李坤英文翻译.docx
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李坤英文翻译.docx
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李坤英文翻译
毕业设计(论文)
外文文献翻译
专业
新能源科学与工程
学生姓名
李坤
班级
能源111
学号
1110604120
指导教师
张胜超
电气工程学院
1、英文原文
SolarTrackingSystem:
MoreEfficientUseofSolarPanels
J.Rizk,Y.Chaiko
Abstract:
Thispapershowsthepotentialsystembenefitsofsimpletrackingsolarsystemusingasteppermotorandlightsensor.Thismethodisincreasingpowercollectionefficiencybydevelopingadevicethattracksthesuntokeepthepanelatarightangletoitsrays.Asolartrackingsystemisdesigned,implementedandexperimentallytested.Thedesigndetailsandtheexperimentalresultsareshown.
Keywords:
RenewableEnergy,PowerOptimization.
I.
INTRODUCTION
Extrectinguseableelectricityfromthesunwasmadepossiblebythediscoveryofthephotoelectricmechanismandsubsequentdevelopmentofthesolarcell–asemi-conductivematerialthatconvertsvisiblelightintoadirectcurrent.Byusingsolararrays,aseriesofsolarcellselectricallyconnected,aDCvoltageisgeneratedwhichcanbephysicallyusedonaload.Solararraysorpanelsarebeingusedincreasinglyasefficienciesreachhigherlevels,andareespeciallypopularinremoteareaswhereplacementofelectricitylinesisnoteconomicallyviable.Thisalternativepowersourceiscontinuouslyachievinggreaterpopularityespeciallysincetherealisationoffossilfuel’sshortcomings.Renewableenergyintheformofelectricityhasbeeninusetosomedegreeaslongas75or100yearsago.SourcessuchasSolar,Wind,HydroandGeo-thermalhaveallbeenutilisedwithvaryinglevelsofsuccess.Themostwidelyusedarehydroandwindpower,withsolarpowerbeingmoderatelyusedworldwide.Thiscanbeattributedtotherelativelyhighcostofsolarcellsandtheirlowconversionefficiency.Solarpowerisbeingheavilyresearched,andsolarenergycostshavenowreachedwithinafewcentsperkW/hofotherformsofelectricitygeneration,andwilldropfurtherwithnewtechnologiessuchastitanium-oxidecells.Withapeaklaboratoryefficiencyof32%andaverageefficiencyof15-20%,itisnecessarytorecoverasmuchenergyaspossiblefromasolarpowersystem.
Thisincludesreducinginverterlosses,storagelosses,andlightgatheringlosses.Lightgatheringisdependentontheangleofincidenceofthelightsourceprovidingpower(i.e.thesun)tothesolarcell’ssurface,andtheclosertoperpendicular,thegreaterthepower[1-7].Ifaflatsolarpanelismountedonlevelground,itisobviousthatoverthecourseofthedaythesunlightwillhaveanangleofincidencecloseto90°inthemorningandtheevening.Atsuchanangle,thelightgatheringabilityofthecellisessentiallyzero,resultinginnooutput.Asthedayprogressestomidday,theangleofincidenceapproaches0°,causingansteadyincreaseinpoweruntilatthepointwherethelightincidentonthepaneliscompletelyperpendicular,andmaximumpowerisachieved.
Asthedaycontinuestowarddusk,thereversehappens,andtheincreasinganglecausesthepowertodecreaseagaintowardminimumagain.
Fromthisbackground,weseetheneedtomaintainthemaximumpoweroutputfromthepanelbymaintaininganangleofincidenceascloseto0°aspossible.Bytiltingthesolarpaneltocontinuouslyfacethesun,thiscanbeachieved.ThisprocessofsensingandfollowingthepositionofthesunisknownasSolarTracking.Itwasresolvedthatreal-timetrackingwouldbenecessarytofollowthesuneffectively,sothatnoexternaldatawouldberequiredinoperation.
II.
THESENSINGELEMENTANDSGNALPROCESSING
Manydifferentmethodshavebeenproposedandusedtotrackthepositionofthesun.ThesimplestofallusesanLDR–aLightDependentResistortodetectlightintensitychangesonthesurfaceoftheresistor.Othermethods,suchasthatpublishedbyJeffDammin‘HomePower’[8],usetwophototransistorscoveredwithasmallplatetoactasashieldtosunlight,asshowninFig.1.
Fig.1Alternativesolartrackingmethod
Whenmorningarrives,thetrackerisinstateAfromthepreviousday.Theleftphototransistoristurnedon,causingasignaltoturnthemotorcontinuouslyuntiltheshadowfromtheplatereturnsthetrackertostateB.Asthedayslowlyprogresses,stateCisreachedshortly,turningontherightphototransistor.ThemotorturnsuntilstateBisreachedagain,andthecyclecontinuesuntiltheendoftheday,oruntiltheminimumdetectablelightlevelisreached.Theproblemwithadesignlikethisisthatphototransistorshaveanarrowrangeofsensitivity,oncetheyhavebeensetupinacircuitundersetbiasconditions.Itwasbecauseofthisfactthatsolarcellsthemselveswerechosentobethesensingdevices.Theyprovideanexcellentmechanisminlightintensitydetection–becausetheyaresensitivetovaryinglightandprovideanear-linearvoltagerangethatcanbeusedtoanadvantageindeterminingthepresentdeclinationorangletothesun.Asaresult,asimpletriangularset-upwasproposed,withthetwosolarcellsfacingoppositedirections,asshowninFig.2.
