Researchin

New&RenewableEnergyDr.LiRanWindPowerRecentStudiesinWindPower

Gearbox

WindTurbine

DoublyFed

InductionGenerator

4QConverter

FilterGridDFIGGridFaultRideThroughRenewableEnergyNetworksGridcodesetsoutrequirementsforgridinterconnection.Mostcurrentrenewablegenerationsystemsaretreatedas“negative”load.FuturesystemsMUSTcontributetosystemfrequencyandvoltagecontrol.Gridinterconnectionusually“makesorbreaks”aproject.Developmentofmany(ALL?)renewableenergyconvertersystemshaveconcentratedonthedeviceitselfwithoutdetailedthoughtofhowtoconvertthepowerforgridinterconnection.FuturedevelopmentsMUSTconsiderthesystemasawhole–REQUIRESINTEGRATEDSYSTEMAPPROACH.GridCode-Example●Thevalueofgrid-faultride-throughisincreasinglyappreciated.●Gridcode,e.g.ScottishHydro-ElectricGuidanceNoteAwindfarmmustremainconnectedunderthefollowingconditionsdependingonfaultvoltagereductionandregisteredcapacityofwindfarm.windfarmregisteredcapacityvoltageduringfault<30MW>=30MW0%July2005January200415%January2004beforeJanuary2004●Thevoltagereferstothatonthetransmissionsystem(275or132kV).Transformerimpedanceandfaultinfeedfromthewindfarmarelikelytoresultinahighervoltageatgeneratorterminal.●Faultisclearedin140msfor132kVand100msfor275kVsystem.Backupclearancetimecanextendto300ms.InitialControlIdea–whycan’titwork?statorvoltagerotorvoltagecontrolirfaultRecentStudiesinWindPower

Gearbox

WindTurbine

DoublyFed

InductionGenerator

4QConverter

FilterGridDFIGGridFaultRideThroughFeasibilityRegionwithProposedControl{super-synchronoussub-synchronousThisplotsaysthattheDFIGcansuccessfullyridethroughagridfaultwhichbringsterminalvoltagedownto0.3pu,evenitinitiallyoperatesatfullspeed.Durham30kWDFIGTestRigprimedrivewithprogrammabledirecttorquecontrolDFIGXPCTargetboxrealtimesystemFilterGridVARIAC4QconvLaboratoryverification9.951010.0510.1-2-1.5-1-0.500.511.52ir-abc(pu)Time(s)9.951010.0510.1-2-1.5-1-0.500.511.52ir-abc(pu)Time(s)Rotorcurrentconstrainedbycontrol

Simulation ExperimentGridFaultRideThroughωr{PowertrackingcontrolD.C.linkvoltagecontrolConfigurationwithdirect-in-lineconvertersAProposedResearchStudyonthetransientbehaviourofandinteractioninanintegratedmachine-convertersystem,including -TransientFEmodellingofmachine(HTUdiscoveredthattheequivalentcktmodelofaDFIGgivesfaultcurrentthatisabout10%toolow–ICEM2004.); -Transientthermalmodellingofsemiconductordevices; -Controlofconverterstosatisfymachineandpowersystemrequirements. Objective:optimizeddesignandcontrolstrategy.

RecentStudiesinWindPowerDirectDrive(Gearless)WindTurbinesTheNacelleofaGearedTurbineGeneratorGearboxDriveShaftBladesPitchMechanismLightningArresterAnemometerMechanicalBrakeHubTowerYawDriveTurbinewithGearboxEpicyclicFirstStage3spurgearstagesHighSpeedBrakeGenerator

13kN.m1500rpmTurbineBladesHubwithPitchcontrolMechanismMainBearingsLowSpeedBrake1MN.m20rpm2MWratedpowerVernierhybridmachine

fordirectdrivewindturbineFluxswitchingmachineIncorporatesmagneticgearingHighshearstressHighforce/torqueatlowspeedLowpowerfactorFour-pole,three-phase,prototypeTheSLiMConcept(fromEGL)ThreekeyaspectsLargediameterusingpre-tensionedspokesandpre-compressedrimsIronlessstatoravoidsmagneticpullPermanentMagnetRotorIronlessStatorVersionRotorsteelrimLargeRareEarthMagnetsStatornon-metallicrimStatorcoilsMagnetfluxpatternSpokedLightweight

