《过程控制技术》课件-检测环节、执行器、被控对象、控制器正反作用的选择

Selectionofpositive/negativeactionofdetectioncomponent,actuator,controlledobject,andcontroller检测环节、执行器、被控对象、控制器正反作用的选择落版在此检测环节、执行器、被控对象、控制器正反作用的选择Selectionofpositive/negativeactionofdetectioncomponent,actuator,controlledobject,andcontroller谢聪XieCong主讲教师Teacher检测环节Detectioncomponent执行器Actuator控制器Controller检测环节、执行器、被控对象、控制器正反作用的选择Selectionofpositive/negativeactionofdetectioncomponent,actuator,controlledobject,andcontroller“感知”“Perception”检测环节Detectioncomponent执行器Actuator控制器Controller“行动”“Action”“指挥”“Command”检测环节、执行器、被控对象、控制器正反作用的选择Selectionofpositive/negativeactionofdetectioncomponent,actuator,controlledobject,andcontroller自动控制系统Automaticcontrolsystem检测环节Detectioncomponent执行器Actuator控制器Controller检测环节、执行器、被控对象、控制器正反作用的选择Selectionofpositive/negativeactionofdetectioncomponent,actuator,controlledobject,andcontroller某车间的温度控制系统，设定温度为80℃。当实际温度降至70℃时，检测环节本应传递“温度偏低”的信号，可因作用选反，传给控制器的是“温度偏高”的信号。​控制器据此让执行器（加热装置）关闭，温度越降越低。Aworkshoptemperaturecontrolsystemwithasettemperatureof80°C.Whentheactualtemperaturedroppedto70°C,thedetectioncomponentshouldsenda"toolowtemperature"signal,butitsenta"toohightemperature"signaltothecontrollerduetoincorrectactionselection.Thecontrollerthencommandedtheactuator(heatingdevice)toshutdown,causingthetemperaturetodropfurther.检测环节、执行器、被控对象、控制器正反作用的选择Selectionofpositive/negativeactionofdetectioncomponent,actuator,controlledobject,andcontroller后来调整了检测环节作用，可执行器又因作用选错，收到升温指令时反而降温，系统彻底失控。Later,thedetectioncomponent'sactionwascorrected,buttheactuatorwasincorrectlysettotheoppositeaction,causingitactuallycooleddowninsteadofrespondingtotheheatingcommand,leadingtocompletesystemfailure.Definethepositive/negativeactionsofeachcomponentinthecontrolsystem定义控制系统各环节的正反作用Definethepositive/negativeactionsofeachcomponentinthecontrolsystem定义控制系统各环节的正反作用当某个环节输入增加时，其输出也增加，称该环节为“正作用”；反之，称为“反作用”。Whenacomponent'sinputincreases,itsoutputalsoincreases,itiscalled“positiveaction”;otherwise,itiscalled“negativeaction”.按此定义：Accordingtothisdefinition:Definethepositive/negativeactionsofeachcomponentinthecontrolsystem定义控制系统各环节的正反作用按此定义：Accordingtothisdefinition:变送器：一般都是正作用，其定义为输出信号随被测变量增加而增加，取“+”，反之取“-”；Transmitter:Itisgenerallysettothepositiveaction,anddefinedthattheoutputsignalincreasesasthemeasuredvariableincreases,markedas"+";otherwisemarkedas"-";执行器：气开阀是正作用“+”，气关阀是反作用“-”；Actuator:Theair-to-openvalveispositiveaction,markedas"+";theair-to-closevalveisnegativeaction,markedas"-";被控对象：若控制变量增加时，被控参数随之增加取“+”，反之则取“-”；Controlledobject:Ifthecontrolledparameterincreasesasthecontrolvariableincreases,itismarkedas"+";otherwise,itismarkedas"-".控制器：控制器正、反作用以测量输入（PV）值与控制器输出（MV）值的关系定义：Controller:Thepositive/negativeactionofthecontrollerisdefinedbytherelationshipbetweenthemeasuredinput(PV)valueandthecontrolleroutput(MV)value:Definethepositive/negativeactionsofeachcomponentinthecontrolsystem定义控制系统各环节的正反作用按此定义：Accordingtothisdefinition:控制器：控制器正、反作用以测量输入（PV）值与控制器输出（MV）值的关系定义：Controller:Thepositive/negativeactionofthecontrollerisdefinedbytherelationshipbetweenthemeasuredinput(PV)valueandthecontrolleroutput(MV)value:正作用Positiveaction偏差e=测量值（PV）–给定值（SV）Deviatione=Measuredvalue(PV)–Setvalue(SV)反作用Negativeaction偏差e=给定值（SV）–测量值（PV）Deviatione=Setvalue(SV)–Measuredvalue(PV)MV与PV变化方向一致，控制器为正作用；反之，控制器为反作用。

