DynamicCharacteristicsofPantograph-CatenarySysteminHighSpeedRailwayAnannual reportsubmittedtoIndianInstituteofTechnologyKharagpurincompletionofrstyearforthedegreeofDoctor of PhilosophybySoumyajitRoy13ME91R02UnderthesupervisionofDr. GoutamChakraborty&Prof. AnirvanDasGuptaDepartmentofMechanical EngineeringIxitx Ixsrircrc cr 1ccnxcicc\ IntitciciKharagpur-721302June18,2015ContentsListofFigures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iiListofTables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii1 Introduction 11.1 BasicCurrentCollectionSysteminRailways . . . . . . . . . . . . . . . . 11.2 TheCatenary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.3 ThePantograph. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.4 InteractionbetweenCatenaryandPantograph . . . . . . . . . . . . . . . 52 LiteratureReview 62.1 ModellingofCatenary . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.2 ModellingofPantograph . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.3 Catenary-PantographInteractionModelling . . . . . . . . . . . . . . . . 83 MotivationandWorkDone 93.1 MotivationofResearch. . . . . . . . . . . . . . . . . . . . . . . . . . . . 93.2 WorkDone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9References 10iListofFigures1.1 BlockdiagramofmodernACelectriclocomotive[1] . . . . . . . . . . . . 21.2 Astitchedcatenary[2] . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.3 Dierentkindsofcatenarysystems[3] . . . . . . . . . . . . . . . . . . . 31.4 Pantographanditskinematics. . . . . . . . . . . . . . . . . . . . . . . . 41.5 Dierentmodernpantographs . . . . . . . . . . . . . . . . . . . . . . . . 52.1 Modelofcatenarysystem[13] . . . . . . . . . . . . . . . . . . . . . . . . 62.2 Aloworder model of pantograph: (a) linear mass-spring-damper, (bi)model with rotational movement of panhead and elasticity of upper frame[(b1): Sideview&(b2): Frontview][9] . . . . . . . . . . . . . . . . . . . 8ListofTables3.1 Detailsofcourseworkdone . . . . . . . . . . . . . . . . . . . . . . . . . 9iiChapter1IntroductionRailway systems are presently experiencing rapid technological advances, and as a resultofit, thehighspeedrailwaysystemhasemergedasthenextgenerationtransportationsystem. Itischaracterizedbyhighstability,highspeedandpassengercomfort. Variousnationshaveputanemphasisondevelopingthetechnology.One of the accompanying problems to the high speed railway system is to ensure con-stantandstablecurrentcollection. Forthestableoperationofarailway,thelocomotivemust be supplied with constant and stable electrical power through solid contact betweenthecatenaryandthepantograph. If thevelocityof therailwayincreases, therangeofthecatenarysdynamicalvariationwillincreaseandthencontactlossbetweenthepan-tographandthecatenarymightoccur. Thisresultsingenerationof electricarcwhichcausesincreasedwearonthepantographanddamagesthecatenaryaswell. Therefore,itbecomesobvioustostudyandanalysethedynamicbehaviourofpantograph-catenarysystemtominimisethecontactlossandtoincreasetheeciencyincurrentcollectionduringhighspeedoperation.1.1 BasicCurrentCollectionSysteminRailwaysThe electric railwayneeds apower supplythat the traincanaccess at all times. Itmustbesafe,economicalandeasytomaintain. Itcanuseeitherdirectcurrent(DC)oralternatingcurrent(AC). ItiseasiertoboostthevoltageofACthanthatofDC, soitiseasiertosendmorepoweroverlongdistancesthroughthetransmissionlineincaseofAC.DC,ontheotherhand,ispreferredforshorterlines. Moreover,ACsystemsarecheapertoinstall.Transmissionofpowerisalwaysperformedalongthetrackbymeansofanoverheadwiresystemoratgroundlevel, usinganextrathirdrail laidclosetotherunningrails.ACsystemsalwaysuseoverheadwiresknownascatenary,DCcanuseeitheracatenaryorathirdrail, botharecommon. Bothoverheadsystemsrequireatleastonecollectorattachedtothetrainsothatitcanalwaysbeincontactwiththepowercable. Thisisaccomplished