Investigation of Oil Conditioning, Real-time Monitoring and Oil ...
Investigation of Oil Conditioning, Real-time Monitoring and Oil Sample Analysis for Wind Turbine
Transcript of Investigation of Oil Conditioning, Real-time Monitoring and Oil Sample Analysis for Wind Turbine
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Investigation of Oil Conditioning, Real-time Monitoring and Oil Sample Analysis for Wind Turbine Gearboxes
Shawn ShengSenior Engineer, NREL/NWTC
AWEA Project Performance and Reliability WorkshopJanuary 12-13, 2011
San Diego, California
NREL/PR-5000-50301
Outline Introduction
• Condition monitoring (CM) for wind turbines• Wind turbine gearbox• Oil conditioning and real-time monitoring• Oil sample analysis
Case Study • Dynamometer test setup• Results
Observations and Recommendations for Practice
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DO
E 1
.5 M
W W
ind
Turb
ine
/PIX
1724
5
NREL 2.5 MW Dynamometer /PIX16913
CM for Wind Turbines Drivetrain
• Main bearing • Gearbox• Generator
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Typical CM Techniques• Acoustic Emission or
Vibration• Oil
Rationale• Different failure modes
require different monitoring techniques
• Examples: subsurface cracks in gear and bearing components, water in lubrication oil
Oil-based techniques• Gearbox only
Main components• Gears • Bearings • Oil
Some failure symptoms[1-3]
• Oil contamination: dirt, wear debris, water, wrong oil, etc. • Oil degradation: additives depletion, oxidation, base stock
breakdown, etc. • Oil and lubrication system performance parameter change:
temperature, pressure, etc. • Elevated vibrations: misalignment, imbalance, subsurface and
surface cracks, etc.
Wind Turbine Gearbox
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Real-time Oil Condition Monitoring Objectives
• Monitor lubricant contamination and degradation• Detect gear and bearing components deterioration• Lubrication system functionality monitoring
Typical Practices• Particle counts: total counts, ferrous and nonferrous in different
size bins• Oil condition: acidic level, water content, etc. • Temperature and pressure (normally part of turbine SCADA
system)
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Oil Conditioning Objective
• Keep oil dry and clean[4]
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Typical Practices[1,2,5]
• Pre-filter: remove initial contaminations in new oil• Inline filter: remove large particles normally down to 10 µm• Offline filter: remove fine particles normally down to 3 µm• Breather for moisture and contamination prevention • Heat exchanger for lubricant temperature control
Oil Sample Analysis Objectives
• Monitor parameters not covered by real-time instruments• Elemental analysis to pinpoint failed components• Assist root cause analysis • Evaluate the functionality of conditioning devices
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Typical Parameters[6]
• Particle counts• Water content• Total acid number• Viscosity• Particle element identification
Dynamometer Test Setup Oil Conditioning
• Pre-filter new oil with a 3 µm filter• Inline filter loop two stage filtration: 50 µm and 10 µm• Offline filter loop continuous filtration: 3 µm• Breather• Heat exchanger
Real-time Monitoring• Inline filter loop: particle counts, greater than 300 µm, sensor K1 in later
slides• Offline filter loop
o ISO 4406 (1999) cleanliness levelo Particle counts: greater than 45/50 µm for ferrous and 135/150 µm for
nonferrous, each type divided into five bins, sensors K2 and K3 in later slideso Oil condition (total ferrous debris, temperature and relative moisture, quality:
reflect changes caused by water and acid levels)
Periodic oil sample analysis• Beyond typical practices mentioned earlier
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Test Setup: Lubrication Diagram
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Results: Oil Cleanliness Level
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Increases when generator speed ramps up Decreases during generator shutdown and the use of a
continuously functional lubricant filtration system Potentially useful for controlling the run-in of gearboxes
Results: Oil Condition
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Units • Moisture - %• Quality - customized
unit, 0 (new oil) to 100 (worst quality)
• Total ferrous debris -ppm
Results did not show substantial changes• Might be due to the short operational time and mild
operational conditions
Results: Particle Counts
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0100200300400500600700800900
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Throughout the test period K1 (left top), K2 (left
bottom) and K3 (right top) Trends are similar, though
particle counts vary
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Results: Particle Counts (Cont.)
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0
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3313
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1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106
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Throughout the 25% rated load test
K1 (left top), K2 (left bottom) and K3 (right top)
Horizontal axis corresponds to time
Results affected by sensor locations
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Results: Oil Sample Analysis
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Particle counts: important to identify particle types[7]
Analysis ResultsReference Limits
Element identification
Performance Evaluation: Oil Conditioning
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Water:o Reference oil: 52
ppmo All samples: less
than 32 ppm ISO Cleanliness Level
o Dropped after the test at one loading level is completed with the filtration system left running
Breather and filter are doing their jobs
0
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pm)
Sample
Observations
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ISO 4406 cleanliness level measurement appears useful for controlling run-in of wind turbine gearboxes
Particle count appears effective for monitoring machine and oil condition, but is affected by sensor mounting locations
If location is appropriate, similar trends in particle counts between the offline filter loop and the inline filter loop can be obtained
Periodic oil sample analysis potentially helps pinpoint failure components and root causes
Particle counts obtained through oil sample analysis need attention on identifying particle types
Oil conditioning equipment is useful to keep oil dry and clean
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Recommendations for Practice
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Combine oil with vibration or acoustic emission-based techniques
Take care of not only symptoms, but also root causes Oil Conditioning:
• Pre-filter, inline and offline filters, breather and heat exchanger
Real-time Monitoring• At minimum, monitor particle counts in either inline or offline filter
loop
Oil sample analysis • Regular sampling to monitor key parameters: particle counts,
viscosity, water, total acid number • In-depth analysis when real time instruments indicate abnormal
scenarios: elemental spectroscopy
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References
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1. M. Graf, “Wind Turbine Gearbox Lubrication: Performance, Selection and Cleanliness”, 2009 Wind Turbine Condition Monitoring Workshop, Oct. 8-9, 2009, Broomfield, CO.
2. J. Stover, “The Roadmap to Effective Contamination Control in Wind Turbines”, 2009 Wind Turbine Condition Monitoring Workshop, Oct. 8-9, 2009, Broomfield, CO.
3. A. Toms, “Machinery Failure and Maintenance Concepts”, presented at the GapTOPSCBM training course, Nov. 16-18, 2010, Pensacola, FL.
4. E. Ioannides, E. Beghini, G. Bergling, J. Goodall Wuttkowski and B. Jacobson, "Cleanliness and its importance to bearing performance”, Lubrication Engineering, 49(9), pp. 657-663.
5. R. Errichello and J. Muller, “Oil Cleanliness in Wind Turbine Gearboxes”, Machinery Lubrication, July/August, 2002, pp. 34-40.
6. D. Troyer and J. Fitch, Oil Analysis Basics, Noria Corporation, Tulsa, OK, 2001. 7. W. Herguth, “Gearbox Reliability Collaborative Dynamometer Test Results”, NREL GRC
All Member Meeting, Feb. 2-3, 2010, Golden, CO.
Thank you!
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HC Sorensen, Middelgrunden Wind Turbine Cooperative/PIX17855