外文翻译原文-电气系统中的能量效率

EnergyEfficiencyinElectricalSystemsD.MaheswaranLarsen&ToubroLimited,Chennai,IV.RK.K.JembuKW.AdithyaKAbstractMitigatingclimatechangeandachievingstabilizationofgreenhousegasatmosphericconcentrationstheobjectiveoftheUnitedNationsFrameworkConventiononClimateChange(UNFCCC)willrequiredeepreductionsinglobalEnergy-relatedCarbonDioxide(CO2)emissions.G-8leaderscalledfora50%reductioningreenhousegas(GHG)emissionsbefore2050toavoidthemostseriousconsequencesofclimatechange.Meetingthisgoalrequirestransformingthewayenergyisproduced,delivered,andconsumedacrossallsectorsoftheeconomyandregionsoftheworld.Energyefficiencyoffersseeminglyglitteringpromisestoall-savingsforconsumersandutilities,profitsforshareholders,improvementsinindustrialproductivity,enhancedinternationalcompetitivenessandreducedenvironmentalimpacts.Asglobalenergydemandcontinuestogrow,actionstoincreaseenergyefficiencywillbeessential.Thetechnicalopportunitiesaremyriadandpotentialsavingsreal,butconsumersandutilitieshavesofarbeenslowtoinvestinthemostcost-effective,energy-efficienttechnologiesavailable.Theenergyefficiencyofbuildings,electricequipment,andappliancesinusefallsfarshortofwhatistechnicallyattainable.Energyanalystshaveattributedthisefficiencygaptoavarietyofmarket,institutionalandtechnicalconstraints.Electricutilityenergyefficiencytechniqueshavegreatpotentialtonarrowthisgapandachievesignificantenergysavings.Thispaperprovidessomeoftherecenttrendsinenergyefficiencytechnologiesthathavebeensuccessfulandalsousedwidelyworldwide.Theyare:1)Energyefficientmotors2)Softstarterswithenergysaver3)Variablespeeddrives4)Energyefficienttransformers5)Electronicballast6)Occupancysensors&Energyefficientlightingcontrols7)EnergyefficientLampsThispaperpresentsCaseStudiesofvariousenergyefficienttechniquesusedinaSteelPlantresultinginconsiderableElectricalenergysavingsvaryingfrom10-15%.Electricmotorsdrivebothcoreindustrialprocesses,likepressesorrollmills,andauxiliarysystems,likecompressedairgeneration,ventilationorwaterpumping.Theyareutilizedthroughoutallindustrialbranches,thoughthemainapplicationsvary.Withonlysomeexceptions,electricmotorsarethemainsourcefortheprovisionofmechanicalenergyinindustry.Inrecentyears,manystudiesidentifiedlargeenergyefficiencypotentialsinelectricmotorsandmotorsystemswithmanysavingoptionsshowingveryshortpaybacktimesandhighcost-effectiveness.Furthermore,almostallelectricityinIndiaisgeneratedbyrotatingelectricalgenerators,andapproximatelyhalfofthatgeneratedisusedtodriveelectricalmotors.Hence,efficiencyimprovementswithelectricalmachinescanhaveaverylargeimpactonenergyconsumption.Thekeychallengestoincreasedefficiencyinsystemsdrivenbyelectricalmachineslieinthreeareas:a.Toextendtheapplicationareasofvariable-speedelectricdrivesthroughreductionofpowerelectronicandcontrolcostsb.Secondly,tointegratethedriveandthedrivenloadtomaximizesystemefficiencyc.Finally,toincreasetheefficiencyoftheelectricalmachine.Lightingisalargeandrapidlygrowingsourceofenergydemandandgreenhousegasemissions.Atthesametimethesavingspotentialoflightingenergyishigh,evenwiththecurrenttechnology,andtherearenewenergyefficientlightingtechnologiescomingontothemarket.Currently,morethan33billionlampsoperateworldwide,consumingmorethan2650TWhofenergyannually,whichisapproximately19%oftheglobalelectricityconsumption.Theintroductionofmoreenergyefficientlightingproductsandprocedurescanatthesametimeprovidebetterlivingandworkingenvironmentsandalsocontributeinacost-effectivemannertotheglobalreductionofenergyconsumptionandgreenhousegasemissionsKeywordsEnergyEfficiency;Energyefficientmotors;variablespeeddrives;energyefficientlightingcontrols.I.INTRODUCTIONEnergyefficiencyreferstothephysicalperformanceofspecificendusesorenergyservicessuchaslighting,heating,cooling,andmotordrive.Greaterenergyefficiencyisachievedbyreplacing,upgrading