电气工程及其自动化专业英语 课件 -Chapter 7 Renewable energy and Distributed Generation

目录Introduction7.1Windpower7.2SolarPower7.3NuclearPowerandOther7.4Chapter7RenewableenergyandDistributedGenerationpolymer['pɔlimə]n.聚合物straw[strɔ:]n.稻草；吸管；一文不值的东西biodiesel[baiɔ:di:zl]n.生物柴油；生质柴油synthetic[sin'θetik]adj.综合的；合成的，人造的diesel['di:zəl]n.柴油机；柴油adj.内燃机传动的；供内燃机用的combustion[kəm'bʌstʃən]n.燃烧，氧化pulverized['pʌlvəraizd]adj.粉状的；成粉末的fission['fiʃən]n.裂变；分裂prognosis[prɔɡ'nəusis]n.预测geothermal[,dʒi:əu'θə:məl]adj.地热的tutorial[tju:'tɔ:riəl]n.专题报告，专题论文

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situations.gasolinedieselbio-oilDormantoilsABCD提交单选题1分nacelle[nə'sel,næ-]n.短舱，引擎舱gearbox['ɡiəbɔks]n.齿轮箱；变速箱kinetic[ki'netik,kai-]adj.动力的；运动的

aerodynamic[,εərəudai'næmik,-kəl]adj.空气动力学的，航空动力学的strategy['strætidʒi]n.战略，策略momentum[məu'mentəm].n.动量；动力teeter['ti:tə]vt.使…摇摆；使…上下晃动hinge[hindʒ]n.转轴；铰链

discrepancy[dis'krepənsi]n.相差；矛盾；不符deviation[,di:vi'eiʃən]n.差异，偏差yaw[jɔ:]n.（火箭、飞机、宇宙飞船等）偏航vt.使…偏航

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thermodynamicsaerodynamichydraulicshydrodynamicsABCD提交单选题1分nocturnal[nɔk'tə:nəl]adj.夜的；夜间发生的diurnal[dai'ə:nəl]n.日记账；日报，日刊portfolio[pɔ:t'fəuljəu,,pəut-]n.业务量；业务责任；公文包turbulent['tə:bjulənt]adj.骚乱的，混乱的；狂暴的anemometer[,æni'mɔmitə]n.风力计，风速计sonic['sɔnik]adj.音波的；声音的hinder['hində]vt.阻碍；打扰align[ə'lain]vt.使成一行；匹配；使结盟gyroscopic[,dʒaiərəs'kɔpik]adj.回转仪的，陀螺的prevail[pri'veil,pri:-]vi.盛行，流行；战胜lull[lʌl]vt.使平静；使安静

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sea.hygrometerbarometeranemometerheliographABCD提交单选题1分photovoltaic[,fəutəuvɔl'teiik]adj.[电子]光电伏打的，光电的criterion[krai'tiəriən]n.标准；准则；规范gallium['ɡæliəm]n.[化学]镓arsenide['ɑ:sənaid]n.砷化物indium['indiəm]n.[化学]铟phosphide['fɔsfaid,-fid]n.磷化物cadmium['kædmiəm]n.[化学]镉telluride['teljuraid,-rid]n.碲化物diselenide[dai'selinaid]n.联硒化物amorphous[ə'mɔ:fəs]adj.非晶形的；无定形的；无组织的

alloy['ælɔi,ə'lɔi]n.合金vt.使成合金

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cells.windelectricityhighvoltagehydroelectricphotovoltaicABCD提交单选题1分susceptible[sə'septəbl]adj.易受影响的epoxy[ep'ɔksi]n.环氧基树脂fiberglass['faibəɡlɑ:s]n.玻璃纤维；玻璃丝siphon['saifən]n.虹吸管；虹吸livestock['laivstɔk]n.家畜；牲畜herd[hə:d]n.兽群，畜群；放牧人electrovalence[i,lektrəu'veiləns,-lənsi]n.电价hortative['hɔ:tətiv]adj.奖励的；劝告的uranium[ju'reiniəm]n.[化学]铀coolant['ku:lənt]n.冷却剂spontaneous[spɔn'teiniəs]adj.自发的；自然的；无意识的photon['fəutɔn]n.光子；辐射量子

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electrovalencewaterpricemedicalfeeoperatingexpensesABCD提交单选题1分目录Introduction7.1Windpower7.2SolarPower7.3NuclearPowerandOther7.47.1IntroductionNowwearefacingtwomajorenergychallenges.Thefirstissustainabilityasworldsemissionsareforecasttorise.Thesecondissecurityofsupplyofthewordisbecomingmoredependentonimportedfuels.Todaytheseaccountfor50%ofourenergyconsumption,butthe2030figureisforecasttobearound65%.现在我们面临着两大能源挑战。首先是可持续性，因为全球排放量预计将上升。二是全球能源供应安全越来越依赖进口燃料。