by using a pantograph. The return circuit is via the wheel and the runningrails back to the substation as shown in gure 1.1. The running rails are at earth potentialandareconnectedtothesubstations.1Figure1.1: BlockdiagramofmodernACelectriclocomotive[1]1.2 TheCatenaryAcatenaryisaperiodicstructureofoverheadcontactwirestoprovideelectricpowertolocomotiveswhichareequippedwithasuitablecurrentcollectingapparatusknownaspantograph.Themostbasiccomponentsofanycatenarysystem(gure1.2)areamessengerwireor catenarywire (calledso, becauseof its resemblancetothecatenarycurves) andacontactwire. The later is attached to the former by means of equally spaced and varyinglengthof droppers. ThecontactwireisgroovedtoallowacliptobexedonthetopFigure1.2: Astitchedcatenary[2]side. Theclipisusedtoattachthedropper. Droppersarestiistensionbutnotsoresistanttocompression. Italsoensurestherequiredhightoftheoverheadcontactwirefromthegroundthroughout thetrack. Boththemessenger andthecontact wirearetensionedwithhighaxial loadbysuspendingweightstominimisethesag. Thewholesystemis periodicallysupportedbymasts. Everymast has amechanismtoholdthe2catenaryandtoprovidenecessaryallowanceforlateral oscillations. However, thetypeof mechanismvarieswiththetypeof catenarywhichitsupports. Asshowningure1.2, the stay(sometimes called a bracket) and the consolewhich collectively support themessengerwirearehingedtothemastbymeansofinsulators. Thesteadyarmattachedtotheregistrationarmholdsthecontactwire. Itprovidesthenecessarystaggertothecontactwirewhichrunsinazigzagfashionoverthecentrelineofthetracktoensureanevenwearofthecarboncontactstriponthepanheadofthepantographwhilethelocoisrunning. Theregistrationarmisfurtherlinkedtotheconsole.Thereareingeneralthreetypesofcatenarysystems 1)Simplecatenary,2)Com-poundcatenaryand3)Stitchedcatenary. Asimplecatenarysystemhasonlyonemes-sengerandonecontactwireasshowningure1.3(a). Acoupledcatenaryhasasecond(a)Simplecatenary (b)Compoundcatenary(c)StitchedCatenaryFigure1.3: Dierentkindsofcatenarysystems[3]support wireknownas auxiliarywire (gure1.3(b)). Droppers support theauxiliaryfrom the messenger wire and additional droppers support the contact wire from the aux-iliarywire. Ontheotherhand,astitchedcatenaryusesanadditionalwireateachpolestructureasshowningure1.3(c). However, thecompoundcatenaryhaslessstinessvariationoveraspancomparedtothatofsimpleandstitchedcatenary[4]. Thisismoredesirableforthehighspeedtrains. Unfortunately,highpriceistheonlydisadvantageofthistypeofoverheadsystem.31.3 ThePantographApantograph is amechanismmountedonthe roof of alocomotive tocollect powerthroughcontactwiththeoverheadcatenary. Itiscalledsobecause,inearlystages,themechanismresembledwithmechanicalpantographsusedforcopyinghandwritingsanddrawings. Todays pantographs are asymmetric and Z-shaped unlike the symmetric anddeltashapedusedinearlydays. Thesearemorecompactandthemodernsinglearmlightweightdesignsuitsthemmoreeectivelyforhighspeedrunning.Thekinematicsandthedesignof pantographsvaryalotfromcountrytocountry.They largely depend upon various matters like the speed of the train, the catenary systemused as overhead, the track on which the train will run, tunnels and bridges on the route,aerodynamiceectsetc. However, here, morecommonlyusedasymmetricpantographsarediscussedbriey. TheGSE-100LightRail Pantograph of G&ZEnterprisesLtd.ispresentedingure1.4(a)forillustrationpurpose. Thelowerpartof thepantograph(a)GSE-100LightRailPantograph[5] (b)Kinematicdiagram[2]Figure1.4: Pantographanditskinematicsasshowninkinematicdiagramingure1.4(b)isbasicallyafour-barmechanismandresponsible for raisingandloweringit. The upper part controls the panhead. Thepantographbaseis placed over