39OPC based distributed real time simulation of co

OPCbaseddistributedrealtimesimulationofcomplexcontinuousprocessesRau´lAlvesSantosa,*,JulioE.Normey-Ricoa,AlejandroMerinoGo´mezb,LuisFelipeAcebesArconadac,Ce´sardePradaMoragacaDepartmentofAutomationandSystems,FederalUniversityofSantaCatarina,88040-900CTC-UFSC,Floriano´polis-SC,BrazilbCenterofSugarTechnology,UniversityofValladolid,EdificioAlfonsoVIII,47011,Valladolid,SpaincDepartmentofSystemsEngineeringandAutomaticControl,UniversityofValladolid,FacultyofSciences,c/RealdeBurgoss/n47011,Valladolid,SpainReceived28July2004;receivedinrevisedform25October2004;accepted28January2005Availableonline9March2005AbstractThispaperpresentsamethodologyforthedevelopmentofdistributedprocesssimulationusingOPC(OLEforProcessControl).ThedistributedcomponentsoperateasOPCserversenclosingcontinuoussimulationsdevelopedwiththesimulationlanguageEcosimPro.ThepaperpresentstheproblemsrelatedtodatainterchangeandsynchronisationinrealtimeandthesolutionsadoptedandgivesresultsabouttheperformanceofOPCinthiskindofapplications.Themethodologyhasbeenappliedtoalargeprocesssimulatorofabeetsugarfactoryusedforcontrolroomoperatortraining.Thisincludesaprocesssimulationoperatinginanetworkofsixcomputers,aSCADAsystemforoperationontheprocess,aninstructorconsoleandthecorrespondingsoftwareforrealtimecommunicationandsynchronisation.Themainadvantagesofthisapproachare:(i)independenceofthedevelopmentofthesimu-lationfromthecommunicationmechanisms,(ii)accesstothesimulationsbyawiderangeof1569-190X/$-seefrontmatter
2005ElsevierB.V.Allrightsreserved.doi:10.1016/j.simpat.2005.01.005*Correspondingauthor.Tel.:[phone].E-mailaddresses:[e-mail](R.AlvesSantos),[e-mail](J.E.Normey-Rico),[e-mail](A.MerinoGo´mez),[e-mail](L.F.AcebesArconada),[e-mail](C.dePradaMoraga).(2005)525–549applications,duetothestandardprovidedbyOPC,(iii)useoflowcostconventionalequip-mentand(iv)supportforlargescalesimulations.
2005ElsevierB.V.Allrightsreserved.Keywords:Process;Distributed;Interactive;Training1.IntroductionThereareanincreasingnumberofsimulationapplicationswhichsizeexceedthecomputationalcapacitiesofconventionalcomputers,mainlyifrealtimeexecutionofthesimulatedmodelsisrequired.Onesolutionforthisproblemthatisbeenadoptedinanincreasednumberofapplicationsisbasedondistributingthecomputationalloadamongasetofinterconnectedcomputers.Insteadofrunningabigsizesimula-tioninasinglecomputer,thesimulationisdividedinseveralmodules,eachofthemsuitableforrunninginacomputeratthedesiredspeed.Inthiswaythesimulationisperformedinparallelinacomputernetworkgainingbenefitoftheincreasedcompu-tationalpower.Keyelementsindistributedsimulationarethepartitioningofthesimulationamongthedifferentmodules,theinterchangeofdatabetweenthemalongthesimu-lationtimeandthesynchronisationoftheexecutionofthemodules.Criteriathatcanbeusedforthedivisionofasimulationinmodulesarequitewide,rangingfromselectingmodulesthatcorrespondtophysicalelementssuchasprocessunits,tolookingforminimumnumberofinterconnectionsamongthemod-ules,orforinterconnectionsinvolvingvariablesthatpresentthesmoothestchanges.Forthedistributedexecutionofsimulationsthereareseveralsoftwareenviron-mentsthatprovidedatainterchangeandsynchronisationservices,amongthem,forinstance,HLAandCAPE-OPEN.TheHighLevelArchitecture(HLA)[15]isastandardoftheDefenseModelingandSimulationOffice[8]oftheDepartmentofDefenseofUSA(DoD)[7],thathavetheirowncommunicationandsynchronisa-tionlibrariescalledRuntimeInfrastructure(RTI).Ontheotherhand,CAPE-OPEN(ComputerAidedProcessEngineeringOpenSimulationEnvironment)[5,6]istheresultofanEuropeanUnionjointprojectandinsteadofprovidinglibrariesforcom-munication,itspecifythecomponentinterfacesfortwomiddlewares,OMGCORBA[13,16]andMicrosoftDCOM[11,12].Inbothcases,thecommonideaisthedevel-opmentofasetofspecificationsonthemodulesorcomponentssothattheycanbedevelopedandre-usedeasily.Inthispaperweapproachthetopicofdistributedsimulationfromtheperspectiveoftherequirementsimposedbythedevelopmentofsimulatorsforcontrol-roomoperatorstrainingintheprocessindustries.Thesesimulatorscombineareal-timesimulationoftheprocess,usuallythewholefactory,withaSCADA(SupervisorControlAndDataAdquisitionSystem)thatactsashumaninterfaceandaninstruc-tormoduleforsupervisionandproblemgeneration.TheprocesssimulationhasbeendevelopedinthesimulationenvironmentEcosimPro[9].Itdisposesofamodern526R.AlvesSantosetal./SimulationModellingPracticeandTheory13(2005)525–549objectorientedmodellinglanguagenamedEcosimProLanguage(EL)thatsupportsboth,continuousanddiscreteeventsystems,andincorporatesstateoftheartinte-grationalgorithmsforsolving(sparse)DAEmodels.Twoimportantcharacteristicsare:first,thatthecomputationalcausalityofthemathematicalmodelsisnotprede-termined,sothatthesecanbere-usedindifferentcontexts,andsecond,thatthesim-ulationmodelsisgeneratedasaC++classthatcanbeintegratedinanyC++application.TypicalprocessmodelsinvolveseveralthousandDAEequationssothatforrealtimeoperationwithtoday
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