今天，这些占我们能源消耗的50%，但2030年的数字预计将达到65%左右。7.1IntroductionTheCounciloftheEuropeanUnionrecentlyagreedthatEuropeshoulddevelopasustainableandintegratedclimateandenergypolicy.BuildingonDenmark’straditionallystrongenvironmentalprofile,theDanishgovernmentputforwardthedocument“AVisionaryDanishEnergyPolicyfortheperiodupto2025”earlierthisyear.Thisaimstostabilizeenergyconsumptionatitscurrentlevel,andcallsforaconsiderableincreaseintheuseofrenewableenergy.欧盟理事会(CouncilofEuropeanUnion)最近一致认为，欧洲应该制定一项可持续的、综合的气候和能源政策。基于丹麦传统上强大的环境形象，丹麦政府今年早些时候提出了“到2025年的丹麦能源政策”文件。这一目标旨在将能源消耗稳定在目前的水平，并要求大量增加可再生能源的使用。7.1IntroductionInitsFourthAssessmentReporttheIntergovernmentalPanelonClimateChange(IPCC)saysthatifwewanttostabilizeatthelowlevel–around500ppm–neededtolimittheglobalaveragetemperatureriseto2.5-3.0°C,emissionsmustpeaksoonandthendecline.政府间气候变化专门委员会(IPCC)在其第四次评估报告中表示，如果我们想要二氧化碳稳定在将全球平均气温上升限制在2.5-3.0°C所需的低水平(约500ppm)，二氧化碳排放必须尽快达到峰值，然后下降。7.1IntroductionTheIPCCstatesthatwemusttakeactionnowifwearetostabilizeatalowlevel.Withtheglobalexpansionofintermittentrenewableenergytechnologiescomesthepressingneedtosolvetheproblemoflong-termvariability.政府间气候变化专门委员会指出，如果我们要稳定在低水平，我们必须现在就采取行动。随着间歇性可再生能源技术在全球范围内的推广，解决长期变化的问题迫在眉睫。7.1IntroductionCarbondioxidecaptureandstorage(CCS)hasmovedtocentrestageinthelastfewyearsasaseriousoptionforlargescaleemissionsmitigation.Windenergyhasseenanaverageannualworldmarketgrowthof17%overthelastfiveyearsintermsofinstalledcapacity.Europeancountriesareleadersinthedeploymentofwindenergy:halfofallthenewwindturbinesinstalledin2006wereinEurope.近年来，二氧化碳捕集与封存(CCS)作为大规模减排的一项重要选择，已成为人们关注的焦点。就装机容量而言，风能在过去五年中以年均17%的速度增长。欧洲国家在风能部署方面处于领先地位:2006年安装的所有新风力涡轮机中有一半在欧洲。7.1IntroductionFuelcellsarewithinthenextfiveyearsattheentrancetotheirbreak-through.Theywillbeusedinthreemainapplications:stationarypowergeneration,transport,andportableequipment.燃料电池将在未来五年内取得突破性进展。它们将用于三个主要应用:固定式发电、运输和便携式设备。7.1IntroductionSolarcells(PV)representoneofthefastest-growingrenewableenergytechnologies,withaglobalannualgrowthofmorethan40%.Polymersolarcellsareapromisingnewtechnology.ThefallingcostofPVsystemswilleventuallymakePVelectricitycompetitiveinDenmark.太阳能电池(PV)是增长最快的可再生能源技术之一，全球年增长率超过40%。聚合物太阳能电池是一项很有前途的新技术。光伏系统成本的下降最终将使光伏发电在丹麦具有竞争力。7.1IntroductionBioethanolispromisingasatransportfuel.Thebestalternativeissecond-generationbioethanolfromwastematerialssuchasstraw.Otherliquidtransportfuelsarebiodiesel,syntheticgasolineanddieselproducedfromgasifiedbiomass.Biomasscanalsobeusedforheating,replacingoilornaturalgasthatcanbeusedasmotorfuel.生物乙醇是一种很有前途的运输燃料。最好的替代品是从秸秆等废料中提取的第二代生物乙醇。其他液体运输燃料是生物柴油、合成汽油和由气化生物质生产的柴油。生物质也可以用于加热，取代可以用作发动机燃料的石油或天然气。7.1IntroductionCoalhas,asthemostabundantfossilfuel,gainedrenewedinterest.MostofDenmark’selectricitycomesfromthecombustionofpulverizedcoal,andDanishcoal-firedpowerplantsleadintheworldinenergyefficiency.Nevertheless,coalwillonlybeanoptionforthefutureifwecancost-effectivelyreduceemissionsfromcoalcombustion.