presented by jens krieger offshoretage, 01.03.2018...
TRANSCRIPT
Health Monitoring of Offshore Wind Turbine
Structures: Lessons Learned
Presented by Jens Krieger
Offshoretage, 01.03.2018 bis 02.03.2018,
Warnemünde
Offshore Track Record
System implementation, concepts, data evaluation, structural health assessment, consultancy in the Offshore Wind Industry (Monitoring):
• OWF alpha ventus
• OWF Borkum West II
• OWF Nordsee 1
• OSS Baltic 2
• OWF Meerwind Süd/Ost
• OWF Butendiek
• OWF Baltic 2
• OWF Nordsee 1
• OWF Wikinger
• OWF Nordergründe
• OWF Hohe See
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SHM Authority Requirements
BSH Standard 2007 vs. 2015
2007 2015
…Representation of the
planned inspection of
the support structure by
a condition inspection
system (CMS) for at
least 1/10 of the offshore
wind turbines…
…In order to monitor
the overall behaviour of
the foundation
elements during the
operating
phase, parameters,
such as shifting,
deformation,
component stress and
frequencies, shall be
measured and recorded
(monitoring) in the area
of the foundation
elements at
representative
offshore wind turbine
sites…Source: BSH Standard Design, 2015
3
SHM Standards
VDI 4551 in progress: ‚Strukturüberwachung und Beurteilung von Windenergieanlagen und Plattformen‘
Vorsitz: Prof. Dr.-Ing. Werner Rücker
Content (preliminary):
• Aims and Tasks of SHM
• Inspection Strategy and Life Time Prognosis
• Support Structures and Modelling
• Periodic Inspections
• Loads
• Design Verification, Condition Monitoring, Damage Assessment
• Measurement Concept
• SHM Requirements
4
SHM – Example Concept
Global Monitoring Concept
• Global monitoring for robust structures
• Ambient Vibration Monitoring (proven technology)
• Model Based Observer for data interpretation
• Few sensors only
• Accessible positions
• Lower operational costs
The one monitoring concept does not exist. Implementation depends on monitoring aims.
acceleration
acceleration
inclination
5
Example Data: Correlations
Correlations give data plausibility and turbine behaviour
Wind Inclination
6
Example: Turbine Comparison, Finding the
‘Odd’ Behaviour
Three distance sensors monitor vertical
displacement in the grout connection
7
Similar structures in a wind farm
show similar behaviour
Example: Lifetime
9
Wind farm
comissioning
20 years. End of
planned lifetime
Start lifetime assessment early:
- Monitoring system is in good state and working
- No information about structure or measurement system is lost
- Original structure designer is still available
5 years
End of warranty
Lifetime
prolongation
Load Cycle Matrix Accumulated Fatigue Damage Lifetime Prognosis
Example: Hidden Reserves
10
Comparison of predicted fatigue damage
profile (design) and actual fatigue damage
of a TP (measured) for a period of 2 years of
offshore operation.
Example: Deviations from Design
Eigenfrequencies are used for design verification and damage
detection
11
Example: Machine Behaviour
Anomalies usually show in several parameters
Pitch algorithm adapted
8 12
Example: Periodic Inspection Support
Sensors can replace or supplement periodic
inspection tasks
13
Automatically
measured data
Data taken
manually
During periodic
inspection
Example: Oberservation Method (EC7)
• Structure inclination is used as indirect
parameter
• Data processing is used for
compensation of statistical loads and
environmental influences
• The use of a high quality inclinometer
allows the monitoring of extremely
small permanent deformations in the
soil
14
Picture source: BSH Standard
Design, 2015
20mm
0,03°
Monitoring of permanent deformation within the soil
Lessons Learned: Clear Aims Necessary
A focus on few aims lead to reduced sensor numbers and lower maintenance costs!
• Structure condition
• Structure integrity / safety
• Loadmonitoring (ULS, FLS, usability)
• Fullfill Authortity Requirements
• Reduce Periodical Inspection Effort
• Data for O&M / Asset Management
• Lifetime prolongation
• Hot Spot Monitoring
• Feedback for designer
15
Lessons Learned: Target Areas
16
Picture source: BSH Standard Design,
2015
BSH requires foundation soil
interaction to be monitored
Application of Observation Method
(EC7)
Grouted connections are subject to
ZiE procedure
Foundation-Tower is an important
contractual interface
Design limits of structure
For maximum project benefit the focus of SHM needs to be on technical
and contractual interfaces
Lessons Learned: SHM Timeline
Planning Installation O&M
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Wind farm
commissioning
End of warranty
period
Change of
ownershipDecommissioning
Wind Farm Lifecycle
SHM Activities
BSH requirement, ZiE,
Observation Method EC7
Lifetime Assessment
Periodic Inspection
suppport
As built status, current
status
Hidden defects
Contractual interfaces define the SHM activities timeline
Lessons Learned: Structural Integrity
Life time prolongation ispossible
The structures do deviate from
design
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Lessons Learned: Soil-Structure
Interaction
With high accuracy
inclinometers and
compensation algorithms
for statistical loads and
environmental influences,
it is possible to detect
permanent foundation
displacements of few mm.
Application:
Observation Method (EC7)
Fullfill BSH requirements
19
Picture source: BSH Standard Design, 2015
20mm
0,03°
Lessons Learned: SHM and periodic
Inspection
Periodic inspection supportis possible
Under water inspection is
expensive and dangerous.
BSH allows flexible
inspection concepts utilizing
SHM systems. Proven
concepts (e.g. risk based
inspection from offshore oil
and gas) can be adapted.
This is still rare.
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Source: API RP 581, 2008