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