煤炭作为储量最丰富的化石燃料，重新引起了人们的兴趣。丹麦的大部分电力来自煤粉的燃烧，丹麦的燃煤电厂在能源效率方面处于世界领先地位。然而，只有在我们能够经济有效地减少燃煤的二氧化碳排放的情况下，煤炭才会成为未来的一种选择。7.1IntroductionThiscanbedoneinthreeways:increasetheenergyconversionefficiency;switchtoafuelwithalowerfossilcarboncontent(includingbiomass);andcaptureandstoreproducedduringcombustion.这可以从三个方面来实现:提高能量转换效率;改用化石碳含量较低的燃料(包括生物质);并捕获和储存燃烧过程中产生的二氧化碳气体。7.1IntroductionNuclearfissionisamajorsourceofcarbon-freeenergy.Itprovides15%oftheworld’selectricity.15countriesarecurrentlybuildingnewnuclearpowerstations,andafurther25plantodoso.Incontrasttopreviousprognoses,nowthatnuclearpowerisassumedtoincreaseby15%by2030.核裂变是一种重要的无碳能源来源，它提供了全球15%的电力。目前有15个国家正在建设新的核电站，另外还有25个国家计划建设核电站。与以往的预测相比，预计到2030年核能将增长15%。7.1IntroductionGeothermalenergyhasbeenshowntohaveahugepotential.Withthepresenthighoilprices,thenumberoftownsembarkingongeothermalprojectsisincreasing.Wavepowerhasgainedrenewedinterestintheworld.ExamplesareWaveDragonandWaveStar.Thesedemonstrationprojectsareverysuccessfulasastartingpointforthecommercialdevelopmentofthistechnology.地热能被证明具有巨大的潜力。随着当前油价的上涨，开始进行地热项目的城镇数量正在增加。波浪能在世界范围内重新引起了关注。WaveDragon和WaveStar是其中的例子。这些示范项目作为商业化发展这项技术的起点非常成功。7.1IntroductionInpromotionoftherenewableenergypolicy,thelargescaleexpansionofconstructionsofthewindandsolarpowerisdevelopinginChina,whoserandomhigh-powerelectricenergyfluctuationcauseshugeshocktothepowergrid.在新能源政策的推动下,中国正在大规模扩建风能和太阳能发电设施，但其随机高功率电能波动给电网带来巨大冲击。Confrontingthisimportantproblemofthepowersystemsafeoperation,itisreallytopurgenttobuildafeasiblesolutiontodevelopthelarge-scalerenewableenergy.面对电力系统安全运行的重要问题，迫切需要建立可行的解决方案来开发大规模可再生能源。7.1IntroductionDistributedgenerationsystem(DGS)basedonvariousrenewableenergyresourcesistheimportantapproachtothedevelopmentofcleanenergy,improvingthereliabilityofpowersupplyandenlargementofthepowersystemcapacity.基于各种可再生能源的分布式发电系统（DGS）是发展清洁能源、提高供电可靠性和扩大电力系统容量的重要途径。7.1IntroductionComparedtothetraditionalcentralizedpowersupplysystem,DGShasmanyadvantages:easystart-stop,goodpeakshaving,beneficialtoloadbalanceandlessinvestment,yieldfasterresult,andsatisfyingpowersupplydemandinthespecialoccasionandlesstransmissionloss,improvingdisasterlevel.与传统的集中式供电系统相比，DGS具有许多优势：启停方便、良好的峰值削减、有利于负荷平衡、投资较少、效果更快、能够满足特殊场合的供电需求、传输损耗较少，提高了抗灾能力。目录Introduction7.1Windpower7.2SolarPower7.3NuclearPowerandOther7.47.2WindpowerWindenergyisafast-growinginterdisciplinaryfieldthatencompassesmultiplebranchesofengineeringandscience.AccordingtotheWorldWindEnergyAssociation,theglobalinstalledcapacityofwindturbinesgrewatanaveragerateof27%peryearovertheyears2005–2009.风能是一个快速发展的跨学科领域，涵盖了工程和科学的多个分支。根据世界风能协会(WorldWindEnergyAssociation)的数据，2005-2009年间，全球风力涡轮机装机容量以平均每年27%的速度增长。