PSCAD-Based Modeling and Analysis of a Gearless Variable Spe

PSCAD/EMTDC-BasedModelingandAnalysisofaGearlessVariableSpeedWindTurbine

Seul-KiKimandEung-SangKim

Abstract—Thispaperpresentsdynamicmodelingandsimula-tionofagridconnectedvariablespeedwindturbine(VSWT)usingPSCAD/EMTDC,http://ponentmodelsandequationsareaddressedandtheirim-plementationsintoPSCAD/EMTDCaredescribed.Controllablepowerinverterstrategyisintendedforcapturingthemaximumenergyfromvaryingwindspeedandmaintainingreactivepowergenerationatapre-determinedlevelforconstantpowerfactororvoltageregulation.Thecomponentmodelsandentirecontrolschemeareconstructedbyuser-de nedfunctionprovidedintheprogram.Simulationstudiesprovidecontrolperformanceanddy-namicbehaviorofagearlessVSWTundervaryingwindspeeds.Inaddition,thesystemresponsestonetworkfaultconditionshavebeensimulated.Thismodelingstudycanbeemployedtoevaluatethecontrolscheme,outputperformanceandimpactsofaVSWTonpowergridatplanningordesigningstage.

IndexTerms—Gearlesswindgenerator,gridconnection,maxi-mumpowercapture,powerelectronicsinterface,reactivepowercontrol,variablespeedwindturbine(VSWT).

Fig.1.SchematicrepresentationofagearlessVSWT.

Id,IqMAXCPλOPTη

Pref,QrefVrefVrmsPFQlimitsSinvd-andq-axiscurrentatVSWTterminal[A]Maximumpowercoef cient

MAX

λwhereCP=CP(λOPT)

Electricalef ciencyofgeneratorandinverterRealandreactivepowertargets[kW],[kVar]Phasevoltagemagnitudetarget

PhasevoltagemagnitudeofVSWT(rms)Desiredpowerfactor

Reactivepowercapabilitylimits[kVar]Ratingofinverter[kVA]

LISTOFSYMBOLS

λωMR

VWINDPMρCPTMfBNP

RPMTURHiKTEθiωMωEEfIfVdcα

Pinv,QinvVinv,IinvVd,Vq

Tipspeedratio

Mechanicalspeedofwindturbine[rad/s]Bladeradius[m]windspeed[m/s]

Mechanicalpowerfromwindturbine[kW]Airdensity[kg/m3]Powercoef cient

Mechanicaltorquefromwindturbine[N·m]Electricalbasefrequencyofgenerator[Hz]Numberofpoles

Ratedspeedofwindturbine[rpm]Inertiaconstantofithmass[s]Shaftspringconstant[Nm/rad]

Electricaltorqueofgenerator[N·m]

Massangleofithmass(referenceongenerator)Mechanicalspeedofgenerator[rad/s]Electricalspeedofgenerator[rad/s]Fieldvoltageofexciter[V]Fieldcurrentofexciter[A]DClinkvoltage[V]IGBTswitchingsignal

Measuredrealandreactivepower[kW],[kVar]Measuredvoltageandcurrentofinverter[V],[A]

d-andq-axisvoltageatVSWTterminal[V]

V

ManuscriptreceivedAugust10,2004;revisedFebruary17,2005.Paperno.TEC-00235-2004.

DigitalObjectIdenti er

10.1109/TEC.2005.858063

I.INTRODUCTION

ARIABLEspeedoperationyields20to30percentmoreenergythanthe xedspeedoperation,reducespower uctuationsandimprovesreactivepowersupply[1].Fallingpricesofthepowerelectronicshavemadethevariablespeedtechnologymoreeconomicalandcommon.Suchwindturbinesystem,aswithothertypesofdistributedgeneration,ismostlyconnectedtodistributionfeeders.Thedistributedgenerationcannotconnecteasilytotheelectricpowernetworkwithoutconductingcomprehensiveevaluationsoncontrolperformanceandgridimpact.Stablegridinterfacerequiresareliabletoolforsimulatingandassessingthedynamicsofagridconnectedvariablespeedwindturbine.

