Wind Energy Institute of Tokyo No.1 Proposal for an amendment to IEC Ed.1 Japanese National Committee for IEC/TC88 March 11, 2010 SUZUKI Akihiro IEC/TC88 CO, U.S.A.

Wind Energy Institute of Tokyo 2 Background JP NC is preparing JIS C 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 3 Scope of Revision Correction and/or modification on 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 4 Proposed 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 , 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.