslymentioned.Afterthat,twosectionsaboutthepowerqualityimpactofEMRTSondistributionsystemsandgroundingdesignarepresented.ThesetoolsallowtheoptimizationofthedesignschemeofrailwayelectrificationforUMTS,takingintoaccountanadequatesizingandnumberoftractionsubstations,andthenumberandlocationofharmonicfilterstoimprovethepowerqualityofthesystem.附錄B中文翻譯城市大規(guī)模交通系統(tǒng)的電力系統(tǒng)建模介紹城市大規(guī)模交通系統(tǒng)(UMTS)，如地鐵，電車，輕軌，需要高標(biāo)準(zhǔn)和可靠性的電力供應(yīng)。所以，這些交通系統(tǒng)的發(fā)展中的重要一步，是電力供應(yīng)系統(tǒng)的規(guī)劃和設(shè)計。通常情況下，列車的UMTS要求的直流電源，通過整流AC/DC變電站，比如牽引變電站(TS)，起到連接城市電力高壓/中壓配電系統(tǒng)的功能。直流系統(tǒng)將電能送入地鐵電車接觸網(wǎng)或第三軌。根據(jù)用戶功需求和鐵路線的長度，考慮供電系統(tǒng)的直流電壓選擇。通常情況下，在輕軌中使用的直流600V到750V電壓，在地鐵系統(tǒng)中使用直流1500V。一些城市也使用直流3000V給電動列車供電。圖1給出一個典型的牽引變電所(TS)，其主要組成部分：交流斷路器MV，MV/LV轉(zhuǎn)換裝置，AC/DC整流器，直流斷路器，牽引直流斷路器。為，供應(yīng)的可靠性得到改善，并能使?fàn)恳╇娤到y(tǒng)更靈活地發(fā)揮作用。了提高可靠性，每個牽引變電站都裝置了備用電源系統(tǒng)。此外，有些供電方案允許通過直流斷路器和隔離開關(guān)將來自鄰居牽引變電站(B)A和B(A)之間的牽引變電所聯(lián)系起來。在這種方式下，增強(qiáng)了牽引變電所間供電的靈活性。因此，這種電力供應(yīng)的規(guī)劃和設(shè)計的一個重要方面是由牽引系統(tǒng)來確定牽引變電所的數(shù)量，規(guī)模和容量電力需求。另一方面，該系統(tǒng)的設(shè)計需要研究考慮牽引系統(tǒng)的影響，對配電系統(tǒng)的性能等。供電系統(tǒng)的操作可能影響牽引系統(tǒng)電源質(zhì)量的不穩(wěn)定。圖1一個典型的牽引變電所(TS)本章介紹些適合于建模的有用工具，分析和研究大規(guī)模的電氣鐵路運(yùn)輸系統(tǒng)(EMRTS)的設(shè)計方案，這些電力供應(yīng)來源于電源分銷公司或電力公用事業(yè)。首先，簡要介紹電力需求開發(fā)的建模和仿真。然后，根據(jù)上一節(jié)的電力需求進(jìn)行部分城市鐵路系統(tǒng)的位置和大小的TS計算建模。之后，電能質(zhì)量(PQ)的影響在于配電系統(tǒng)接地設(shè)計EMRTS這個部分，這個科目需要使用以前的負(fù)載需求模型。2.電力運(yùn)輸系統(tǒng)的電力需求計算本節(jié)介紹一種有用的數(shù)學(xué)模型來模擬城市鐵路系統(tǒng)的計算模型，考慮到用戶的參數(shù)，通過計算電力系統(tǒng)大規(guī)模的鐵路運(yùn)輸系統(tǒng)的瞬時功率(EMRTS)，如地鐵，輕軌或電車，加速度，速度變化，制動EMRTS，車廂數(shù)量，每節(jié)車廂的乘客數(shù)，整流變電站的數(shù)量，客運(yùn)車站等。除其他因素外，允許使用一個更為準(zhǔn)確的方法在實際的系統(tǒng)中對其進(jìn)行物理和電特性的仿真。此模型將牽引變電所的靜態(tài)和動態(tài)變量的電氣特性聯(lián)系起來，以確定電力功率消耗?；诔鞘熊壍罓恳碚摰幕A(chǔ)，參數(shù)化的牽引和制動的作用曲線已應(yīng)用于城市輕軌和地鐵軌道。