The Configuration and Communication of Integrated Substation Automation Systems 配置及变电站综合自动.docx

The Configuration and Communication of Integrated Substation Automation Systems 配置及变电站综合自动.docx

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TheConfigurationandCommunicationofIntegratedSubstationAutomationSystems配置及变电站综合自动

TheConfigurationandCommunicationofIntegratedSubstationAutomationSystems

Abstract

Basedonadiscussionofthefeatureofasubstation,thepaperpresentstheconceptthatasubstationiscomposedofbasicunits（BC）.ThehardwarestructureoftheIEDofaBCisdescribed.Next,thepaperdiscussesthecommunicationmodeofthecurrentintegratedSubstationAutomationSystems（ISA）anddescribesthehardwarestructureandthefunctionsoftheISAwithfieldbus.AtlastthepaperpresentstrendsinthedevelopmentofISA.

Keywordssubstationautomationcommunicationfieldbus

1.Introduction

Sincethebeginningof90`s,hundredsofISAsystemhavebeenputintooperationinChina.Thesesystemshaveplayedaveryimportantroleinsubstationperformancehavebeendemonstratedinmanyways.Thissystemshouldbeamulti-functionintegratedanduniformlydesignedrealtimecontrolsystemwithhighefficiencyandreliability.Itshouldimplementamostallthefunctionsofsecondaryequipmentofmodernsubstation,realizetherealtimedatasharingandexchange,andshouldbeexpandableforfutureuse.HowtodesignanISAsystemtomeetalltheaboverequirementsisdiscussedinthepaper.

First,afteradiscussionofthefeatureofsubstation,thepaperpresentstheconceptthatasubstationiscomposedofbasicunits（BC）,suchaslines,transformers,bussesandVoltAmpereReaction（VAR）compensationequipment,andsoon.ThecircuitbreakersandswitchesaremergedintherelevantBCsastheirattachedcontrolfacilities.ThehardwarestructureofaBCisdescribed.Next,thepaperdiscussesthecommunicationmodeofthecurrentISAandpointsoutthefieldbuswouldbethewaytorealizereliable,real-timeandaccurateinformationcommunicationamongintelligentelectronicdevice（IED）.Then,ifpresentstheconfigurationandfunctionsofthedistributedISAwithfieldbus.Atlast,thepaperpresentstrendsinthedevelopmentofISA.

2.BasicUnitsandConstruction

Asubstationisaveryimportantunitinpowersystemforpowertransmissionanddistribution.Asubstationisrequiredtoruncontinuously,reliablyandstably.Substationsofvariousvoltagelevelsandcapacityhaveasimilarconfigurationwhichiscomposedofpowertransmissionanddistributionfacilitiessuchastransformers,VARdeviceswithdifferentvoltagelevels.Thedistinctionbetweendifferentsubstainsisthequantityandvoltageleveloffacilitiesandthewayconnectiononly.

Tomonitorandcontrolthesubstationoperation,abusisequippedwithpotentialtransformers（PT）andtherearecurrenttransformers（CT）ineachwindingofthetransformer,eachlineandtheswitchgearbayoftheVAPequipment.INthesecondarysystem,instantaneousvaluesofvoltageandcurrentareobtainedthroughPTandCT,andthesevaluesarefurtheranalyzedandprocessedtogiveoperationaldataofthesubstationsuchasvoltage,currentandpoweretc.Nom-electricaldatasuchasoiltemperatureandgassignalsarealsoprovidefortransformersandVARequipment.Statusdataofcircuitbreakers,isolatorswitchesandotherauxiliaryequipmentintheswitchgearbaysaregatheredthroughauxiliarycontactsandtransducers.Thesubstationsecondarysystemcollectsandprocessesallthesedatatodetectanyfaultorabnormality.Ifthereisafault,thesecondarysystemwillsendoutacircuitbreakertrippingcommandtotheswitchbaycorrespondingtothefaultedequipmentsothatthefaultcanbeisolated.Ifthereisabnormality,awarningsignalwillbegiven.

Ithasbeenshownbyrelevantreferencethatthefaultcharacteristicsofbuses,lines,transformersandVARequipmentaredifferentfromeachotherasaresultoftheirdifferentphysicalfeature.Thereforerequirementsfortheirmonitoringandcontrolaredifferentfromeachother.

Forfaultsinlines,transformers,VARequipmentorbuses,therearenoothercontrolmeasuresthantrippingthecircuitbreakersofthecorrespondingequipment.

Undernormaloperationcondition,transformersandVARequipmentparticipateinvoltageandVARcontrolcoordinatedbythesystemtomeettherequirementsofpowernetworkvoltagelevelandVARcompensation.

Coordinatedbythesecondarysystem,severalcircuitbreakersmaybecontrolledtomaintainpowersystemstabilityorpowersupplyreliabilityofthesubstation.Commonexamplesareunderfrequencyloadsheddingandbusautomatictransfer.

Tosummarize,themainfeaturesofasubstainsystemare:

Buses,lines,transformersandVARdevicesarethebasicequipmentinasubstation.Theyfunctiontogethertotransferanddistributepower.

Requirementsforthemonitoringandcontrolofbuses,lines,transformersandVARdevicesdifferfromeachother.