7.2WindpowerAttheendof2009,theinstalledcapacityintheUnitedStateswasabout35,000MW,whiletheworldwideinstalledcapacitywasapproximately160,000MW.Windisrecognizedworldwideasacosteffective,environmentallyfriendlysolutiontoenergyshortages.2009年底，美国的装机容量约为35000兆瓦，而全球装机容量约为16万兆瓦。风能在世界范围内被认为是解决能源短缺的一种成本效益高、环境友好的解决方案。7.2WindpowerAlthoughtheUnitedStatesreceivesonlyabout2%ofitselectricalenergyfromwind,thatfigureinDenmarkisapproximately20%.ThecomprehensivereportbytheU.S.DepartmentofEnergylaystheframeworkforachieving20%oftheU.S.electricalenergygenerationfromwindbytheyear2030.Thisreportcoverstechnological,manufacturing,transmissionandintegration,market,environmental,andsittingfactors.虽然美国只有2%的电能来自风能，但丹麦的这一比例约为20%。美国能源部的这份综合报告为到2030年实现风能发电占美国总发电量的20%奠定了框架。该报告涵盖了技术、制造、传输和集成、市场、环境和选址等因素。7.2WindpowerDespitethegrowthintheinstalledcapacityofwindturbinesinrecentyears,engineeringandsciencechallengesremain.Becauselargerwindturbineshaveenergy-captureandeconomicadvantages,thetypicalsizeofutility-scalewindturbineshasgrownbytwoordersofmagnitudeoverthelastthreedecades.尽管近年来风力涡轮机的装机容量有所增长，但工程和科学方面的挑战依然存在。由于较大的风力涡轮机具有能量捕获和经济优势，电网规模的风力涡轮机的典型尺寸在过去三十年中增长了两个数量级。7.2WindpowerSincemodernwindturbinesarelarge,flexiblestructuresoperatinginuncertainenvironments,advancedcontroltechnologycanimprovetheirperformance.由于现代风力涡轮机是在不确定环境下运行的大型柔性结构，先进的控制技术可以改善其性能。7.2WindpowerForexample,advancedcontrollerscanhelpdecreasethecostofwindenergybyincreasingturbineefficiency,andthusenergycapture,andbyreducingstructuralloading,whichincreasesthelifetimesofthecomponentsandstructures.Thegoalofthistutorialistodescribethetechnicalchallengesinthewindindustryrelatingtocontrolengineering.例如，先进的控制器可以通过提高涡轮机效率来降低风能成本，从而提高能量捕获，并通过减少结构负载来增加组件和结构的使用寿命。本教程的目标是描述风电行业中与控制工程相关的技术挑战。7.2WindpowerAlthoughawindturbinecanbebuiltineitheravertical-axisorhorizontal-axisconfiguration,wefocusonhorizontal-axiswindturbines(HAWTs)becausetheydominatetheutility-scalewindturbinemarket.Attheutilityscale,HAWTshaveaerodynamicandpracticaladvantages.虽然风力涡轮机可以采用垂直轴或水平轴配置，但我们主要关注水平轴风力涡轮机(HAWTs)，因为它们主导着电网规模的风力涡轮机市场。在实用规模上，sitting具有气动和实用的优势。7.2WindpowerSmallerverticalaxiswindturbines(VAWTs)aremorelikelytousepassiveratherthanactivecontrolstrategies.ThegeneratingcapacityofcommerciallyavailableHAWTsrangesfromlessthan1kWtoseveralmegawatts.Activecontrolismorecosteffectiveonlargerwindturbinesthansmallerones,andthereforethistutorialfocusesonHAWTswhosecapacityis600kWorlarger.较小的垂直轴风力涡轮机(VAWTs)更有可能使用被动控制策略而不是主动控制策略。商用热发电机组的发电能力从不足1千瓦到几兆瓦不等。主动控制在大型风力涡轮机上比小型风力涡轮机更具成本效益，因此本教程主要关注容量为600千瓦或更大的风力涡轮机。7.2WindpowerThenextsectiondescribestheconfigurationsandbasicoperationofwindturbines.Wethenexplainthelayoutofawindturbinecontrolsystembytakinga“walk”aroundthewindturbinecontrolloop,withdiscussionsonwindinflowcharacteristics,availablesensorsandactuators,andturbinemodelingforuseincontrol.下一节介绍风力涡轮机的配置和基本操作。然后我们沿着风机的控制回路来解释风力涡轮机控制系统的布局，并讨论风场流动特性、传感器和执行器以及控制用的涡轮机模型。