THE IMPACT OF ATMOSPHERIC TURBULENCE ON WIND TURBINE DESIGN AND OPERATIONS

Dr. Neil Kelley

National Wind Technology Center

National Renewable Energy Laboratory

Experience with the large, multi-megawatt prototype wind turbines in the late 1970’s and early 1980’s revealed the structural loads experienced by these machines significantly exceeded predicted levels which contributed to, in some cases, operating lifetimes much shorter than expected. Closer examinations of these predictions determined that the excess loads were directly attributable to the impact of atmospheric turbulence encountered by the turbine rotor blades. In 1988, an effort within the Federal Wind Program established goals to develop:

(1) a physical understanding of the role of inflow turbulence in the structural response of wind turbines, and

(2) numerical simulations of this turbulence that incorporate those properties of the flow that have significant influence in the dynamic response of wind turbines and can serve as the excitation for structural design codes.

We will discuss the results of recent research into the characteristics of turbulent inflows that can cause excessive structural loads on wind turbine rotors. Some early results from a recently concluded experiment at the National Wind Technology Center using a 42-meter planar measurement array upwind of a 600 kW wind turbine will be presented. Finally, turbulence issues related to the deployment of wind turbines higher into the planetary boundary and their potential impact on turbine operations will be discussed.