ring tem - sut | society for underwater technology f d n d nes cs on 7 d n : an w on ng gues x : nci...
TRANSCRIPT
DNV GL © 2015 SAFER, SMARTER, GREENERDNV GL © 2015
Floating wind turbines: a large range of engineering disciplines in a single system
1
SUT Evening Meeting, 3rd November 2016 at Imperial College, London
Ricard Buils Urbano
DNV GL – Energy Advisory, Turbine Engineering
DNV GL © 2015
Contents
Introduction to DNV GL
History, recent and future achievements
Technology summary
Market predictions and developments required
Design stages of floating wind
Conclusions
2
DNV GL © 2015
Introduction to DNV GL
3
DNV GL © 2015
DNV GL experience for the offshore wind industry
4
DNV + GL + KEMA + Nobel Denton + Garrad Hassan =
DNV GL Energy
The world’s largest certification and advisory firm in renewable energy
DNV GL © 2015
DNV GL Energy Advisory – Floating wind expertise
5
ENERGY
RENEWABLE
CERTIFICATIONRENEWABLE
ADVISORY
DNV GL © 2015
DNV GL Energy Advisory – Floating wind expertise
6
RENEWABLE
ADVISORY
Support from Concept to Verification, with design support in all areas and stages of the concept design, from blade tip to the anchor, including integrated coupled analysis of the whole system.
Support in technical due diligence
Several teams of engineers working in Bristol, Netherlands, Høvik, China, etc.
DNV GL © 2015
Strategic Decision Support
Third Party
Analysis
Concept Design Support
Software
The Required Push in Floating wind
7
1-2
2-3
3-5
5-6
6-8
8-9
Most
appropriate
to lower TRLs
Most
appropriate
to higher
TRLs
Appropriate
to all stages
along the
TRL
Technolo
gy R
eadin
ess L
evels
DNV GL © 2015
Turbine Engineering Support
8
Engineering excellence at the service of wind energy and marine renewables technology
Key services:
Technology evaluation
Design load analysis
Control system development
Mechanical engineering design support
Wave & tidal technical services
DNV GL © 2015
Knowledge transfer: tools and training
Device modeling Array modeling Training courses
We empower our customers to enhance their own capability
9
DNV GL © 2015
History, recent and future achievements
10
DNV GL © 2015
Brief history of floating wind:
1970’s: early concept by Professor E. Heronemus
1990’s: first small scale tests
2000’s: 10-100 kW range
2010’s: several 2 – 2.5 MW prototypes tested
Technical feasibility has been demonstrated now
Current focus: increase TRL and reduce CoE
DNV GL © 2015
Key recent milestones for floating wind technology
2013: Fukushima Compact Semi 2MW
2013: Fukushima floating substation – floating
substation
2015: Fukushima V shaped semi sub 7MW
2016: Fukushima Advanced spar 5MW
12
2009: Hywind demo – 1st spar buoy
2011: WindFloat demo – 1st semi-sub – decommissioned in 2016
2012: Kabashima/Goto Spar – 1st concrete/steel
2013: VolturnUS – 1st concrete semi-sub
DNV GL © 2015
Looking forward, the first small projects are coming soon
WindFloat Atlantic
27.5 MW off Portugal’s coast
30 m€ in funding from
NER300
Operation aimed for 2018
13
Hywind Scotland
30 MW off Peterhead in
Scotland
5 x 6MW turbines
Financed by ROCs
In operation from 2017
France: 2 out of 4 projects awarded
Gruissan/Mediterranean: Quadran, 4 x 6MW Senvion, IDEOL (damping
pool), Bouygues
Groix/Atlantic: Eolfi + CGN (China), 4 x 6 MW GE Alstom 6MW, DCNS,
Vinci
Installation 2018-2019
2 more projects to be announced this autumn
WindFloat Pacific: abandonned
DNV GL © 2015
Looking forward, the first small projects are coming soon
14
Gicon SOF
First ever large scale TLP
prototype
Siemens 2.3 MW
Baltic Sea
Commissioning planned for
2016
Japan: NEDO funding
Confirmed consortium: Hitachi Zosen, Ideol (platform designer)
Two 3-5MW turbines, steel and concrete Ideol platforms
Commissioning 2017-2018
Kincardine Pilot
wind farm
48 MW south east of
Aberdeen
Semi-subs platforms
Taiwan
Eolfi to develop at least 4 commercial
floating wind farms up to 2GW / 300
turbines in total
By 2025
FLOATGEN
Demonstration project in France
Ideol platform
DNV GL © 2015
Looking forward, the first small projects are coming soon
Hywind US
First Californian offshore
wind project
In planning stage
765MW
DNV GL has secured first
contract
15
VolturnUS array
2 x 12 MW in 95 meters of water depth
3m USD from DoE to assist completion
of a full scale design
40m USD private investments secured
Goal to install up to 5 GW of floating
wind in Maine by 2030
... and many more!
DNV GL © 2015
Technology summary
16
DNV GL © 2015
The three “classic” floating wind technology types
17
SPAR Semi-Submersible
TLP
DNV GL © 2015
Other concepts
18
Source: MHI
Source: Ideol
Source: Fukushima Forward
DNV GL © 2015
Semi-submersibles
• Stability achieved by buoyancy
• High deflections and heel angles
• Interaction with aerodynamics and control
system
• Turbine to be designed for acceleration
• Catenary or taut mooring
• Varying complexity
• Dry-docking possible
DNV GL © 2015
Spar-buoy systems
• Stability achieved by ballast
• Simple, inexpensive structure
• High depths required
• High mass
• High deflections and heel angles
• Interaction with aerodynamic control
system and mooring
• Special or modified turbine design
• Catenary or taut mooring
• Yaw control -> complicated taut mooring
DNV GL © 2015
Tension-leg Platforms
• Stability from mooring force
• Stable platform, low roll and pitch angles
• Small mooring area (footprint)
• Expensive taut mooring (pre-stressed
cables)
• Cables have to be always in tension
• Prone to fatigue loading (connections)
• Sensitive to yaw load
• High water depth required
DNV GL © 2015
Market predictions and developments required
22
DNV GL © 2015
Why floating wind at all?
Advantages against fixed:
– Deeper water available (better wind resource) – only viable option for some
countries
– ... but also shallower water possible depending on concept
– Easier and cheaper transport/installation and maintenance? (no need of heavy
lift vessels)
– Less site dependent – more standardisation
Disadvantages:
– More coupled dynamics – more overall system motion – more integration
– More Technical integration required
– More Contractual integration required
– CAPEX higher: platform, moorings, dynamic cables, ...
Potential for equal/reduced CoE for offshore wind
23
And it’s cool!
DNV GL © 2015
Floating wind landscape
Three geographical areas: Europe, Japan, United States
24
Source: DNV Kema for The Crown Estate, “UK Market potential and technology assessment for
floating offshore wind power, 2012”
Source: “Floating Offshore Wind:
Market and Technology Review”,
Carbon Trust, June 2015
DNV GL © 2015
Water depth in Europe
25
< 50m depth
DNV GL © 2015
Deep waters close to major population centres
26
DNV GL © 2015
Floating wind markets - JAPAN
Steep electricity prices – high feed-in tariff
Generation & transmission capacity shortage
Wind energy targets of 75 GW by 2050 - 18 GW by floating
Strong maritime tradition
27
Water depths between 100 – 500 meters, within 50 km from shore is indicated by the yellow areas (DNV GL)
DNV GL © 2015
Floating wind has just started to move into the CRI scale
28
Source: http://arena.gov.au/files/2014/02/Commercial-Readiness-Index.pdf
Pilot wind farms developments
TRL CRI
DNV GL © 2015
Commercialization prediction for different concepts
29
Source: DNV Kema for The Crown Estate, “UK
Market potential and technology assessment for
floating offshore wind power, 2012”
Source: “Floating Offshore Wind: Market and
Technology Review”, Carbon Trust, June 2015
DNV GL © 2015
CAPEX breakdown for a commercial scale floating wind farm
30
Source: “Floating Offshore Wind: Market and Technology Review”, Carbon Trust, June 2015
DNV GL © 2015
CAPEX reduction from prototype to commercial scale floating wind farm
Source: “Floating Offshore Wind: Market and Technology Review”, Carbon Trust, June 2015
31
OPEX?
