Appendix II: IEC Classification of Wind Turbines

Abstract

Wind turbine class I II III S V ave (m/s) 10 8.5 7.5 User defined V ref (m/s) 50 42.5 37.5 V 50,gust (m/s) 70 59.5 52.5 I ref A 0.16 B 0.14 C 0.12 In the table (IEC61400-1: 2005): 1. Rayleigh distribution is assumed, i.e. k = 2. 2. V ave is the annual mean wind speed at hub height; V ref is the 50-year extreme wind speed over 10 minutes; V 50,gust is the 50-year extreme gust over 3 seconds; I ref is the mean turbulence intensity at 15 m/s. 3. A, B and C are the categories of higher, medium and lower turbulence intensity characteristics respectively. Wind Resource Assessment and Micro-siting, Science and Engineering, First Edition. Matthew Huaiquan Zhang.