This presentation details how wind turbine gearboxes fail to meet 20-year design life and how the Gearbox Reliability Collaborative (GRC) is addressing the challenges

Oyague, F.

UNT Digital Library

NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.Presenter Francisco OyagueMay 23-26, 2010Dallas, TexasNREL/PR-500-48176Gearbox Reliability Collaborative Experimental Data Overview & AnalysisNational Renewable Energy Laboratory                                                                                         Innovation for Our Energy Future2Drivetrain and the Cost of EnergyWind turbine gearboxes fail to meet 20-year design life• Premature failure of gearboxes increases cost of energy– Turbine downtime– Unplanned maintenance – Gearbox replacement and rebuild– Increased warranty reserves• The problem:– Widespread– Affecting many OEMs– Not caused by manufacturing practicesNational Renewable Energy Laboratory                                                                                         Innovation for Our Energy Future3• Facilitate dialog among all parties– Designers and consultants– Suppliers and rebuilders– Operations and maintenance organizations• Understand gearbox response to specific loading– Pure torque, bending, thrust (dynamometer)– Turbulence (field)• Understand physics of premature failure of wind turbine gearboxes • Identify gaps in design process • Suggest improvements in design practices and analytical tools Field Test Dynamometer TestAnalysis• Load cases• System loads• Internal loads• Test plan• Test turbine• Test setup & executionGearbox Reliability Collaborative (GRC)• Test plan• Test turbine• Test setup & executionNational Renewable Energy Laboratory                                                                                         Innovation for Our Energy Future4Failure Database Condition MonitoringAccelerometerAcoustic emission sensorProximity probeFrequency range to  above 20 kHzPhoto Sources: ProvibTech, Machine Condition Monitoring Ltd, Physical Acoustics CorporationGearbox Reliability Collaborative (GRC)National Renewable Energy Laboratory                                                                                         Innovation for Our Energy Future5Gearbox RedesignGearbox redesign to reflect MW fleet• Floating sun• Bearing arrangement • Lubrication • Gearing micro geometry DOE-owned GRC gearbox design distribution• Detailed technical specifications• Drawings and solid models  • Material Round Robin Analysis• Standardized analytical approaches• Results from many commercial and in-house codes InstrumentationNational Renewable Energy Laboratory                                                                                         Innovation for Our Energy Future6• Relative motion– Planet carrier– Sun  – Planet  – Housing • Forces, moments on main shaft• Tooth load sharing between planet gears • Bearing roller load distribution• Temperature gradients of bearings• Planet bearing collective roller slip Planet Carrier MotionNational Renewable Energy Laboratory                                                                                         Innovation for Our Energy Future• Implemented 4 sets of proximity sensor• Machined Target surface• Monitor of axis motions and angular motionPlanet CarrierPlanet Target surfacePlanet Carrier DeformationNational Renewable Energy Laboratory                                                                                         Innovation for Our Energy Future• Target surface deformation captured by the proximity sensors• Deformation of planet carrier body correlated to planet pin misalignmentPlanet Carrier DeformationNational Renewable Energy Laboratory                                                                                         Innovation for Our Energy Future• Target surface deformation captured by the proximity sensors• Deformation of planet carrier body correlated to planet pin misalignmentAnalysis Versus Experimental Data • Finite element model validation using 75% rated power • Two gearboxes produced slightly different behavior• Boundary conditions are adjusted to account for the differences National Renewable Energy Laboratory                                                                                         Innovation for Our Energy FutureExperimental data Simulated resultsNational Renewable Energy Laboratory                                                                                         Innovation for Our Energy FutureGear Tooth Contact Stress ForceArea=LoadNational Renewable Energy Laboratory                                                                                         Innovation for Our Energy FutureGear Tooth Contact Stress ForceArea=LoadBearing Load National Renewable Energy Laboratory                                                                                         Innovation for Our Energy Future• Equivalent load location => Bearing load distribution• Life reduction of 8% due to gearbox manufacturing variability (planet pin misalignment only)Up-wind BNG Down-wind BNGNational Renewable Energy Laboratory                                                                                         Innovation for Our Energy Future14GRC Current and Future Work• Facilitation and communication between the various parties involved in the design process • Multi-fidelity analysis validation through a round robin approach• Acquisition of field and dynamometer test data for post-processing analysis• Evaluation of analytical assumptions and other assumptions imbedded in the design process• Implementation and population of database in order to truly understand the problem  National Renewable Energy Laboratory                                                                                         Innovation for Our Energy Future15GRC Current and Future Work• Long term– Produce multiple topical reports– Provide reference data set for future testing of analytical tools and analysis approaches– Provide support for standards updates • Redirect research and narrow focus by using the database statistics• Expand project to include full drivetrain study• Expand project to other drivetrain configurations

Gearbox Reliability Collaborative Experimental Data Overview & Analysis

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