基于PLC模糊控制的变频调速矿井提升机系统的研究与仿真.docx

基于PLC模糊控制的变频调速矿井提升机系统的研究与仿真.docx

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基于PLC模糊控制的变频调速矿井提升机系统的研究与仿真

StudyandSimulationonVariableFrequencySpeed-

RegulatingSystemofMineHoistBasedonPLC

FuzzyControl

YanxiangWU

ZhanfeiTian

CollegeofEngineering,ShanghaiOceanUniversity

Shanghai,China

MinjieXue

FacultyofEngineeringandInformationTechnology,

UniversityofTechnologySydney

NSW,Australia

Abstract—BasedonthetraditionalspeedcontroltechnologyfortheMineHoistsystem,thispaperintroducesanewmethodtocontrolthespeedofACinductionmotorbycombiningthefuzzycontrollerusingtheProgrammableLogicController（PLC）andthegeneralfrequencyinverter.Theproposedmethodmakesthesystemmorereliable,stableaswellasintelligent,andisexpectedtohaveapromisingfuture.ThesimulationiscarriedoutundertheSIMULINKenvironmentinordertooptimizethesystemperformance.

Keywords—PLC;MineHoist;FuzzyControl;Simulink

I.INTRODUCTION

Nowadays,astothetimevariantofthespeedcontrolofminehoistinminingindustry,itisbecomingmorecommontocontrolthevelocityofminehoistbyjointlyusingPLCandfrequencyinverter.However,itisdifficulttobuildthemathematicalmodelforthespeedcontrollerandimplementtheautomaticcontrolbecauseofitsnonlinearcharacteristic.

Thefuzzycontroltheory,whichisanintelligentcontroltheory,solvestheproblemproperly.Fuzzycontrolisbasedonthepracticalexperienceofoperatingthecontrolobject.Theinternalstructureandmathematicalmodelofthecontrolobjectisnotnecessaryforthefuzzycontrol,whichisverybeneficialtotheautomaticcontrolofvariablefrequencyspeed-regulatingofminehoist.

Asanotherimportantelementinthecontrolsystem,PLChasstrongfunctioncommandsandcooperatesvariousfunctionalmodules,whichmakesitpossibleforPLCtosupportmanycomplicatedprocesscontrolsystems.

II.GENERALDESIGN

Thevariablefrequencyspeed-regulatingcontrolsystemofMineHoistbasedonPLCfuzzycontrolconsistsofthepowerplant,thehydraulicstation,thePLCcabinet,theconvertor,theoperationpanelandthecontrolandsupervisionsystem,asshowninfigure1.

Figure.1HardwareFrameDiagramforVariableFrequencySpeed-RegulatingSystemofMineHoist

1.Thepowerplant:

Itincludesthemainmotor,thereducer,thewindingdrum,thebrakeandthebase.Thepowerplantisresponsiblefortransportationofpeople,materialsandsupplies.

2.Thehydraulicstation:

Itprovidesdrivingforceforthehoister.Whenthebarrowstops,amechanicalbrakeresistanceisappliedtothewindingdrumthroughthehydraulicstationfollowedbytheremovalofthedirectcurrent（DC）brakeresistance.Whenthebarrowstarts,aDCbrakeresistanceisappliedtothemotor.Thenloosenthebrakestickingincaseofrolling,inordertoinsurethesystemsafetyandreliability.

3.ThePLCcabinet:

ItincludestwoPLCs.Oneofthemisservedastheprotectingsystemforthehoister,takingchargeofthelogicoperationcontrolandthefaultjudgementandtreatment;whiletheotheristhestrokecontrolsystem,inchargeofthegivingofScurvewhichisahighfunctionalspeedcurveforthehoister.SiemensS7-300isadoptedinthesystem.ItisconnectedtotheMPInetworkthroughR-485whichhasstrongeranti-interference

4.Thefrequencyconversioncabinet:

Itistheenergysupplyunitofthepowerplant.Itconvertstheinputfrequencypowerintofrequencyadjustablepowersuppliedtoalternatingcurrent（AC）motors,soastoadjustthespeedoftheACmotors.

5.Theoperationpanel:

Itisthecontrolcentralofthewholetransportsystemoftheminehoist.Theoperationpenalisresponsibleforsettingthesystem’sworkpiecepatternandcontrolpattern,issuingsystem’scontrolordersandreceivingthefeedbacksignalsfromthefrequencyconversioncabinet.Accordingly,theoperationpanelisabletocarryoutcontrolfunctionsofthehoistersuchasstarting,acceleration,smoothrunning,slowingdown,parking,emergencybrakingandetc.

6.Thecontrolandsupervisionsystem:

Variousworkparameters,workconditions,faultparametersandfaultconditionsofthehoister’stransportsystemwillbemonitoredonlinebythecontrolandsupervisionsystem,throughWINCCflexiblesoftwareofSIMATICHMIsystemwiththeconnectiontoPLCandtheuppermonitorscreenTP27.Thecontrolandsupervisionsystemcontrolsthesystemprocessesallthetimeandkeepthecontinuousrunningoftheequipment.

III.FUZZYCONTROLSYSTEM

ThetraditionalPIDcontrolwasusedinconventionalspeedregulatingcontrolsystem.Ithasthehighovershoot,longmodulationtimeandweakcontroleffect.Inordertoovercometheseshortcomings,thefuzzylogicisusedtorealizethefuzzycontrolofmotorspeed.Thusthespeedcontrolsystemwillbemoreadaptiveandrobust,andeasiertoimplementthroughcomputersoftware.