,ormaintainingexistingequipmenttoreducetheamountofenergyneeded.Energyefficiencyisusuallymeasuredbytheoutputquantityperunitofenergyinput(milespergallonorlumensperwatt,forexample).Becauseenergyisoneofseveralfactorsofproduction(labor,capital,andmaterialsareothers),energyefficiencyimprovementscontributetogreaterenergyproductivityandeconomicefficiency.2012IEEEInternationalConferenceonPowerElectronics,DrivesandEnergySystemsDecember16-19,2012,Bengaluru,India978-1-4673-4508-8/12/$31.002012IEEEEfficientuseofelectricityandchangesintheelectricpowersectorwillplayavitalroleinanystrategyforachievingamoreenergy-efficientsociety.Ifthethreatofglobalclimatechangepromptsconcertedactiontoreducecarbonemissions,maximizingenergyefficiencywillbeanimperativeandamajoroverhaulofhowenergyservicesareprovidedandpaidforwillberequiredonamoreacceleratedschedule.Utilities&othershaveconsistentlyfoundthattherearenumerouscost-effectiveopportunitiestouseelectricitymoreefficientlyandtoavoidthecostsandpollutionassociatedwithnewplantconstructionandstillhavethesameenergyservices,theyare:-Improvementsinthebuildingservices.Improvementsintheefficiencyofelectricequipment.Lightingimprovements.Netefficiencygainsfromshiftingenergysourcesfromfossilfuelstoelectricity(electrification).Optimizationofelectricityusethroughbetterenergymanagementcontrolsystems,shiftsintimeofuse,andconsumerbehaviorandpreferencechanges.A.PresentScenarioinIndiaDemandforpowerinIndiahasbeenincreasingduetotherisingpopulation,growingeconomy,andchanginglifestyleswithCoalhavingthemajorcapacityandmajorcontributiononCO2emissionasshowninFig.1.Fig.1Break-upofinstalledgenerationcapacity.Withtheeverincreasingdemandforpower,CO2emissionsarefollowingtheincreasingtrend.AsperthestatisticstakeninSeptember-2012,Indiaalonecontributes6%ofthetotalCO2emissionsinworldwithEurope,USA&ChinatoppingthelistasshowninFig.2.Fig.2showsmajorcountriesemittingCO2in2012OnethirdoftheCO2emissionsinIndiaareduetoElectricitygeneration&HeatasshowninFig.3Fig.3CO2emissionsSourcesinIndiaB.NationalElectricalPolicyBytheendof2012,IndianNationalElectricityPolicy(2005)aims:Percapitaavailability1000unitsInstalledcapacityover200,000MWSpinningreserves5%MinimumlifelineconsumptionofoneunitperhouseholdperdayInter-regionaltransmissioncapacity37,000MWEnergyefficiency/conservationsavingsabout15%Qualityandreliablepowersupply.II.ENERGYEFFICIENTTECHNOLOGIESINELECTRICALSYSTEMSAsglobalenergydemandcontinuestogrow,actionstoincreaseenergyefficiencywillbeessential.Thetechnicalopportunitiesaremyriadandpotentialsavingsreal,butconsumersandutilitieshavesofarbeenslowtoinvestinthemostcost-effective,energy-efficienttechnologiesavailable.Theenergyefficiencyofbuildings,electricequipment,andappliancesinusefallsfarshortofwhatistechnicallyattainable.Energyanalystshaveattributedthisefficiencygaptoavarietyofmarket,institutionalandtechnicalconstraints.Electricutilityenergyefficiencytechniqueshavegreatpotentialtonarrowthisgapandachievesignificantenergysavings.Thispaperprovidessomeoftherecenttrendsinenergyefficiencytechnologiesthathavebeensuccessfulandalsousedwidelyworldwide.Theyare:Fig.4EnergyEfficientTechnologiesA.EnergyEfficientMotorsItisestimatedthatElectricalMotor-DrivenSystemsaccountforbetween43%and46%ofallglobalelectricityconsumption.Thispaperprovidesadetailedstudyconsideringalowerboundof0.75kWandanupperboundof200kWintoaccountthestandardpowersizesandthenewproposedInternationalElectrotechnicalCommission(IEC)6003430efficiencyclassificationstandardonmotorefficiencyasshowninFig.5.Fig.5EfficiencyclassesforfourpolemotorsofstandardIE3,IE2andIE1classes,andthenewIE4classIE3&IE4Motorshavehighefficiencyatanyambienttemperature.HencethesearecostlythanIE2Motors.Thematerialscostofthemotorisincreasedbyafewpercent.Whiletryingtoreducecopperlosses,weendupincreasingcoreloss.Hencethestartingcurrentofmotorishigh(