7.2WindpowerSubsequently,wedescribethecurrentstateofwindturbinecontrol,whichisfollowedbyadiscussionoftheissuesandopportunitiesinwindturbineandwindfarmcontrol.Attheend,wegivesomeconcludingremarks.随后，我们描述了风力发电机控制的现状，随后讨论了风力发电机和风电场控制中的问题和机遇。最后，本文作了总结。7.2WindpowerSubsequently,wedescribethecurrentstateofwindturbinecontrol,whichisfollowedbyadiscussionoftheissuesandopportunitiesinwindturbineandwindfarmcontrol.Attheend,wegivesomeconcludingremarks.随后，我们描述了风力发电机控制的现状，随后讨论了风力发电机和风电场控制中的问题和机遇。最后，本文作了总结。7.2.1WindTurbinebasicsThemaincomponentsofaHAWTthatarevisiblefromthegroundarethetower,nacelle,androtor,asshowninFigure7-1.Thewindfirstencounterstherotoronthisupwindhorizontal-axisturbine,causingittospin.Thelow-speedshafttransfersenergytothegearbox,whichstepsupinspeedandspinsthehigh-speedshaft.从地面上可以看到的主要部件是机塔、机舱和旋翼，如图7-1所示。风首先遇到逆风水平轴涡轮机上的转子，使其旋转。低速轴将能量传递给齿轮箱，齿轮箱加快速度并旋转高速轴。7.2.1WindTurbinebasics

Fig7.1风力发电机部件7.2.1WindTurbinebasicsThehigh-speedshaftcausesthegeneratortospin,producingelectricity.Alsoshownistheyaw-actuationmechanism,whichisusedtoturnthenacellesothattherotorfacesintothewind.Theairfoil-shapedbladescapturethekineticenergyofthewindandtransformitintotherotationalkineticenergyofthewindturbine’srotor.高速轴使发电机旋转，产生电力。还显示了偏航驱动机制，这是用来转动机舱，使转子面向风。翼型叶片捕获风的动能，并将其转化为风力涡轮机转子的旋转动能。转子带动低速轴，低速轴带动齿轮箱。7.2.1WindTurbinebasicsTherotordrivesthelow-speedshaft,whichinturndrivesthegearbox.Thegearboxstepsuptherotationalspeedanddrivesthegeneratorbymeansofthehigh-speedshaft.Thegearbox,highspeedshaft,andgeneratorarehousedinthenacelle,alongwithpartofthelow-speedshaft.Directdriveconfigurationswithoutgearboxesarebeingdevelopedtoeliminatecostlygearboxfailures.齿轮箱提高转速，通过高速轴带动发电机。变速箱、高速轴和发电机与部分低速轴一起安装在机舱内。正在研发没有变速箱的直接驱动配置，以消除昂贵的变速箱故障。7.2.1WindTurbinebasicsWindturbinesmaybevariableorfixedspeed.Variablespeedturbinestendtooperateclosertotheirmaximumaerodynamicefficiencyforahigherfractionofthetimebutrequireelectricalpowerprocessingsothatthegeneratedelectricitycanbefedintotheelectricalgridattheproperfrequency.风力涡轮机可以是可变速或固定速度的。可变速涡轮机倾向于在更长的时间内接近其最大空气动力效率，但需要进行处理，以便将发电的电力以合适的频率馈送到电网中。7.2.1WindTurbinebasicsVariable-speedturbinesaremorecosteffectiveandthusmorepopularthanconstant-speedturbinesattheutilityscalebecauseofimprovementsingeneratorandpowerelectronicstechnologies.Variable-speedoperationcanalsoreduceturbineloads,sincesuddenincreasesinwindenergyduetogustscanbeabsorbedbyanincreaseinrotorspeedratherthanbycomponentbending.可变速涡轮机在效益规模上比恒速涡轮机更具成本效益，因为发电机和功率电子技术的改进。由于因阵风引起的风能突然增加可以由风机转子的加速吸收掉而不会令风机构件弯曲，因此，变速运行可以减少风力涡轮机的负荷。7.2.1WindTurbinebasicsThegoalsandstrategiesofwindturbinecontrolareaffectedbytheturbineconfiguration.AHAWTcanbeupwind,withtherotorontheupwindsideofthetower,ordownwind,withtherotoronthedownwindsideofthetower.Thischoiceaffectstheturbinedynamicsandthusthestructuraldesign.风力涡轮机控制的目标和策略受到涡轮机配置的影响。水平轴风力涡轮机可以是上风式，即转子位于塔的上风侧，也可以是下风式，即转子位于塔的下风侧。这个选择会影响涡轮机的动力学特性，从而影响结构设计。