Alargeamountofdatainasubstationisfromswitchgearbays,asmalldatatothem.

Protectionandmeasurementformonitoringhavethesamedatasourcebutdifferentrequirementsforsamplingfrequencyandcontrolalgorithms.

Relayprotectionisafundamentalfunctionanditsnormaloperationshouldbeensuredevenifotherdevicesfailtowork.

Thereislittleinformationexchangebetweenswitchgearbays.

Thecontrolofacircuitbreakerinswitchgearbaysmayhavevariouscausesuchaslinefaults,lossofsystemsynchronism,equipmentoverloading,underfrequencyloadshedding,normalnetworkoperationsandsoon.Whateverthecauseis,theoperationisthecontrolofcircuitbreakers.

TransformersandVARdeviceshavetwokindsofcontrol,i.e.,controlinfaultcondictionsandinnormalsystemoperations.

Basedontheaboveanalysisandfromthepointofviewofmonitoringcontrolandmanagementofpowertransferanddistributioninsubstation,thispaperproposesthatasubstationconsistsofsuchBCsasbuses,lines,transformers,VARequipmentandsoon.ABCprovidesdatathroughoneorseveralswitchgearbaystoandreceivescontrolcommandsfromthesecondarysystem.EachBChasitsowncharacteristicsandrequirementsformonitoringandcontrol.

ThusaBCinsubstationcanbetreatedasabasicresearchobjectofmonitoringandcontrol.Thesetofallbasicresearchobjects,managed,coordinatedandcontrolledbythesubstationmaincomputer,formaanISAsystem.

ThehardwarestructureofaBCisnotedasIED.AccordingtothefunctionalrequirementsofaBC,IEDisdesignedbythefaultindependentruleandfunctionindependentrule.EachBChasitscorrespondingIEDwhichmainlydiffersinI/OinterfacesfromthatofanotherBC.Forexample,thetransformerIEDnotonlyinterfaceswithtemperatureandpressuretransducers,butalsohasalargernumberofI/OthanalineIEDhas,Itmustcontrolallthebreakersonthesideofeachwindingunderfaultconditionsandcontroltheon-loadtap-changerundernormaloperations.TheIEDofaVARdeviceoralineBCprovidesaserialporttocommunicatewithaintelligentVARdevice,ortheprotectiondevicelocatedontheothersideofaline.AtypicalIEDhardwarestructureofaBCisshowninFig,.1.

TheAC/DCsamplingandBinaryI/OpartsareconnectedtoabaythroughPT/CTandopticalinsulators,acquiringdatafromthebayandcontrollingthebreaker.TheProcessControlpartanalyzes,calculatesandprocessestheacquireddata,andperformsprotectionfunctionsbytrippingthebreakeriffaultsaredetected.ThroughFieldbusinterface,anIEDcommunicateswiththesubstationcomputersystem（SCS）orotherIED.IttransmitsrealtimedatatotheSCSforsupervisionandreceivescommandsfromSCSorotherIEDforcontrol.

MMIisusedfordisplayingtheacquireddataandparameters,testingandmaintenanceoftheIED.

ThebusIEDacquiresdirectlythecurrentandstatusdatafromthebaysanddetectsbusfaults.Ifafaultisdetected,allbreakersofallunitsconnectingthebusaretrippedbythebusIED.

ThefunctionofunderfrequencyloadsheddingisrealizedbythebusandlineIED,coordinatedbytheSCS.

3.InformationExchangeandFieldBus

ThecommunicationinterfacebetweenthecurrentIEDofISAismainlybyRS-422/485seriesportandonlyafewisbylocalareanetwork（LAN）.UsingRS-422/485communicationinterface,thelinkamongnodescanbedone,butthenumberofnodeslinkedcannotbemorethan32andcannotsuitthefuturedemandsofISA.Inaddition,thecommunicationmodeismaster/slaveandhasdrawbackasfollows:

Onlyonenodeismaster,andtheothersareslavesinthecommunicationnet.Ifthemasternodeisatfault,thesystemwillimmediatelyfail.

Thecommunicationmodeofmaster/slavestructureisunbalanced.Theslaverespondstothecommandsfromthemasterandsendsdatatothemaster.Theefficiencyofdatatransmissionislowandimportantdataintheslavecannotbetransmittedimmediatelyuntilitreceivesthecommandfromthemaster.Thelargerthesystemscale,thelowerthereal-timeofsystemperformance.

Themaster/slavecommunicationmodecannotmeettherequirementsofcommunicationbetweenanytwonodes.

UsingRS-422/485seriesportinterface,itiseasytoconnecteachother.ButtheprotocolamongtheIEDisdifferentandnostandardinchinaisfollowed.Therefore,thecommunicationcontroliscomplicatedanditisdifficulttorealizehigh-speed,reliableandaccurateinformationexchangebetweenIED.Themediaforcommunicationislimitedandsystemsengineersareoccupiedwithprogrammingandtestingcommunicationsoftware.ApplyingLANtechnology,thedatacanbetransmittedinhighspeedandthefunctionsofcentralprocessing.Butinthefieldofprocesscontrol,theadvantagesofLANarelessobviousowingtothefollowingreasons:

·IntheLAN,largequantityofdataaretransmittedinapackageofmessage,buttheyarenotfrequentlytransmitasmall