外文翻譯-基于ControlLogix5550+PLC的鍋爐水位控制系統(tǒng)

BoilerlevelcontrolsystembasedonControlLogix5550PLCAbstract-ThispaperisaresearchdesignbasedonEFPTprocesscontroldevice.Inthedesign,actualindustryfieldhasbeensimulatedandcorrespondingmodelinghasbeencarriedonfortheboilerlevelsystem.ThentheappropriatePIDparameterhasbeensortedoutandControlLogia5550PLChasbeenusedtocontroltheentireboilerlevelsystem.Atlast,acorrespondingcontrolinterfacehasbeenestablishedandtheboilerlevelhasbeenunderasafeandaccuratecontrolKeywords：EFPT，PID，Modeling，Boilerlevel;1IntroductionThetaskoftheindustrialboilerlevelcontrolistomaintainadynamicbalancebycontrollingthewaterflowandevaporation,sothatthedrumlevelcanbemaintainedinthetechnologicallevel,whichisanecessityforensuringsafeoperationandalsooneofthemainindicatorsoftheboiler'snormaloperation.Waterlevelwhichistoohighwillaffecttheeffectofthesteam-waterseparation,buttoolowitiswillbreakringcycleorevencauseboilerexplosion.Toensureasafeandefficientproduction,theboilerlevelmustbestrictlycontrolledinmaintainingconstantorchangingonlyaccordingtoacertainrule.UsingLogix5550PLCwithanalogyI/Omodules,launchedbyRockwellAutomationCompanyascontrollers,andEFPTprocesscontrolexperimentaldeviceascontrolobject,thissystemhavebroughttheboilerwaterlevelunderanaccuratecontrolinaminiboilersystemwithsensorsandactuatorsthatusedinindustrialproduction.Fig.1Boilerlevelsettingvalueadjustmentsystem2SystemOverviewThissystemiscomposedofanEFPTprocesscontroldevice,aninverter,aLogix5550PLCandacomputer.EFPTprocesscontroldeviceisasimulatedheatingandwatersupplyanddrainagesystemforamicro-smallboiler.Itrealizesprocesscontrolinaminiboilersystemwithsensorsandactuatorsusedinindustrialproduction.Theactuatorincludesnotonlymeasuringappliance,butalsoACinverter,heatingcontroller,heaterandsoon.Thesystemsimulatesindustryscenethroughamini-boilerheating,watersupplyanddrainagesystem,whichisreliableandvisual.Inthedesign,boilerLevelwasselectedasthecontrolledvariable.Thecontrolledobjectiscomposedofthewatertrough,theforcepump,theboilerandthepipe-linevalve.MicroMaster6SE9214-ODA40inverteristakenastheactuatorandtheboilerleveliscontrolledbyLogix5550.ConfigurationsoftwareRSView32andtouchscreenPanelView1000arecombinedtorealizethereal-timemonitoring.Inthedesign,asimpledesignofsingle-loopboilerliquidlevelvalueadjustmentisselectedforthestudy.ThecompositionofthesystemisshowninFig.1.Inthedesign,theinverterasanactuatordirectlyreceivesPLCanalogyI/Oportoutput,andconvertersintofrequencyofinvertersoastodrivethe3-phasemotorintheliftpump,changetheinlet,andadjusttheboilerleveltothedynamicbalanceatlast.Andtheconfigurationsoftwareisusedtodesignmonitoringpicturetorealizethecomputerandthetouchscreentotheboilerlevellong-distanceandthescenemonitoring.[1].Pumpstarted,pidcontrollerpressuretransmittertothecontrolpointtoprovidethepressuresignal,whenthepressurepointisnotequaltosetvalue,pidcontrollerbyadjustingtheinverteroutputfrequencytochangethepumpspeedtoregulatethepipelinepressureconstitutesaclosed-loopfeedbackcontrolsystem,waterpressureregulatorsothatuserstimely,smallfluctuationsinresults.Andintheprocesscontrolsystemdesignedtotakefullaccountoftheprincipleofloadbalancing,totake"first-in-firstout"strategyofliningup,thewaytheimplementationoftherotatingfrequencytoensurethatthebasicbalanceofthewaterusage.

