hewindturbinesbythebladebythebladeangleadjustments.Thecompleterepresentationofthewindfarmischosenbecausethecommonlyaskedquestionconcerninglargewindfarmsiswhethertherecanbeelectromechanicalinteractionbetweenalargenumberofthecloselyplacedwindmillsexcitedbydisturbancesinthepowersystemwhenthewindmillsareworkingatdifferentset-points,equippedwithrelativelysoftshaftsandevenhavingdifferentmechanicaldata,aedwithconventionalinductiongeneratorsandac-connectedtothepowersystem.Incaseofashortcircuitfaultinthepowersystem,thosewindmillsareeasilyoverspeededand,then,automaticallydisconnectedfromthepowersystemandstopped.Suchautomaticdisconnectionswillbeveryfastandorderedbythewindmillprotectionsystemrelaysettings.Whentheon-landwindmillsareautomaticallydisconnected,thereisnodynamicreactivecompensationdemandsrelatedtothem,despitetheirlargepowercapacity.Whenthevoltageisre-established,theon-landwindmillswillbeautomaticallyre-connectedtothepowersystemin-minafterwardsandcontinuetheiroperation,Theon-landwindmillrelaysettingsaredecidedbythewindmillmanufacturersorthewindmillownersandthese,asusual,cannotbechangedbythetransmissionsystemoperator.Incaseofthelargeoffshorewindfarms,thepowersystemoperatorhasformulatedtheSpecificationsforConnectingWindFarmtoTransmissionNetwork.InaccordancewiththeSpecifications,thevoltagestabilityatfailureeventsintheexternalpowersystemshallbemaintainedwithoutanysub-sequentialdisconnectionofthelargeoffshorewindfarms.Establishingdynamicreactivecompensationofthelargeoffshorewindfarmscanbe,therefore,necessary.Theamountofdynamicreactivecompensationdepends,generally,onthewindmilltechnologyandinthewindfarmsandisinfluencedbythewindmillelectricalandmechanicalparameters.Inothercountries,similarspecificationsmaybefoundastheresultoflargeincorporationofwindpowerintothelocalpowersystem..WindfarmmodelThewindmilltechnologyinoffshoresettingshastoberobust,developedandknownpracticalapplications.Thewindturbineconceptwithconventionalinductiongeneratorshasbeeninoperationinon-landsettingsinDenmarkduringmanyyears,whichiswhyitmaybeconsideredthatthistechnologywillbeusedoffshoreaswell.Thewindturbinesareequippedwithbladeanglecontrolsystem-pitchoractivestallthatmakeitpossibletoadjusttheset-pointsofthewindturbinesbythebladebythebladeangleadjustments.Thecompleterepresentationofthewindfarmischosenbecausethecommonlyaskedquestionconcerninglargewindfarmsiswhethertherecanbeelectromechanicalinteractionbetweenalargenumberofthecloselyplacedwindmillsexcitedbydisturbancesinthepowersystemwhenthewindmillsareworkingatdifferentset-points,equippedwithrelativelysoftshaftsandevenhavingdifferentmechanicaldata,a路流畅和减少短路容量到MVA,不会导致电压不稳定。这保证可能电压不稳定仅仅是因风车超速短路而引起结果。.动态电抗补偿这方面工作,有力反应补偿近海风力大农场是svc能力,有必要保持短期稳定电压.SVC模型在Ref中是交流。.风车停转操作浆叶角控制为风涡轮机械动力优化主要使用关于接踵而来风并且,这控制能力不是必要可利用在外部电力系统故障中与维护短期电压稳定有关.这意味倾斜或有效延迟作为风力机被常规停运。同样方式对风车在陆地也一样,除非他们可能是连接。作为案例对境外风力涡轮数据,转子绕组阻抗upRR..,发电机惯性sHG.,米尔惯量sHM.,和轴坚硬radelupK./...。如果没有应用动态电抗性,短路故障和短路线路将导致电压不稳定,见图。风车将会由保护继电器和后备保护进行加强。