Structural Integrity of Offshore Wind Turbines Oversight of Design, Fabrication, and Installation - Special Report 305 (2011) / Chapter Skim
Currently Skimming:
3 Standards and Practices
3 Standards and Practices
Pages 38-61
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 38... ...
Definitions of these terms can be found in the glossary, and some are discussed further in Appendix A INTERACTIONS BETWEEN NONSTRUCTURAL FAILURES AND WIND TURBINE STRUCTURAL INTEGRITY Although the committee's charge is limited to structural integrity (see Chapter 1)
|
From page 39... ...
Examples of organizations that follow a recognized standards development process are the International Organization for Standardization, the International Electrotechnical Commission (IEC) , the American National Standards Institute, the American Wind Energy Association, and the American Petroleum Institute (API)
|
From page 40... ...
In this report, "guideline" refers to any document devel oped by a group or company for which no recognized protocol or consensus vote is necessary. Examples of guidelines referred to in this report are Guideline for the Certification of Offshore Wind Turbines, developed by Germanischer Lloyd; Design of Offshore Wind Turbine Structures, developed by Det Norske Veritas; and Guide for Building and Classing Offshore Wind Tur bine Installations, developed by the American Bureau of Ship ping (ABS 2010)
|
From page 41... ...
• The industry wanted to make sure that all wind turbines complied with the same standard so that price competition could take place on a uni form basis (excluding substandard wind turbine designs)
|
From page 42... ...
Because it is part of a series of international standards that address the broader wind industry's needs, such as verification testing for performance, structural design compliance, power quality, gearbox design requirements, and small turbines, it is the best available standard for addressing the issues of structural design for offshore wind turbines. The IEC certification standard for type and project certification is IEC 61400-22, Wind Turbines -- Part 22: Conformity Testing and Certification (IEC 2010b)
|
From page 43... ...
Owners and operators choose to require type-certified wind turbines for their projects. The type certification process is outlined in Figure 3-1.
|
From page 44... ...
Poor geotechnical investigation and foundation design have led to delays and cost overruns at European wind farms (Gerdes et al.
|
From page 45... ...
Wind turbines and their support structures are mass produced, as opposed to the customized design approach typically applied for offshore oil and gas installations. Final permitting of wind power plants results in the installation of many turbines of the same design type (hence the term "type certification" for a turbine that meets a generic design class, rather than site-specific environmental conditions)
|
From page 46... ...
For structural design, API RP 2A-WSD, the commonly applied standard for fixed offshore platforms, uses an elastic component design methodology prescribing load development procedures, structural design methods, extreme load conditions, material and component safety factors, and the character and return periods for design-level extreme events for both sea states and wind conditions. The standard focuses mainly on sea states rather than wind because that is the primary source of platform loads (usually about 70 percent of the total load on a fixed platform)
|
From page 47... ...
API RP 2A does not address the scope and range of all con ditions relating to the design of wind turbine support structures such
|
From page 48... ...
for the types of facilities. One final issue is that floating platforms for wind turbines are explicitly not covered by IEC 61400-3.
|
From page 49... ...
DET NORSKE VERITAS DNV is a leading contributor to research on offshore oil and gas design requirements, plays a leading role in development of standards for offshore wind, and provides certification services worldwide. DNV worked with RISØ Danish National Laboratory researchers to develop national standards for wind turbines.
|
From page 50... ...
However, it does not cover offshore electric service platforms, nor does it specifically cover floating support structures for offshore wind turbines. The GL Bluebook is highly prescriptive, and as such it is viewed by some in the industry as inflexible and restrictive in its applications.
|
From page 51... ...
Requirements with regard to the survey during construction and installation and the survey after construction are generally in accordance with established ABS rules for offshore structures. Alternative survey schemes are also acceptable to account for the uniqueness of offshore wind turbines, such as serial fabrication and installation.
|
From page 52... ...
This standard covers development, design, implementation, operation, and decommissioning of offshore wind farms within the scope of the Marine Facilities Ordinance and regulates the various structural components of an offshore wind farm. It refers to another BSH standard, Standard for Geotechnical Site and Route Surveys -- Minimum Requirements for the Foundation of Offshore Wind Turbines, issued in August 2003.
|
From page 53... ...
ONGOING STANDARDS DEVELOPMENT AND RELATED RESEARCH: NATIONAL AND INTERNATIONAL American Wind Energy Association Development of Offshore Recommended Practices In October 2009, the American Wind Energy Association (AWEA) , in conjunction with the National Renewable Energy Laboratory, initiated an effort to develop a set of recommended practices for assessing the local, national, and international standards and guidelines that are being used for all wind turbines in the United States and to make recommendations on their use and applicability.
|
From page 54... ...
Group 1, Structural Reliability, is addressing design issues relating to structural reliability of offshore wind turbines. Because many wind turbines targeted for installation in the United States may have already been designed and type-certified to IEC design classes (see Chapter 3)
|
From page 55... ...
. Bureau Veritas Guidance for Floating Offshore Wind Turbines In January 2011, Bureau Veritas issued guidelines for the "Classification and Certification of Floating Offshore Wind Turbines." The guidelines specify the environmental conditions under which floating offshore wind turbines may serve, the principles of structural design, load cases for the platform and mooring system, stability and structural division,
|
From page 56... ...
The project focuses on governing load cases and load effects for offshore wind turbines subject to revolving storms on the U.S. OCS and on calculation methods for breaking wave slamming loads inflicted on offshore wind turbine support structures.
|
From page 57... ...
• Offshore wind turbines in the Great Lakes will encounter freshwater ice, which may induce first-order loading from numerous new DLCs. Research and specification development for ice loading in the Great Lakes are needed, because the loads cannot be estimated from prior wind energy experience in the Baltic Sea.
|
From page 58... ...
are IEC 61400-1 (Wind Turbines -- Part 1: Design Requirements) and IEC 61400-3 (Wind Turbines -- Part 3: Design Requirements for Offshore Wind Turbines)
|
From page 59... ...
pro mulgated by the U.S. Department of Interior's BOEMRE require that detailed reports for design, construction, and operation of offshore wind turbines be submitted for BOEMRE approval, they do not spec ify standards that an offshore wind turbine must meet.
|
From page 60... ...
REFERENCES Abbreviations ABS American Bureau of Shipping API American Petroleum Institute AWEA American Wind Energy Association BSH Bundesamt für Seeschifffahrt und Hydrographie DNV Det Norske Veritas GL Germanischer Lloyd IEC International Electrotechnical Commission MMS Minerals Management Service ABS.
|
From page 61... ...
2011. Work program for IEC TC 88 project IEC/TS 61400-3-2, Wind Turbines -- Part 3-2: Design Requirements for Floating Offshore Wind Turbines.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.