Windsail turbine technicaladvantages.docx

Windsail turbine technicaladvantages.docx

《Windsail turbine technicaladvantages.docx》由会员分享，可在线阅读，更多相关《Windsail turbine technicaladvantages.docx（16页珍藏版）》请在冰豆网上搜索。

Windsailturbinetechnicaladvantages

TechnicalfeaturesandadvantagesoftheWind-sailturbines.

Thebasicgoalofthe3KwsixbladeturbinedesigneffortwasaproductthatwouldbesuitableforUrbanorSuburbanuse,inclass3windconditionsorabove.（ThreeKilowattsisthenameplateratingat11meterspersecondwindspeed.）

Someoftherequirements:

Theunitmustbenearlysilent.（Teststodateconfirmthatwemetthisgoal.）

Theunitshouldnotkillbirds（howeverwecan’tavoidthosecommittingsuicideinthematingseason.）

Theunitshouldbecosteffective.（Studiesshowthatinmassproductionwecanmeetcostgoals.）

Theunitshouldmakesenseindistributedpowerapplication:

（Thisisanelusiverequirementthatchangesfromsitetosite,andwiththeprospectivebuyer.Howeverbasedonthecontinuedinquiriesfrompotentialcustomerswebelievewecanserviceasignificantsegmentofthemarket.）

Implications:

Tocapturepowerfromlowerwindspeedstheairfoilsneedtobehighlyefficient,theturbineneedstobeself-starting;theairfoilsneedtobeabletoextractpowerastheycutacrossthewindinbothdirectionsoverawiderangeofangles.Theturbineneedstodealwithvariablewinddirections.

TheaerodynamicsspecialistsatMSRCspentagreatdealofeffortcalculatingvariousbladeshapes,computermodelsweremade,thenbladesegmentswerefabricatedfortestinginthehydrodynamicsfacility.Theresultisaspecificbladeshapethathasbeendefinedforapatentapplication.Thefollowingarephotosofbladesegmentsatthehydrodynamicsfacility.

Sincemostpeopleliveinareasofclassthreewindconditionsorless,wedeterminedthat,inareaswherepeoplelive,peakwindspeedsoccurlessthan1.5%ofthetime.Buildingawindmillsystemtocapturetheserelativelyrarepeakpowermomentsgreatlyincreasesthecostofthesystem,withoutgreatbenefittotheusers.Belowareexamplesofwindspeeddistributionsinspecificlocations.

Fromamathematicalpointofview,duetotheincreaseinpowerasthecubeofthewindvelocity,the1.5%ofthetimewithhighwindspeedsrepresentsasignificantportionofthetotalwindpoweravailableoverthecourseoftheyear.Howeverbuildingasystemtocaptureandusethispeakpowerisnotpractical.Tomakethispointunderstandable:

Awindmillinahurricanecanproducemorepowerduringthehurricanethanitcouldduringtherestoftheyear.Soifoneusedonlypowerproductionasameasurement,weshouldbuildwindmillstocapturepowerfromhurricanesandignoretherestofthewind.

Intherealworld,wefindthatwhilepowerproducerswanttomaximizetheamountofpowerproducedandsold,theusersofpoweraremoreinterestedinhavingsmalleramountsofpoweronamorereliablebasis.Thuswindfarmswithlargeturbinesoperatedforpowersellershaveaverydifferentsetofeconomicsthanpowerconsumers,particularlyconsumersofoffgridpower.

Tocapturesmalleramountsofpowerwithgreaterfrequency,itisnecessarythatthewindturbinebeself-startinginverylightwindconditions.Toaccomplishthisrequiresacombinationoffactors;theairfoilsmustbeofthecorrectshape,theymustbeplacedinthecorrectposition,thebearingfrictionmustbeverylowandthealternatormustnotpresentresistanceuntilafterthesystemisataworkingspeed.

ThedirectlydrivenalternatordesignedbyEmpireMagneticsInc.hasnoswitchedironinthemagneticcircuit,sounlikeotherpermanentmagnetalternators,thisdesignhaszerocogging,presentingnearzerostartingresistance.Inadditionthereisnomagneticattractionorloadsplacedonthebearinguntilpowerisbeingconsumedfromthealternator.Thesetwofactorsallowtheturbinetobeginturninginverylightwindconditions.Byusingalargediameterdirectdrivealternatordesignweeliminatelossesandcostsassociatedwithgearsorothermechanicaldrivesystems.Sincewehavenoswitchedironinthemagneticsystem,itisfeasibletousethestructuralironofthewindmillascomponentsinthemagneticdesign;thisintegrationallowscostreductionsnotpossiblewithotheralternatordesigns.

Forthosenotacquaintedwiththeelectricmotor/alternatorindustryitiseasytotaketheavailabilityofasuitablealternatorforgranted.Howeverthisismostdefinitelynotthecase.Thereareveryfewpeoplewiththetechnicalskillsneededtodesignasuccessfulalternator.Thereareevenfewercompanieswiththeresourcestomanufacturethesedesignsinaneconomicmanner.Thecompaniesthatareintheelectricmotorbusinesstendtobelarge,andtheyarefocuseduponmanufacturedproductsthatprofitablyloadtheirexistingfactories.Windmillcompaniesthatapproachthemotormanufacturingcompanieswillbepresentedwiththemotorproductsthatareavailablefromtheproductionlines.Theseproductsareillsuitedtowindpowerapplications.