IfMVandPVchangeinthesamedirection,thecontrollerispositive-acting;otherwise,itisnegative-acting.Definethepositive/negativeactionsofeachcomponentinthecontrolsystem定义控制系统各环节的正反作用偏差eDeviatione控制器Controller执行器Actuator被控过程Controlledprocess变送器Transmitter给定值SetvalueSV被控参数Controlledparameter干扰Disturbance++反作用Negativeaction正作用Positiveaction正作用Positiveaction正作用Positiveaction-过程(测量)值PVProcess(measured)valuePVMV各个环节的正反作用组合不当Impropercombinationofpositive/negativeactionsineachcomponent会使控制系统形成正反馈Maycausethecontrolsystemtoformpositivefeedback破坏生产过程的稳定AffectingthestabilityoftheproductionprocessDefinethepositive/negativeactionsofeachcomponentinthecontrolsystem定义控制系统各环节的正反作用偏差eDeviatione控制器Controller执行器Actuator被控过程Controlledprocess变送器Transmitter给定值SetvalueSV被控参数Controlledparameter干扰Disturbance++反作用Negativeaction正作用Positiveaction正作用Positiveaction正作用Positiveaction-过程(测量)值PVProcess(measured)valuePVMV因为执行器和被控（对象）过程有正、反作用的区别，为了保证控制系统负反馈，控制（调节）器必须有正、反作用调整功能。Sinceactuatorsandcontrolled(objects)processescanbepositive-actingornegative-acting,thecontrollermusthavepositive/negativeactionadjustmentfunctiontoensurenegativefeedbackinthecontrolsystem.Selectionofcontrollerpositive/negativeaction控制器正反作用的选择Selectionofcontrollerpositive/negativeaction控制器正反作用的选择给定值Setvalue＋－测量变送器Measuringtransmitter控制器Controller执行器Actuator被控过程(对象)Controlledprocess(object)操作量Operatingvariable被控参数Controlledparameter干扰/扰动fDisturbancefSVPVMV（负）反馈控制系统的控制作用对被控变量的影响，应与扰动作用对被控参数的影响相反，才能使被控参数值回复并保持在给定值（附近）。Thecontroleffectofthe(negative)feedbackcontrolsystemonthecontrolledvariableshouldbeoppositetotheeffectofthedisturbanceonthecontrolledparameter,sothatthevalueofthecontrolledparametercanreturnandremainclosetothesetvalue.为了保证负反馈，必须正确选择控制（调节）器的正反作用方式。Toensurenegativefeedback,thepositive/negativeactionmodeofthecontrollermustbecorrectlyselected.Selectionofcontrollerpositive/negativeaction控制器正反作用的选择偏差eDeviatione控制器Controller执行器Actuator被控过程Controlledprocess变送器Transmitter给定值SetvalueSV被控参数Controlledparameter干扰Disturbance++反作用Negativeaction正作用Positiveaction正作用Positiveaction正作用Positiveaction-过程(测量)值PVProcess(measured)valuePV控制器正反作用的确定原则：Principlefordeterminingcontrollerpositive/negativeaction:控制器正反作用实现（参见图3-10中切换开关S7）Implementationofcontrollerpositive/negativeaction(refertoselectorswitchS7inFigure3-10)保证系统构成负反馈EnsurethesystemformsnegativefeedbackSelectionofcontrollerpositive/negativeaction控制器正反作用的选择偏差eDeviatione控制器Controller执行器Actuator被控过程Controlledprocess变送器Transmitter给定值SetvalueSV被控参数Controlledparameter干扰Disturbance++反作用Negativeaction正作用Positiveaction正作用Positiveaction正作用Positiveaction-过程(测量)值PVProcess(measured)valuePV简单的判定方法：Simpledeterminationmethod:控制器正反作用实现（参见图3-10中切换开关S7）Implementationofcontrollerpositive/negativeaction(refertoselectorswitchS7inFigure3-10)闭合回路中有奇数个反作用环节Theclosedloopcontainsanoddnumberofnegative-actingcomponentsSelectionofcontrollerpositive/negativeaction控制器正反作用的选择TTTC反Negative正Positive正Positive正Positive燃料进料流量Feedingfuelflow出料Dischargingmaterial进料Feeding加热炉Heatingfurnace例1确定加热炉出口温度控制系统控制器正反作用Example1Determinethepositive/negativeactionofthecontrollerinafurnaceoutlettemperaturecontrolsystem解Solution按前面的控制器正反作用选取原则，温度控制器应选反作用。Accordingtotheselectionprincipleofcontrollerpositive/negativeactionmentionedearlier,thetemperaturecontrollershouldbenegative-acting.