CCC负荷分配简介

©2001CompressorControlsCorporationMenuFwdPrevRew负荷分配控制©2001CompressorControlsCorporationMenuFwdPrevRew•在压缩机网络中，压缩机通常并联运行，有时也有串联运行•形成网络运行的目的包括：–备份–灵活操作–增加额外的能力•通常注重单元机组的运行而忽略网络的优化控制•压缩机制造商通常集中于单元机组的控制。•从“网络”的观点来看，应实现优良的喘振保护和网络的负荷分配优化控制。压缩机网络©2001CompressorControlsCorporationMenuFwdPrevRew并联机组控制系统的目标是：•保持主性能变量稳定（压力或流量）•将负荷优化分配到网络中的各台机组上，同时：–发生喘振的机率最低。–最低的能耗–在启动或停开单一机组时将所带来的工艺扰动降到最低。压缩机网络©2001CompressorControlsCorporationMenuFwdPrevRewProcessPIC11UICVSDSCompressor12UICVSDSCompressor2HIC1Suctionheader用于调节负荷的压缩机满负荷运转的压缩机注：•所有控制系统均为独立运行•变送器未标明。基本负荷法©2001CompressorControlsCorporationMenuFwdPrevRewRc,1qr,12Rc,2qr,22Compressor1Compressor2•MachinesoperateatsameRcsincesuctionanddischargeofbothmachinesaretiedtogetherPIC-SP•Baseloadoneormorecompressorsandlettheother(s)absorbtheloadswingsSwingmachineBasemachine•BasemachineisfullyloadedandrunswithoutrecycleQC,2=QP,2•SwingmachinecanberunningwithrecycleQC,1QP,1where:QP=FlowtoprocessQC=TotalcompressorflowQC-QP=Recycleflow•Loadcouldbere-dividedtoeliminaterecycleQP,1QP,1+QP,2=QP,1+QP,2注：•基本负荷法效率较低。•基本负荷法增加了#1压缩机组发生喘振的危险性，这是由于#1压缩机将独立承担调整任何扰动。•基本负荷法需要操作人员的经常干预。•基本负荷法并不是推荐的方式基本负荷法控制QP,2©2001CompressorControlsCorporationMenuFwdPrevRewProcessPIC11UICCompressor1VSDSCompressor2SuctionheaderNotes•Performancecontrollersactindependentofantisurgecontrol•HighercapitalcostduetoextraFlowMeasurementDevices(FMD)•HigherenergycostsduetopermanentpressurelossacrossFMD’s1FIC2FIC2UICoutoutRSPRSPoutRSPEqualFlowDivisionLoadsharingFlowDiagramforControlProcessVSDS©2001CompressorControlsCorporationMenuFwdPrevRew•Machine2operateswithrecyclewhilemachine1stillhasturndown•MachinesoperateatsameRcsincesuctionanddischargeofbothmachinesaretiedtogether•Equalflowdivisionmightworkifbothmachinesareidentical•Machinesareneveridenticalexceptbycoincidence•BiasrelayonremotesetpointwouldonlyworkifcurveshavesamesteepnessNotes:•RequiresadditionalcapitalinvestmentinFMD’s•RequiresadditionalenergyduetopermanentpressurelossacrossFMD’s•Poorpressurecontrolduetopositivefeedbackincontrolsystem(seenext)•EqualflowdivisionisNOTrecommendedRc,1qr,12Rc,2qr,22PIC-SPQP,1QP,2QC,2EqualflowEqualflowQP,1=QP,2EqualFlowDivisionLoadsharingParallelCompressorControlCompressor1Compressor2where:QP=FlowtoprocessQC=TotalcompressorflowQC-QP=Recycleflow©2001CompressorControlsCorporationMenuFwdPrevRewQ2RcN1N3N2•Inatypicalmaster-slavecontrolschemetheslaveneedstobeapprox.5timesfasterthanthemasterA•ThemachineisoperatinginpointA•Thisistheintersectionof4lines:•ResistancelineR1•PerformancecurveN1•PIC-SP•FIC-SP=OutputofPICR1PIC-SPFIC-SP•ProcessdisturbancecausestheresistancetochangefromR1toR2R2•AsaresultthemachinemovestopointBB•SincethePICisslowitdoesnotmoveitsoutputyetwhichistheFIC-SP•TheFICreactsfastandwilltrytomaintainitsSP•TheFICwillspeedupthemachinetopointCatspeedN3C•Thedisturbanceisamplified•Positivefeedbacksystem•OnlyasthePICstartstoreduceitsoutputtocontrolpressuretheFIC-SPcomesdownandthepressureisrestoredDNotes•Causesinstabilitynearsurge•PoorpressurecontrolduetopositivefeedbackincontrolsystemPIC1OUTRSPFIC1OUTRSPMasterSlaveSIC1DynamicResponse/PressureToFlowCascade•Pressurecontroller(PIC)providesRemoteSetPoint(RSP)forFlowcontroller(FIC)•TheFICprovidestheRSPforthespeedcontroller(SIC),suctionthrottlevalveorguidevanes•ThePICisthemasterandtheFICistheslaveMasterSlave©2001CompressorControlsCorporationMenuFwdPrevRewNotes•Allcontrollersarecoordinatingcontrolresponsesviaaserialnetwork•MinimizesrecycleunderalloperatingconditionsProcess1UICVSDSCompressor1VSDSCompressor2Suctionheader1LSIC2UICoutRSPSerialnetworkoutRSP2LSIC1MPICSerialnetworkSerialnetworkEquidistantLoadsharingFlowDiagramforControlProcess©2001CompressorControlsCorporationMenuFwdPrevRew•MachinesoperateatsameRcsincesuctionanddischargeofbothmachinesaretiedtogetherPIC-SP•TheDEVisadimensionlessnumberrepresentingthedistancebetweentheoperatingpointandtheSurgeControlLine•LinesofequalDEVcanbeplottedontheperformancecurvesasshown0.10.20.3DEV=00.10.20.3•MachinesarekeptatthesamerelativedistancetotheSurgeControlLine(SCL)•ThismeansinpracticethesameDEVforbothmachinesDEV1DEV2•RecyclewillonlystartwhenallmachinesareontheirSCL•SinceDEVisdimensionlessallsortsofmachinescanbemixed:small,big,axials,centrifugals•TheDEVwillbethesameforallmachinesbuttheywilloperateatdifferentspeedsandflowratesSCL=SurgeControlLineRc,1qr,12Rc,2qr,22Compressor1Compressor2Dev1=Dev2Q1=Q2N1=N2Notes:•Maximumturndown(energysavings)withoutrecycleorblow-off•Minimizestheriskofsurgesinceallmachinesabsorbpartofthedisturbance•Automaticallyadaptstodifferentsizemachines•CCCpatentedalgorithmEquidistantLoadsharingParallelCompressorControl©2001CompressorControlsCorporationMenuFwdPrevRewLoadsharingControllerLoopDecouplingFAModePIRTLoopDecoupling+AntisurgeControllerAnalogInputs+DEVToantisurgevalveToperformancecontrolelementPrimaryresponseDEVDEVPrimaryresponseToperformancecontrolelementDEV0Don’tchangeoutputxYesNoPrimaryresponsePrimaryresponseDon’tchangeoutputNoxYesApplyloadsharinggainToantisurgevalveDEV0CompressorsinParalleltheprimaryresponseMasterControllerPVSPPID•M