变电站毕业设计外文翻译.docx

变电站毕业设计外文翻译.docx

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变电站毕业设计外文翻译

山东理工大学

毕业设计

（外文翻译材料）

ReliabilitymodellingandanalysisforSheffieldSubstation220kVupgradeproject

CarolineLeeTransend,NetworksPtyLtd,Tasmania

DrSudhirAgarwal,SanDiego,California,USA

ABSTRACT

ThispaperdescribestheapplicationofadefensibleprobabilisticprocessinreliabilityevaluationforSheffield220kVSubstationredevelopmentproject.SheffieldSubstationisahubof220kVtransmissionsystemintheNorthandNorth-WestregionsofTasmania.ItprovidesconnectiontoWestCoastandMerseyForthhydropowerstationsandfacilitatespowertransfersfromthesepowerstationstomajorindustrialcustomersinGeorgeTownareaandretailandindustrialloadsintheNorthandNorth-WestregionsofTasmania.Therefore,itisimportantthatintegrityofSheffieldSubstationisprotectedasmuchaspossibleandconsequencesofunplannedoutagesminimisedtopreventpossiblewidespreadsystemdisturbances.TogetherwithGeneralReliabilityfromSanDiego,California,TransendundertookthereliabilityevaluationoffourredevelopmentoptionsforSheffieldSubstationusingSUBREL,substationreliabilityandTRANSREL,transmissionsystemreliabilityprograms.

1.INTRODUCTION

Transend,asaTransmissionServiceProviderandTransmissionNetworkOperatorinTasmaniaisresponsibleforprovidingreliableelectricitysupplyandprovidingcosteffectivedevelopmentsolutionsofthetransmissionnetwork.Transendhasidentifiedaneedforacomprehensiveandmoreobjectiveprocessinjustificationofdevelopmentprojectsfromitscapitalworksprogram.Theneedtocombinecustomerreliabilitytargetsandeconomicstoachievecosteffectivedevelopmentsolutionshasbeenlongrecognised.Ahierarchicalframeworkforoverallpowersystemreliabilityevaluationispresentedin[1].Differentdesign,planningandoperatingprinciplesandtechniqueshavebeendevelopedindifferentcountriesovermanydecadesinanattempttofindbalancebetweenreliabilitytargetsandeconomicconstraints[2].Followingthereliabilityconceptandprinciples,differentutilitiesapplieddifferentreliabilitycriteriatojustifyprojectsfromtheircapitalworksprogram.Reliabilitycriteriacanbeviewedasconditionsthatshouldbesatisfiedbyelectricitygeneration,transmissionanddistributionsystemsinordertoachieverequiredreliabilitytargets.Reliabilitycriteriausuallyfallintotwocategories:

establishednumericaltargetlevelsofreliability（eglevelofexpectedenergynotsupplied）andperformancetestcriteria（egN-1,N-2incidentsthatthesystemhastowithstand）.AnattempttocombinethesetwocategoriesintoonesetofreliabilitycriteriaiscurrentlyunderwayinTasmania[3].Theuseofreliabilitycriteriafromthefirstcategoryisthecoreofprobabilisticreliabilityevaluationapproach.Thesecondcategoryisadeterministicreliabilityevaluationapproach.Theusefulnessofdeterministiccriteriaandsecuritystandardsinjustificationofprojectsfromcapitalworksprogramischallengedin[4].Instead,anapproachinvolvingcustomersindecisionmakingandsimulatingarealisticsystemoperationandfailureiscommended.Thebasicstepssuggestedinproperreliabilityevaluationsarebasedoncompleteunderstandingoftheequipmentandsystembehaviourincluding:

•Understandingthewaytheequipmentandsystemoperate;

•Identifythesituationsinwhichequipmentcanfail;

•Understandconsequencesofthefailures;

•Incorporatetheseeventsintothereliabilitymodel;

•Usetheavailableevaluationtechniquestocalculatereliabilityindicesandcosts.

Withthisunderstandingofthesystembehaviourprobabilitytheoryisthenonlyseenasatooltotransformthisunderstandingintothelikelysystemfuturebehaviour.

2.SELECTIONOFEVALUATIONTECHNIQUEANDSOFTWARETOOLS

Therearetwomaincategoriesofevaluationtechniques[5]:

analytical（stateenumeration）andMonteCarlosimulation.Theadvantagesanddisadvantagesofbothmethodsarediscussedin[1].AnalyticaltechniquewaschosenbyTransendbecauseofitsusefulnessincomparingdifferentdevelopmentoptionsfornetworkdevelopmentprojects.ThisapproachwaspresentedalsointheElectricitySupplyAssociationofAustraliaGuidelinesforReliabilityAssessmentPlanning[6].Consequently,decisionwasmadetoacquireSUBREL,andTRANSREL,substationreliabilityandtransmissionsystemreliabilityprogramsfromGeneralReliability,USA.

2.1.SUBREL-SUBSTATIONRELIABILITY

PROGRAMSUBRELisacomputerprogramwhichcalculatesreliabilityindicesforanelectricityutilitysubstationandgeneratingstationswitchyard[7].Themethodologyusedtoanalyseimpactofsubstationgeneratedoutagesonoverallsystemreliabilityperformanceshasbeendescribedin[8].Theprogrammodelsthefollowingoutageevents,includingallrequiredsubsequentautomaticandmanualswitchingoperations:

1.Forcedoutageofanysubstationcomponent:

•Breaker

•Transformer

•BusSection

•Disconnector

2.Forcedoutageofanincomingline.

