LACflex:AeroelAstic

simulAtion softwAre

M o d e l l i n g · S i m u l at i o n · L o a d c a l c u l at i o n

overviewLACflex simulation software is an advanced platform for carrying out load calculations and wind turbine performance analysis and other analysis tasks. LACflex contains a number of functionalities:• Comprehensiveturbinemodeling• Onshore&offshoresimulation• Extendedpre-andpostprocessing• Flexibleresultsviewingandreportingoptions

LACflex is more than a standard application. Besides reliability and unprecedenteduser-friendliness,theprogramisalsocustomizabletoalargeextentinordertooptimallyfitcustomerspecificrequire-ments. LACflexisyourcustomizablesoftwaretoolusedtodesignreliableandeffectivewindturbines.At LACflex’scoreisanimprovedversionoftheFLEX5turbinesimulationcode.LACengineeringhasnumerousyearsofexperiencewithturbinedesign,loadcalculationsandloadanalyses.Thisexperi-enceconstitutesthebasisfordevelopingFLEX5intooneofthebestperforming and most comprehensive aeroelastic analysis software applications in the industry.

other toolsWind generatorWave generatorReport generator

modeling capabilitiesTurbinemodelingEnvironmentmodelingLoadcasedefinition

calculation toolsSimulation Post-processingLoadextrapolationLinearizationPerformance analysis

LACflex

LACflexisacommercialsoftwareapplicationwhichservesthepur-pose of aeroelastic analysis. It is widely used in wind turbine design phasefor:loadcalculations,controldesignandotheranalysistasksinvolving closed loop dynamic simulations. Thecoreoftheprogramisbasedonbasedonthethoroughlyvali-datedcode“Flex5”whichhasbeenusedintenselyintheindustryformorethan20years.LACflexisbuiltonmanyyearsofpracticalworkwithin the science of performing reliable aeroelastic simulations. LACengineeringhasaccumulatedextensiveexperienceintermsofprojectmanagement,administeringthecomprehensiveamountofgenerateddatainmodernloadcalculationaccordingtoIECedition3(onshoreandoffshore)andGLstandards.

LACflexcanbeeffectivelyappliedinwindturbinedesignprocessesfromtheinitialdesignloadcalculationsthroughcertificationofthewindturbine.Theprogramaddsvaluetothewindturbinedesignprocess from the initial conceptual stages through design and approvaltofinalcommissioningandimprovementoftheturbineoperation.Theuserisofferedatoolaffectingtheentirevaluechain,includingsiteevaluation,initialfeasibilityandconceptstudies,de-signloadcalculationsofallmajorcomponents,controllerdesignandoptimization,subsystemdesignandselection,rootcauseanalysisand improvement of turbine operation.

LACflexprovides:• efficient and fast calculating tool to perform various analyses and

optimization issues • design tool for onshore and offshore WTGs (wind turbine generators). • platform to design and optimize subsystems for optimal implementa-

tion• overall WTG performance optimization strategy. • aid in certification processes

Duetothehighdiversityandspecificityofissuesintheindustry,LACflexwasdevelopedtoeasilyadapttocustomerneeds.Theplatformcanbetailoredtointegratewithcustomerworkflowandsystems,thusprovidingaveryflexibletoolforWTGanalysisandde-sign.LACflexinterfacessmoothlywithDLLsenablingtheinclusionofrefinedsub-models(controller,pitchsystem,drivetrain,etc).

Comparedtoothercommercially-availableaeroelasticcodesonthemarket,LACflex:• has outstanding computational speed, allowing realization of multi-

ple simulations in a very short period of time. A full IEC load calcula-tion takes only a few hours from defined design basis to automatic generated load reports equal to more 30 times real time.

• supports low shifting costs from other codes through: an intuitive user interface developed by experienced engineers, offering the pos-sibility to import DLLs created in other widely available codes on the market.

• allows customization to a very deep level, becoming an optimum platform that efficiently meets the needs of each user individually

• comes with a large and flexible array of training options, varying from dozens of video tutorials, online remote desktop sessions, online meetings, internship-based seminars or hands-on intensive training with our most experienced engineers and developers.

ItisourstrongbeliefthatinvestinginLACflexwilladdvaluetobusi-nesses for many segments of the wind energy industry including OEMs,assetowners,subsystemsuppliersandwindenergyconsult-ants. Furthermore,theperformanceofthesoftwareisconstantlybeingimproved,thusservingbothmorediverseandmorespecificpur-poses.Inordertomaintainadynamicrelationtotheever-changingmarketneeds,LACengineeringdoesintensiveresearchandisinclosecontactwithLACflexuserswhosupplyfeedbackandcontrib-ute to the innovative nature of the software’s functionalities.