approx.9.24timesincludingIStolerance),whichincreasesfaultlevelsandinturncablesize.Howeverthesedisadvantagesareovercomeasthepaybackperiodforthecustomercanbeaslittleassixmonthsforacontinuouslyloadedmotor.Thusenergy-efficientelectricmotorsreduceenergylossesthroughimproveddesign,bettermaterials,andimprovedmanufacturingtechniques.Replacingamotormaybejustifiablesolelyontheelectricitycostsavingsderivedfromanenergy-efficientreplacement.Thisistrueifthemotorrunscontinuously,powerratesarehigh,themotorisoversizedfortheapplication,oritsnominalefficiencyhasbeenreducedbydamageorpreviousrewinds.EconomicalbenefitsandenergysavingsareillustratedthroughaCaseStudyinChapter-IIIofthispaper.B.SoftStarterwithenergysaversWhenstarting,ACInductionmotordevelopsmoretorquethanisrequiredatfullspeed.Thisstressistransferredtothemechanicaltransmissionsystemresultinginexcessivewearandprematurefailureofchains,belts,gears,mechanicalseals,etc.Additionally,rapidaccelerationalsohasamassiveimpactonelectricitysupplychargeswithhighinrushcurrentsdrawing+600%ofthenormalruncurrent.Softstarterprovidesareliableandeconomicalsolutiontotheseproblemsbydeliveringacontrolledreleaseofpowertothemotor,therebyprovidingsmooth,steplessaccelerationanddeceleration.Motorlifewillbeextendedasdamagetowindingsandbearingsisreduced.However,asthe%loadingincreases,the%savingsdecrease.Energysavingsareofappreciablequantityonlyifthetimeperiodismorethan5yrs.C.VariablespeeddrivesWhendiscussingenergysavingsandvariablefrequencydrives(VFD)theattentionoftenfocusesonacentrifugalfanorpumpapplication.However,oneshouldnotoverlookotherapplicationswhichalsohavelargepotentialenergysavingsandenergyrecovery.Applicationsinvolvingregeneration,powerfactorcorrection,commonbusapplicationsoracombinationofthethreecanalsoquicklyachieveasignificantreductioninenergyuse.Invariabletorqueapplications,thetorquerequiredvarieswiththesquareofthespeed,andthehorsepowerrequiredvarieswiththecubeofthespeed,resultinginalargereductionofhorsepowerforevenasmallreductioninspeed.Themotorwillconsumeonly12.5%asmuchenergyat50%speedthanat100%speedasshowninFig.6.Thefollowinglawsillustratetheserelationships:FlowisproportionaltospeedTorqueisproportionalto(speed)2Powerisproportionalto(speed)3Fig.6PowersavingsusingVFDD.EnergyefficientTransformersMostenergylossindry-typetransformersoccursthroughheatorvibrationfromthecore.Thestrategydevelopedtomakepoweravailabletoallby2012includespromotionofenergyefficientproductsanditsconservationinthecountry,whichisfoundtobetheleastcostoptiontoaugmentthegapbetweendemandandsupply.Thenewamorphouscoretransformerswithhighefficiencyminimizetheselosses.Theexpectedreductioninenergylossoverconventional(SiFecore)transformersisroughlyaround70%,whichisquitesignificant.Byusingthisamorphouscorewithuniquephysicalandmagneticproperties-thesenewtypesoftransformershaveincreasedefficienciesevenatlowloads-98.5%efficiencyat35%load.E.ElectronicBallastTheconventionalballastsmakeuseofthespikecausedbysuddenphysicaldisruptionofcurrentinaninductivecircuittoproducethehighvoltagerequiredforstartingthelampandthenrelyonreactivevoltagedropintheballasttoreducethevoltageappliedacrossthelamp.Oneofthemajoradvantagesofelectronicballastistheenormousenergysavingsitprovides.Thisisachievedintwoways.Thefirstisitsamazinglylowinternalcoreloss,quiteunlikeoldfashionedmagneticballasts.Andsecondisincreasedlightoutputduetotheexcitationofthelampwithhighfrequency.Iftheperiodoffrequencyofexcitationissmallerthanthelightretentiontimeconstantforthegasinthelamp,thegaswillstayionizedand,therefore,producelightcontinuously.Thisphenomenonalongwithcontinuedpersistenceofthephosphorsathighfrequencywillimprovelightoutputfrom8-12%.ThisispossibleonlywithhighfrequencyelectronicballastF.Occupancysensors&eneryefficientlightingcontrol&LampsThesesensorsswitchlightingONwhenoccupancyisdetected,andOFFagainafterasettimeperiod,whennooccupancymovementdetected.Theyaredesignedtooverridemanualswitchesandtopreventasituationwherelightingisleftoninunoccupiedspaces.Withthistypeofsystemitisimportanttoincorporateabuilt-intimedelay,sinceoccupantsoftenremainstillorquietforshortperiodsanddonotappreciatebeingplungedintodarknessifnotconstantlymovingaround.CFLhavetakenoverfromincandescentbulbsandthepresenttrendisLEDswhichsavemoreenergywhileprovidingthesameluxlevels.Proposedactivities:1.Timercircuitsforexternallocationsviz.Coalyard,Coke/FerrousStockhousesetcaretobeprovided.2.Connectingphotosensitivedevicestothelightingpanelswhichareoperatedmanually.3.Reducingoperatingvoltagebyadjustinglightingtransformertap(where-everpossible)4.ReplacementofincandescentlampsbyCFLandenergyefficientlampslikeLEDs.5.Forstreetlightingapplications,implementationofSolarcells&LEDswillresultinhigherenergysaving.6.TochangethetimersettingofO&SbuildingCentralizedACsoastoswitchitOFFearlierduringeveningpeak.III.CASESTUDYThefollowingcasestudieshavebeenperformedforasteelplantespeciallyforrollingmillswithdatacollectedoveraperiodof2years.Thefollowingtable(Table.I)providesaglimpseenergyefficienttechnologies&suitabilityalongwithpaybackperiodforequipmentwheretherewasscopeofenergysavings.AreaEnergyefficientTechnologySuitabilityPaybackMotorsEnergyefficientMotorsSoftstartersVeryGood1-1.5yrsMillmotorVFDVeryGood6-8monthsWaterPumpsVFDVeryGood6-8monthsBlowerpumpVFDVeryGood6-8monthsLightingEnergyefficientcontrolGood1.5-2yrsTable.IEnergyefficienttechnologiesinrollingmillsEnergysavingsprovidedhereareonlyforaFanandPump.However,thesamephilosophyhasbeenfollowedforothermotorslikeconveyors&Millmotors.A.StatuswithoutVFDParameterMeasurementFAN(6.6kV)PUMP(6.6kV)MotorRating1760775Totalairflowatfullload650TPH-Flow-10000m3/hrFanSpeed600RPM560RPMCurrent182A88APeakPowerConsumption1760kW775kWTable.IIEnergywithoutVFDB.RunningwithVFDParameterMeasurementFAN(6.6kV)PUMP(6.6kV)MotorRating1760775Totalairflowatfullload650TPH-Flow-10000m3/hrFanSpeed580RPM490RPMCurrent145A45APeakPowerConsumption1480kW556kWTable.IIIStatuswithVFDC.ComparisonbetweenFanandPumpParameterFAN(6.6kV)PUMP(6.6kV)Powerfactorimprovement0.970.97Motorefficiency96.5%97%Reduction280kW219kWAveragerunningtimeperyear5000hrs.3200hrs.Energysaving(MWh/year)1400700.8Table.IVEnergySavingswithVFDD.EnergySavingswithSoftStarters%Loading%Savings1058203730204011507604.5703802901.5Table.V%EnergySavingswithSoftStartersE.EnergySavingswithenergyefficientTransformersInthiscasestudyweconsideredairon-steelindustrywithaverageelectricityloadingof60MW.About30MWoftheloadingisusedathighervoltages(mainlyhigh-voltagemotors)andarethereforenotdistributedbydistributiontransformers.Theelectricityconsumptionisrelativelyconstantduring24hoursaday,7daysaweek.Thetransformerratingisbetween630kVAand4000kVA.Thereareabout20transformers.10transformers(50%)are1250kVA;25%ofthetransformers1600kVAand25%otherratings.Almostalltransformersaredry-typetransformersbecauseofproblemsinthepastwithPCBinoil.MostofthetransformershavebeenreplacedwithAmorphousCoretransformers.Weevaluatedtheenergysavingbetweenthenormaldry-transformersandtheamorphouscoredrytypetransformersfortheratings1250and1600kVAcomparedwiththeactualpresenttransformers.Ifthelifecycleofthealreadyexistingdrytypetransformersisexceeded,amorphouscoretransformerwithhighefficiencyandlowlossescanreplacetheseexistingdrytypetransformers.TransformerUnitDrytypetransfor-merAmorphousCoreDrytypetransformerDiffe-renceratingkVA12501250no-loadlossW24002200-200loadlossW1356811712-1856AnnuallosseskWh/a7124162618-8623CO2emission0,4kg/kWhton/a28,525,0-3,5Payback(years)2.5Table.VIEnergySavingswithEnergyefficientTransformerF.Energyefficientlightingcontrols,Ballasts&LampsTheCombinationofOccupancySensors&lightingcontrolsresultedinasavingof27,275kWhperyear.No.ofLampsWattage