PSCAD/EMTDCisanindustrystandardsimulationtoolforstudyingthetransientbehaviorofelectricalnetworks.Itsgraphic-baseduserinterfaceallowstheusertographicallyassemblethecircuit,runthesimulation,analyzetheresults,andmanagethedatainacompletelyintegratedgraphicalenvironment.Itscomprehensivelibraryofmodelssupportsmostofpowerplantacanddccomponentsandcontrols.Itprovidesthe exibilityofbuildinguser-de nedmodelseitherbyassemblingthemvisuallyusingexistingmodelsorbyutilizinganintuitivelygraphicaldesigneditorandwritingcodesinFortran,PSCADscript,CandMATLAB.Itprovidesapowerfulresourceforassessingtheimpactofnewpowertechnologiesinthepowernetwork[2],[3].

ThepurposeofthispaperistoprovidesimulationanddynamicperformanceandgridimpactanalysiscapabilityofagearlessVSWTbasedonPSCAD/EMTDC.TheschematicdiagramofthewindgenerationmodelisshowninFig.1.The

0885-8969/$25.00©2005IEEE

http://ponentsofaproposedsimulationmodel.

TABLEI

PARAMETERSFORWINDTURBINEM

ODEL

modelsystemiscomposedofa xed-pitchstallregulatedwindturbine,agearlessdirectdrivegeneratorandacontrollablepowerelectronicssystem,whichconsistsofasimpledioderecti erandasix-IGBTvoltagesourceinverter(VSI)[4].Agraphic-basedmodelsuitableforelectromagnetictransientstudieshasbeenproposedbasedonmathematicalequationsandpowerelectronicscontrolscheme.Thelargebaseofprogram’sbuilt-incomponentsanduser-de nedmodels,ifaparticularmodeldoesnotexist,havebeenusedformodelingtheVSWTcomponentsandcontrolscheme.SimulationresultsdemonstratethemodelingstudyprovidesareliableandusefulsimulationtoolforassessingthedynamicbehaviorofagearlessVSWTintegratedintopowersystem.

II.PSCAD/EMTDCBASEDMODELING

Fig.2presentsaschematicdiagramoftheproposedsimula-tionmodel,whichconsistsofthefollowingcomponents:

Windmodel;Windturbine;

Directdrivegenerator;Shaftdynamics;

Recti erandvoltagesourceinverter;andPowerelectronicscontrol.

semblingbuilt-infunctionsandlogiccircuitsprovidedintheprogram.B.WindTurbine

Windbladetorquefromwindspeedisdescribedbythefol-lowing(2)–(4)

λ=PM=TM

ωMRVWIND

13ρπR2CPVWIND2

(2)(3)(4)

2ωMPM15

==ρπRCP3.ωM2λ

Themechanicaltorqueobtainedfrom(4)entersintotheinput

torquetothewindgenerator,andisdrivingthegenerator.CPmaybeexpressedasafunctionofthetipspeedratio(TSR)λgivenby(5),[7]

π(λ 2)

0.00184(λ 2)β

13 0.3β

(5)

whereβisthebladepitchangle.Fora xedpitchtype,thevalueofβissettoaconstantvalue.TheTableIshowsparametersenteredfortheuser-de nedwindturbinemodel.CP=(0.44 0.0167β)sinC.Direct-DriveGenerator

Thecost,weightandmaintenanceneedsofmechanicalgear-ingplaceaseriouslimitationonfurtherincreaseofpowerratings.Direct-coupled,low-speedgeneratorsareunderdevel-opmentinresponsetotheseneedsandsomearealreadyinservice[8].Unlikecommonsynchronousgenerators,th …… 此处隐藏：23106字，全部文档内容请下载后查看。喜欢就下载吧 ……