02

reliAble Designof effectivewinD turbines

03

moDellingcApAbilities

turbine modelingLACflexoffersacomprehensiveparameterizationofthewindturbinemodel,forinstanceselectionofactivedegreesoffreedom,aerodynamicmodelparameters,turbinegeometry,mechanicalsubsystems(e.g.pitchsystem,yawsystem,brake),controlsystemandwindclimate.Thisprocessmakesitpossiblefordesignerstodefinetheparametersnecessaryforacompleteandrelevantspecifi-cation of the wind turbine. Mechanical,electricalandcontrolsystemsaremodeledinsepa-rate modules and can easily be tailored to the customer’s needs or replaced by the customers own models.

04

Whendesigningawindturbine,thesimulationofturbineperfor-mance and prediction of dynamic loads and is one of the most importantanddifficulttasksinthecompletedesignprocess.Duetonon-lineardynamicbehavior,timedomainsimulationistheonly way to predict dynamics of turbines.

LACflexisanAero-Servo-Elasticcodedesignedtomodeldynamicbehaviorofhorizontalaxiswindturbines.Aero-Servo-Elasticityimpliesthatbothaerodynamic,controlandelasticforcesandtheirmutualinteractionaretakenintoaccountinthesimulation.Thestructuraldynamicsaremodeledusingrelativelyfew,butcare-fullyselected,degreesoffreedomusingshapefunctionsforthedeflectionsofthetowerandtheblades,whileusingstiffbodiesconnectedbyflexiblehingestomodelthenacelle,rotorshaftandhub.TheaerodynamicloadsonthebladesarecalculatedusingtheBlade-Element-Momentummethodincludingdynamicstallandwake models.

Theprogramrunsintime-domainandproducestimeseriesofsimulatedloadsanddeflections.Duetothedynamicmodelingconcepttheprogrambatch-executemanytimesfasterthanreal-time,whichisclearlyanadvantage,asacompleteloadbasiscomplyingwiththeIECcaneasilyamountto1000-2000distinctdesign load cases.

In addition to the rigorous aeroelastic modeling capabilities LAC-flexhasbuilt-infunctionalitiessupportingthecompleteloadcalcu-lationprocessincludingcomprehensivemodelparameterization,controllerdesignandperformanceanalysis,loadcasedefinition,postprocessing,dynamicstabilityevaluationandreporting.

Thewindmodelconsistsofbothdeterministicandstochastic(turbulent)wind.Thestationarywindmodelincludesshear,skewedandinclinedinflow,allIECgustsanduserdefinedfielde.g.whenreproducingmeasurements.Theturbulentwindmodelisfullythree-dimensionalandavailableturbulencemodelsareVeersandMannasrecommendedintheIECstandard.Theseaenvironmentincludesdeterministicandstochasticwavesand well as current model and tide model.Theprogramcansimulatemultidirectionaldistributionsofvariouswind and sea parameters and handles misalignment between wind and waves.

Load case definitionTheloadcasesinLACflexaredifferentoperationscenariosoftheturbine,whicharesimulatedtodeterminethecompleteloadhis-tory. LACflex load case designer module makes it easy to set up and manage load cases.

Propertiessuchassimulationtime,windconditions,seaconditionscanbedefinedforanentireturbinemodelorbeoverriddeninasingleloadcase.Inadditionoperationcommands,faultconditionssuchaspitchsystemfaults,sensorfaultsandelectricfaultetc.)canbedefinedforeachloadcase.

Multiplewindspeeds,yawerrors,windseeds,waveseeds,winddirectionsandwavedirectionscanbedefinedforasingleloadcaseandmakesiteasytoquicklysetupalargenumberofsimulations.Eachuniquecombinationcanbeselectedindependentlyforsimula-tion.

05

cAlculAtiontools

simulation LACflexhelpstheusertoanalyzethebehaviorofthewindturbinewhensubjectedtodynamicloading,suchaswind,wavesorearth-quakes.LACflexsimulationsruninthetime-domain,whichenablestheexaminationofWTGbehaviorunderdynamicloadingovertime.TheaerodynamicloadsonthebladesarecalculatedusingtheBlade-Element-Momentumtheory,whichisthefoundationforalmostallanalysesofturbineaerodynamics,asitdealswiththedetailedflowand loading of the blade. It provides an accurate analytical tool that can be applied in the wind turbine design process.

Thepredictionoflocalwindspeedonthebladeisfurtherrefinedusingdynamicstallandwakemodels,correctionforyawedinflow,towershadowandtiplosseffect,etc.Thecouplingbetweentheaerodynamicmodelandthestructural,elasticmodelallowstheusertosimulatethedeflection,velocityandaccelerationofthecompletewind turbine due to aerodynamic and inertial forces.

Simulated data with LACflexarestoredintimeseries,whichmakesitpossibletoexaminetheturbine’sbehaviorovertime.

