Transcript Introduction to ANSI/AGMA/AWEA 6006

Improving Wind Turbine
Gearbox Reliability
Walt Musial
National Renewable Energy Laboratory
Golden, Colorado USA
[email protected]
Coauthors: Sandy Butterfield and Brian McNiff
European Wind Energy Conference
Milan, Italy
May 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, Italy
May 7-11, 2007
Bearing Failure Observations
General adherence to design standards
ISO 281:2007
Proprietary 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, Italy
May 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, Italy
May 7-11, 2007
Typical Wind Turbine Architecture
European Wind Energy Conference
Milan, Italy
May 7-11, 2007
Typical Gearbox Mounting
Hub
Main Low
Speed Shaft
Bearing
Trunnion
Mounts
Mainshaft
Bedplate
European Wind Energy Conference
Milan, Italy
May 7-11, 2007
Gearbox
Trouble Spots
1. Planet bearings
2. Intermediate shaft-locating bearings
3. High-speed locating bearings
3
1
European Wind Energy Conference
Milan, Italy
May 7-11, 2007
2
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 measurements
Condition monitoring
Expert failure analysis and forensics
European Wind Energy Conference
Milan, Italy
May 7-11, 2007
Three Point Approach
European Wind Energy Conference
Milan, Italy
May 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, Italy
May 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, Italy
May 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, Italy
May 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, Italy
May 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.
European Wind Energy Conference
Milan, Italy
May 7-11, 2007
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