insulators on the roof of the train. The lowerlinkand thelowerarmareconnectedtothebasebyspherical andrevolutejointrespectively. Theextendedtoparmcompletesthelowerfour-barlinkageandisattachedtothelowerlinkandlowerarm. Thepanheadislinkedtothetoparmandtothetoplinkbymeansofstabilizationarm. Thecontactstripswhichareincontinuouscontactwiththeoverheadlinearemountedoverisolatorsonthetopof thepanhead, sothattheeectof baseexcitation does not aect the current collection. Actuations are done by both pneumaticand spring devices. Generally, piston of the pneumatic device attached to one of the twolower links actuates it toraisethesystem, and, ontheother hand, springs lower thepantograph. Theviceversaisalsoseen. Howeveracompletepneumaticactuationisalwayspreferredduetoitsbettercontrollability.There are various types of modern pantographs which are suitably developed for high4speedrunning. Themost favourableoneis thetwo-linkdesignas as showningure1.5(a). Thesetypesofpantographsusestabilizationntousetheaerodynamicliftinafavourable way to control the contact force. Single link pantographs are also seen (gure1.5(b)). InJapan, asimplepneumaticdeviceisseentobeusedaspantograph(gure1.5(c))inhighspeedrails. Inonlygoesupstraighttomakethecontactandgoesdownwhenrequired.(a)Two-linkpantograph[6] (b)Single-linkpantograph[7] (c)PantographinJapan[7]Figure1.5: Dierentmodernpantographs1.4 InteractionbetweenCatenaryandPantographThecarboncontactstripsplacedonthetopofpanheadmakecontactwiththecontactwireof thecatenarysystemtocollectrequiredpowerforthelocomotive. Thecontactpointmovessidewiseonthecontactstripsduetothestaggerprovidedtothecatenanytoensureanevenwearofthestrips. Theidealinteractionbetweenthecontactwireandthe pantograph should be the steady and controlled contact to get maximum eciency incurrentcollection. However,inactualcondition,thisisnotpossibleandtherateoflossofcontactincreaseswiththeincreaseintrainspeed. Thelossofcontactisdeterminedby contact force at the interface. If the contact force is too low, increased separation willresultinexcessivearcwhichcauseserosionincontactstripsaswell asdamagetothecontactwireduetoexcessiveheatgeneration. Ontheotherhand,ifthecontactforceistoohigh,thepantographwillalwaysmaintainthecontactwiththecontactwire,butatthecostofincreasedwearinthecarbonstrips. Therefore,thecontactforceneedstobemaintainwithinaspeciedrange[8]andthisleadstothenecessityofdynamicanalysisofboththesystemsaswellastheinterface.5Chapter2LiteratureReviewTheinteractionbetweenpantographandcatenaryisthepresentproblematicofcurrentcollectioninelectricrailways. Currentcollectionenhancementisakeyrequirementforrail speed-upinrailwayindustry. Several modelshavebeenproposedinthissenseinvariousliteraturestoinvestigatethedynamicresponseof pantograph-overheadcontactline. Kiaetal. [9] andPoetschetal. [10] havepresentedexcellentreviewof variousliteraturesandcomparedtheresults. Abriefreviewofliteratureshasbeenprovidedinthischapter.Tostudythedynamicsofthewholesystem,asuitablemathematicalmodelisneces-sary and it should essentially include three main aspects of the system 1) Modellingofcatenary, 2) Modelling of pantographand 3) Interaction between catenary and pantographi.e. Contact modelling. Apart from these, other aspects like active control of pantograph,aerodynamiceects,etc. arealsostudied.2.1 ModellingofCatenaryThe catenary and the pantograph together form a dynamically coupled vibrating systemaecting each other by contact force. The quality of current collection is assessed throughlossofcontactwhichisdeterminedbymeasuringthecontactforce. Themajorsourceofvibrationisthespatialstinessvariationofthecatenaryalongthespan[9].Figure2.1: Modelofcatenarysystem[13]6A simpliedoverhead system is modelled by Wu et al. [4] where only the static