Initsrestposition,thesolarcellsbothreceiveanequalamountofsunlight,astheangleofincidence,althoughnot90°,isequalinbothcasesasseeninFig.3.
Fig.2Set-upofsolarreferencecellsFig.3Solarreferencecellsatrestposition
Fig.4Solarreferencecellsatasignificantangletothesun
ItcanbeseeninFig.4thatasthesunmovesinthesky,assumingthatthesolartrackerhasnotyetmoved,theangleofincidenceoflighttothereferencepanelswillcausemorelighttofallononecellthantheother.
Thiswillobviouslycauseavoltagedifference,wherethecellthatisfacingthesunwillhavehigherpotentialthantheother.Thisphenomenonwillresultinadetectablesignalateachcell,whichcanbeprocessedbyasuitablecircuit.
III.APROTOTYPESOLARTRACKER
ThefinalstageinvolvedcouplingthecircuitrytothemotorandmountingitontothebracketThefinalproductisseencompleteinFig.5.IthasaSolarex9Wsolararraymadeofpolycrystallinesiliconmountedontheflanges,whichwasborrowedfromthetechofficers.
Quitesimplyhavingtwotestsubjectscarriedouttesting.Thefirstscenarioinvolvedremovingthepanelfromthetrackerandlayingitinaflatorientation.Theoutputwasconnectedtoaloadthatwoulddissipate9Wthatwouldmatchthepanel’s
rating.9Wat12Vcorrespondstoacurrentof0.75A,sobyOhm’slaw;aload
resistancewascalculatedasbeing16Ω.A15Ω50Wresistorwastheclosestvaluefoundandwasconnectedtothepanel.Thetrackingdevicestillrequirespower,buta12Vbatterythatisconnectedinachargingarrangementwiththesolarpanelsuppliesit.Thevoltageacrossandcurrentthroughtheloadwasmonitoredusingtwoseparatemultimeters,andwasrecordedeveryhalf-houronacleardayintoanExcelspreadsheet.Thereadingsweretakenonaspanofdaysthatpossessedsimilarconditionsincludingnocloudcover.ThereadingsareshownbelowinagraphgeneratedbyExcelinFig.6.
Itispossibletocalculateapercentageincreaseandanaverageincreasebywritingtheappropriatecalculationsinexcel.Itwasfoundthatinthiscase,thefixedpanelprovidedanaverageof39%ofits9W,or3.51W,calculatedovera12-hourperiod.Bycontrast,thetrackedsolarpanelachievedanoverall71%output,or6.3Woverthesametimeframe.Attheearlierandlaterhours,thepowerincreaseoverthefixedpanelreachedupto400%.Thisamountstoanaverage30%increaseinpowersimplybymaintainingthesolarpanelasperpendicularaspossibletothesun.
Toensurethatpowerwasnotbeingwasted,thedeviceitselfwasalsomonitoredforcurrentdrawntopoweritself.Whenthedevicewasatrest,anammeterwasplacedinserieswiththebattery.Thetotalcurrentat12Vwasmeasuredasonly4mA,whichcorrespondedtoapowerdissipationof48mWundernoload.
Fig.5AprototypesolartrackerFig.6Experimentalresultsofpowerincreasefor
trackedpanel
IV.CONCLUSION
Asolartrackerisdesignedemployingthenewprincipleofusingsmallsolarcellstofunctionasself-adjustinglightsensors,providingavariableindicationoftheirrelativeangletothesunbydetectingtheirvoltageoutput.Byusingthismethod,thesolartrackerwassuccessfulinmaintainingasolararrayatasufficientlyperpendicularangletothesun.Thepowerincreasegainedoverafixedhorizontalarraywasinexcessof30%.
REFERENCES
[1]Fahrenburch,A.andBube,R.1983,Fundamentalsofsolarcells,AcademicPress,NewYork.
[2]Partain,L.D.1995,SollarCellsandtheirapplications,JohnWiley&Sons.NewYork.
[3]EWeise,RKlockner,RKniel,MaShengHong,QinJianPing,“RemotePowerSupplyUsingWindandSolarenergy–aSino-GermanTechnicalCooperationProject”,BeijingInternationalConferenceonWindEnergy,Beijing,1995
[4]WichertB,LawranceW,FrieseT,FirstExperienceswithaNovelPredictiveControlStrategyforPV-DieselHybridEnergySystems,Solar’99
[5]DuryeaS,SyedI,LawrenceW,AnAutomatedBatteryManagementSystemforPhotovoltaicSystems,InternationalJournalofRenewableEnergyEngineering,
Vol1,No2,Aug1999
[6]TwidellJ,WeirJ,RenewableEnergySystems,ChapmanandHall,1994
[7]CentreforResourcesandEnvironmentalStudies,ANU,SustainableEnergySystems–PathwaysforAustralianEnergyReforms,CambridgeUniversityPress,1994
[8]Damm,J.Issue#17,June/July1990.Anactivesolartrackingsystem,HomeBrewMagazine.
2、
对应的中文翻译
出处:
WorldAcademyofScience,EngineeringandTechnology,2008,41:
313-315
中文2847字
太阳能跟踪系统:
更有效率地运用的太阳能电池板
J.里兹克Y.查克
摘要:
本文展示了由使用步进电机和光传感器来简单跟踪太阳的内部系统。
通过改进跟踪系统,在跟中太阳光的过程中,使得太阳能电池板与太阳成一个直角。
该文章包含了太阳能跟踪系统的设计、实施和实验
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