from r&d to an industrial application · 01.11.2012 to 31.10.2015 qs-m grout quality assurance...
TRANSCRIPT
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 1
Offshore foundation monitoring – from R&D to an industrial application Andreas Nuber, Herbert Friedmann, Moritz Häckell, Bernd Wölfel, Peter Kraemer
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 2
We are experts in this world. It is our home. We support our customers with engineering services and products for the analysis, prognosis and solution of tasks in the fields of vibrations and noise. Vibrations and noise are almost always unwanted. Their reduction provides safety, prevents damage and avoids unnecessary costs.
Welcome to the world of vibrations, structural mechanics and acoustics
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 3
In which industries are we currently active?
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 4
Introduction
Extremely high operational demands due to a complex superposition of cyclic and stochastic dynamic loading from
• wind
• waves
• operation
Impact on
• Global stability
• Welding seams
• Failure of foundation is possible
• Regulations of BSH (German maritime authority)
• Support structures (Tower, foundation) have to be revised with respect to corrosion, cracks, scouring etc.
• Every tenth plant must be equipped with a SHM system (2007), frequent inspections are required (2015)
Due to costs a reduction of inspection effort is necessary!
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 5
UnderwaterINSPECT
Structural Health Monitoring of offshore foundations
01.11.2012 to 31.10.2015
QS-M Grout
Quality assurance and SHM of grouted joints on underwater supporting structures of OWT
01.11.2014 to 30.10.2017
UnderwaterINSPECT was funded by a grant of the German Federal Ministry of Economic Affairs, contract number 03SX345A
QS-M Grout is funded by a grant of the German Federal Ministry of Economic Affairs, contract number 03SX372A
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 6
Mode of Operation of a vibration based SHM system
Basic principle of the SHM system is the analysis of the structural response due to operational and environmental vibrations.
The linearized structural behavior can be described by the equation of motion:
Mass , Damping and Stiffness govern the dynamic behavior of the foundation.
Structural vibrations are an indicator of
• Stability,
• Stiffness,
• Wind- and wave loads,
• Operational loads,
• Mode of operation of a turbine.
The structural response can be measured in the form of deformations, vibration velocities or accelerations.
However, the frequency changes are very small: 0,5 % - 1 % 0.005 Hz - 0.01 Hz
Measurement of the structural response of a rotor blade
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 7
The Method
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 8
Damage Indicators
Stochastic Mathematics: Two Stochastic Subspace Identification (SSI) algorithms:
Covariance-driven Stochastic Subspace Identification algorithm, SSI-COV
Use in conjunction with output-only modal analysis or operational modal analysis, OMA Low order stochastic state space models derived from measured time histories. Changes comply with changes in the modes of vibration.
Null Space-based Fault Detection algorithm, NSFD
High order stochastic state space models derived from measured time histories.
NSFD method is more sensitive to structural changes as SSI-COV, but at the same time also to changes in the EOC. Therefore the compensation of the ambient conditions is even more challenging than in SSI COV.
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 9
Experiments in TTH, Test center for foundations in Hannover
Test of measurement technique basis for the following system development
Measurement data from
• Undamaged foundation,
• Operational loads,
• Peak loads,
• Changes in environmental conditions,
• damages
serve as a basis for the development of automatically operating algorithms for damage detection, for the compensation of EOC and for determining the sensitivity of the method. The following measurements were performed:
• Reference measurements, at the same time observations to soil degradation,
• Load variations, changes in the EOC,
• Loss of stiffness of the supporting structure, damage,
• Influence of marine fowling, changes in the EOC,
• Scouring, damage
• Misalignment by extreme loads, damage.
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 10
Experimental setup
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Reference measurement and soil degradation
• Excitation by a Shaker
• Remote control of the experiment
• Force: 400 N 350 N 250 N RMS
• Power spectral density Structural response due to excitation with white noise from 2 to 50 Hz
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 12
Soil degradation
Reference measurement shows significant changes in the first natural frequency of the pile at 4,3 Hz.
M. Link 2015: Hardening of the sediment; however piles are rammed!
Soil behavior is specific to the experimental set-up
Initial soil degradation
• Monopile installation by vibrations,
• No time for settlement,
• No water pressure,
• Incomplete water saturation of the sediment
• Higher Frequencies
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 13
Sensitivity with regard to stability of the foundation
Soil degradation and scouring obscured all other changes in the signals
For compensation specific signal analysis methods are necessary
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 14
Loss of Stiffness with the Pile
Reproducible structural damage is modelled by a flange with 20 screws between pile and tower:
Loosening of 2, 4 and 6 screws,
SSI-COV is based on the analysis of 4 natural frequencies; safe detection of 4 and 6 loosened screws.