1FrequencyControlConstantPressureWaterSupply

Principle

FrequencyControlConstantPressureWaterSupplySystembytheprogrammablelogiccontroller(plc),converter(built-pid),pressuretransmitter,low-voltageelectricalandpumpcomponents,suchasFigure

1.Mapm1~m3forwaterpumpmotors,p1~p3forpumps,km1~km6formotorstartingandstoppingeachoftheACcontactorswitch.Basicworkingprincipleofthesystem:bytheplcasignaltotheinvertertocontrolthewatercyclework,whenthelargevolumeofwaterconsumedbytheplccontrolofallwaterlineinstalledintheoutletpipeofthepressuretransmitter,pressurestandardsignalsintodc0v~10vintotheanalogsignalconverterwithpidregulator,pressuresettingsandpressurefeedbackvaluesaftertheimplementationofpidcalculatedvaluesoftheoutputofafrequencyconvertertosetthevalueforthepumpbytheinvertertoprovidevariablefrequencyelectricalpowertorealizesteplessspeedregulationofelectricpumpstoregulatetheexitofthewatersupplypipenetworkpressure,constantpressurewatersupplytoachievethepurpose.Pressurefeedbacksignalinordertoensureanaccuratevalue,yetthevalueoffeedbacksignaltosetthefiltertimeconstant.Thescopeofthepowerconverter,Figure1canincreasethenumberofthemotortoachieve"amulti-trailers,"Optimizationoftheprogram.3EstablishingMathematicsmodelforthechargedobjectOneofthemaintasksofestablishingcontrolsystemmathematicalmodelistodeterminethemathematicalmodelofthecontrolledobject.Generally,therearetwokindsofbasicmethodsforestablishingprocesscontrolmathematicalmodel:mechanismanalysisandexperimentalmethod.However,forcontrolledobjectwhosestructureandinternalprocessisverycomplex,itisverydifficulttodeterminetheobjectjustbyitsowninternalphysicalprocessandtosolveoutthedifferentialequationssystematically.Besides,consideringthenonlinearfactor,mechanismanalysisusedsomeapproximationandhypothesisformathematicaldeduction.Althoughtheseapproximationandassumptionshavepracticalbasis,butnotfullyreflectactualsituation,andevencauseincalculableeffects.Therefore,inthisdesign,theexperimentalmethodischosentoestablishamathematicalmodelforcontrolledobject.Thiskindofmodelingisbasedontheinputandoutputintheactualproductionprocess,thatistosay,establishingmathematicalmodelforthecontrolledobjectthroughprocessidentificationandparameterestimation.Inthisdesign,stepresponsecurvemethodisusedtoidentifymathematicalmodelsoftheprocess.A20Hzstepdisturbanceinputsignalisappliedtothechargedobject,andtheresponsecurveoftheoutputthatchangeswithtimecanbemapped.Aftertheanalysis,thetransferfunctionofthecontrolledobjectcanbedefined.Intheprocessofexperiment,theobjectwasconductedseveraltests.UsingRSLogix5000trendmonitoringfunctioncurve,morethan10chargedobjectstepresponsecurvehavebeenrecorded.Toalltheparametersforaverage,steadytime:ts≈821.525s,steadyvalue:h(∞)=58.5,peaktime:tp=394.4sovershoot:a%}29%.Accordingtothetheoreticalanalysis,thecontrolledobjectisthemostlikelysecond-orderobject.However,thedifferenceisveryapparentbetweentheidealsecond-ordercontrolledobjectstepresponsecurveandtheactualcurves.Sotheidealcurvecan'tresponsetoitsactualcharacteristics.Itisinferredthatthecontrolledobjectmaybethesecond-ordercontrolledobjectthatincludeszero.ThetryanderrormethodandMATLABsimulationtoolsareusedtogetacurvewhoseparametersareclosetotheaveragedynamicparametersofthecontrolledobject'sresponsecurve.ItisshowninFig.2.Someadjustmentscanbemadeaccordingtothefollowingrules:1)Whenthezeroisclosertotheimaginaryaxis,settlingtimewillbelongerandtheovershootwillbebiggerandpeaktimewillbesmaller.Withthezeroclosingtotheimaginaryaxis,theeffectismoreobvious.2)Theeffectwhichtheclosedloopdominantapiceshaveondynamicperformanceisincreasingthepeaktime,reducingtheovershootandadjustingtime.Nonparametricmodelisusedtodescribethecontrolledobject.Inotherwords,stepresponsecurvewhichapproximatelydescribethecontrolledobjectisusedbecauseofthecontrolledobject'scomplexityanduncertainty.Toaconstantwatersupply,landinginthewaterpressuretoincreasetheinverteroutputfrequency,whenthemaximumfrequencyconverterandaconstantpressurepumpcannotmeettherequirements,whilerunningthepumpfrequencytoswitchtotherunningfrequency,Atthesametimeneedtostartasecondfrequencyorthirdpumpuntilthewatersupplytomeettherequirements.Needtodeterminecriteriaforthelaunchofanewwaterpumpistheinverteroutputfrequencyissettoreachtheupperlimit.Inordertodeterminethefrequencyoftheinverterlimitstheaccuracyofleastsquaresbychanceshouldbethefrequencyofthefrequencyoffluctuationsintheceilingfromthesituation.Invertercontrolmotorpumpsareactivatedeachtimethesoft-start,andrequirestheuseofwaterpumpsmustturntoserveasacontinuousvariablefrequencypumpoperationshallnotexceed3h,eachtimewhentheneedtolaunchanewwaterpump,thepumpwillrunfromtheexistingremovaloftheinverter,andreplacethepower-frequencyoperation,resettheinverterandrunthepumpforanewstart.ThreepumpstocontrolthedutycycleistheuseofpumpNo.1waytoachieve(to3intheplus1equaltozero),orcombinedwiththetotalnumberofpumppumppumprotationtoachieveitswork.4Theinstallationofcontrollerparameter4.1TheselectionofcontrolalgorithmAfterestablishingtheapproximatemathematicalmodelofthecontrolledobject,acompletefeedbackcontrolsystemcanbeformedtoimprovetheperformanceoftheopen-loopcontrolsystem.PIDisanidealcontrollawinthatintegralisintroducedbasingontheproportion,whichcaneliminatetheresidualerror,plusthederivativeaction,whichcanalsoimprovethestabilityofthesystem.Accordingtothecharacteristicsofthecontrolledobjectandlaboratoryconditions,asingle-loopfeedbackcontrolloopforthecontrolledobjectisestablished,andPIDalgorithmisusedtorealizeboilerlevelcontrol.TheschematicdiagramoflevelcontrolisshowninFig.3.Opentheoutletvalvetoacertaindegree,andmakethehydraulicdischargeinvariable.Comparingtheprocessvariablesofthewaterlevelinfeedbackwiththegivenvolume,thedeviationcanbeobtained.PIDinstructiondoesPIDoperationonthedeviation,andtheresultsisacontrolvariable,sothefrequencyoftheinvertercanbechangedtocontroltherotatespeedofthepump.Iftheliquidlevelisonthehighside,theresultsmakethecontrolvariablesmaller,andreducetherateofinflow,makeliquidlevellower;ifthelevelisonthelowside,theresultsmakethecontrolvariablelarger,andincreasetherateofinflow,makeliquidlevelhigher.4.2TheParameterTuningofPIDBecausethetransferfunctionofthecontrolledobjectincludesazerosecond-orderlink,thecomputationworkloadisquitebigregardlessofusingtheroot-locusmethodorthefrequencycharacteristiclawamongtheorymethodswhentuningPIDparameter.Andtheprocessmathematicalmodelcanonlyreflectdynamicparameterapproximately,sothereliabilityoftheparametervaluewhichisobtainedbythetheoreticalcalculationisnotveryaccurateanditwillbeadjustedconstantlyinthescene.Therefore,engineeringparametertuningischosentoseekthePIDparameterinthedesign.Thecommonmethodofengineeringtuningaredynamiccharacteristicparameters,thestableboundarylaw,thedecaycurvelawandfieldexperiencesettingmethod,etc.IntheprocessofPIDparameters,the4:1decaycurvelawisadopted.Thestepsare:1)Intheclosedsystem,regulator'sintegraltimeissetthelargest(Ti≈∞)anddifferentialtimeTdissetzero(Td=0).Theproportionistakenthegreatvaluetoperformthegivenvalueperturbationexperimentrepeatedly,andtheproportionisreducedgraduallyuntiltherecordcurvepresentsupto4:1weaken.Thentheproportioniscalled4:1weakenproportionssandthedistancesbetweentwoneighboringwaveridge'sarecalled4:1dampedcycleTs.Intheexperiment,thelevelquantitativetestissetforthe200mm,andthenthesystemresponsecurveisobtainedandreorganized4:1decaycurve(thickredlineisshowninFig.4'Thusmeasuring:δs≈8，Ts≈2.2;2)Accordingtothefollowingformula,eachparameteroftheregulatorsisδ=0.8,δs≈6.4;Ti=0.3,Ts≈6.6;Td=0.1,Ts≈2.23)Accordingtotheseresults,regulatorparametersareset.Thenthedynamicprocessofsystemisobservedandtheparametersaremadeadjustmenttodeterminetheoptimumparameters.5MonitoringDesignFrequencyaccordingtotheprincipleofconstantpressurewatersupplysystemthedesignwaterlevelcontrolsystemofthewatertowerblockdiagramshowninFigure2,thecitywaternetworkeqwiththewaterlevelcontrollertocontroltheinjectionvalveyv1,aslongasthewaterlevelbelowthehighwatermark,thentothepoolwaterautomatically.Poolofhigh/lowwaterlevelsignaldirectlytotheplc,asahigh/lowlevelalarm.Inordertoensurecontinuityofsupply,thewaterlevelofthesmallerdistancebetweentheupperandlowerlimits.Domesticwaterandfirewaterpumpthreeshared[3],usuallyyv2solenoidvalveinastateofloss,theclosureofthefirepipenetwork,whenafireoccurs,thesolenoidvalvewasyv2electricity,waterdistributionnetworkwiththeclosureoflife,threewaterpumpsforfireuse,andmaintainhigh-pressurefirewatervalue.Aftertheliftingofthefire,threeusedomesticwaterpumpreplacedandthecycleofoperation,tomaintainconstantlowwatervalue.Eachpumpmotorcanrunfrequency,andfrequencycanberun.Whenthesmallvolumeofwaterconsumed,awaterpumpunderthecontroloftheconverterstableoperationoflargequantitiesofwatertothepumpwhenrunningatfullspeedthereisnoguaranteethatthepressureonnetworkstability,plcpressuregiventhelowerlimitoftheinvertersignalandhigh-speedsignalatthesametimeplcwasdetected,plcautomaticallyworkintheoriginalstateofthepumpfrequencyintofrequencyoperation,inordertomaintainthecontinuityofpressureatthesametimeusethenextpumpputintooperationafterstart-upconverterinordertoincreasethesupplypipenetworkpressureofwatertoensurestability;ifrunningtwopumpscannotmeettherequirementsofthepressure,thefrequencyofworkwillbefollowedbyastateintothepump-frequencyoperation,andthenpumpintoavariablefrequencyoperation;whenthewaterconsumptionreduction,thefirstperformanceinverterhasbeenworkingeffectivelyatthelowestspeedsignals,whenthepressuresignal,suchastheceilingisstillthere,plcwillbethefirstfirstrunofthepumpfrequencytoquitinordertoreducethevolumeofwatersupplied,whenthetwosignalswhentherearestill,plcandthenquitsecondfrequencyofthepumptorununtilaconstantpressurewatersupplypumpwithfrequencyconverter.Allpumpmotorsstartfromastoptoandfromthestarttostopbytheinvertertocontroltoachievesoft-startwithset,toavoidthestartofhigh-currentimpacttothepumpmotortoextendthelifeofthemotor.Atthesametime,theuseofvariablefrequencyoperationofthesystempumpswatercycleinorderto"firsttoopenthefirstgate"oftheorderofrelatedpumps,sothatboththewatersupplysystemtoensureback-upwaterpumps,waterpumpsandthesystemhavethesamerunningtimeaseffectiveinpreventingback-uppumpdeathoccurrednotlong-termphenomenonofrustandimprovethecomprehensiveutilizationrateofequipment,reducingmaintenancecosts.