3.Forcedoutageoverlappingamaintenanceoutageforsubstationequipmentoranincomingline.

4.Stuckbreaker（failuretoopenwhenneededtoclearthefault）.

SUBRELcalculatesthefollowingloadpointindices:

•FrequencyofInterruption（peryear）

•NumberofCircuitsInterruptions（peryear）

•OutageDuration（minutesperoutage）

•AnnualTotalOutageDuration（minutesperyear）

•CustomerMinutesofInterruptionCMI（peryear）

•ExpectedUnsuppliedEnergy（EUE）（kWhperyear）

•ExpectedOutageCost（$peryear）

SUBRELalsocalculatesthefollowingsubstationortotal

systemindices:

•SAIFI,SystemAverageInterruptionFrequencyIndex

•SAIDI,SystemAverageInterruptionDurationIndex

•CAIDI,CustomerAverageInterruptionDurationIndex

•ASAI,AverageServiceAvailabilityIndex

•EUE,ExpectedUnsuppliedEnergy（kWhperyear）

•ExpectedOutageCost（$peryear）

SUBRELgeneratesalistofsubstationgeneratedoutagesthatcanbeusedfurtherbyTRANSRELtoanalyseimpactonoverallsystemreliabilityperformance.

2.2.TRANSREL–TRANSMISSIONSYSTEMRELIABILITYPROGRAM

TRANSRELusescontingencyenumerationoftransmissioncontingenciestoevaluatepowernetworkreliability.Itisdesignedtoaidelectricutilitysystemplannersforreliabilityassessmentofbulkpowersystems.Theprocessinvolvesspecifyingcontingencies（outagesoftransmissionlinesandstationoriginatedoutages）andperformingloadflowanalysistodeterminesystemproblemssuchascircuitoverloads,low/highbusvoltages,busseparationorislanding.Usingtheprobability,frequencyanddurationofthecontingenciesevaluated,indicesofsystemproblemsasmeasuresofsystemunreliabilityarecalculated.Bothpostcontingencyandpostremedialactionindicescanbecalculated.Ifnoremedialactionsaretakentoalleviateaproblem,thepostcontingencyindicesmayprovideapessimisticassessmentofsystemreliability.Ifremedialactionssuchasgenerationredispatch,switchingoffacilities,curtailmentofloadalleviatessomeofthesystemproblems,thepostremedialactionreliabilityindicesprovideamorerealisticmeasureofsystemperformance.Theamountofloadsheddingisusedasanindicatorofcontingencyseverityorsystemcapabilitytowithstandcontingencies.Usingprobabilitiesofcontingencies,expectedloadcurtailmentatbusescanbecalculatedasreliabilityindices.TRANSRELwasusedwithloadflowprogram,PTIPSS/Etoexaminetheimpactofanoutageonsystemperformance.Thetypesoffailuresidentifiedforcheckingtheimpactofacontingencyonsystemperformanceare:

Transmissioncircuitoverloads-bycomparingflowsbasedontheloadflowsolutionwithuserselectedcircuitratings;Busvoltageviolations-bycheckingbusvoltagesagainsthighandlowvoltagelimits,ormaximumallowablevoltagedeviationfromthebasecase;Loadcurtailment-bytabulatingtheamountofloadcurtailedasaresultofsystemfailure;

Loadflowdivergence-bytabulatingthebusmismatchesaboveapredefinedtolerance.TRANSRELcomputesreliabilityindicesusingacontingencyenumerationapproach,whichinvolvesselectionandevaluationofcontingencies,classificationofeachcontingencyaccordingtospecifiedfailurecriteria,andcomputationofreliabilityindices.Reliabilityindicesincludefrequency,durationandseverity（overloads,voltageviolations,loadcurtailed,andenergycurtailed）.Bothsystemandbusindicesarecalculated.

3.SUBRELANDTRANSRELAPPLICATIONFORSHEFFIELD220KVSUBSTATIONSheffieldSubstationisahubof220kVtransmissionsystemintheNorthandNorth-WestregionsofTasmania.AsshownonFigure1,itprovidesconnectionsfromtheWestCoastandMerseyForthhydropowerstationstotherestofthesystem.Inaddition,itsuppliesAuroraEnergycustomersinNorthandNorth-WestregionsandmajorindustrialcustomersintheGeorgeTownarea.Duringwintermonths,fromMaytoSeptember,theamountofenergysuppliedthroughandtransferredfromSheffieldSubstationcanreachmorethan50%oftheenergysuppliedtotherestofthesystemasshowninFigure2.Assuch,SheffieldSubstationhasbeenrecognizedasavulnerablepointintheTasmanianpowersystem.ThetotallossofSheffieldSubstationduringtimesoflargepowertransferfromWestCoastofTasmaniatotherestofthesystemcouldpossiblyleadtoalargesystemdisturbanceinTasmania.WiththepresentSheffieldSubstation220kVlayout,thetotallossofSheffieldSubstationcanbecausedbyasingleelementfailure.

3.1.DEVELOPMENTOPTIONSANALYSED

Theneedtoredesigntheexistingsubstation220kVlayouthasbeenrecognisedlongtimeago.Thefollowingthreeoptionshavebeenselectedfordetailedmodelingandanalysis:

Option1:

Triplebusbararrangement