7.2.1WindTurbinebasicsThegoalsandstrategiesofwindturbinecontrolareaffectedbytheturbineconfiguration.AHAWTcanbeupwind,withtherotorontheupwindsideofthetower,ordownwind,withtherotoronthedownwindsideofthetower.Thischoiceaffectstheturbinedynamicsandthusthestructuraldesign.风力涡轮机控制的目标和策略受到涡轮机配置的影响。水平轴风力涡轮机可以是上风式，即转子位于塔的上风侧，也可以是下风式，即转子位于塔的下风侧。这个选择会影响涡轮机的动力学特性，从而影响结构设计。7.2.1WindTurbinebasicsAwindturbinecanalsobevariablepitchorfixedpitch,meaningthatthebladesmayormaynotbeabletorotateabouttheirlongitudinalaxes.Variable-pitchturbinesmightallowallorpartoftheirbladestorotatealongthepitchaxis.风力涡轮机还可以是可变桨距或固定桨距，意味着叶片可以或不可以绕其纵向轴旋转。可变桨距涡轮机可以允许其部分或全部叶片沿桨距轴旋转。7.2.1WindTurbinebasicsFixed-pitchmachinesarelessexpensivetobuild,buttheabilityofvariable-pitchturbinestomitigateloadsandaffecttheaerodynamictorquehasdriventheirdominanceinmodernutility-scaleturbinemarkets.固定桨距机器的建造成本较低，但可变桨距涡轮机通过减轻负荷和影响空气动力扭矩的能力，在现代大型涡轮机市场上占据主导地位。7.2.1WindTurbinebasicsTheexamplegiveninFigure7.2showspowercurvesfora2.5-MWvariable-speedturbineanda2.5-MWfixed-speedturbine,aswellasacurveshowingtheavailablewindpowerforaturbinewiththesamerotorsizeasthesetwoturbines.图7.2中给出的示例显示了一个2.5兆瓦可变速涡轮机和一个2.5兆瓦固定速度涡轮机的功率曲线，以及一个显示与这两个涡轮机具有相同转子尺寸的涡轮机可利用风能的曲线。

Figure7.2说明性功率曲线7.2.1WindTurbinebasicsForbothturbines,whenthewindspeedislow,thepoweravailableinthewindislowcomparedtolossesintheturbinesystem;hence,theturbinesarenotrun.对于这两种涡轮机，当风速较低时，与涡轮机系统的损失相比，风中可利用的功率较低，因此涡轮机不会运行。7.2.1WindTurbinebasicsWhenthewindspeedisabovetheratedwindspeed,powerislimitedforbothturbinestoavoidexceedingsafeelectricalandmechanicalloadlimits.Inthisexample,lowwindspeedisconsideredtobebelow6m/s,whereashighwindspeedisabovetheratedwindspeedof11.7m/s.当风速超过额定风速时，为了避免超过安全电气和机械负载限制，两种涡轮机的功率都受到限制。在这个示例中，低风速被认为是低于6米/秒，而高风速则是高于11.7米/秒的额定风速。7.2.1WindTurbinebasicsThemaindifferenceintheexampleshowninFigure7.2betweenthetwotypesofturbinesappearsformid-rangewindspeeds.Thewindpowercurveshowsthepoweravailableinthewindfortheexamplevariable-andfixed-speedturbineswiththesamerotordiameter.图7.2中示例中两种涡轮机类型之间的主要差异出现在中等风速范围内。风能曲线显示了示例可变速和固定速度涡轮机在相同转子直径下的风中可利用的功率。7.2.1WindTurbinebasicsTheturbinesarestartedupat6m/swindspeedwhenthereisenoughwindtoovercomelossesandproducepower.Above11.7m/swindspeed,powerislimitedtoprotecttheturbines’electricalandmechanicalcomponents.当有足够的风来克服损失并产生电力时，涡轮机在6米/秒的风速下启动。当风速超过11.7米/秒时，为了保护涡轮机的电气和机械部件，功率被限制。7.2.1WindTurbinebasicsBothturbinesgeneratethesamepoweratthefixedspeedturbine’s10m/sdesignpoint,butthevariablespeedturbinegeneratesmorepoweratallwindspeedsinRegion2,withamaximumdifferenceofabout150kWat6m/s.windspeedsbetween6and11.7m/s.虽然在固定速度涡轮机的10米/秒设计点上，两种涡轮机产生相同的功率，但可变速涡轮机在区域2的所有风速下产生更多的功率，风速在6米/秒到11.7米/秒之间时最大差异能到150千瓦。