vibration measurements in wind power turbines
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Vibration measurements in wind power turbines
Alex LollioNov, 2010
Agenda
• Why vibration measurements?• National Instruments solution
– Hardware– Software
• Positioning vs competition• Conclusions
Introduction:damage due to structural vibrations
• Resonance problems
• High mechanical stress
1940: Tacoma bridge disaster
Introduction:damage due to high rotational speed
2009: Denmark Wind Turbine Failure
• High rotational speed generates high vibrations
• High mechanical stress
Vibrations in wind power turbines
Example:blades imbalance problem
• Torque momentum• High vibration level
Mechanical stressNoise emission
10 kg
10 kg
10.1 kg
Possible causes: rotor, engines, blades, transmission
How to monitor the system vibrations?
Mounting a 3D accelerometer
• It is useful to monitor the machine condition and prevent faults
• It needs a PC or PLC to collect dataKey point : System integration
Agenda
• Why vibration measurements• National Instruments solution
– Hardware– Software
• Positioning vs competition• Conclusions
NI Hardware PlatformAp
plica
tion
Com
plex
ity
Channel Count
USB
cDAQ
PXI-Laptop
PXI
Multi-Chassis
The simplest NI hardware solutions
NI 9234 (4-channels, 24 bit IEPE, 51kS/s)
Price: 1564 €
Carrier USB 9162 Carrier WLS-9163
Price: 251 € Price: 443 €
Carrier ENET-9163
Price: 342 €
++
+
The best NI hardware solutionsNI cRIO-9025Real-Time Controller: 800 MHz, 512 MB DRAM, 4 GB Storage
Price: 4190 €
• Embedded controller runs LabVIEW Real-Time for deterministic control, data logging, and analysis
• 800 MHz processor, 4 GB nonvolatile storage, 512 MB DDR2 memory
• Dual Ethernet ports with embedded Web and file servers for remote user interfacing
• Hi-Speed USB host port for connection to USB flash and memory devices
• RS232 serial port for connection to peripherals; dual 9 to 35 VDC supply input
Software: LabVIEW Sound and Vibration Meas. Suite
• Vibration Level• Spectrum Analysis (baseband, zoom,
subset FFTs)• Frequency Response (broadband, swept-
sine, impact, shock-response)• Short-time Frequency Analysis (STFT)• Over 60 examples using both hardware
and simulated data• Hardware independent (but has example
support for all DAQmx devices)• UNI/EN standard
Price: 3887 €
Labview Order Analysis Toolkit:What is Order Analysis?
•Many noise and vibration signal components are directly related to running (rotating) speed
•Order analysis normalizes the measurements to the rotating speed to better dissect these signal components
• For analysis of mechanical systems with rotating components (engines, gearbox, rotors, turbines)
Example: Power Spectrum
Rotating Speed:60 Hz
(3600 RPM)
Rotating Speed:50 Hz
(3000 RPM)
Frequency components
shift with speed
change
Order Power Spectrum
Rotating Speed:60 Hz
(3600 RPM)
Rotating Speed:50 Hz
(3000 RPM)
Order components remain fixed with speed
change
Relationship of Orders and Faults
• We can diagnose machine faults by knowing the order:– Imbalance– Misalignment– Loose Coupling– Valve Noise– Bearing Defects / Wear– Blade Pass Frequency– Gear Mesh
Low Order
High Order
Overview of the Order Analysis Toolkit
• Calculate and examine rotational speed
• Measure power in the order domain as a function of rotational speed
• Extract individual orders• Measure magnitude and phase
of any order component as a function of rotational speed
• Present data in a waterfall, orbit, or polar plot
• UNI/EN standard
Resampling• Data is converted to angular domain from time domain
Resampling:post processing samples extrapolation
NI hardware acquire the signal using a fixed sampling rate:FS= highest RPM * highest order to measure * 2,56
Samples extrapolation(8 samples per period)
Interpolation type:
• Coerce• Linear (default)• Spline• Filter basedResult:
Sample at constant angle
Agenda
• Why vibration measurements?• National Instruments solution
– Hardware– Software
• Positioning vs competition• Conclusions
Positioning vs Competition• NI Strengths
– Less expensive per channel (NI: € 270-770; Others: € 770-3900)– More expandable – up to 5000 channels in a distributed architecture– Compliance with ANSI and IEC Standards – Competition will try to say we don’t
meet these standards – UNI/EN certification– More flexible software (LabVIEW support for custom analysis and mixed signal)
Competitor Field Strengths WeaknessesBruel & Kjaer, LMS
Noise and vibration
Turn-key software, modal analysis software
Very expensive, fixed functionality, limited expandability
Bently Nevada Machine condition monitoring
Turn-key software, machine protection certification
Extremely expensive, limited flexibility
Conclusions
• NI platform for vibration analysis is flexible and modular
• Easy to integrate into existing systems
• NI Sound and Vibration Measurement Suite is not hardware dependent
• UNI/EN cerfitication
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