Post on 14-Jan-2016
European Wind Energy Conference
Milan, ItalyMay 7-11, 2007
Improving Wind Turbine Gearbox Reliability
Walt MusialNational Renewable Energy Laboratory
Golden, Colorado USAwalter_musial@nrel.gov
Coauthors: Sandy Butterfield and Brian McNiff
European Wind Energy Conference
Milan, ItalyMay 7-11, 2007
Observations on the basic problems
Actual life is below expected design life.
Problems are generic in nature.
Poor quality is not the primary cause.
Most failures initiate in the bearings.
Problems are more dependent on bearing
configuration than size.
European Wind Energy Conference
Milan, ItalyMay 7-11, 2007
Bearing Failure Observations
General adherence to design standardsISO 281:2007Proprietary codes prevent design
transparency.Bearing manufacturers are not equipped to
solve the problem on their own.No single, simple solution is expected.Collaborative approach is needed.Weaknesses in the design process are
suspected.
European Wind Energy Conference
Milan, ItalyMay 7-11, 2007
Possible Design Process Weaknesses
Missing Load Cases
Irregular or unanticipated bearing responses
Excessive flexibility of gearbox mount.
Non-uniform safety applied to gearbox
subcomponents.
European Wind Energy Conference
Milan, ItalyMay 7-11, 2007
Typical Wind Turbine Architecture
European Wind Energy Conference
Milan, ItalyMay 7-11, 2007
HubMain Low
Speed Shaft Bearing Trunnion
Mounts
Gearbox
Bedplate
Mainshaft
Typical Gearbox Mounting
European Wind Energy Conference
Milan, ItalyMay 7-11, 2007
Trouble Spots
1. Planet bearings2. Intermediate shaft-locating bearings3. High-speed locating bearings
1
3
2
European Wind Energy Conference
Milan, ItalyMay 7-11, 2007
Test Articles (phase I)
Test platform between 600-kW and 900-kW. 2 gearboxes with identical instrumentation.Upgrade both units to state-of-the art.
Cooling, filtration, gear finish, lubrication, and bearing types.
Measure External and internal loads and displacements.
Thermal measurementsCondition monitoringExpert failure analysis and forensics
European Wind Energy Conference
Milan, ItalyMay 7-11, 2007
Three Point Approach
European Wind Energy Conference
Milan, ItalyMay 7-11, 2007
NREL Dynamometer Specifications 2.5 MW power delivery Full power regeneration at 480/575/690 or 4160 volts
Torque input range 0 - 1.62 million N-m. Speed range from 0 - 2250 RPM ~500 kN non-torque shaft loads capacity. SCADA and automated torque/speed controls
European Wind Energy Conference
Milan, ItalyMay 7-11, 2007
Dynamometer Testing
Measure bearing responses to controlled load cases.
Increase load complexity and build confidence.
Develop non-torque load capability and simulate actual operating conditions.
Establish transfer functions between shaft loading and bearing responses.
European Wind Energy Conference
Milan, ItalyMay 7-11, 2007
Field Testing
Ponnequin Windfarm in Northern Colorado USA
Extensive measurements on a single turbine.
Characterize load events Correlate loads with
component internal gearbox responses.
Site-wide failures and statistics.
European Wind Energy Conference
Milan, ItalyMay 7-11, 2007
Drivetrain Analysis
Multi-body dynamic analysis of test article.
Codes: FAST, Simpack, LVR
Model bearing response under various load conditions measured in Dyno and Field.
Model drivetrain solutions with tuned model.
European Wind Energy Conference
Milan, ItalyMay 7-11, 2007
Summary
Bearing failures are contributing to fleet-wide
reductions in wind turbine gearbox life.
A comprehensive three-part program to
identify and fix weaknesses in the design
process was initiated at NREL.
A collaborative long-term approach is
required involving all stakeholders.
Panel Questions
Panel Questions 1
1. What is different with the Wind Turbine application compared to other industries
2. What efforts (technical) are happening with your part of the industry to improve reliability (changes, research, design tools etc)
3. Is there something in the design process that is lacking or needs more emphasis (loads description, rating methods, design tools
Panel Questions 2
4. Where do uncertainties exist in the loads, design, rating and system integration?
5. For prototype validation what should be tested/ validated/ verified to improve confidence in designs
6. What future research needs to be done to improve reliability