重庆大学-过程控制-process-control-中文-翻译-第五章-(2)

1ProcessControlCollegeofAutomationChongqingUniversity2AnalysisofSingleLoopSystemsOutlinePIDControllersP-controller,PIcontroller,PDcontroller,PIDcontrollerAGeneralSISOSystemTransferfunctionwithprocessmodelSignaltransmitterControllerActuator(controlvalves)Closed-LoopResponseSevenexamplesChoiceofcontrollers3AnalysisofSingleLoopSystemsClosed-LoopTransferFunctionsAgeneralSISOsystem:Thestirred-tankheaterrevisited再来观察搅拌加热器模型Theheatbalanceisrepresentedas热平衡方程WhereUistheoverallheattrans.coef.热传递系数,Aistheheattransferarea加热面积,isfluiddensity,流体密度Cpistheheatcapacity,热容量Visthevolume（体积）ofthevesselTi=Ti(t)istheinlettemperature入口TH=TH(t)issteamcoiltemperature蒸汽线圈的温度Qistheflowrate流量TistheoutlettemperaturewiththeinitialconditionisT(0)=Ts,T是出口温度初始条件是T(0)=Ts4AnalysisofSingleLoopSystemsClosed-LoopTransferFunctionsThestirred-tankheaterrevisited:whereAfterLaplacetransformNowpistheprocesstimeconstantKdandKparesteadystategains5AnalysisofSingleLoopSystemsClosed-LoopTransferFunctionsAgeneralSISOsystemTemperatureTisbasedon1.inletTi,and2.jackettemperatureTH套管温度TH6AnalysisofSingleLoopSystemsClosed-LoopTransferFunctionsAgeneralSISOsystemSteamtemperatureTHischosenasthemanipulatedvariable（被控变量）1.Becauseofthephysicalintuition,alsodueto2.HavingahigherprocessgaincomparedtoTiReminder（提醒）:BothTHandTiaretheinputstotheprocess,butnotnecessarilytheinputstothesystemTH和Ti是过程的输入，但不一定系统输入7AnalysisofSingleLoopSystemsClosed-LoopTransferFunctionsAgeneralSISOsystemSystemoutputisT,calledthecontrolledvariableCSyteminputisR,calledthesetpoint,orthereferenceTheotheraffectingtheresponseareconsideredasload（扰动）(e.g.,theinlettemperatureTi)Reminder:Inputsmeansdifferentthingsforprocess,andtheclosed-loopsystem8AnalysisofSingleLoopSystemsClosed-LoopTransferFunctionsAgeneralSISOsystemThetransferfunctionsforthesystemareGpfortheprocess(plant)GLfortheload(disturbance扰动)GcforthecontrollerGmforthemeasuringdevice（测量仪器）,withthesteadystategainKmGafortheactuator（执行器）Reminder:IntroducingKmonRforsummingup（总结）withthesameunits9AnalysisofSingleLoopSystemsClosed-LoopTransferFunctionsDerivingthesinglelooptransferfunctionAtthesummingpoint:在求和点Fortheprocess:SubstitutingEintoC,wehave:用C取代E,有Rearranging（重排）theequationabove:10AnalysisofSingleLoopSystemsClosed-LoopTransferFunctionsDerivingthesinglelooptransferfunctionThecharacteristicpolynomial（特征多项式）Thetermiscalledtheforwardlooptransferfunction（前向通道传递函数）Thetermbelow（下面方程的专业术语）iscalledtheopen-loopfunctionGFL=GcGaGp11AnalysisofSingleLoopSystemsAGeneralSISOSystemThesystemfunctionC=GspR+GloadL1.The1sttermaccountsforthesetpointchange,calledthecommandtrackfunction（？）2.The2ndtermaccountfortheeffectofchangeindisturbanceReminder:ThesimultaneouschangesofbothRandLisnottakenintoaccountinthederivationabove（以上没有考虑RandL同时改变）参考方程12AnalysisofSingleLoopSystemsConsideringthefollowingtwocasesCase1:Servoingproblem（伺服问题）Changesinsetpointwithnodisturbance(L=0)resultsinC=GspRThiscouldperfectlytrackthesetpoint（能完全反应输入）:C=RCase2:Regulatorproblem（调节器问题）Changesindisturbancewithafixed（固定的）setpoint(R=0)C=GloadLThiscouldperfectlyreject（除去）thedisturbance:C=0Reminder:weareworkingwithdeviationvariables（偏差变量）13AnalysisofSingleLoopSystemsConsiderationsofChoosingVariablesChoiceofcontrolledvariables（受控变量）Thosethataredictatedbytheproblem那些取决于这个问题Thosethatarenotself-regulating那些无法自动调节Thosethatmayexceedequipmentorprocessconstraints那些可能超过设备或工艺约束Thosethatmyinteractwithothervariable那些受其他变量干扰14AnalysisofSingleLoopSystemsConsiderationsofChoosingVariablesChoiceofmanipulatedvariables（操纵变量）Thosethathaveadirecteffectontheprocess（直接影响过程）,especiallytheoutputvariable.Thosethathavealargesteadystategain.(Goodsensitivity)(高敏感度)Thosethathavenodeadtime(usuallynotsatisfied).（无延迟）Thosethathavenointeractionwithothercontrolloops.（与其他控制环没有相互作用）Reminder:theremaining（剩下的）onesaretakenas（被当作）load（干扰）variablesinaSISOsystemafterchoosingthecontrolledandmanipulatedvariables15AnalysisofSingleLoopSystemsSynthesisofaSingleLoopSystemThestirred-tankheaterrevisited.Eachtransferfunctionwithitselement现实中：许多因素在传递环中影响的安全性、可靠性、准确性、动态性和成本。工程师需要综合考虑16AnalysisofSingleLoopSystemsSynthesisofaSingleLoopSystemThestirred-tankheaterrevisited.Eachtransferfunctionwithitselement17AnalysisofSingleLoopSystemsSynthesisofaSingleLoopSystemThestirred-tankheaterrevisitedPhysicalunitconversionamongtransferfunction传递函数的物理单位转化18AnalysisofSingleLoopSystemsSynthesis（综合）ofaSingleLoopSystemProcessmodel(i.e.,processidentification识别)Transferfunctionsareusuallyderivedbasedoneither1.Scientificorengineeringprinciples,or2.Makingasetpointexperimentandfittingthedatatoamodel制造了一组实验拟合数据模型Thestirred-tankheaterhas,Assuming（假设）Kp=0.85oC/oCp=20min19AnalysisofSingleLoopSystemsSynthesisofaSingleLoopSystemSignaltransmitter（信号发射器）Thetransducerisplacedfardownstream,orwellinsulated.Theresponseisslow,then该传感器尽可能地放在下游,或好绝缘的地方,响应较慢：whereKmisthemeasurementgainofthetransducer传感器的量度增益misthetimeconstantofthedevicetdisaccountsfortransportlag传输延迟20AnalysisofSingleLoopSystemsSynthesisofaSingleLoopSystemSignaltransmitterWhatyouseei