负反馈验证NegativefeedbackverificationSelectionofcontrollerpositive/negativeaction控制器正反作用的选择TTTC反Negative正Positive正Positive正Positive燃料进料流量Feedingfuelflow出料Dischargingmaterial进料Feeding加热炉Heatingfurnace当某时刻燃料压力↑Whenfuelpressureincrease↑燃料流量↑Fuelflowincreases↑炉膛温度↑Furnacetemperatureincrease↑出料温度偏离设定值（SV）上升↑Dischargingmaterialtemperaturedeviatesfromthesetvalue(SV)andincreases↑TT输出（PV）↑TheTToutput(PV)increases↑TC输入（PV）↑TheTCinput(PV)increases↑TC输出（MV）↓TheTCoutput(MV)decreases↓燃料阀关小↓Thefuelvalveclosesslightly↓燃料流量↓Thefuelflowdecreases↓炉膛温度↓Thefurnacetemperaturedecreases↓出料温度↓恢复到设定值Dischargingmaterialtemperaturedecreases↓andreturnstothesetvalueSelectionofcontrollerpositive/negativeaction控制器正反作用的选择例2确定储槽液位控制系统控制器正反作用Example2:Determinethepositive/negativeactionofthestoragetanklevelcontrolsystemcontroller解Solution按前面的控制器正反作用选取原则，液位控制器应选正作用。Accordingtotheselectionprincipleofcontrollerpositive/negativeactionmentionedearlier,thelevelcontrollershouldbesettopositive-acting.LTLCM正Positive正Positive正Positive反Negative出料Dischargingmaterial进料FeedingSelectionofcontrollerpositive/negativeaction控制器正反作用的选择LTLCM正Positive正Positive正Positive反Negative出料Dischargingmaterial进料Feeding负反馈验证Negativefeedbackverification设某时刻进料量↑Supposethefeedingmaterialflowincreasesatacertainmoment↑储槽液位偏离设定值（SV）上升↑Theliquidlevelinthestoragetankdeviatesfromthesetvalue(SV)andincreases↑LT输出（PV）↑TheLToutput(PV)increases↑LC输入（PV）↑TheLCinput(PV)increases↑LC输出（MV）↑TheLCoutput(MV)increases↑阀开大出料量↑Thevalveisopenedwidertoincreasethefeedingflow↑储槽液位↓并恢复到设定值（SV）Theliquidlevelinthestoragetankdecreases↓andreturnstothesetvalue(SV)检测环节、执行器、被控对象、控制器正反作用的选择Selectionofpositive/negativeactionofdetectioncomponent,actuator,controlledobject,andcontroller课程小结CourseSummary检测变送器：Measuringtransmitter:通常为正作用，即被控参数增大时，输出信号随之增大。Itistypicallypositive-acting,meaningwhenthecontrolledparameterincreases,theoutputsignalincreasesaccordingly.选择时需关注量程精度与响应时间，要与工艺需求匹配，防止信号失真。​Whenselecting,considertherangeaccuracyandresponsetime,whichshouldmatchprocessrequirementstopreventsignaldistortion.​检测环节、执行器、被控对象、控制器正反作用的选择Selectionofpositive/negativeactionofdetectioncomponent,actuator,controlledobject,andcontroller课程小结CourseSummary执行器：Actuator:正反作用由类型决定，气开阀为正作用（输入信号增大，开度增大），气关阀为反作用（输入信号增大，开度减小）。Itpositive/negativeactionisdeterminedbyitstype;theair-to-openvalveispositive-acting(inputsignalincreases,openingincreases);theair-to-closevalveisnegative-acting(inputsignalincreases,openingdecreases).选择需结合工艺安全等因素。​Considerprocesssafetyandotherfactorswhenselecting.​检测环节、执行器、被控对象、控制器正反作用的选择Selectionofpositive/negativeactionofdetectioncomponent,actuator,controlledobject,andcontroller课程小结CourseSummary被控对象：Controlledobject:如果控制变量增加，被控参数输出变小，则为反作用；Ifthecontrolledparameteroutputdecreasesasthecontrolvariableincreases,itisnegative-acting;反之，则为正作用。Otherwise,itispositive-acting.检测环节、执行器、被控对象、控制器正反作用的选择Selectionofpositive/negativeactionofdetectioncomponent,actuator,controlledobject,andcontroller课程小结CourseSummary控制器：Controller:如果测量值增大，控制器输出也增大，则为正作用；Ifthecontrolleroutputincreasesasthemeasuredvalueincrease,itispositive-acting;反之，则为反作用。Otherwise,itisnegative-acting.检测环节、执行器、被控对象、控制器正反作用的选择Selectionofpositive/negativeactionofdetectioncomponent,actuator,controlledobject,andcontroller课程小结CourseSummary核心原则：Coreprinciple:确保整个控制系统形成负反馈，使各环节协同工作，当被控参数偏离设定值时，通过各环节作用让偏差逐渐缩小，保证系统稳定运行。Ensuretheentirecontrolsystemformsnegativefeedba