Integrationofthealternatorintothewindturbineassemblyisagreatwaytocutthecostofthewindmill.Howeverdoingsochangesnearlyeverythingtheelectricmotormanufacturingcompanydoesorprovides.Thereforeunlessthemotorcompanyhappenstoownthewindmillcompanytheyhavelittleincentivetocooperateinthedevelopmentofsuitablealternatordesigns.ItisnotanaccidentthatGeneralElectricandSimensarebothelectricmotormanufacturingcompanies,andproducersoflargewindmills.

Severaldifferentsmallwindturbinecompanies,eachinthestartupmode,haveapproachedEmpireMagneticsInc.,seekingcosteffectivealternativestoavailableofftheshelfalternatorproducts.Havingworkedwiththesestandardalternatorproductstheyfind:

Thespeedrangeofthemotorsisnotmatchedtothewindturbinewhichrequiresgearingorothermechanicaladaptationswhichincreasecomplexityandcostwhilereducingefficiencyandreliability.Thevoltagefactorsofthestandardmotorsarenotinthecorrectrange,thepolecountsaretoolow,thepowerfactorsaretoohigh,magneticcoggingforcesaretoobig,theironinthemagneticcircuitcorrodesintheweather,themagneticforcesappliedtothebearingsshortenthelifeoftheturbine,andfinallythesmallcompanyhasnowaytoinfluencethecostofthealternators.Otherthanthateverythingisjustfine.

Photoofalternatormagnetsmountedtothehubofthewindturbine.

IntheWind-sailturbinedesign,themechanicalbearingsystemisplacedatthemiddleoftheassembly,wherethewindloadingonthetopoftheassemblyisapproximatelyequaltothatonthebottom.Thisarrangementinconjunctionwiththespecificbearingdesignresultsinverylowfrictioninlightwindconditions,exactlywhatweneededfortheintendedpurpose.

Aswescaleuptolargerturbinedesigns,thebearingsbecomemorecritical.Bearinglifeisdecreasedasthecubeoftheload,andthesquareofthespeed.Largerturbinesareheavierandbecausethediametersarelargerthesurfacespeedofthebearingisincreased.Toovercomethisproblemwehavedesignedpassivemagneticbearings.Suchbearingsarenotspeedlimited,theydonotwearout,andbasedonourdesigntheyarelessexpensivethanmechanicalalternatives.Theexactarrangementofthemagnetswebelievecanbepatented.FEAindicatesthemassofmagnetisreducedbyafactoroftwoascomparedtotheobviousapproach.Howeverthereisacompanythathaspatentedtheuseofmagneticbearingswithwindmills,andsoitwouldbenecessarytoreachanagreementwiththemforthecountrieswheretheyhavepatents.

AsthescientistsatMSRCfocusedontheexactshapeoftheairfoil,theydidextensivemathmodeling.Thiseffortresultedinhighefficiency,self-starting,bi-directionalairfoils,butalsoidentifieduniqueoperationalfeaturesasshowninthefollowinggraph.Thesefeaturesallowedustocreateacontrolsystemthatisspecifictotheturbineandbladedesign.Inthemiddleofthegraphisacurvedepictingthenon-lineareffectsonpoweroutputversusrotationalspeedoftheturbine,withrespecttothewindspeed.Thecontrolsystemtakesadvantageofthisfeaturetomaximizepoweroutputfromwindspeedsbelow3kw,butdeclinetogeneratepowerabove3Kw.Thissubtledistinctioniseasytomiss.Ifwedon’tgenerateextrapower,wedon’thavetheexpenseofdisposingofit.

Thewaytoobtainmorepowerinlightwindconditionsistomaketheturbinelarger,buttodosowithoutasignificantcostincrease.Fromtheoutsetweplannedtomaketheairfoilsbyalowcostmassproductionprocess,extrusionorpultrusionaretheobviouscandidates.Sowedesignedtheairfoilswithconstantcrosssectionsinordertoaccommodatealowcostmanufacturingprocess.Oncethemachinesaresetupandrunning,thebladecanbemadeinlongproductionruns,withsectionscuttolengthaftertheyexitthemachine.Thisfocusonamanufacturingprocessaswellasatechnicaldesigngivesustheflexibilitytomaketurbinebladesofdifferentlengthsatverylowcost.AllowingWind-sailtoprovidemorewattsperdollarinlightwindconditionsthanthecompetition.

Belowisaphotoofairfoilsandgraphicdepictingmanufacturingmethod.

Sinceourbladesarelowincosts,theturbineisarelativelylowcostcomponentascomparedtotherestofthewindpowersystem;oversizingtheturbinetogatherwindpoweravailablemostofthetime,whenpeoplewantit,providesmorereliableandmoreusefulpower,withoutagreatcostpenalty.Howeveravoidingthecostassociatedwithcapturingthepeakpowerrequiresstrictmanagementdiscipline.Humannatureandtechnicalanalysisofmomentaryorevenannualpowerproductiontemptsmanydesignersintotryingtocapturepeakpower,itisonlywhenabusinessmindedmanagerplacescostconstraintsuponthetechn