Laboratory test of FBG interrogators for wind turbine blade monitoring
Transcript of Laboratory test of FBG interrogators for wind turbine blade monitoring
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www.ecn.nl
Load measurements of bladesFibre Optics, ready for implementation?
Theo VerbruggenWind Turbine Condition Monitoring Workshop, October 8-9, 2009
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Contents
• Applications• Principles• Suppliers• Tests• Hardware developments• Software developments• Conclusions
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Applications of blade load measurments
• Load measurements for certification
• Turbine control• Blade monitoring• Operation and
maintenance
Blade load measurements can be used for :
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Principles of FBG-based measurements
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Principles
TDM: Time Division multiplexing
WDM: Wavelength Division Multiplexing
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Suppliers
• Smart Fibres TDM
• Insensys TDM
• HBM WDM
• (Micron Optics) WDM
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User experienceWhat is demonstrated…
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User experienceOr even more...
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User experienceAnd this are the details….
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User experience
•Inaccuracies in strain•Large differences foropposite locations
•Spikes / missing data•Strain modulation on temperature measurements
•Unreliable instrumentation•Complex repair due to required skills and tools
•Long installation time Still promising!But how to proceed?
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Still promising!
But how to proceed?
• Selection of reliable interrogator which meets requirements for in house developments and on site testing
• Development of user friendly sensor assembly, suitable for on site installation
• Development of user friendly data processing and interface
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Selection of interrogator
• Accuracy / resolution / long term stability
• Thermal sensitivity• Acceleration / environmental
conditions• Stability during operation /
polarization effects• Reliability / robustness
Reference grating (AOS)
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Accuracy / resolution
Single micro strain simulator
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Thermal sensitivity
Climate room
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Acceleration
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Polarization
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Remarks interrogator • Required accuracy not ensured• Long term stability not ensured• Thermal effects found• Acceleration effects minimal• Polarization effects (Strong!)• Reliability / robustness• Strong sensitivity for Bragg grating properties• Strong effects due to attenuation
But we made our choice for our sensor development
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Sensor developments
• Complicated installation- Skilled personnel / not certified- Special tools
• Time consuming- Gluing process- Curing time and fixation
• Result- Not robust- Prone to damage
Experience:
• Inaccuracies- Strain- Temperature
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Sensors development
Requirements: • Life time > 20 years• Easy installation• No drift• Temperature compensation• No (re-)calibration• Easy replaceable• Robust
These requirements are met by the ECN sensor development
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Software development (Blade monitoring)
Purpose• Fully automatic• Very limited data to be
stored• Robust to measurement
faults• Applicable for various
platforms• Applicable for various
turbines• Auto-reporting / warning• Friendly user interface
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Conclusions
• Load measurements are essential for various wind applications
• Fibre Bragg grating is still promising and still expensive
• Users friendly components still required• Data processing / reduction essential for
monitoring applications
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Thank you for your attention!