FWP 2017 l Guillaume DAMBLANS, FEM “Drawing on experience from fixed offshore wind, what are the technological challenges for substations and connections used for floating wind”

1. EXPORT DYNAMIC CABLE, A CRITICAL COMPONENT:
CONTEXT, FEEDBACK, STATE OF THE ART AND INVESTIGATIONS

2. #FWPAtlan*c
GUILLAUME DAMBLANS
TECHNOLOGICAL RESEARCH PROGRAM MANAGER

3. 3
FRANCE ENERGIES MARINES, THE MRE RESEARCH INSTITUTE
Key Facts
A team of 20
research
scien*sts,
engineers and
admin staff
10 M€ co-
financing
budget for
projects
2015-2017
20 projects
completed
or in
progress
A roadmap based on European SETPLAN objectives
4 Research programs
Our model
Coastal
regions
and
overseas
Research
labs
Industrial
groups
SME
Tools & Method
for site
Characteriza*on
Technology
Design Tools
for MRE
Applica*on
Array
Architecture
& Network
Integra*on
Environment
&
Socio-Economic
Impact
4 Research
Programs

4. 4
EXPORT DYNAMIC CABLE: A CRITICAL COMPONENT
§ Feedback from fixed wind turbine farms
§ Feedback & differences with O&G industry
§ FEM inves*ga*ons: The OMDYN project
§ Sensi*vity to marine growth
§ Fouling: Cable-environment / Environment-cable impact ?

5. 5
FIXED WIND FARM: AN LCOE DRIVER
§ impac*ng Installa*on & maintenance costs (LCOE)
§ « 80% of European wind farm insurance claims are related to export
cable »
§ Despite the fact that:
à Sta*c cable
à Par*ally or completely buried
§ The Carbon Trust (February 2015), ‘Cable burial risk assessment methodology – guidance for the preparaIon of cable burial depth
of lowering soecificaIon’ CTC 835’

6. 6
O&G INDUSTRY: LEARNINGS & DIFFERENCES
Oil & Gas FWT
Smaller floater
Stronger seas
Shallow water
Higher floater mo*ons
Higher wave kinema*c
Higher cable layout sensi*vity
Higher cable dynamic
Higher thermal
and electrical effects
MT to HT
REX:
LT – Low power cable

7. 7
STATE OF THE ART- DYNAMIC CABLE DESIGN
Strong cable dynamic Strong thermal & electrical influence
Today (cumulated damage approach) Coupled cycles in opera*on
1 - Electrical cycles
?
2 - Mechanical cycles
- IdenIfy coupling effects;
- Level of each contribuIon
- Propose adapted experimental and
numerical approaches
OMDYN Objec*ves

8. 8
OMDYN: A MULTI-PHYSICS COUPLING ANALYSIS
Iden*fied Impact
Poten*el Impact
Negligable Impact
Unknown Impact
Global
Local
FreYng
Thermal effect: mechanical
proper*es, pre-stress, s*ffness
Thermal expansion of
components higher in water
Water treeing: sensi*vity to trac*on/
compression
Intensity varia*on due to local compression
Corrosion by fre^ng
Screen displacement
à di-electric field

9. 9
THERMO-MECHANICS / HYDRODYNAMICS
FOWT 2017
Mechanical issue: Address global dynamics and assess local components fa*gue
Source: ECN,
CNRS
Basin campaign: Calibra*on of hydrodynamic loads
Thermo-Mechanical coupling?
Mul*-physics
computa*ons
Coupling concentrated within
a phase
• Analy*cal Model
JoliCoeur/Cardou model
• Valida*on
Finite Element
• Fa*gue Analysis
Rainflow: S/N curve + local model
Iden*fy an accurate local model

10. 10
SENSITIVITY TO MARINE GROWTH – STATIC IMPACT
Es*ma*on of the fouling influence on cable
M in water : 21 kg/m
Min air : 37 kg/m
Naked cable
133 kg/m
Colonized Cable
3.6
39 kg/m
1.8
Data used for es*ma*on (industry and DNV) (30
MW) :
• D = 142 mm
• M in air = 37 kg/m
• M in water = 21 kg/m
• Thickness MG up to 100 mm
• Norme DNV : ρmussel = 1325kg/m3? © Université de Nantes, Moules bleues
Sta*c Impact
à Observed density of organic species, recovery % (area,
secon), open or closed mussels?
Cable installa@on
Too much buoyancy
Too low buoyancy
Floater
Fond

11. 11
Heterogeneous
lineic mass
distribu*on
SENSITIVITY TO MARINE GROWTH – DYNAMIC IMPACT
- Iner*a loads increase
- Lower natural mode
94 kg/m
Iner*a load 5.8
Ma: 16 kg/m
Roughness
In-situ In-situ Numerical
Excentricity
Li4
U Fd’
FL
Heterogeneous sec*on mass distribu*on
- Possible fluid/structure instabili*es
(Gallop)
Picture: Tacoma Bridge (1940)

12. 12
SENSITIVITY TO MARINE GROWTH – THERMAL IMPACT
§ Skin T°C ≈ ambiant T°C in water only
§ Possible fouling scenario?
T0
Cable installa*on–
High thermal
convecIon
T1
Biofilm
coloniza*on– Weak
impact on thermal
convecIon?
T2
Macrofouling
coloniza*on –
Insula*on effect?
Impact on Thermal
convecIon? T3
T3
Fouling
maintained?
Fouling death or
disappearance?
?
T3

13. 13
FOULING: CABLE-ENVIRONMENT / ENVIRONMENT-
CABLE IMPACT ?
§ High design impact / Posi*ve impact: Reef effect
§ Mul*-disciplinaries science
© Joe Platko, New-York Times
© Université de Nantes
ABIOP
Accoun:ng for BIOfouling through established
Protocols of quan:fica:on
(Nolwenn Quillien, biologist research fellow
@ FEM)

14. 14
FOULING: CABLE-ENVIRONMENT / ENVIRONMENT-CABLE
IMPACT ?
§ Eletromagne*c impact?
Insula*on shield:
Faraday shield?
?
AC: 20μT
DC : 170μT
Source: Normandeau Associates, Inc « Effect of EMFs from Undersea
Power Cable on Elasmobranchs and Other Marine species
Magne*c field buried cable

15. 15
FOULING: CABLE-ENVIRONMENT / ENVIRONMENT-
CABLE IMPACT ?
FEM inves*gates the eletro-magne*c field impact of sta*c cable on
benthic communi*es:
Ø Sta*c cable - 3 sites (SEMREV, Brehat, Jersey)
Ø Bas*en Taormina, PhD FEM/IFREMER
SPECIES project
(Submarine PowEr Cables Interac:ons with Environments & associated Surveys)
Reef & Reserve
Effects
EMF Field
Temperature
field
ü Ini*al state already defined
ü Opera*onnal state defini*on is on-going

16. #FWPAtlan*c
THANK YOU FOR YOUR
ATTENTION
QuesIons?
THE FEM/ANR PROJECTS MENTIONED HERE BENEFITED FROM BOTH FRANCE ENERGIES MARINES FINANCING AND STATE AID MANAGED BY THE NATIONAL
RESEARCH AGENCY UNDER THE INVESTMENTS FOR THE FUTURE PROGRAM BEARING THE REFERENCES
OMDYN: ANR- 10-IED-0006-09 ABIOP: ANR- 10-IED-0006-21 SPECIES: ANR- 10-IED-0006-17