外文翻譯-基于ControlLogix5550+PLC的鍋爐水位控制系統

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摘要本文是基于EFPT過程控制設備的研究設計。實際工業(yè)領域的設計，已經模擬和相應的建模beencarried鍋爐水位系統。然后適當的PID參數已整理出ControlLogix5550PLC已被用來控制整個鍋爐水位系統。最后，相應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水平，這是確保鍋爐平安運行的必要條件和主要指標之一。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，甚至導致鍋爐爆炸。為了確保平安和高效的生產，必須嚴格控制鍋爐水位，保持恒定或在一定的范圍內變化。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，該系統帶來了在一個小型鍋爐系統的精確控制，把傳感器和執(zhí)行器的鍋爐水位用于工業(yè)生產。2系統概述該系統由EFPT過程控制設備，變頻器，Logix5550PLC和一臺電腦組成。EFPT過程控制設備是模擬加熱和一個微型小鍋爐的供水和排水系統。在工業(yè)生產中使用的傳感器和驅動器在一個小型鍋爐系統，實現過程控制。執(zhí)行機構包括不僅儀表，還有AC逆變器，加熱控制器，加熱器等。該系統通過一個小型鍋爐供熱，供水和排水系統，是可靠和視覺模擬的工業(yè)現場。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)行機構采取Logix5550控制鍋爐水位。組態(tài)軟件RSView32和觸摸屏PanelView1000相結合，實現實時監(jiān)控。在設計上，設計簡單的單回路鍋爐液位值調整被選定為研究對象。該系統的組成如圖1。圖1鍋爐水位設定值調節(jié)系統變頻器作為執(zhí)行機構的設計，直接接收PLC的類比I/O端口輸出，并轉換成使變頻器頻率帶動揚程水泵三相電機，改變進氣口，鍋爐水位調整到在最后的動態(tài)平衡。和配置軟件用于監(jiān)控畫面設計，以實現計算機和觸摸屏的鍋爐水位長途和現場監(jiān)測。1

變頻調速恒壓供水系統的原理變頻調速恒壓供水系統主要由可編程控制器(plc)、變頻器(內置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,當用水量大時,由plc控制全部水安裝在出水管網上的壓力變送器,將壓力信號轉換成標準的dc

0

v~10

v的模擬量信號送入變頻器內的pid調節(jié)器,壓力設定值與壓力反響值進行比擬后,經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,實現水泵電機的無級調速,調節(jié)管網出口處供水壓力,到達恒壓供水目的。為了保證水壓反響信號值的準確、不失值,對反響信號設置濾波時間常數。在變頻器功率范圍內,圖1中的電機數量可以增加,實現“一拖多機〞的優(yōu)化方案。3建立被控對象的數學模型建立控制系統數學模型的主要任務之一是確定被控對象的數學模型。一般來說，建立過程控制的數學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，其結構和內部流程是非常復雜的，它是很難確定的對象，只是通過自身內部的物理過程，并解決了系統的微分方程。此外，考慮非線性因素，分析機制，用一些數學推導的近似和假設。雖然這些近似和假設有實踐根底，但不能完全反映實際情況，甚至造成不可估量的影響。因此，在本設計中，選擇實驗方法建立被控對象的數學模型。這種造型的根底上，在實際生產過程中，也就是說，建立數學模型為控制對象，通過過程識別和參數估計的輸入和輸出。在這個設計中，階躍響應曲線法用于識別過程的數學模型。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曲線。經過分析，控制對象的傳遞函數可以被定義。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曲線已被記錄。平均，穩(wěn)定時間，所有的參數：TS≈821.525s，穩(wěn)定值：H〔∞〕=58.5，頂峰時間：TP=394.4s超調量：σ≈29％。根據理論分析，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接近被控對象的響應曲線的平均動態(tài)參數。如圖2所示可根據以下規(guī)那么做一些調整：1〕當零接近虛軸，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)主導根尖動態(tài)性能的影響是增加的頂峰時間，減少超調量和調整時間。非參數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曲線是由于控制對象的復雜性和不確定性。為了恒定供水,在水壓降落時要升高變頻器的輸出頻率,當變頻器到達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準就是變頻器的輸出頻率是否到達設定的上限值。為了判斷變頻器工作頻率達上限值的準確性,應濾去偶然的頻率波動起的頻率到達上限的情況。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(到3在加1時等于零),即用水泵的總數結合水泵號實現水泵的輪換工作。4安裝控制器參數4.1控制算法的選擇近似??被控對象的數學模型建立后，形成一個完整的反響控制系統，可以提高開環(huán)控制系統的性能。PID是一個理想的控制律，