风力发电外文文献翻译中英文Word文档格式.docx

风力发电外文文献翻译中英文Word文档格式.docx

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Abstract

Aftertremendousgrowthofwindpowergenerationcapacityinrecentyears,Chinanowhas44.7GWofwind-derivedpower.Despitetherecentgrowthratesandpromisesofabrightfuture,twoimportantissues-thecapabilityofthegridinfrastructureandtheavailabilityofbackupsystems-mustbecriticallydiscussedandtackledinthemediumterm.

Thestudyshowsthatonlyarelativelysmallshareofinvestmentgoestowardsimprovingandextendingtheelectricityinfrastructurewhichisapreconditionfortransmittingcleanwindenergytotheendusers.Inaddition,thebackupsystemsareeithergeographicallytooremotefromthepotentialwindpowersitesorcurrentlyfinanciallyinfeasible.Finally,theintroductionofwindpowertothecoal-dominatedenergyproductionsystemisnotproblem-free.Frequentrampupsanddownsofcoal-firedplantsleadtolowerenergyefficiencyandhigheremissions,whicharelikelytonegatesomeoftheemissionsavingsfromwindpower.

Thecurrentpowersystemisheavilyreliantonindependentlyactingbutstate-ownedenergycompaniesoptimizingtheirpartofthesystem,andthisispartlyincompatiblewithbuildingarobustsystemsupporting

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renewableenergytechnologies.Hence,strategic,top-downco-ordinationand incentivesto improve the overall electricity infrastructure isrecommended.

Keywords:

Windpower,China,Powergrids,Back-upsystems

1.Introduction

China’swindenergyindustryhasexperiencedarapidgrowthoverthelastdecade.SincethepromulgationofthefirstRenewableEnergyLawin2006,thecumulativeinstalledcapacityofwindenergyamountedto44.7GWbytheendof2010[1].Thenewlyinstalledcapacityin2010reached18.9GWwhichaccountedforabout49.5%ofnewwindmillsglobally.ThewindenergypotentialinChinaisconsiderable,thoughwithdifferingestimatesfromdifferentsources.AccordingtoHeetal.[2],theexploitable wind energy potential is 600–1000GW onshore and100–200GWoffshore.Withoutconsideringthelimitationsofwindenergysuchasvariablepoweroutputsandseasonalvariations,McElroyetal.[3]concludedthatiftheChinesegovernmentcommitstoanaggressive lowcarbon energyfuture, wind energyis capableofgenerating6.96millionGWhofelectricityby2030,whichissufficienttosatisfyChina’selectricitydemandin2030.

TheexistingliteratureofwindenergydevelopmentinChinafocusesonseveraldiscussionthemes.Themajorityofthestudiesemphasizetheimportanceofgovernmentpolicyonthepromotionofwindenergy

industry in China[4],[5],[6],[7]. For instance, Lema andRuby[8]comparedthegrowthofwindgenerationcapacitybetween1986and2006,andaddressedtheimportanceofacoordinatedgovernmentpolicyandcorrespondingincentives.SeveralstudiesassessedotherissuessuchasthecurrentstatusofwindenergydevelopmentinChina[9];

thepotential of wind power[10];

the significance of wind turbinemanufacturing[11];

windresourceassessment[5];

theapplicationofsmall-scale wind power in rural areas[12];

clean developmentmechanisminthepromotionofwindenergyinChina[4],social,economicandtechnicalperformanceofwindturbines[13]etc.

There are few studies which assess the challenge of gridinfrastructure in the integration of wind power. For instance,Wang[14]studied grid investment, grid security, long-distancetransmissionandthedifficultiesofwindpowerintegrationatpresent.Liaoetal.[15]criticisedtheinadequacyoftransmissionlinesinthewindenergydevelopment.However,webelievethatthereisaneedtofurtherinvestigatetheseissuessincetheyarecriticaltothedevelopmentofwindpowerinChina.Furthermore,windpowerisnotastand-aloneenergysource;

itneedstobecomplementedbyotherenergysourceswhenwinddoesnotblow.Althoughtheviabilityandfeasibilityofthecombinationofwind powerwith otherpower generation technologieshave beendiscussedwidelyinothercountries,noneofthepapersreviewedthe

situationintheChinesecontext.Inthispaper,wediscussandclarifytwomajorissuesinlightoftheChinesewindenergydistributionprocess:

1）thecapabilityofthegridinfrastructuretoabsorbandtransmitlargeamountsofwindpoweredelectricity,especiallywhenthesewindfarmsarebuiltinremoteareas;

2）thechoicesandviabilityofthebackupsystemstocopewiththefluctuationsofwindelectricityoutput.

2.Istheexistingpowergridinfrastructuresufficient?

Windpowerhastobegeneratedatspecificlocationswithsufficientwindspeedandotherfavourableconditions.InChina,mostofthewindenergypotentialislocatedinremoteareaswithsparsepopulationsandlessdevelopedeconomies.Itmeansthatlesswindpoweredelectricitywouldbeconsumedclosetothesource.Alargeamountofelectricityhastobetransmittedbetweensupplyanddemandcentresleadingtoseveralproblemsassociatedwiththeintegrationwiththenationalpowergridsystem,includinggridinvestment,gridsafetyandgridinterconnection.

