IEC class of NREL 5MW wind turbine

Hello everyone,

I’m confused about the IEC class of NREL 5MW wind turbine.

The technical report “Definition of a 5-MW Reference Wind Turbine for Offshore System Development” (Jonkman et al. 2009) does not specify the class of the wind turbine; the report “Dynamics Modeling and Loads Analysis of an Offshore Floating Wind Turbine” (Jonkman, 2007) specifies that this wind turbine is class IB (Page 95, Table 5-2). However, I noticed that some of the discussions in this forum are based on the assumption that the turbine is classified as IA.

So, can I trust the results of simulations with this wind turbine in which the environmental conditions are more severe than class IB, such as V_ave=10m/s, I_ref=0.16 (IEC class IA) and V_ref=57 (IEC class T) if OpenFAST doesn’t show any warning message?

Thanks in advance and best regards,
Xingchao Wang

Dear @Xingchao.Wang,

The NREL 5-MW baseline wind turbine was not “designed” per se, that is, the size of its structural components were not defined so as to be able to withstand the stresses brought about by specific load case simulations. Rather, the NREL 5-MW baseline wind turbine is a composite of information from various sources and few structural component details were specified.

You can simulate load cases for various conditions, but it doesn’t mean that a physical structure built per the specifications would actually survive these conditions.

Best regards,

Dear @Jason.Jonkman,

Thanks for your answer, it is very helpful.

Best regards,
Xingchao Wang.