ElectricalcontrolsystemmaincircuitseeFigure3.ACcontactorkm1,km3,km5werethreepumpmotorcontrolm1,m2,m3frequencyoperation;ACcontactorkm2,km4,km6respectivelycontrolm1,m2,m3ofFrequencyoperation;fr1,fr2,fr3thermalrelayforprotectionofthethreepumpmotoroverload;qs1,qs2,qs3,qs4respectively,andthreepumpmotorinvertermaincircuitisolationswitch;fu1~fu3mainlyThefusecircuit.Thesystemworksinmanualmode,plcalarmdetectiononlybytheartificialadoptionofpanelbuttonsandswitchesFromwaterpumpstostopandswitch;thesystemworksinautomaticmode,allcontrolledbytheplccompletedreporttothepolice.RSView32softwareandPanelBuilder32softwareofRockwellAutomationCompanyarerespectivelyusedtodesignmonitorscreentocompletesuchfunctionasanimatingdisplay,parametersetting,reportoutput,thecurrentcurvedisplayandhistorycurvedisplayandsoon.Andmakethecomputerandtouchscreenachievetheremoteandon-sitecontroltotheboilerliquidlevel.ThepicturescreenofsystemmonitorisshowninFig.5Themainworkofrealizingconfigurationistoestablishlevelcontrolobjectsandmakeanimatingdisplayscenes.Controlledobjectsincludeinlettingwaterflow,exportingwaterflowandthenumericalobjectoftheboilerlevel.Whenanimationconnectionisestablished,thebasicgraphicelementsandanimationcomponentlibraryarecalledintheuserwindowtoconstructconfigurationdiagram.Graphicobjectsanddataobjectsdefinedbythestatearesetinthestateofthecorrespondingattributeandanimationconnectionisdefined.Havingfinishedthedesignofthedevelopingsystem,youcanswitchtorunmodetocarryonthereal-timemonitoringtothecontrolsystemandtestconfiguration.6ConclusionsThispaperhasintroducedthecompositionandrunningofEFPTprocesscontrolsystembasedonControlLogix5550PLCcontrol,themathematicalmodelestablishingofcontrolledobjectandtheparametertuningofPID.Theuseofconfigurationsoftwareextendsthecommunicationfunction.Throughexperimentaltesting,thecontrolcurve'sovershootissmallandthetransitiontimeisshort,sothecontroleffectisquiteideal.Thisdevicebeingreliableandintuitiveissuitableforscientificresearchandteaching,andhasimportantapplicationvalueintheactualindustrialproduction.thedesignofthetowersthewaterlevelcontrolsystemusesaprogrammablelogiccontroller,inverterbasedonchangesinwaterpressuretransmitterthroughthepidtorealizesteplessspeedvariablefrequencydrivepumpmotorinthewaterchangestomaintainconstantwaterpressuremeetthewaterrequirements,soastoachievethepurposeofconstantpressurewatersupply.Intheprocesscontrolsystemdesignedtotakefullaccountoftheprincipleofloadbalancing,totake"first-in-firstout"strategyofliningup,thewaytheimplementationoftherotatingfrequencytoensurethatthebasicbalanceofthewaterusage.FrequencyConstantPressureWaterSupplytochangethesupplyofthepreviousquantitativemethodstoachieve"DAMA"principle,constantpressurewatersupplyfrequencymodethussavingenergy,easytooperate,highdegreeofautomation.基于ControlLogix5550PLC的鍋爐水位控制系統(tǒng)摘要本文是基于EFPT過程控制設(shè)備的研究設(shè)計。實際工業(yè)領(lǐng)域的設(shè)計，已經(jīng)模擬和相應(yīng)的建模beencarried鍋爐水位系統(tǒng)。然后適當(dāng)?shù)腜ID參數(shù)已整理出ControlLogix5550PLC已被用來控制整個鍋爐水位系統(tǒng)。最后，相應(yīng)的控制界面建立好了，鍋爐水位也已在平安和精確控制下關(guān)鍵詞：EFPT，PID控制，建模，鍋爐水平;1引言工業(yè)鍋爐水位控制的任務(wù)是維持一個動態(tài)的平衡，通過控制水的流量和蒸發(fā)，使汽包水位保持在技術(shù)水平，這是確保鍋爐平安運行的必要條件和主要指標(biāo)之一。鍋爐水位太高會影響汽水別離的效果，但太低了，也會破壞循環(huán)周期，甚至導(dǎo)致鍋爐爆炸。為了確保平安和高效的生產(chǎn)，必須嚴(yán)格控制鍋爐水位，保持恒定或在一定的范圍內(nèi)變化。使用Logix5550PLC的I/O模塊，控制器，把羅克韋爾自動化公司推出EFPT過程控制實驗裝置作為控制對象，該系統(tǒng)帶來了在一個小型鍋爐系統(tǒng)的精確控制，把傳感器和執(zhí)行器的鍋爐水位用于工業(yè)生產(chǎn)。2系統(tǒng)概述該系統(tǒng)由EFPT過程控制設(shè)備，變頻器，Logix5550PLC和一臺電腦組成。EFPT過程控制設(shè)備是模擬加熱和一個微型小鍋爐的供水和排水系統(tǒng)。在工業(yè)生產(chǎn)中使用的傳感器和驅(qū)動器在一個小型鍋爐系統(tǒng)，實現(xiàn)過程控制。執(zhí)行機構(gòu)包括不僅儀表，還有AC逆變器，加熱控制器，加熱器等。該系統(tǒng)通過一個小型鍋爐供熱，供水和排水系統(tǒng)，是可靠和視覺模擬的工業(yè)現(xiàn)場。選定鍋爐水位為控制變量。被控對象組成的水槽，磁力泵，鍋爐和管道閥門。微碩士6SE9214-ODA40變頻器作為執(zhí)行機構(gòu)采取Logix5550控制鍋爐水位。組態(tài)軟件RSView32和觸摸屏PanelView1000相結(jié)合，實現(xiàn)實時監(jiān)控。在設(shè)計上，設(shè)計簡單的單回路鍋爐液位值調(diào)整被選定為研究對象。該系統(tǒng)的組成如圖1。圖1鍋爐水位設(shè)定值調(diào)節(jié)系統(tǒng)變頻器作為執(zhí)行機構(gòu)的設(shè)計，直接接收PLC的類比I/O端口輸出，并轉(zhuǎn)換成使變頻器頻率帶動揚程水泵三相電機，改變進氣口，鍋爐水位調(diào)整到在最后的動態(tài)平衡。和配置軟件用于監(jiān)控畫面設(shè)計，以實現(xiàn)計算機和觸摸屏的鍋爐水位長途和現(xiàn)場監(jiān)測。1

變頻調(diào)速恒壓供水系統(tǒng)的原理變頻調(diào)速恒壓供水系統(tǒng)主要由可編程控制器(plc)、變頻器(內(nèi)置pid)、壓力變送器、低壓電器及水泵等組成見圖