7.2.1WindTurbinebasicsExceptforthefixedspeedturbine’sdesignoperatingpointof10m/s,thevariable-speedturbineinFigure7.2convertsmorepowerateachwindspeedthanthefixed-speedturbine.Thisexampleillustratesthefactthatvariable-speedturbinescanoperateatmaximumaerodynamicefficiencyoverawiderrangeofwindspeedsthanfixed-speedturbines.除了固定速度涡轮机的设计工作点10米/秒外，图7.2中的可变速涡轮机在每个风速下转换的功率都比固定速度涡轮机更高。这个例子说明了可变速涡轮机可以在更宽的风速范围内以最大空气动力效率运行，而固定速度涡轮机则不能。7.2.1WindTurbinebasicsThewindspeedprobabilitydistributioncanbemodeledasaWeibullfunction,withscaleandshapeparametersthatdefinethefunction.InthecaseofaWeibulldistributionhavingashapeparameterk=2andscaleparameterc=8.5,thevariable-speedturbinecaptures2.3%moreenergyperyearthantheconstantspeedturbine.风速概率分布可以建模为威布尔函数，用尺度和形状参数定义该函数。在形状参数k=2，尺度参数c=8.5的威布尔分布情况下，变速水轮机比恒速水轮机每年多捕获2.3%的能量。7.2.1WindTurbinebasicsAwindfarmratedat100MWandoperatingwitha35%capacityfactorcanproduceabout307GWhofenergyinagivenyear.IfthecostofenergyisUS$0.04perkilowatthour,eachgigawatthourisworthaboutUS$40,000,andeach1%lossofenergyonthiswindfarmisequivalenttoalossofUS$123,000peryear.一个额定100兆瓦的风电场，以35%的容量系数运行，在给定的一年里可以产生大约307千兆瓦时的能量。如果能源成本为每千瓦时0.04美元，那么每千兆瓦时的价值约为4万美元，而这个风电场每损失1%的能源就相当于每年损失12.3万美元。7.2.1WindTurbinebasicsNotshowninFigure7.2isthehighwindcut-out,thewindspeedabovewhichtheturbineispowereddownandstoppedtoavoidexcessiveoperatingloads.Highwindcutouttypicallyoccursatwindspeedsbetween20and30m/sforutility-scaleturbines.在图7.2中没有显示的是高风速切断，高于该风速，涡轮机将被关闭并停止，以避免过大的运行负荷。对于电网规模的涡轮机来说，高风力切断通常发生在风速在20到30米/秒之间。7.2.1WindTurbinebasicsMomentumtheoryusinganactuatordiscmodelofawindturbinerotorshowsthatthemaximumaerodynamicefficiency,calledtheBetzlimit,isapproximately59%ofthewindpower.Theaerodynamicefficiency,whichistheratiooftheturbinepowertothewindpower,isgivenbythepowercoefficient利用风力涡轮机转子的驱动器盘模型的动量理论表明，最大的空气动力学效率，称为贝茨极限，大约是风力的59%。气动效率，即涡轮功率与风力功率之比，由功率系数给出7.2.1WindTurbinebasicswhereistheinstantaneousturbinepowerand

istheinstantaneouspoweravailableinthewindforaturbineofthatrotordiameter.In(2),istheairdensity,isthesweptareaoftherotor,istherotorradius,andistheinstantaneouswindspeed,whichisassumedtobeuniformacrosstherotorsweptarea.Thesweptareaistheareaofthediskcircumscribedbythebladetip.是涡轮的瞬时功率，是该转子直径的涡轮机在风中可用的瞬时功率。式(2)中为空气密度，为转子扫掠面积，为转子半径，为瞬时风速，假设瞬时风速在转子扫掠面积上均匀。扫掠面积是由叶尖围成的圆盘面积。7.2.1WindTurbinebasicsFinally,utility-scalewindturbinesareeithertwoorthreebladed.Two-bladedturbinestypicallyuseateeteringhingetoallowtherotortorespondtodifferentialloads.Thisteeterhingeallowsonebladetomoveupwindwhiletheothermovesdownwindinresponsetodifferentialwindloads,muchlikeaseesawallowsonechildtomoveupwhileanothermovesdown.最后，电网规模的风力涡轮机要么是两个叶片，要么是三个叶片。双叶片涡轮机通常使用摇摇晃晃的铰链，以允许转子响应不同的负载。这种摇摆铰链允许一个叶片在风向上移动，而另一个叶片在风向下移动，以响应不同的风荷载，就像跷跷板允许一个孩子向上移动而另一个向下移动。7.2.1WindTurbinebasicsForaturbinewithanevennumberofbladesplacedsymmetricallyaroundtherotor,whenonebladeisattheuppermostposition,anotherbladeisintheslowerwindcausedbyeitherthetowershadowbehindthetowerorthebowwakeinfrontofthetower.