DirectDriveWindMachine(SLiM)EvolvingGenerationLtdInitialPowerConversionArrangementStatorcoilsInvertermoduleInvertermoduleOutputtogridEGLOnGoingResearchResearchonpowerconversionandcontrolSchemestryingtoachieveFaulttolerantoperationAir-gapsupportTransformerlessgridinterfacethatsatisfiesgridcodesLowcost100%ratedconverterIntegrationofPEandmachinecoil?OnGoingResearchconditionmonitorVoltageregulatorAuxiliarypowerpickupMainoutputcoilsD.c.-d.c.converterBrakeresistorH-bridgeCascadeinserieswithotherbridgesinthesamephaseBypassswitchOpticalgatesignals&ThyristoranddioderectifierFigure1:ApossiblemoduledesignOnGoingResearchSaiaibicec,eb,eaSbSc+-+-+-+-+-+-gridCircuitDiagramChoppercutoutspeed:9m/sCurrentatcutout:3AGeneratorcutout(usingcircuitbreaker):18.5m/sGeneratorcutoutcurrent:17AMaximumhighfrequencyripplecurrent:3AMaximumtransistorcurrent:3AMaximumdiodecurrent:17AConverterdesign:systemsimulationTrackingSimulationAnnualEnergyCaptureAveragewindspeed(m/s)AnnualEnergyCapture(kWh)BatteryPartConverterFullConverterMaximum537145145345466907627717797108311441168122991848189119542520Averagewindspeed(m/s)PartiallyratedconverterFullyratedconverterIncreasefromdirectconnection(kWh)PercentageincreaseIncreasefromdirectconnection(kWh)Percentageincrease58021.6%8222.1%67210.4%8111.7%7615.6%857.9%9432.3%1065.7%WaveEnergyDemonstrationofAbsorbingWaveEnergyabcdWaveEnergyConvertersShorelinedevices Simplemaintenanceandgridconnection costoflandintrusion Example:OWC

Nearshoredevices,typically10-25mdeep,devicescanbetightmooredtotheseabed

Deepwaterdevices,slackmooredtomaintaingeographicalpositiononlyWaveEnergyConvertersTerminatortype Principleaxisparalleltoincidentwavecrests Wavesarestoppedastheyreachthedevice Example:SalterDuckAttenuatortype Principleaxisperpendiculartowavecrests Energyconversionbyrelativemotionofparts ofthedeviceasawavepassesunderneath Example:Pelamis

Pointabsorber Oscillatingbody(nextslide)ConceptofDirectDriveWaveEnergyConverterCouplemovingpartdirecttogeneratorRemoveintermediatemechanicalsystemsSlowreciprocatingmotionWaveEnergyWavegen

Oscillatingwatercolumn,IslayOceanPowerDeliveryPelamis,SROcontractforMachirBayTeamworksTechnologyArchimedesWaveSwingDirectDriveWaveMachine3-phaseac/acconverterPoweroutput-300Wperhalfphasedclink150Vnewinverter,800VdclinkConverterPowerCurrent,IVoltage,VPowerin=VxIPoweroutofMachineIntoConverterDirectDriveMachine

ElectricalRequirementsAt1m/s,100kW,Force=100kNConventionalmachines,=20-30kN/m2TransverseFluxMachines,=200kN/m2Highforcedensityelectricalmachines-problemsHighairgapclosingforcesMaxwellstressαB2AirgapclosingforceForceatzerocurrentHighforcedensityelectricalmachines-problemsLowpowerfactorHighopencircuitvoltage(e.g.60volts)Internalresistance=1.5OhmExpectedshortcircuitcurrent40A?Expectedpower2.4kW?Highforcedensityelectricalmachines-problemsActualshortcircuitcurrent1.5AmpsActualpowerapprox.3.3W!RequireactiverectifierLowforcedensityelectricalmachinesGoodmagneticcircuitforhighshearforceisrootofitsproblemsPresenceofironincircuitNoiron=poorermagneticcircuitNoMaxwellstressLowerinductanceIronless/aircoredCylindricalopposedrareearthPMsCoilsnotsupportedinsteelAircoredtubularmachinePowerConversionScheme11’12’28’8RR’1’12’28’8YY’1’12’28’8BB’RYR,Y,BR’,Y’,B’~700VpeakVandI:370V/phase75ALargecoilresistance:bypassinactivecoilsPowerConversionScheme2e(t)LRcontroltarget:i(t)=|e(t)|/(2R)commond.c.linkfromothercoilscoilPowerConversionScheme2-coilEMF-coilcurrentDownStreamPowerConversion<vcoil15coil14coil1searchcoili+dc1-dc1+dc1-dc1+dc1-dc1vi+dc2-dc2RYBcurrentcontrollerbufferampboostd.c.-d.c.chopperincluding:1.aircorechoke2.Skiip942GB120AlstomALSPAMV3000CpowersmoothingcontrollerdutyratioPhaseAPhaseBPhaseC1:v<200V200VTitlePowerConversionStage:BlockDiagramSizeRevDocumentNumber:001energystoragecapacitorbankInverte