Some of the standard outputs are: •Windspeed,winddirection,yawerror•Pitchangle,pitchspeed•Rotorspeed,generatorspeed•Forcesandmomentsatspecifiedbladeandtowersections•Forcesandmomentsonshaft,mainbearings,hub,mainframe,

pitch system•Drivingtorque,electricpower,aerodynamicpowerandloss.•Pitchactuatorstatesandsignals•Aerodynamicinformationalongblade(inflowangle,CL,CD,etc.)•Nacelleacceleration•Controlleroutputs:operationstate,torqueorpowerandpitchor

control voltage

Inaddition,itispossiblefortheusertodefinecustomoutputstoevaluate the loading of other subcomponents.Theoptiontorunmultipleconcurrentsimulationsmeansthatthealready fast LACflexsimulationscanbedoneevenquicker.

06

load extrapolationTheloadextrapolationmodulecomplieswiththelatestIECstandardandallowspredictionofextremeloadsanyoftheavailableturbinesignalsusingloadextrapolation.Themodulehasvariousoptionsforpeakextractionmethod,distributionfunctionsandconvergencecri-teria and has been matured during several load calculation projects involving approving authorities.

post-processingLACflexoffersawiderangeofhighlyflexiblepost-processingfacilities,enablingcustomerstospecifyrequirementstospecificpost-processingtasks.Post-processingcapabilitiessupporttheIEC61400-1,Ed.3standard.Thesimulatedoutputisprocessedtosuitspecificdesigntraditionswithinallsub-components,asgearbox,bearings,blades,foundation,etc.

performance analysisTheperformanceanalysismoduleenablestheusertoevaluateandoptimizethecontrollerperformancepriortoexecutingtheloadcal-culation.Thisisavaluabletooltoensurecorrectturbineoperationasevaluatedfrompowerproduction,pitchactivityandspeedvaria-tions. Performance analysis is used as integrated tool the controller development and tuning process.

linearizationThelinearizationmodulesenablescalculationofcoupledandanun-couplednaturalfrequenciesinstandstillandoperationofthecompleteturbinestructure.Thisallowstheidentificationofcriticalfrequencieswithrespecttotheloadinputandthusstructuraltailor-ingtoavoidresonanceeffects.

finite element substructureIn LACflex it is possible to simulate an integrated substructure aspartofthewindturbinemodel.ThismodelcanbecompletelydefinedinLACflex’sgraphicalinterface,wherethesubstructureisshownin3D.ThesubstructureconsistsofTimoshenkoand/orBernoulli-Eulerbeamelements.Themodelincludeswaveandcur-rentloading(Morisonequation)andhydrodynamicdamping.Thepropertiesofthesoilcanbedefinedaslinearsprings.

Advanced modeling interfacesLACflexprovideexternalinterfacetoanumberofsubsystems.Thisallowstheusertodevelopmoreenhancedmodelsofpitchsystem,drivetrain,generatororcontroller.Thesub-modelscanbedevel-oped in Simulink or other dedicated tools that supports DLL genera-tion. By integrating sub models of e.g. pitch system into LACflex it is possible to make closed loop simulations and determine the influenceofthepitchsystemperformanceontheturbineoperationor to derive signals from the system to determine e.g. wear.

reportsThereportgeneratorallowsfastgenerationofreportsdocumentingturbinemodel,designloadcasesandloads.ThegeneratedreportsensuredaneffectiveandqualityassureddocumentationandthereportssatisfytherequirementsdefinedintheIECandGLcodesforcompleteandcertifiableloadcalculations.Thereportgeneratorhasvariousoptionsforgeneratinguserdefinedreports.

sub-systems

Dllinterface LACflex

07

technology transfer and trainingTrainingandtechnologytransferisprovidedbytheLACengineeringexperts,whohaveover50yearsofexperiencefromR&Dworkforsome of the leading companies in the industry and have profound experiencewithsystemsimulation,loadcalculationandperfor-mance analysis.

Inordertoprovideourcustomerswiththeknow-howtoobtainareliableandeffectivewindturbinedesign,technologytransferincludesanassessmentofthecustomer’sneedsandrequirements.Basedontheassessment,LACflexcanbecustomizedtofitthecustomer’sneeds,bye.g.individualizingmodelingofspecificmechanicaldesignorcontrolstrategy,orcustomizingpre-andpostprocessing facilities.

As part of the LACflextechnologytransfer,LACengineeringofferscustomer-specifictrainingcoursesfornewusersofthesoftware.

Dependingonthecustomer’srequirements,trainingcoursesareheldon-siteorattheLACengineeringpremisesinHinnerup,Den-mark. Astandardtrainingcourserunsfor3workingdaysandcanbesup-plementedaccordingtocustomerrequirementsandambitions.ThetrainingcoursewillincludelecturesonLACflex and its func-tionsandtheparticipantswillgethands-onexperiencewithLAC-flex,underthedirectsupervisionofourexperiencedengineersandsoftware developers.

LACengineeringApSBogøvej158382HinnerupDenmarklAcengineering.comPhone:+4587622277Fax:+4586986961Email:mail@lacengineering.com