一般來說，有三個因素限制了機(jī)車牽引速度：最大牽引力受限于空調(diào)車輛乘客的數(shù)量，列車的最大速度，最大功耗?；谶@些因素，制定一個仿真模型是在每個時間段(1秒，例如)計算每趟列車在鐵路線的加速度，速度和位置。所以，功耗或再生制動也分為每一個時間段來計算，還需知道行進(jìn)中每個列車的具體位置，來計算每個TS的電力需求。2.1城市列車的電力消耗模式電動列車的功耗取決于列車在每個時刻的速度和加速度。其計算的基礎(chǔ)依賴于牽引力電氣特性(電機(jī)由生產(chǎn)商提供的)，乘客的數(shù)目和各車站之間的距離(Vukan，2007年)，(Chen等，1999)，(睿Vernard，1991)。電動列車在兩個車站之間呈現(xiàn)以下四種運(yùn)行狀態(tài)：加速，惰行，恒速和減速。圖2示出了列車在每一個運(yùn)行狀態(tài)的速度，以及電動車輛的牽引力和功率消耗經(jīng)過的時間和空間狀態(tài)(Hsiang，2001)。圖2兩車站間列車速度，牽引力和功耗(Hsiang&chen，2001年)在第一狀態(tài)(I)中，列車的移動正加速度恒定，所以速度將增加。當(dāng)車輛到達(dá)低于恒定速度的預(yù)定速度時，第二運(yùn)行狀態(tài)開始。在這種狀態(tài)下，加速度減小，但速度會持續(xù)增加。在第三狀態(tài)(III)時，達(dá)到穩(wěn)定速度，列車加速度為零。在第四狀態(tài)(IV)中，列車開始制動操作進(jìn)入負(fù)加速度狀態(tài)，它以恒定的速率減速，最后停止在目標(biāo)車站(Vukan,2007),(Chenetal.,1999),(Perrin&Vernard,1991),(Hsiang&Chen,2001).2.2仿真模型在2.1節(jié)提出的模型可以讓我們對每列列車在鐵路線的功耗和運(yùn)行時間的特性(T，X)進(jìn)行計算。當(dāng)然，此仿真須涉及一條鐵路線上n座乘客站和k輛(往返)電動列車。這些電氣特性的集成需要依賴于每個列車乘客數(shù)量的流動性建模。它可以采取概率模擬的方式。在每個車站(j)進(jìn)入或離開列車(i)和在各站的列車的停止時間來進(jìn)行乘客的數(shù)量計算。首先，就像模型1一樣，使用以下參數(shù)：乘客的上車和下車率以及每名乘客上下車歷時的時間。3.城市軌道交通牽引變電所(整流器)的布局和大小在本節(jié)中，牽引變電所的位置和大小的選擇方法，依據(jù)可靠地電氣接線方案其供電可靠性水平得到了保障。在這個方案中，每個牽引變電所(TS)能夠承擔(dān)相鄰變電站的負(fù)荷。這意味著，在一個牽引變電所(TS)的情況下，當(dāng)故障發(fā)生時，供電系統(tǒng)的相應(yīng)常開觸點自動合閘，并允許兩個相鄰變電站分別提供供電故障的變電站(每一個變電所承擔(dān)一半的故障)的負(fù)載的一半。根據(jù)需求功率來計算變電站的容量大小，在前一節(jié)中已經(jīng)說明。另一方面，每個牽引變電所(TS)的位置都存在著相應(yīng)的優(yōu)化問題。此問題中一個給定的配置的總成本投資，即組成(整流器，變壓器和保護(hù)與控制器)，組成的AC損耗(與變壓器)和DC能量損失(相關(guān)聯(lián)的成本最小化整流器)及整流失敗成本，代表年度預(yù)期的能耗供給(EENS)的成本。3.1牽引變電所(TS)配置城市軌道系統(tǒng)供電方案必須滿足相應(yīng)的電力條件，如：操作限制，通過接觸網(wǎng)或第三導(dǎo)軌(通常，在一般情況下，直流部分)的電壓下降和大容量的變壓器。獨立系統(tǒng)需要電力系統(tǒng)必須能在以下各狀態(tài)下正常的運(yùn)行，即在正常狀態(tài)或高壓/中壓變電站故障應(yīng)急狀態(tài)下，或者牽引變電所，或一個DC部分故障時等。因此，TS的位置和配置的選擇是密切相關(guān)的問題。圖3示出了三種可能方案的MV中壓網(wǎng)絡(luò)連接到一組TS。每個TS旨在提供(在正常運(yùn)行狀態(tài)下)的DC牽引部分的長度