DNV GL © 2015
Floating wind commercialisation initially likely driven by technology improvements
32
100 %
55 %
2015 2020 2025 2030
LC
OE
, co
st
ind
ex in
%
Estimated LCOE reduction 2015 – 2030
TECHNOLOGY IMPROVEMENTS
MARKET GROWTH
TECHNOLOGY IMPROVEMENTS
MARKET GROWTH
STABLE POLICY ENVIRONMENT
COMPETITION IN SUPPLY CHAIN
Predictions for 2020s• Potential for reaching cost
parity with fixed bottom• £85-95MWh
DNV GL © 2015
Average LCOE of onshore wind 1984-2011 (Eur/MWh)
Source: Bloomberg New Energy Finance, ExTool
14%
Global
Denmark and
Germany
1984 1990 2000 2004 201110
50
100
500
1000
100 1,000 10,000 100,000 1,000,000
MW
14% drop in LCOE for every
doubling of installed capacity
DNV GL © 2015
Next steps
Currently floating wind depends heavily on public subsidies for demonstrators
Next steps:
– Pilot wind farms
– Increase TRL
– Practical issues: transport/installation
– Gain knowledge from naval/oil&gas industries
– Decrease CoE
– Shared risks!
– New investment and risk sharing mechanisms needed
– Wind turbine OEMs still a bit skeptical/lack of engagement: some interested,
some keep dropping out of projects... Risk-averse mentality to new
technology... especially after offshore fixed experience?
34
DNV GL © 2015
Historical offshore wind CAPEX trends
Source: DNV GL
35
DNV GL © 201536
DNV GL © 2015
IN-FLOAT concept: example of industrialization
https://www.youtube.com/watch?v=ypzkuV8d_Mc
(4min video)
37
DNV GL © 2015
Design stages of floating
38
DNV GL © 2015
Turbine+platform: iterative design process
39
Turbinedesign
Platformdesign
Numericalmodelling
Scale model testing
Numericalmodel
validation
Control design
Loadcalculations
Certification
Prototype +
commercialization
Platform strength analysis/optimisation
Control re-tune/turbine re-design?
DNV GL © 2015
Turbine+platform: iterative design process
40
Turbinedesign
Platformdesign
Numericalmodelling
Scale model testing
Numericalmodel
validation
Control design
Loadcalculations
Certification
DNV GL © 2015
Turbine design
• Normally pre-designed to type class
• Very flexible
• Frequency constraints
• Active controller
Platform design
• Normally pre-designedaccording to naval experience
• Relatively rigid
• Often self-called “turbineagnostic”
Turbine + floating platform
41
Strong coupling
between the two!
Close interaction is
needed between two
parts from early start
Turbine changes typically needed:
- Re-design controller
- Re-design tower and perhaps other
components
DNV GL © 2015
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
Sp
ectr
al
Den
sit
y
Frequency (Hz)
Excitation frequencies
42
1P 3P
Wave energy spectrum
Platform rigid
body modes
Controller
bandwith
Rule of thumb: avoid freqs
(periods) in the range of
0.04Hz (25s) to 0.25Hz (4s)
DNV GL © 2015
Turbine+platform: iterative design process
43
Turbinedesign
Platformdesign
Numericalmodelling
Scale model testing
Numericalmodel
validation
Control design
Loadcalculations
Certification
DNV GL © 2015
Critical Design Issue: Load Analysis
• Aerodynamic and hydrodynamic loading
• Consideration of dynamics
– Rigid body movement
– Mooring
– Large deflections
– Interaction with control system
– A range of simulation codes exist and
ongoing further development, but need
to be validated further
– Model tests
– Prototype tests
– New load cases needed
DNV GL © 2015
Different levels of modelling fidelity
Full CFD-FEM methods
– Navier-Stokes equations
– Continuum mechanics
Aero-hydro-servo-elastic codes
– State-of-the-art for coupled dynamic analysis
– BEM aerodynamics
– Morison/Potential flow for hydro
– Include effect of the controller
Reduced order models
– Coupled/de-coupled
– Semi-empirical
– Frequency domain methods
45
Detailed component
design
Wind turbine +
platform dynamics,
control design and
loads analysis
Accura
cy
Com
puta
tionalspeed
Initial studies
DNV GL © 2015
Floating turbine modelling in Bladed
Industry standard turbine design software
In 2010 Bladed had its structural dynamics core
replaced with a multi-body formulation to make it
simpler and more accurate to model complex
structures
A floating module was released for the first time
with Bladed v4.1 (2011)
This allows fully coupled simulations which include
– both wind and wave loading
– structural dynamics
– global support structure translations and rotations
‘Advanced hydrodynamics’ in Bladed v4.6 (2014)
4 November 2016Private and confidential
46
DNV GL © 2015
Hydrodynamics Modelling Options in Bladed
4 November 2016Private and confidential
47
Morison Model
• Semi-empirical
• Added mass radiation
• Froude Krylov excitation
• Instantaneous hydrostatics
• Viscous drag
• Wide range of sea state
definition options
• Diffraction correction based
on MacCamy Fuchs
BEM Model
• Analytical, reliant on
potential flow solver
• Added mass and damping
radiation
• Froude Krylov and diffraction
excitation
• Linear hydrostatics
• Viscous drag (from Morison)
• Linear, Airy waves only
Future/ongoing developments:
Dynamic moorings
Second order wave forcing
DNV GL © 2015
Iterative design process
48
Turbinedesign
Platformdesign
Numericalmodelling
Scale model testing
Numericalmodel
validation
Control design
Loadcalculations
Certification
Main purpose is to validate/calibrate numerical model and reduce design risk. May lead to design optimisationNote wave/wind scaling issues
DNV GL © 2015
Iterative design process
49
Turbinedesign
Platformdesign
Numericalmodelling
Scale model testing
Numericalmodel
validation
Control design
Loadcalculations
Certification
DNV GL © 2015
The wind turbine controller
4 November 2016Private and confidential
50
Controller
Flexible blades
Flexible shafts
Pitch actuators
Flexible tower
Flexible mountings
Power and speed transducers
Torque drive
Measured powerMeasured speedWind speedYaw errorBlade loadsTower acceleration…
Pitch demandsTorque demandYaw demandBrake on/offContactor on/off…
The controller is the heart of the wind turbine. It makes use of the available inputs to determine its operation and is responsible for its performance & safety.
