Investigation of the IEC Safety Standard for Small Wind Turbine Design Through Modeling and Testing

Since 1999, the International Electrotechnical Commission (IEC) Maintenance Team 2 (MT2) has been working on a revision of the IEC 61400–2 standard on the safety, quality, integrity, and design requirements of small wind turbines (SWTs). During this effort, a study was conducted to evaluate the quality of the structural design criteria specified by the original –2 standard. Test measurements and aeroelastic predictions of loads were gathered for a collection of SWTs and evaluated against the simplified load models and load cases specified in the standard. The collection of turbines included variations in rotor size, blade number, rotor location (upwind / downwind), hub type (rigid / teetered), yaw mechanism (free / active), and others. In general, the comparison of load measurements and model predictions exemplified the inaccuracy of the design load levels in the original –2 standard and suggested methods of improvement. Revisions being made to the standard include enhanced load models, new load cases, and improved safety factors. This work should culminate in a revised IEC 61400–2 standard that has a higher degree of applicability and dependability than the original.