2.1.Powergridinvestment

Althoughthetwostategridcompanies-（SGCC）StateGridCorporationofChinaand（CSG）ChinaSouthernGrid-haveinvestedheavilyingridconstruction,China’spowergridisstillinsufficienttocopewithincreasingdemand.Forexample,somecoal-firedplantsinJiangsu,whichisoneofthelargestelectricityconsumersinChina,hadtodroptheloadratioto60percentagainsttheinternationalstandardof80

percentduetothelimitedtransmissioncapacity[16].Thissituationisaresultofanimbalancedinvestmentbetweenpowergridconstructionandpowergenerationcapacity.Forexample,duringtheEighthFive-YearPlan,NinthFive-YearPlanandTenthFive-YearPlan,1powergridinvestmentsaccountedfor13.7%,37.3%and30%oftotalinvestmentintheelectricitysector,respectively.Theratiofurtherincreasedfrom31.1%in2005to45.94%in2008,thecumulativeinvestmentinthepowergrid

is still significantly lower than the investments in powergeneration[17].Fig.1givesacomparisonoftheratiosofaccumulativeinvestmentsinpowergridandpowergenerationinChina,theUS,Japan,theUKandFrancesince1978.Inmostofthesecountries,morethanhalfoftheelectricpowerinvestmenthasbeenmadeongridconstruction.Bycontrast,theratioislessthan40%inChina.

AccordingtotheArticles14and21oftheChineseRenewableEnergyLaw,thepowergridoperatorsareresponsibleforthegridconnectionofrenewableenergyprojects.Subsidiesaregivensubjecttothe length of the grid extension with standard rates. However,Mo[18]foundthatthesubsidieswereonlysufficienttocompensateforcapitalinvestmentandcorrespondinginterestbutexcludingoperationalandmaintenancecosts.

Again,similartogridconnection,gridreinforcementrequiressignificantamountsofcapitalinvestment.TheThreeGorgespowerplant

hasprovidedanexampleoflarge-scaleandlong-distanceelectricitytransmissioninChina.Similartowindpower,hydropowerisusuallysituatedinlessdevelopedareas.Asaresult,electricitytransmissionlinesarenecessarytodelivertheelectricitytothedemandcentreswherethemajorityarelocated;

thesearetheeasterncoastalareasandthesouthernpart of China. According to SGCC[19], the grid reinforcementinvestmentoftheThreeGorgespowerplantsamountedto34.4billionyuan（about5billionUSdollars）.Thiscouldbealothigherinthecaseofwindpowerduetoanumberofreasons.First,thetotalgeneratingcapacityofThreeGorgesprojectisapproximately18.2GWatthismomentandwillreach22.4GWwhenfullyoperating[20],whilstthetotalgeneratingcapacityofthemassivewindfarmsamounttoover100GW.Hence,moretransmissioncapacitiesareabsolutelynecessary.Second,theThreeGorgeshydropowerplantislocatedincentralChina.Anumberoftransmissionpathsareavailable,suchasthe500kVDCtransmissionlinestoShanghai（withalengthof1100km）,Guangzhou（located inGuangdong province, withalength of1000km）andChangzhou（locatedinJiangsuprovince,withalengthof1000km）with

atransmissioncapacityof3GWeachandthe500kVACtransmissionlinestocentralChinawithtransmissioncapacityof12GW.Bycontrast,themajorityofwindfarmbases,whicharelocatedinthenorthernpartofChina,arefarawayfromtheloadcentres.Forexample,Jiuquanlocated

inGansuhasaplannedgenerationcapacityof20GW.ThedistancesfromJiuquantothedemandcentresoftheCentralChinagridandtheEasternChinagridare1500kmand2500km,respectively.ForXinjiang,thedistancesareevenlongerat2500kmand4000km,respectively.Asaresult,longertransmissionlinesarerequired.Fig.2depictsthedemandcentresandwindfarmsindetail.

2.2.Gridsafety

Thesecondproblemisrelatedtogridsafety.Thelarge-scalepenetrationofwindelectricityleadstovoltageinstability,flickersandvoltageasymmetrywhicharelikelytocauseseveredamagetothestabilityofthepowergrid[21].Forexample,voltagestabilityisakeyissueinthegridimpactstudiesofwindpowerintegration.Duringthecontinuousoperationofwindturbines,alargeamountofreactivepoweris absorbed, which lead to voltage stability deterioration[22].Furthermore,thesignificantchangesinpowersupplyfromwindmightdamagethepowerquality[23].Hence,additionalregulationcapacitywouldbeneeded.However,inapowersystemwiththemajorityofitspower from base load provider,the requirements cannot be meteasily[24].Inaddition,thepossibleexpansionofexistingtransmissionlineswouldbenecessarysinceinteg