DNV GL © 2015
Why it is important
4 November 2016Private and confidential
51
Rotor diameter (m)
Rated power (kW)
The role of control algorithm design
• Reducing component cost and increasing component lifetime
• A real enabler with constantly increasing rotor sizes
• The larger benefits are obtained where control design is integrated at
an early stage in the overall design process to explore trades
DNV GL © 2015
Elements of the turbine controller
Power production control
– Regulation of power and/or speed
– Avoiding excessive actuator demands
– Alleviating turbine loads
– Maximise controller robustness against model uncertainties and nonlinearities
Supervisory control
– Logic for start-up, shutdown
– Alarms, fault detection and handling
– Health monitoring and data collection
Safety system
– It is NOT part of the control algorithm
– Simple hardware to ensure failsafe operation
– Activated when, as a result of an internal or external failure or of a dangerous
event, a wind turbine is not kept within its normal operating limits
4 November 2016Private and confidential
52
DNV GL © 2015
Floating wind controllers: low frequency dynamics challenge
Platform natural periods chosen to avoid wave excitation
However they clash with the wind excitation
53
Flo
atin
g tu
rbin
e s
urg
e m
ode
Flo
atin
g tu
rbin
e s
urg
e m
ode
Wave spectrum Wind spectrum
Wind Spectrum based on work by van der Hoven (1957)Wave spectra of a fully developed sea for different wind
speeds according to Moskowitz 1964
DNV GL © 2015
Damping of tower/platform motion
Pitch control can have adverse effects on the damping of the 1st tower fore-aft
mode (or, in floating turbines, of the platform surge and pitching modes)
Damping of these modes can be increased by adding a parallel control loop, which
uses the nacelle fore-aft acceleration signal to generate an additional pitch demand
This results in a decrease in the structural loads related to these modes
4 November 2016Private and confidential
54
WIND TURBINE
TOWER/PLATFORM STABILISATION
PITCH-SPEED CONTROL
+
GENERATOR SPEED
NACELLE FORE-AFT ACCELERATION
PITCHDEMAND
DNV GL © 2015
Iterative design process
55
Turbinedesign
Platformdesign
Numericalmodelling
Scale model testing
Numericalmodel
validation
Control design
Loadcalculations
Certification
DNV GL © 2015
Standards relating to floating wind
• DNV, Design of Floating Wind Turbine Structures DNV-OS-J103, 2013
• GL RC, Guideline for the Certification of Offshore Wind Turbines, 2012
• IEC 61400-3-2: under development
• Bureau Veritas, Classification and Certification of Floating Offshore Wind Turbines, 2010
In addition to this, industry needs to develop best practices for floating wind load calculations – and to share new knowledge within industry!
DNV GL © 2015
How do environmental conditions differ from offshore fixed?
Prone to larger misalignments wind-waves due to swells?
– Wind-wave misalignment more onerous?
– Two peaked spectra appropriate?
Ice accumulation: turbine and platform?
Sea ice: to platform, moorings,..?
Breaking waves?
Slamming, sloshing, green water
Particular gust cases for floating: EOG, EDC, ECD
Additional fault cases?
4 November 2016
57
DNV GL © 2015
New DNV GL Design of floating wind turbine structures standard under development based on DNV-OS-J103
DNV-OS-J103 developed through a Joint Industry Project (JIP), first issued in
2013. Can be downloaded for free on www.dnvgl.com
Being updated during 2016 as part of the harmonization of the DNV GL codes for
the wind industry after the DNV GL merger in 2013
Since 2013 the industry has developed:
– numerous guidelines for the design of floating wind turbine structures have
been published by various certifying bodies
– an IEC technical specification on the subject is under way
– several prototypes have been installed and the first small array of floating
turbines are currently being developed
The new revision is intended to reflect
– the experience gained after the first issue was published in 2013
– the current trends within the industry
58
DNV GL © 2015
DNV GL JIP on Recommended Practices for Floating wind turbines
59
TLP Spar Semi Barge
Modelling & validation
Model Test Analysis
Industrial agreed recommended practices, based on:
Experience from the selected case studies
Experience from all participants
New analysis run during the project to validate/integrate
the state of art experience
DNV GL © 2015
Conclusion
60
DNV GL © 2015
Next steps
Priority areas for further technology development:
– Reduce platform size / CAPEX
– Installation and maintenance procedures (particularly for TLP and spar buoys)
– Improved mooring and anchoring systems
– Advanced control systems
Maintain/increase public funding
Gain more engagement from turbine OEMs and private investors
New mechanisms for shared investments / risks within the consortiums
Technology has been demonstrated, now it needs to be made cost effective
61
DNV GL © 2015
DNV GL vision
62
DNV GL © 2015
SAFER, SMARTER, GREENER
www.dnvgl.com
Let’s make this happen!
63
Ricard Buils Urbano