MW将要立刻上马。为恢复短路故障以后电压,使用MVAr动态电抗补偿将是必要。图给出了模拟仿真中电压和速度曲线。发现风力涡轮动力特性,例如电压、发电机速度等,呈现波动行为在动力传动系统.虽然风力涡轮机已初步确定不同点,显示了风车一致反应事件未对外交通运输网络,使处于波动阶段,在同一频率.波动频率是极限模式风车槽.当电压恢复后,任何电气或机械特性波动已不再出现.没有自励风场有大量配备异步发电机风力涡轮发电机因为异步发电机是被动,并没有同步扭矩迅速控制了应用..改进传统技术动态稳定性风车运动公式计算质量体系是)()(GMEMLHHTTdtd(a)MT和ET分别是机械转矩和电磁转矩,L是角速度。,GMGGMMLHHHH(b)M和G分别是发电机机械角速度和电磁角速度,MMMwPT)(是特定风。动态稳定范围内发现动作方程式(a)和(b)作为角速度L当EMTT时。解决方案是风车临界速率C,所以过度临界速率CL,因为风车超速运行(防止电压不稳定性),导致保护断开。在Ref中可以发现这个定义理论解释,它绘画插图如图。从动态稳定性极限定义,在以下被给一定数量稳定改善方法可以被介绍根据常规风车技术。.发电机参数电磁转矩对速度曲线形状,)(GET,由风车异步发电机参数影响依照)()()()()(GTGTGTGGSGEXRRVT()风车发电机接头电压SV作为发电机速度公式,发电机阻抗为)()(GTGTjXR为异步电动机电参数例如定子电阻SR,定子电抗SX,磁阻抗MX,转子电阻R,转子电抗RX,在Ref中给出。短期电压稳定,当风车临界车速被扩展,总将改进。它可以被影响当以下情况:()MSSXXR,,andRX值下降()转子电阻R值上升转子电阻值上升在图中表示,R,转子电阻值慢慢上升,见图。增加电动子抵抗由因素,像在例子中,导致重大扩展重要风车速度,C,显著减少动态电抗性补偿要求。当转子电阻为...upRR,只将有必要使用MVAr电压在风场连接点显示在动态电抗性补偿。见图。MVAr动态电抗性补偿与电抗性补偿要求比较,在那情况下转子电阻值R在第部分被发现MVAr。显著减少动态电抗性补偿要求。另一方面,当动力系统在正常运行时,这种解答在电动子电路导致增加功率损失。.机械工程实施它是一个共同观点,当转动系统惯性更高时,更加稳定操作在动力系统在故障情况下被期望。根据动态稳定性极限定义,惯性值对风车临界速率不影响。二个风轮机以相同发电机数据和不同惯量值MH和MH,当MH>MH时,有同样临界速率值CC。由于不同惯量值,风轮机将会不同地加速在故障时并且有不同关键失效时间CCtt。因此,重风轮机显示更好稳定行为比较锡风涡轮,只要故障时间不是太长。在实用情况,故障时间是足够短,并且重风轮机将是首选关于维护电压稳定。风车装备轴系统,从发电接头观看有效轴硬度是低.在正常运行,在轴那里将被积累相当数量势能,并且轴硬度越低,势能积累越多。在短路故障,轴是松弛,并且势能被释放到发电机转子动能。这导致发电机转子有更大加速度。对轴放松造成发电机转子速度贡献是)/(GMGKHT。增加轴硬度K,因此导致在故障时风车超速减少,见图,并且导致瞬间电压稳定改善,与动态稳定性极限考虑符合。模仿结果应付动态电抗性补偿要求在风车机械建筑变化参量,MH和K,收集在表中。风车机械建筑执行有一个重大正面作用在短期电压稳定改善。文献来源:国际科学杂志电力能源系统edwithconventionalinductiongeneratorsandac-connectedtothepowersystem.Incaseofashortcircuitfaultinthepowersystem,thosewindmillsareeasilyoverspeededand,then,automaticallydisconnectedfromthepowersystemandstopped.Suchautomaticdisconnectionswillbeveryfastandorderedbythewindmillprotectionsystemrelaysettings.Whentheon-landwindmillsareautomaticallydisconnected,thereisnodynamicreactivecompensationdemandsreModellingandtransientstabilityoflargewindfarms.IntroductionDenmarkhascurrentlyaboutMWwindpowercapacityinon-landandfewoffshoresettings,whichcorrespondstomorethanofpowerconsumption(inaverage).Further,constructionoftwolarge-scaleoffshorewindfarmsofMWpowercapacityeachhasbeenannounced.ThefirstlargeoffshorewindfarminDenmarkwillbeconstructedatHomsRevbytheyearintheareaofthesystemoperatorELTRA.ThiswillbefollowedbythefirstintheareaoftheEasternDanishsystemoperator,ELKRAFTSystem,largeoffshorewindfarmatRodsandbytheyear.Theinstalledcapacityinon-landsettingsandincombinedheat-powerunits(UHP)willincreaseaswell,whilstthepowerproductionandcontrolabilityoftheconventionalpowerplantswithrespecttovoltageandfrequencyarereduced.Intheyearstocome,thepowerproductionpatternintheDanishpowersystemwillchangefromthepowersupplyfromconventionalpowerplants―asitisknowntoday―toapowersupplymix,whereabout-ofpowerconsumption(inaverage)iscoveredbywindpower.Inotherwords,thepowertechnologywillundergochangesfromawell-knowntechnologybuilt-upaboutconventionalpowerplantstoapartlyunknowntechnology―windpower.Intheyeartocomeitwillbefocusingonmaintainingpowersystemstabilityandvoltagestability,forexampleatashortcircuitfault,ensuringpowersupplysafetyandotherimportanttasksasamountofwindpowerisdrasticallyincreasing.Thissituationmakesitnecessarytofindsolutionswithrespecttomaintainingdynamicstabilityofthepowersystemwithlargeamountofwindpoweranditsreliableoperation.Thesesolutionsarebasedonanumberofrequirementsthatareformulatedwithrespecttooperationofthelargeoffshorewindfarmsandtheexternalpowersystemincaseoffailureeventsintheexternalsystem.Thepapercontainsseparatesubjectsdealingwithdesignofwindmillsforlargeoffshoreapplicationsandtheircontrolthatshallbetakenintoaccountwithrespecttoimprovingtheshort-termvoltagestability..systemstabilityrequirementsIntermsofshort-termvoltagestability,themajorgoalisthevoltagere-establishingafterfailureeventsinthepowersystemwithlargeamountofwindpower.Thetransmissionsystemoperatorisresponsibleformaintainingpowersystemstabilityandreliablepowersupply.Asthesituationistoday,themajorityoftheDanishwindmillson-landarestallwindturbinesequippedwithconventionalinductiongeneratorsandac-connectedtothepowersystem.Incaseofashortcircuitfaultinthepowersystem,thosewindmillsareeasilyoverspeededand,then,automaticallydisconnectedfromthepowersystemandstopped.Suchautomaticdisconnectionswillbeveryfastandorderedbythewindmillprotectionsystemrelaysettings.Whentheon-landwindmillsareautomaticallydisconnected,thereisnodynamicreactivecompensationdemandsrelatedtothem,despitetheirlargepowercapacity.Whenthevoltageisre-established,theon-landwindmillswillbeautomaticallyre-connectedtothepowersystemin-minafterwardsandcontinuetheiroperation,Theon-landwindmillrelaysettingsaredecidedbythewindmillmanufacturersorthewindmillownersandthese,asusual,cannotbechangedbythetransmissionsystemoperator.Incaseofthelargeoffshorewindfarms,thepowersystemoperatorhasformulatedtheSpecificationsforConnectingWindFarmtoTransmissionNetwork.InaccordancewiththeSpecifications,thevoltagestabilityatfailureeventsintheexternalpowersystemshallbemaintainedwithoutanysub-sequentialdisconnectionofthelargeoffshorewindfarms.Establishingdynamicreactivecompensationofthelargeoffshorewindfarmscanbe,therefore,necessary.Theamountofdynamicreactivecompensationdepends,generally,onthewindmilltechnologyandinthewindfarmsandisinfluencedbythewindmillelectricalandmechanicalparameters.Inothercountries,similarspecificationsmaybefoundastheresultoflargeincorporationofwindpowerintothelocalpowersystem..WindfarmmodelThewindmilltechnologyinoffshoresettingshastoberobust,developedandknownpracticalapplications.Thewindturbineconceptwithconventionalinductiongeneratorshasbe 1Modellingandtransientstabilityoflargewindfarms1.IntroductionDenmarkhascurrentlyabout2300MWwindpowercapacityinon-landandfewoffshoresettings,whichcorrespondstomorethan20%ofpowerconsumption(inaverage).Further,constructionoftwolarge-scaleoffshorewindfarmsof150MWpowercapacityeachhasbeenannounced.ThefirstlargeoffshorewindfarminDenmarkwillbeconstructedatHo