重庆大学-过程控制-process-control-中文-翻译-第十章(1)

1ProcessControl陈刚CollegeofAutomationChongqingUniversity2MultiloopSystemsOutlineImproving（disturbancerejection干扰抑制)performancecascadecontrol级联控制feedforwardcontrol,前馈控制ratiocontrol,and比例控制timedelaycompensation时间延迟补偿withSmithpredictor.smith预估补偿3MultiloopSystemsImprovingtheDRPerformanceCascadeControlControlofafurnacetemperature；炉温DR:DisturbanceRejection4TTTCTspMultiloopSystemsImprovingtheDR干扰抑制performanceS-loopcontrolsolution单环开环控制1.measureTbyTT,2.computepbyTC,3.sendtheptothevalve5MultiloopSystemsCascadeControlMotivationof动机CascadeControlIffluctuation波动inthefuelgasflowrate燃气流速,thesystemwillnotcounter计数thedisturbanceuntilthecontrollersensesthat感知thetemperaturehasdeviatedFrom偏离thesetpoint(Tsp)6MultiloopSystemsCascadeControlCascadecontrolsolutionItconsistingof包含:master(primary)loopslave(secondary)loopTT:temperaturetransducer温度传感器FT:flowtransducerTC:temperaturecontrollerFC:fuelgascontrollerTwomeasuredvariablesdisturbanceisnowinslaveloop副回路fluctuation波动7MultiloopSystemsCascadeControlCascadecontrolsolutionTCinmaster-loopsendsitssignaltoslave-loop副回路,intermsof依据thedesiredflowrate(casualrelation)thesignalisthesetpointofthesecondaryflowcontroller(FC).FCinslaveloopadjuststheregulatingvalve调节阀FCcomparesthedesiredandmeasuredfuelgasflowratesrespondingimmediatelytofluctuationsinthefuelgasflow立即对波动的燃气速率做出反应toensurethattheproperamountof数量的fuelisdelivered.8MultiloopSystemsCascadeControlCascadeDesignCriteria设计标准Cascadeisdesiredwhen1.single-loopperformanceunacceptable2.ameasuredvariableisavailable测量值可用Asecondaryvariable次要变量must3.Indicate指出theoccurrenceof发生的animportantdisturbance4.haveacausalrelationship因果关系fromprimarytosecondary(cause→effect)5.haveafasterresponsethantheprimary9MultiloopSystemsCascadeControlCascadeControlSolutionReducingtheblockdiagram方块图SettingGm1=Gm2=1where10MultiloopSystemsCascadeControlReducingtheblockdiagramFromthereducedblockdiagramE=R-C11MultiloopSystemsCascadeControlCascadecontrolsolutionTheclosed-loopcharacteristicpolynomial特征多项式Commentsontheslave-loop1.reducingdisturbanceinthemanipulatedvariable被控变量减少来自被控变量的干扰.2.accomplishafasterresponseinthevalve,3.makethesystemmorestable12MultiloopSystemsCascadeControlExample1:thefurnacetemperaturecontrolthemasterloopusesaPIcontroller,theslaveloopusesap-controller,withthefirstorderfunctions13Problem(a):choosingKc2properlyforbetterperformanceMultiloopSystemsCascadeControlExample1.thefurnacetemperaturecontrolSubstituting取代Gc2=Kc2andGv=Kv/(vs+1)intoG*vwheresubstitutingGL=KL/(Ls+1)intoG*LSolution:14MultiloopSystemsCascadeControlExample1.thefurnacetemperaturecontrolastheproportionalgainKc2becomeslarger1.K*v1,moreeffectivechangeinmanipulatedvariable,2K*L0,manipulatedvariableislesssensitivetochangesinload,操纵变量对负载的变化敏感度降低3*vsmaller,fasterresponseoftheregulatingvalve调节阀Problem(a):choosingKc2properlyforbetterperformancevcvcvKKKKK221*vcvvKK21*LcLLKKKK21*15MultiloopSystemsCascadeControlExample1.thefurnacetemperaturecontrolProblem(b):findKc2while*v=0.1vwithKv=0.5,v=1s,and*v=0.1s,wehavethusslaveloophasa10%offsetwithrespectivetothedesiredsetpointchangesinthesecondarycontroller.次循环在二级控制器的设定点有10％的偏移变化Solution参考方程16MultiloopSystemsCascadeControlExample1.thefurnacetemperaturecontrolProblem(c):Nowthat既然certainlyanoffset偏移intheinnerloop,whydowestaywith继续做p-controlhere?Solution1.slaveloopwith10%offsetisacceptableinmostcases2.masterloophasintegralaction积分作用,a)TCadjust调整itsoutputtoensurethatb)thereisnosteadystateerrorinthecontrolledvariable受控变量17MultiloopSystemsCascadeControlExample1.thefurnacetemperaturecontrolProblem(d):Choosetheproperintegraltimeconstantamongthegivenvaluesof0.05,0.5,and5s,suchthat1.guaranteeing保证thesystemstable,2.allowingaslightly稍微的underdampedresponse3.makingsystemresponseasfastaspossible18MultiloopSystemsCascadeControlExample1.thefurnacetemperaturecontrolSolutionof解决problem(d):withPImastercontroller,theentireclosed-loopsystemis19MultiloopSystemsCascadeControlExample1.thefurnacetemperaturecontrolProblem(e):determineKcofPIcontrollerthatguaranteessystemstablewhenI=0.5withoutcascadeSolution:systemisasingle-loopsystemwhennocascadecharacteristicequationofitsclosed-loopequationisSystemisstableifandonlyifKc7.520MultiloopSystemsCascadeControlExample1(cont.)thefurnacetemperaturecontrolSolutionofproblem(e):comparedwith与……相比较cascadecontrolcascadecontrolisalwaysstablewhenI=0.5,from(d)thesystemisstablebyRouth-Hurwitz劳氏判据analysis21MultiloopSystemsCascadeControlSummaryof总结cascadecontrolbasedon基于example11.thesystembecomesmorestable,and2.allowingtousealargerKcinmastercontroller3.muchfasterresponseoftheactuatorintheinnerloopSingleloopcontrolCascadecontrol22MultiloopSystemsImprovingtheDRPerformanceFeedforwardControlControlofafurnacetemperatureagainDR:DisturbanceRejection23MultiloopSystemsImprovingtheDRPerformanceMotivationoffeedforward(FF)control前馈控制的动机TemperatureTcanalsobeeffectedbythecoldprocessstreamflowrateFsFsOurideasare1.MeasurethedisturbanceinFs测量Fs中的干扰2.AdjustthevalvebeforethechangeofFshasnochancetoaffectTReminder: