建筑电气英文论文.docx
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建筑电气英文论文
ARCHITECTURALANDCOLLABORATIVECONTROL
SYSTEMSACOMPLEMENTARYSYMBIOSIS
-Lookingattoday’scontrolsystemonecanfindawidevarietyofimplementations.Frompurearchitecturaltocollaborativecontrolsystem(CCS)toolkitstohomegrownsystemsandanyvariationin-between.DecisionsonthetypeofimplementationshouldbedrivenbytechnicalargumentsRealityshowsthatfinancialandsociologicalreasonsformthecompletepicture.Anydecisionhasit’sadvantagesandit’sdrawbacks.Reliability,gooddocumentationandsupportareargumentsforindustrialcontrols.Financialargumentsdrivedecisionstowardscollaborativetools.Keepingthehandsonthesourcecodeandbeingabletosolveproblemsonyourownandfasterthanindustryaretheargumentforhomegrownsolutionsoropensourcesolutions.Theexperienceofmanyyearsofoperationsshowsthatwhichsolutionistheprimaryonedoesnotmatter,therearealwaysareaswhereatleastpartoftheotherimplementationsexist.Asaresultheterogeneoussystemshavetobemaintained.Thesupportfordifferentprotocolsisessential.Thispaperdescribesourexperiencewithindustrialcontrolsystems,PLCcontrolledturnkeysystems,theCCStoolkitEPICSandtheoperabilitybetweenallofthem.
-INTRODUCTION
ProcesscontrolsingeneralstartedatDESYintheearly80thwiththeinstallationofthecryogeniccontrolsystemfortheacceleratorHERA(Hadron-Elektron-Ring-Anlage).Anewtechnologywasnecessarybecausetheexistinghardwarewasnotcapabletohandlestandardprocesscontrolssignalslike4to20mAinputandoutputsignalsandthesoftwarewasnotdesignedtorunPIDcontrolloopsatastablerepetitionrateof0.1seconds.Inadditionsequenceprogramswerenecessarytoimplementstartupandshutdownproceduresforthecomplexcryogenicprocesseslikecoldboxesandcompetecompressorstreets.
Soonitwasnecessarytoaddinterfacestofieldbusesandtoaddcomputingpowertocryogeniccontrols.SincetheinstalledD/3system[1]onlyprovidedandocumentedserialconnectiononamultibusboard,thedecisionwasmadetoimplementaDMAconnectiontoVMEandtoemulatethemultibusboard’sfunctionality.ThenecessarycomputingpowerfortemperatureconversionscamefromaMotorolaMVME167CPUandthefieldbusadaptertotheinhouseSEDACfieldbuswasrunningonanadditionalMVME162.TheoperatingsystemwasVxWorksandtheapplicationwastheEPICStoolkit.
SincethisimplementationwassuccessfulitwasalsoimplementedfortheutilitycontrolswhichwerelookingforagenericsolutiontosupervisetheirdistributedPLC’s.
ASELECTIONOFPROCESSCONTROLSYSTEMSATDESY
DCS(D/3)
AsaresultofamarketsurveytheD/3systemfromGSEwasselectedfortheHERAcryogenicplant.ThedecisionwasfortunatebecauseoftheDCScharacteroftheD/3.Thepossibilitytoexpandthesystemonthedisplay-andontheI/OsidehelpedtosolvetheincreasingcontroldemandsforHERA.ThelimitingfactorforthesizeofthesystemisnotthetotalnumberofI/Obutthetrafficonthecommunicationnetwork.Thistrafficisdeterminedbythetotalamountofarchiveddatanotbythedataconfiguredinthealarmsystem.Thetechnicalbackgroundofthislimitationisthefactthatarchiveddataarepolledfromthedisplayserverswhereasthealarmsarepushedtoconfigureddestinationslikealarm-files,(printer)queuesordisplays.
SCADASystemswithDCSFeatures(Cube)
ThefactthattheD/3systemmentionedabovehadsomehardcodedlimitationswithrespecttotheY2Kproblemwasforcingustolookforanupgradeorareplacementoftheexistingsystem.AsaresultofacallfortenderthecompanyOrsiwiththeirproductCubecameintoplay[2].Theprojectincludedacompletereplacementoftheinstalledfunctionality.ThisincludedtheD/3aswellastheintegrationoftheDESYfieldbusSEDACandthetemperatureconversioninVME.Theprojectstartedpromising.Butsoontechnicalandorganizationalproblemswerepushingthescheduletoit’slimitswhichweredeterminedbytheHERAshutdownscheduledatthattime.Thefinalacceptancetestatthevendorssiteshoweddramaticperformanceproblems.Twofactorscouldbeidentifiedasthecauseoftheseproblems.ThefirstonewasrelatedtotheunderestimatedCPUloadofthe6thgradepolynomialtemperatureconversionrunningat1Hz.ThesecondonewastheadditionalCPUloadcausedbythecomplexfunctionalityoftheexistingD/3system.Hereitwasunderestimatedthateachdigitalandanaloginputandoutputchannelhadit’sownalarmlimitsintheD/3system.InaSCADAlikesystemasCubethebasefunctionalityofachannelistoreadthevalueandmakeitavailabletothesystem.Anyadditionalfunctionalitymustbeadded.Lastnotleasttheloadonthenetworkforpollingallthealarmlimits–typicallyforaSCADAsystem–wasalsodrivingthenetwor