standard development for floating wind turbine structures
DESCRIPTION
Standard Development for Floating Wind Turbine Structures. EWEA 2013. Outline of presentation. Development of a standard for design of floating wind turbine structures Certification process for floating wind turbines. Joint Industry Project (JIP). - PowerPoint PPT PresentationTRANSCRIPT
A. L. Hopstad, K. Ronold, C. Sixtensson, J. Sandberg2013-02-07
Standard Development for Floating Wind Turbine StructuresEWEA 2013
Standard Development for Floating Wind Turbine Structures
2013-02-07
2
Outline of presentation Development of a standard for design of floating wind turbine structures
Certification process for floating wind turbines
Hywind WindFlo DIWET WindSea
StatoilNorway
Future Emerg. Tech.EU
Blue HNetherlands
WindSea ASNorway
Standard Development for Floating Wind Turbine Structures
2013-02-07
Joint Industry Project (JIP) Objective: Develop a (DNV) standard for design of floating wind turbine structures
10 participants from the industry- Statoil- Navantia- Gamesa- Alstom Wind- Iberdrola- Sasebo Heavy Industries- Nippon Steel- STX Offshore & Shipbuilding- Glosten Associates- Principle Power
Kick off: September 2011
External/internal hearing: tentatively March/April 2013
Expected release: Q2 2013
3
Standard Development for Floating Wind Turbine Structures
2013-02-07
Why develop a standard for floaters? Until recently existing standards have been
restricted to bottom-fixed structures only:- IEC61400-3 - DNV-OS-J101 - GL (IV Part 2) - ABS #176
This forms the background for the new floater standards issued by ABS, NKK, GL and for the standard to be issued by DNV later in 2013
The standard will contain normative requirements that shall be satisfied in design of tower and support structure
Development of this standard will lead to:- Expert / industry consensus on design principles- Experience from the industry reflected in the contents- Innovative designs and solutions - Economically optimized designs
4
Courtesy: Principle Power
WindFloat, Principle Power
Standard Development for Floating Wind Turbine Structures
2013-02-07
5
Three main technologies:Spar buoys, Semi-submersibles, Tension leg platforms (TLP)
Weight-buoyancy stabilized structure with large draught+ Simple, inherently high stability substructure+ “Proven” technology- Substructure weight- Draught implication on site flexibility
Tension restrained structure with relatively shallow draught+ Low steel weight+ Small seabed footprint- Sensitive to soil conditions- Stability in intermediate phases
Free-surface stabilized structure with relatively shallow draught+ Simple transport & installation+ Flexible design with respect to site- Substructure weight and complexity- Motions in extreme wave conditions
Spar
Semi-submersible
TLP
Standard Development for Floating Wind Turbine Structures
2013-02-07
Technical issues covered by the standard Safety philosophy and design principles
Site conditions, loads and response
Materials and corrosion protection
Structural design
Design of anchor foundations
Stability
Station keeping
Control system
Mechanical system
Transport and installation
In-service inspection, maintenance and monitoring
Cable design (structural)
Guidance for coupled analysis
6
Photo: Knut Ronold
Standard Development for Floating Wind Turbine Structures
2013-02-07
Safety philosophy The safety class methodology is based on the
failure consequences
The safety class is characterized by a target annual failure probability
Safety class LOW => target annual probability of failure of 10-3
Safety class NORMAL => target annual probability of failure of 10-4
Safety class HIGH => target annual probability of failure of 10-5
In DNV-OS-J101 and IEC rules: safety class Normal
Requirements for load factors to be used in design depend on the target safety level of the specified safety class
7
HywindPhoto: C.F. Salicath
Standard Development for Floating Wind Turbine Structures
2013-02-07
What shall the safety level be in large floating wind farms? The current safety class NORMAL was originally
developed for small, individual turbines on land and has been extrapolated to be used also for:
1. Larger MW size turbines on land2. Offshore turbines3. Support structures for offshore turbines4. Many large turbines in large offshore wind farms
Is it possible to reduce the target safety level based on having large wind farms with many turbines offshore?
The consequence of failure is primarily a loss of economic value => cost-benefit analysis
8
Kabashima demonstration turbinePhoto: Knut Ronold, DNV
Standard Development for Floating Wind Turbine Structures
2013-02-07
Cost – benefit analysis Establish which safety level is necessary / acceptable in design of floating support
structures
Find optimum between choice of safety class in design and net present value (NPV) for a wind farm development
The analysis is to be used as part of the basis for selecting target safety level
Input:- Insurance companies estimated maximum loss philosophy- Cost data for CAPEX and OPEX- Cost data for replacing turbines and support structures- Cost differences when applying different safety classes - Electricity prices
9
Standard Development for Floating Wind Turbine Structures
2013-02-07
10
Cost – benefit analysis – example of results
Optimum
Low CAPEX, low safety level
High CAPEX, high safety level
Standard Development for Floating Wind Turbine Structures
2013-02-07
Structural design Special provisions for the different floater types
and for floater specific issues
Design rules and partial safety factors for structural components- Ultimate Limit State (ULS)- Fatigue Limit State (FLS)- Accidental Limit State (ALS)
Existing design standards from oil & gas industry has been capitalized on:- DNV-OS-C101 for offshore structures- DNV-OS-C105 for tendons- DNV-OS-E301 for mooring lines
Design Fatigue Factors (DFFs) specific for floating support structures and station keeping system have been established
11
Kabashima demonstration turbinePhoto: Knut Ronold, DNV
Kabashima demonstration turbinePhoto: Knut Ronold, DNV
Standard Development for Floating Wind Turbine Structures
2013-02-07
Station keeping Develop design rules and requirements for station keeping of floating wind turbines
The JIP has received data on load/response from three developers:- Hywind (full-scale data, mooring lines)- Pelastar (analysis data, tendons)- WindFloat (analysis / full scale data, mooring lines)
Load factors for tendons and mooring lines for different safety classes are established- Capitalize on “PosMoor” rules (DNV-OS-E301) - Reliability-based calibration for validation has been performed based on received data
12
Demonstration turbine in JapanPhoto: Knut Ronold, DNV
Standard Development for Floating Wind Turbine Structures
2013-02-07
13
Project Certification for Offshore wind farms Provide evidence to stakeholders that a set of requirements laid down in standards
are met during design and construction and maintained during operation
DNV-OSS-901 Project Certification of Offshore Wind Farms (2012) - developed for DNV service for bottom-fixed wind farms
Phases:- Phase I – Verification of Design Basis- Phase II – Verification of design- Phase III – Manufacturing Survey- Phase IV – Installation Survey- Phase V – Commissioning Survey- Phase VI – In-Service
Standard Development for Floating Wind Turbine Structures
2013-02-07
14
Project Certification for Floating Wind Farms DNV is currently in the process of extending the project certification service to also
cover floating wind farms
Extended scope for Phase II – Design verification:- Floater stability- Station keeping- Validation of software- Verification by model testing
Current floating wind turbine concepts capitalize on novel technology to various degrees
Technology items not covered by any standards may need to be taken through a technology qualification process to obtain documentation required for certification
Standard Development for Floating Wind Turbine Structures
2013-02-07
15
Type Certification Type certification of floating units for a specific
environmental class is foreseen as a possible new service in the case of mass-produced floater units
The station keeping system including anchor design would need to be qualified for each site
WindFloatPhoto: Principle Power
Standard Development for Floating Wind Turbine Structures
2013-02-07
16
Thank you
Thank you foryour attention
Standard Development for Floating Wind Turbine Structures
2013-02-07
www.dnvkema.com