Standards and Practices - Structural Integrity of Offshore Wind Turbines - page 34

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Standards and Practices
This chapter addresses Task I of the committee's charge—“Standards and
Practices” (see Box 1-2). It provides background on and a summary of the
applicable regulations, standards, recommended practices, and guidelines
that have been used in the offshore wind industry, and it describes the state
of maturity of each of these documents. The terms “regulations,” “stan-
dards,” and “guidelines” are discussed in Box 3-1.
In its review of standards and practices, this chapter discusses technical
terms related to risk assessment, strength analysis, and other areas. Defi-
nitions 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), malfunction or failure of nonstructural components and
systems during operation can result in structural overload or failure.
This interaction is dealt with through the definition of “design load cases”
(DLCs) in standards and guidelines. Such cases specify the combination of
loads that a facility must be designed to resist or withstand. Although the
committee has not reviewed the DLCs in detail, it notes that DLCs nor-
mally include the structural loads placed on the turbine as a result of fail-
ure or malfunction of ancillary systems such as control systems, protection
systems, and the internal and external electrical networks. In such DLCs,
failures in ancillary systems are normally postulated as occurring under
unfavorable wind and wave conditions. For example, in International
Electrotechnical Commission (IEC) 61400-3, DLC 2.3 involves both an
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