1.圖中m1~m3為水泵電機,p1~p3為水泵,km1~km6為電機起、停及互相切換的交流接觸器。系統(tǒng)根本工作原理:由plc向變頻器發(fā)出信號,控制水泵循環(huán)工作,當(dāng)用水量大時,由plc控制全部水安裝在出水管網(wǎng)上的壓力變送器,將壓力信號轉(zhuǎn)換成標(biāo)準(zhǔn)的dc

0

v~10

v的模擬量信號送入變頻器內(nèi)的pid調(diào)節(jié)器,壓力設(shè)定值與壓力反響值進行比擬后,經(jīng)pid計算輸出一個執(zhí)行值作為變頻器的頻率給定值,由變頻器為水泵電機提供可變頻率的電源,實現(xiàn)水泵電機的無級調(diào)速,調(diào)節(jié)管網(wǎng)出口處供水壓力,到達(dá)恒壓供水目的。為了保證水壓反響信號值的準(zhǔn)確、不失值,對反響信號設(shè)置濾波時間常數(shù)。在變頻器功率范圍內(nèi),圖1中的電機數(shù)量可以增加,實現(xiàn)“一拖多機〞的優(yōu)化方案。3建立被控對象的數(shù)學(xué)模型建立控制系統(tǒng)數(shù)學(xué)模型的主要任務(wù)之一是確定被控對象的數(shù)學(xué)模型。一般來說，建立過程控制的數(shù)學(xué)模型的根本方法有兩種：機理分析與實驗方法。然而，為控制對象，其結(jié)構(gòu)和內(nèi)部流程是非常復(fù)雜的，它是很難確定的對象，只是通過自身內(nèi)部的物理過程，并解決了系統(tǒng)的微分方程。此外，考慮非線性因素，分析機制，用一些數(shù)學(xué)推導(dǎo)的近似和假設(shè)。雖然這些近似和假設(shè)有實踐根底，但不能完全反映實際情況，甚至造成不可估量的影響。因此，在本設(shè)計中，選擇實驗方法建立被控對象的數(shù)學(xué)模型。這種造型的根底上，在實際生產(chǎn)過程中，也就是說，建立數(shù)學(xué)模型為控制對象，通過過程識別和參數(shù)估計的輸入和輸出。在這個設(shè)計中，階躍響應(yīng)曲線法用于識別過程的數(shù)學(xué)模型。20Hz的階躍擾動輸入信號施加到被控對象，并且，隨著時間的變化可以映射輸出的響應(yīng)曲線。經(jīng)過分析，控制對象的傳遞函數(shù)可以被定義。在實驗的過程中，對象進行了屢次測試。使用RSLogix5000趨勢的監(jiān)測功能曲線，10多個被控對象的階躍響應(yīng)曲線已被記錄。平均，穩(wěn)定時間，所有的參數(shù)：TS≈821.525s，穩(wěn)定值：H〔∞〕=58.5，頂峰時間：TP=394.4s超調(diào)量：σ≈29％。根據(jù)理論分析，控制對象是最有可能的二階對象。然而，區(qū)別是非常明顯的理想二階被控對象的階躍響應(yīng)曲線和實際曲線之間。所以理想的曲線不能反響其實際的特點。據(jù)推斷，控制的對象可能是第二階控制對象，其中包括零。的嘗試和錯誤的方法和MATLAB仿真工具，用于獲取曲線的參數(shù)接近被控對象的響應(yīng)曲線的平均動態(tài)參數(shù)。如圖2所示可根據(jù)以下規(guī)那么做一些調(diào)整：1〕當(dāng)零接近虛軸，穩(wěn)定時間將更長，沖會更大，頂峰時間會更小。與零閉幕虛軸，效果更明顯。2〕閉環(huán)主導(dǎo)根尖動態(tài)性能的影響是增加的頂峰時間，減少超調(diào)量和調(diào)整時間。非參數(shù)模型來描述受控對象。換句話說，其中約描述受控對象的階躍響應(yīng)曲線是由于控制對象的復(fù)雜性和不確定性。為了恒定供水,在水壓降落時要升高變頻器的輸出頻率,當(dāng)變頻器到達(dá)上限頻率且一臺水泵還不能滿足恒壓要求時,那么把變頻運行的水泵切換到工頻上運行,同時需要變頻啟動第二臺或第三臺水泵,直到滿足供水要求。判斷需不需要啟動新水泵的標(biāo)準(zhǔn)就是變頻器的輸出頻率是否到達(dá)設(shè)定的上限值。為了判斷變頻器工作頻率達(dá)上限值的準(zhǔn)確性,應(yīng)濾去偶然的頻率波動起的頻率到達(dá)上限的情況。變頻器控制水泵電機的每一次啟動均為軟啟動,并規(guī)定各臺水泵必須交替使用,任一臺泵連續(xù)變頻運行不得超過3

h,因此每次需啟動新水泵時,將現(xiàn)行運行的水泵從變頻器上切除,并換上工頻電源運行,將變頻器復(fù)位并用于新運行水泵的啟動。三臺水泵的工作循環(huán)控制是使用水泵號加1的方法實現(xiàn)(到3在加1時等于零),即用水泵的總數(shù)結(jié)合水泵號實現(xiàn)水泵的輪換工作。4安裝控制器參數(shù)4.1控制算法的選擇近似??被控對象的數(shù)學(xué)模型建立后，形成一個完整的反響控制系統(tǒng)，可以提高開環(huán)控制系統(tǒng)的性能。PID是一個理想的控制律，