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]
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