stinessvariationalongthespanisconsidered, thusneglectingthevertical stinessvariationofdropperswithaconstanttraintravellingspeed. Itisshownthatcompoundcatenaryhassmallerstinessvariationcomparedtosimplecatenary. Thecontactforceisgreatlyaected by stiness variation along the span as well as wave propagation in the catenarywire. ThestaticstinessvariationhasbeenalsoproposedbyWuetal. [11]usingniteelementmethod(FEM)andbyParketal. [12]usingbeammethod.As speed of the train increases, wave reection plays the major role and the simpliedmodelbecomesinsucienttopredictthe variationincontactforce. Moreover,theeectofbrackets,registrationarms,droppersshouldbetakenintoaccountasshowningure2.1. Therefore, asuitablebeammodel likeEuler-Bernoulli-Timoshenkobeammodel isproposedbyCho[13]andSchaubetal. [14]. TheEuler-Bernoullibeammodeltakesthebendingstinessofthewireintoaccountand,inaddition,theTimoshenkobeammodelconsiderstheeectsofsheardeformationandrotaryinertia.The modal analysismethod is more convenient for real time simulation of pantograph-catenaryinteractionasdiscussedbyZhangetal. [15],Restaetal. [16]andFacchinettiet al [17]. This method decomposes the catenary wire displacement in the sum of innitederivablestationarysinusoidal functionstorepresentwavepropagationphenomena. Itisalsocapableofdescribingverynedisplacementsofcatenary. Themassandstinessmatrixofeachelementsuchasmessengerwire, contactwire, bracket, registrationarm,support,steadyarm,etc. inthecatenarysystemareevaluatedbymeansofkineticandpotentialenergyintheLagrangeform.Theresultsof all thesetheremodelsarereviewedandcomparedbyKiaetal. [9]andit is concludedthat theFEMmodel basedonEuler-Bernoulli-Timoshenkobeamts almost perfectlywithreal systems. However, it consumes highest computationaltimewithhigherdegreesoffreedomcomparedtomodalanalysistechniquehavinglesserdegreesoffreedomstillconsuminglessercomputationaltimeandprovidingsatisfactoryresults for the real systems. On the other hand, simple models are only capable to modeltherstresonancefrequencyofthesystemwithonedegreeoffreedom. Buttheresultsarefarfromtheactualscenario.2.2 ModellingofPantographThepantographisthecounterpartof catenarysysteminelectriedrailways. So, im-provement of dynamic behaviour of pantograph leads to better current collection quality.Lowordermodelsarecommonlyusedbymanyresearchers. However, real pantographcontains non linear force element as well as non linear kinematics. Therefore, models withlinear degree of freedom are only valid for one pantograph layout and for one operationalpoint[9].Loworderpantographmodel variesfromonemasstothreemasssystemwithlinearforcelawstomodeljointfriction. Inadditiontothat, therotationalmotionofthepanhead as well as the approximate elasticity of the upper frame is modelled by Schaub et al.[14] asshowningure2.2. Thesourceofnon-linearitieslikepneumaticbellows, eectsoffrictioncanalsobeincludedthemodel.Another type of recent development is multibody model (gure 1.4(b)). A pantograph,generally,consistsofrigidlinksconnectedbykinematicpairswhichensurestherelativemotionbetweenthelinks. Relevantinternal forceswhichrepresentinteractionbetween7Figure 2.2: A low order model of pantograph: (a) linear mass-spring-damper, (bi) modelwithrotational movementof panheadandelasticityof upperframe[(b1): Sideview&(b2): Frontview][9]rigid bodies are modelled as deformable elements like springs and dampers. The equationofmotionofpantographformsacoupledsystemofpartialdierentialequations(PDEs)for the catenary and dierential algebraic equations (DAEs) for the pantograph which isachallengingproblemfrommathematical andmechanical pointofviewasanalyzedbySimeoni etal. [18] andArnoldetal. [19]. Amultibodymodel providesmorerealisticresultsasshownbymanyresearcherslikeRauteretal. [20]andAmbrosioetal. [21].2.3 