对于偶数叶片对称放置在转子周围的涡轮，当一个叶片在最上面的位置时，另一个叶片处于由塔后的塔影或塔前的艏尾迹引起的较慢的风中。7.2.1WindTurbinebasicsThisdiscrepancyisexacerbatedbytypicalwindshearconditions,whichresultinhigherwindspeedshigherabovetheground.Three-bladedturbinestendtoexperiencemoresymmetricalloadingthantwo-bladedturbines,butata50%increaseinbladecost.典型的风切变条件加剧了这种差异，导致地面以上的风速更高。三叶涡轮机往往比两叶涡轮机更具有对称载荷，但叶片成本增加50%。目录Introduction7.1Windpower7.2SolarPower7.3NuclearPowerandOther7.47.3.1SolarcellsSolarcellsaredeviceswhichabsorblightandconvertitintoelectricalenergy.Theabsorptionoflightinsemiconductorscreatesadditionalelectricalchargecarriers,bothelectronsandholesequally.Ifanelectricfieldexistswithinthesemiconductor,thenegativeelectronsandpositiveholesmoveinoppositedirections,andthiselectricalchargeseparationresultsinthecreationofavoltage.太阳能电池是一种吸收光并将其转化为电能的装置。半导体对光的吸收产生了额外的电荷载体，电子和空穴都是一样的。如果半导体内部存在电场，则负电子和正空穴向相反方向移动，这种电荷分离导致电压的产生。7.3.1SolarcellsThisisthephotovoltaiceffect-thecreationofavoltagebytheactionoflight.Themovementoftheelectricchargesconstitutesanelectriccurrent,sobothcurrentandvoltagearegeneratedsimultaneously,asshownschematicallyinFig.7.7.这就是光电效应——通过光的作用产生电压。电荷的运动构成电流，因此电流和电压同时产生，如图7.7所示。7.3.1Solarcells

Fig.7.7光伏效应示意图7.3.1SolarcellsThesimplestwaytoestablishanelectricfieldinasemiconductoristomakeap-njunction.Theelectricfieldatthejunctionattractselectronsfromthep-sideandforcesthemtothen-sidemakingitnegativelycharged.Similarlyholesfromthen-sideareforcedtothep-side,makingthispositivelycharged,andthuscreatingavoltage.Theelectriccurrentisfedviathemetalcontactsonthepandthennlayerstoanexternalload.在半导体中建立电场最简单的方法是制造pn结。结处的电场吸引p侧的电子并迫使它们到n侧，使其带负电荷。类似地，n侧的空穴被强迫到p侧，使其带正电，从而产生电压。电流通过p层和n层上的金属触点馈送到外部负载。7.3.1SolarcellsTherequirementsforasolarcellarethus:(i)Asemiconductordiodeoflargearea,tocollectasmuchlightaspossible.(ii)Electricalcontactsoneachsideofthediode.Onesidemustcollecttheincidentlight,sothecontactmustbeastransparentaspossible.Itcanbeatransparentconductororfinemetalfingersspacedwidelyapart,asshowninFig.7.8.太阳能电池的要求如下:(i)大面积的半导体二极管，以收集尽可能多的光。(ii)二极管两侧的电触点。一面必须收集入射光，因此接触面必须尽可能透明。它可以是透明导体，也可以是间距很大的细金属，如图7.8所示。7.3.1Solarcells

Fig.7.8太阳能电池的结构7.3.1SolarcellsThefirstcriterionforchoosingasolarcellmaterialisitsenergygap.Thevoltagewhichacellcangenerateisafraction(knownasthevoltagefactor)ofitsenergygap,sothelargertheenergygapthehigherthevoltage.Asemiconductorwillabsorblightonlyiftheenergyofthephotonsisgreaterthantheenergygapofthesemiconductor.选择太阳能电池材料的第一个标准是它的能隙。电池能产生的电压是其能量间隙的一小部分(称为电压因子)，因此能量间隙越大，电压越高。只有当光子的能量大于半导体的能隙时，半导体才会吸收光。7.3.1SolarcellsForalightsourcesuchastheSunwithitsenergyspreadoverawiderangeofphotonenergy(colours)thehighertheenergygapthesmallerthefractionofsunlightwhichcanbeabsorbed,andthereforethelowerthecurrent.Thereisthusanoptimumenergygapforasolarcellatwhichtheproductofvoltageandcurrentisamaximum.对于像太阳这样的光源，它的能量分布在一个很宽的光子能量(颜色)范围内，能量间隙越高，可以吸收的太阳光的比例就