NSFD is able to detect all damage levels with 2, 4 and 6 screws.
NSFD-based Indicator
SSI-COV based Indicator
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 15
Fouling
Restricted possibilities to simulate fouling with an experimental set-up like in TTH!
Special case: fouling in the tidal reach with low water.
Bio mass is hanging in the air additional mass of 4, 20 and 30 kg on a structure with a mass of about 1 t
SSI-COV is not able to detect such small changes of the mass satisfactorily
NSFD-Indicator is able to detect all changes
Additional mass of 4, 20 or 30 kg
NSFD-Indicator
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 16
Scouring
Scouring changes the depth of embedding into the sediment; the contact region between pile and sediment is reduced; experiments with 30, 60 and 80 cm depth of the scour.
Changings of the boundary conditions of a cantilever beam have a significant influence to natural frequencies
Initial soil degradation
Scouring of 5 cm depth can be detected!
Both indicators SSI-COV and NSFD are able to detect scouring very well
Problem: Obscuring other changes in the signals
NSFD-Indicator
SSI-COV-Indicator
Depth of scour 30 cm
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 17
Misalignment
Hydraulic forces for the simulation of maximum loads like gusts or waves with a 50 year recurrence period
Changings within the mechanical system is detected by SHM
It is possible to detect a misalignment of the pile using accelerometers;
however it is easier to use an inclinometer
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 18
UnderwaterINSPECT
Structural Health Monitoring of offshore foundations
01.11.2012 to 31.10.2015
QS-M Grout
Quality assurance and SHM of grouted joints on underwater supporting structures of OWT
01.11.2014 to 30.10.2017
UnderwaterINSPECT was funded by a grant of the German Federal Ministry of Economic Affairs, contract number 03SX345A
QS-M Grout is funded by a grant of the German Federal Ministry of Economic Affairs, contract number 03SX372A
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 19
QS-M Grout: Measurement setup and sensor positions
• Intended measurement levels
• Level 0 – below flange foundation pile
• Level 1 – above flange grout bottom
• Level 2 – In grout area
• Level 3 – below flange grout top
• Level 4 – above flange tower bottom
• Level 5 – above clamp
• Level 6 – below flange tower top
• Instrumentation has to be movable between test pit and test bed (level 1-6)
• Clamp for loading must be mounted during complete experiment
shaker
clamp for loading
grout
test pit
6x (3x2) SG Wölfel (15x)
1x 2D-inclinometer
15x (5x3) acceleration sensors
3x surface microphone
Level 0
Level 3
Level 2
Level 1
Level 4
Level 5
Level 6
test bed
120°
240°
0°
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 20
Installation of sensors
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 21
Industrial application of R&D results: Monitoring of offshore foundations
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 22
Wölfel CMS – communication concept
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 23
Wölfel Structural health monitoring – modular data analysis
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 24
Wölfel Structural health monitoring – online web portal
WEA-01
WEA-04
WEA-05
WEA-06
WEA-07
WEA-08
WEA-02
WEA-03
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 25
Wölfel Structural health monitoring – hardware (example)
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 26
Wölfel Structural health monitoring – hardware (example)
Transition Piece
acceleration &
inclination
Platform 3
acceleration
Platform 5
acceleration &
inclination
Overview Close-Up Position 145°
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 27
Wölfel Structural health monitoring – hardware (example)
acceleration
sensor
inclination sensor
acceleration sensor 22.5°
acceleration and
inclination sensor 202.5°
SG
SG
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 28
Selection of references
Experiences in the field of foundation and blade SHM
ALPHA VENTUS Foundation-CMS (Jacket, Tripod)
EnBW /SIEMENS CMS for dynamical behavior of offshore wind turbines
RWE / SENVION Foundation and Grout-CMS
IBERDROLA / ADWEN Foundation (Monopile, Jacket) and Grout-CMS
TENNET Monitoring Converter Platform
E.ON Continuous Condition Validation of offshore turbines
NORDEX Lifetime monitoring tower; Blade monitoring
ENERCON Blade monitoring
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 29
References Offshore Wind
© Wölfel 2016. All rights reserved. 7. GIGAWIND Symposium / Offshore foundation monitoring / CONFIDENTIAL HF/Nu, 02.03.2017 30
Wölfel-Group Max-Planck-Str.15 97204 Höchberg, Germany Phone: +49 931 49708-600 Fax: +49 931 49708-650 E-Mail: [email protected] www.woelfel.de
Dr. Andreas Nuber Phone: +49 931 49708-365 E-Mail: [email protected]
Thank you for your attention!