Thefuzzycontroltechnologyisahighlytheoreticalandcrosssubjecttechnologywidelysupportedbythefuzzymathematics,thecomputerscience,theartificialintelligenceandtheautomaticcontrol.Fuzzycontrolisawidelyusedintelligentcontrolmethodandparticularlyapplicabletothecomplicatednonlinearsystemwiththelargedelaytimeandstrongcoupling.Itconvertspeople’sexperienceintofuzzycontrolrulesbyimitatingthewaypeoplethinkandjudgeandsummarizingtheexperienceofcontrolexpertsandtechnician.Thefuzzycontrolisimplementedbymodulecalledfuzzycontroller

A.StructureoftheFuzzyControlSystem

ThefuzzycontrolsystemisshowninFigure2.

Figure.2StructureofFuzzyControlSystem

Atwo-dimensionalMamdanifuzzycontrollerisadopted.Intheschematic,theinputvariablesareerrorebetweentheactualspeedyofthemotorandthegivensystemrevolutionrandtheerrorvarianceratiode/dt,whiletheoutputistheinstantaneouscontrolmodifieruwhichisthevariationfortheconverter’svoltage.Theinstantaneousmodifiercanbeusedtocontroltheconverter’soutputfrequency.Inthefigure,Ke,Kecandkudenotethequantitativefactorforerrore,errorvarianceratiode/dtandcontrolmodifierurespectively.Thusatwo-input-one-outputfuzzycontrollerisdesignedforthefrequencycontrolsystem.

B.DesignoftheFuzzyController

Designoffuzzycontrolrulesisthecoreofdesignofthefuzzycontroller.Fuzzycontrolrulesareequivalenttothecorrectingdeviceorcompensatorinthetraditionalcontrolsystem.Thecorrespondinglanguagevariablesforthespeederrore,theerrorratede/dtandtheoutputcontrolvariableuareE,ECandU,respectively.Theyaredividedintofivestatesandeverystatecorrespondstoafuzzysubset,asshowninthefollowingtable.

TABLEⅠ.TableforSystemControlRules

ThelanguagevariablesusedtodescribethestateofE,ECandUare:

negativebig（NB）,negativesmall（NS）,zero（ZE）,positivesmall（PS）andpositivebig（PB）.

AsthevaluesindomainNj=[-njnj]aresymmetrical,wecantransformtheerrorofeindomain[-25,25],theerrorofde/dtindomain[-18,18]andtheerrorofuindomain[-35,35]into[-5,5]accordingtotheconversionformulagivenby:

K=2n/（b-a）

（1）

inwhichaisthelowestvalue-5andbisthehighestvalue5.Thus:

Ku=7,Ke=0.2,Kec=5/18and1/Kisthequantitativefactor.

WecangetthegeneralfuzzyimplicationrelationmatrixRforthebasicfuzzycontrollerinthefrequencyconvertersystem,basedonthe“union”operationofthe25（i=1,2,…,25）fuzzyrelation,asshownin

（2）.

R=R1∪R2∪...∪R25=

（2）

“Defuzzication”isusedtoconvertthefuzzysetintosinglevalues.Oneofthemostcommonlyusedmethodsistheaveragevaluemethodinthemaximummembershipmethods,asshownin（3）inwhichj=1,2,….n,andnpointsofthemembershipsreachmaximumvalue.

（3）

c.TheOutputoftheControlledVariables

Thede-fuzzedrulesareadoptedbySiemensPLCseriestorealizefuzzycontrolfunction.Thesystemacquiresinputdatathroughananaloginputmodule,thencommandstheexecutiveunitthroughananalogoutputmodule.Thesystemwillgetthevalueoftheerrorefromthegivenspeedandtheactualspeedsampledbyencoder,thenmultiplyeandde/dtbywouldbecountedbyfuzzycontrolquantityUwhichisfixedbyEandEC,multipliedbytheproportionalfactorKu.Thenthemotorspeedcanbecontrolledbytheconvertor.Thefollowingchart（Figure3）istheflowchartforfuzzycontrolalgorithm.

Figure.3FlowChartforFuzzyControlAlgorithm

Thefuzzy-controllookuptableisthemostimportantpartinprogramdesign.Itcanberealizedasthefollowingchart,Fig.4:

Figure.4ladderdiagram（LAD）forfuzzy-controllookuptable

InFig.4,CMPisthecompareinstruction.WhentheinputrelayI1.2changesfrom0to1,thedataofthefirstoperand（VW102）willbecomparedwiththepresetdatastoredinsevenconsecutivedigitalregistersstartingfromthesecondoperand（VW110）.Ifthedatainthefirstoperandisthesameasoneinthesecondoperand,thentheauxiliaryrelayM2.0inthethirdoperandwillbesetto“ON”;otherwise,itwillbe“OFF”.The25controlresultsoffuzzyrulesarestoredsequentiallyinVW60-VW84.ThedatainVW102andVW103willbecomparedwiththeelementsininputdomain（VW110-VW116）respectively.TheresultwillbeexportedtoVW100accordingtothestatelookupresultsofM2.0andM2.1.Asthecapacityofthefuzzy-controllookuptableislimited,thedesignedprogramhasaquickresponseandgoodcontrolperformance.

IV.COMPUTERSIMULATION

A．TheConnectionofFISandSIMULINK

BasedonFuzzyInferenceSystem（FIS）,thefuzzycontrolsystemissimulatedthroughtheSIMULINKmoduleintheMATLABsoftware.The“FuzzyLogicController”inthe“FuzzyLogicToolbox”mustbeusedinthestructureofthesimulationmodelforfuz