Inflow Characteristics Associated with High Blade Loading Events in a Wind Farm

The stochastic characteristics of the turbulent inflow have been shown to be of major significance in the accumulation of fatigue in wind turbines. Because most of the wind turbine installations in the United States have taken place in multi-turbine or wind farm configurations, the fatigue damage associated with the higher turbulence levels within such arrangements must be taken into account whenmaking estimates of component service lifetimes. The simultaneous monitoring of two adjacent wind turbines over a wide range of turbulent inflow conditions has given us more confidence in describing the structural load distributions that can be expected in such an environment. The adjacent testing of the two turbines allowed us to postulate that observed similarities in the response dynamics andload distributions could be considered 'quasi-universal,' while the dissimilarities could be considered to result from the differing design of the rotors. The format has also allowed us to begin to define appropriate statistical load distribution models for many of the critical components in which fatigue is a major driver of the design. In addition to the adjacent turbine measurements, we alsobriefly discuss load distributions measured on a teetered-hub turbine.