Evaluation of Select IEC Standard Wind Turbine Design Cases on the Combined Experiment Wind Turbine Model

Wind turbine design standards have been under development in many countries. Recently, a sub-committee of the International Electrotechnical Commission (IEC) completed a draft wind turbine design standard for evaluation and final acceptance. If adopted, it will specify design criteria for all wind turbines sold internationally. The standard specifies certain extreme wind conditions and extreme load conditions which all wind turbines must be designed to safely withstand. If the load cases specified are too conservative (extreme), the designer will be forced to design a more costly turbine than is needed to withstand the actual environment. On the other hand, if the standards are not conservative enough the designer may be mislead into designing a turbine which will fail prematurely. Therefore, it is important that the standards be appropriate. This can be judged by comparing the standards with test cases and correcting them where they are too conservative or not conservative enough. The standard classifies wind turbines based upon the external conditions considered in the design of the turbine. Five turbine classes are specified as shown in Table 1. The analysis performed in this task involved six wind cases as defined for Class I.