Wind Energy Institute of Tokyo

No.1

Proposal for an amendmentto IEC 61400-3 Ed.1

Japanese National Committee for IEC/TC88March 11, 2010

SUZUKI Akihiro

IEC/TC88 Meeting @Boulder, CO, U.S.A.

Wind Energy Institute of Tokyo

2Background

• JP NC is preparing JIS C1400-3• Incorporating of regional

meteorological and marine conditions

• Similar conditions in China, Korea and others

• Additional Wave models– Oceans, Large and deep

• Extreme Conditions– Tropical storms (typhoon)

Wind Energy Institute of Tokyo

3Scope of Revision

• Correction and/or modification on 61400-3 Ed.1

• Additional Informative Annex– “Methodology of extrapolating

extreme wind and wave conditions from available data set”

– for evaluation of extreme conditions

Wind Energy Institute of Tokyo

4Proposed changes

1. Add ISO 21650:2007 “Actions from waves and currents on coastal structures” to the normative references,

2. Modify the definition of the extreme significant wave height,3. Add definitions of significant wave height,4. Modify clause 6.2 “wind turbine classes” to specify the offshore

wind turbine class,5. Modify descriptions for NWH, SWH, ESS, EWH, RWH and sea

currents,6. Change “breaking wave induced surf currents” to “Wave-induced

nearshore currents” and revise clause 6.4.2.3,7. Modify clause 12.4 “Assessment of waves”,8. Modify Annex B “Wave statistics and spectral formulation”,9. Modify Annex C “Shallow water hydrodynamics and breaking

waves”,10.Add requirements to specify the design value and the methodology

for the offshore wind turbine selection in extreme conditions, Annex I “Methodology of extrapolating extreme wind and wave conditions from available data sets” as a new informative annex.