Modeling the Influence of Variations in Wind Speed and Direction in the Atmospheric Boundary Layer on Utility-Scale Wind Turbine Power Production
Storm Mata, Massachusetts Institute of Technology
Wind speed and direction in the atmospheric boundary layer (ABL) are often spatially non-homogeneous. The change in speed and direction over the spatial domain is called shear. Vertical shear, or changes in wind speed and direction as a function of height, are particularly relevant to wind energy modeling as turbines continue to extend farther into the ABL. Previous studies show that vertical shear can affect utility-scale wind turbine power production. Shear alters the inflow angle of the wind vectors incident on the turbine blades, consequently modifying the lift and drag forces induced. This changes the efficiency of the airfoils and thereby affects power production of the turbine. In this study, we compare four models for turbine power production, three that account for variations in wind speed and direction over the rotor, and one that does not. Two of the models, including the model that does not account for shear, are taken from the current wind industry standard for wind resource assessment, IEC Standard 61400-12-1. Each model is driven with LiDAR wind speed and direction measurements and the predictions for power are compared to contemporaneous power measurements from a utility-scale wind turbine located adjacent to the LiDAR system. One of the models tested, a blade element model, is observed to produce both higher correlation and lower overall error with empirical power measurements based on arbitrary wind speed and direction inputs than the other models in this study.
Abstract Author(s): Storm A. Mata, Michael F. Howland