Copyright © TWI Ltd 2014
Jesus Jimenez
Bristol – 29th January 2015
Integrated Condition Monitoring System for Tidal Energy Generators
TWI Ltd
Copyright © TWI Ltd 2014
Presentation Outline
Introduction Design of a Tidal Device Mock-up
Techniques - Sensors
Experimental trials
Vibration vs AE results
Underwater tests (Video)
Operational demonstration (Video)
Q&A&Demo
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Introduction
Maximise tidal generator availability time
Minimise life cycle maintenance costs
Condition Monitoring using
AE and Vibration Analysis
Detect faults in early stages
Low cost repaired at
scheduled maintenance works
To analyse reliability of tidal devices
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Drive train mock up has been developed to validate the Condition Monitoring System
Designed to generate noise and vibration representative of a full scale tidal power system
A pair of motor and gearbox are used to represent the tidal turbine drive train both in healthy and damaged conditions.
Driving rotors to replicate operational loadings when under water.
Design of a Tidal Device Mock-up
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Design of a Tidal Device Mock-up
Orders Frequency (Hz)
Shaft 1 1x 24.47 Hz
Shaft 2 0.63x 15.36 Hz
Shaft 3 0.066x 1.62 Hz
Shaft 4 0.014x 0.35 Hz
GM Stage 1 27x 660.79 Hz
GM Stage 2 6.3x 153.65 Hz
GM Stage 3 0.92x 22.64 Hz
3 stages Gearbox
3 phase motor 750W
Motor and Gearbox
Controlled by VFDs
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Design of a Tidal Device Mock-up
System features
- To replicate real loadings by driving the three blades - Loads proportional to the flow speed and the rotor speed - Apertures to create misalignment if necessary
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Acoustic Emissions are defined as transient elastic waves generated from rapid release of strain energy caused by deformation or damage within or on the surface of the material.
Monitoring Techniques
Acoustic Emission (AE) Vibration Analysis (VA)
Relates to the motion of a body regarding a reference point (centre line of a shaft). It is a result of an excitation force and may be random or periodic.
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Sensors
Vibration Sensors - Accelerometers Acoustic Emission Sensors
Performance tested underwater
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Establish a correlation between AE and Vibration signals with the condition of the gearbox deteriorating
Experimental Trials
Case 1: Healthy Motor
Case 2: Lubricant Removal– Oil starvation
Case 3: Addition of 4g Iron Oxide Particles– Debris
Case 4: Addition of 12g Iron Oxide Particles – Debris
Case 5: Induced Gear Teeth Defect – Macro-pitting
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Experimental Trials
Case 1: Healthy Motor
Case 2: Lubricant Removal - Oil starvation
• Rotational Frequency: 50 Hz. • Healthy motor without any kind of defect.
• Rotational Frequency: 50 Hz.
• Remove the oil from the gearbox. • Run the motor for 15 min prior to acquiring data. • Start acquiring AE and Vibration data.
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Experimental Trials
Case 3: Addition of 4g Iron Oxide Particles - Debris
Case 4: Addition of 12g Iron Oxide Particles - Debris
• Rotational Frequency: 50 Hz
• Refill the gearbox with clean oil.
• Introduced debris gradually in the area where the gears mesh.
• It was done with the motor running at very low speed to spread them homogeneously.
• Iron Oxide particles as debris
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Experimental Trials
Case 5: Induced Gear Teeth Defect – Macro-pitting
The seeded defect was
introduced on the tooth
Development of higher damage
levels (still low) creating
macro-pitting scuffing
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AE Results
- Low amplitude due to attenuation from bearings and gears to the case and lubrication - Continuous noise - No discreet AE events
Healthy condition AE signal
Faulty condition AE signal
FFT of filtered AE Signal
- Waveform acquired with high amount of debris - Discrete AE event generated by abrasion of the particles
- Activity 30 – 160kHz
AE event
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Vibration Results
Fast Fourier Transform
1x Trending
- High speed shaft frequency (1x)
- Second Harmonic of the main frequency (2x)
- Changes occurring in the 1x peak level as the level of damage in the gearbox is higher - Increase in the peak amplitude - More sensitivity in the last two scenarios
1x
2x
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AE – Better Quantitative Results
Vibration – Better Qualitative Results
Comparison AE - Vibration
Damage Level
Vibration Progress AE Progress
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Underwater Tests
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Operation Video
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Conclusions and next steps
The REMO technology has proved its capabilities to detect machinery faults at early stage which can lead to financial benefits for O&M operations in Tidal Energy Devices.
Further failure mechanisms specific to Tidal Energy systems can be under control using parallel technology solutions developed by TWI.
Feedback, awareness and guidance from industry developers will help to increase the TRL for commercialisation.