Catenary-PantographInteractionModellingTheinteractionbetweenpantographandcatenaryisthroughthecontactbetweenthecontactwireandcontactstripofpantographwhichisaectedbyseveralimportantfac-tors such as contact wire wear and irregularities (discussed by Bruni et al. [22] and Rauteret al. [23]), aerodynamic disturbance (discussed by Bocciolone et al. [24]), locomotive vi-bration (shown by Zhai et al. [25]), presence of multiple pantographs (analyzed by Hareiretal. [26])andelectricalarc(discussedbyMidyaetal. [27],[28]). Studyingofcatenaryandpantographinteractionwithout contact model, limit thefrequencybandwidthto30Hz. ItisshownbyBrunietal. [22]thatthemodelincludingthecontactwireirregu-larities, contact loss and aerodynamic disturbance improves the frequency bandwidth upto100Hz.8Chapter3MotivationandWorkDone3.1 MotivationofResearchThecatenary-pantographsystemisfairlycomplex. Makingmodicationofcurrentsys-temsisalsoverydicult. Ontheotherhand,owingtogreatdicultyinplanningandimplementation of full-scale measurement, full-scale test runs have become quite challeng-ing. Thedesignaswellascontrolofthesystemvariessignicantlyindierentcountriestosuitbesttheconditionthere. However, Indialacksinhigh-speedrailway. Notonlycurrent infrastructureis unsuitablefor highspeedrunningbut, maintainingincreasedspeedonitisalsoverychallenging. Installationofnewsystemisconsiderablyexpensiveandthis makes thesituationmoretoughfor India. Thehighspeedtrains shouldbeeconomicandmustbewithinthereachofgeneralpeople.Therefore, before going to install a new system, it is much desirable to study, analyseandpredictthedynamicbehaviourof theexistingcatenary-pantographsystembefore-handwithpropermathematical modellingandnumerical simulation. Understandingofthis complex interaction of moving pantograph beneath the stationary overhead line withkeepingasteadycontactall thetimebetweenthemalsoneedsproperanalytical study.This will help to change the design and control strategy for the existing system if possibleortoimplementanewonewhichiswithinthereachofall.3.2 WorkDoneAll the requisite courses have been completed with satisfactory grades. The result of com-prehensiveexaminationheldinMechanicalEngineeringDepartmentisalsosatisfactory.Thedetailsaretabulatedintable3.1SubjectNo. SubjectName Type Credit Session Grade/RemarksHS63002 EnglishforTechnicalWriting CompulsoryCourse 4 2013-2014-Autumn ATS70003 WavePropagationinContinuousMedia InterdisciplinaryCourse 4 2013-2014-Spring EXME60401 AppliedElasticity RecommendedCourse 4 2013-2014-Autumn AME60417 VibrationControlandIsolation RecommendedCourse 4 2013-2014-Autumn EXN/A EngineeringMechanics ComprehensiveExamination N/A 2013-2014-Spring SuccessfulN/A MechanicsofSolids ComprehensiveExamination N/A 2013-2014-Spring SuccessfulTable3.1: Detailsofcourseworkdone9References[1] Thephysicsofelectriclocomotives,03July,2014,http://www2.hesston.edu/Physics/electricloco/eleclocop.html[2] J. Pombo, J. Ambrosio, Environmental and track perturbations on multiple panto-graphinteractionwithcatenariesinhigh-speedtrains,ComputersandStructures,vol.124,pp.88-101,2013.[3] J. 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Cai, Eect of locomotive vibrationonpantograph-catenarysystemdynamics,Journal ofVehicleDynamics,vol.28,no.S1,pp.47-58,1998.[26] P. Hareir, L. Drugge, M. Reijm, Multiplepantographoperationeectsof sectionoverlaps,Journal ofVehicleSystemDynamics,vol.41,pp.687-696,2004.[27] S.Midyaetal.,Pantographarcinginelectriedrailwaysmechanismandinuenceof various parameters part I: with dc traction power supply, IEEETransactionsonPowerDelivery,vol.24,no.4,pp.1931-1939,2009.[28] S.Midyaetal.,Pantographarcinginelectriedrailwaysmechanismandinuenceof variousparameterspartII: withactractionpowersupply, IEEETransactionsonPowerDelivery,vol.24,no.4,pp.1940-1950,2009.11