Lidar measurements as an alternative to traditional anemometry in Wind Energy research

Accurate measurements of the wind-flow characteristics over the entire height of the modern turbine rotors can reduce the uncertainty in wind resource assessment and power production, and thus decrease turbine operational and maintenance costs.

As the capacity and size of modern wind turbines continues to grow, the uncertainty in vertical extrapolation of wind measurements from surface meteorological stations or towers instrumented by sonic/cup anemometers, can increase significantly. It is expensive and more difficult to build tall (120-200 m) meteorological towers especially over the complex terrain or offshore.

The High Resolution Doppler Lidar (HRDL), designed and developed at NOAA, has demonstrated the ability to provide continuous measurements of wind flow with sufficient spatial and temporal resolution at turbine heights. These measurements can identify and adequately describe the atmospheric processes that may impact the operational reliability and lifetime of wind turbines and their components.

This paper presents HRDL measurements of wind characteristics important for the wind energy industry during two field programs conducted in the Great Plains region.

Quantities of interest that can be easily monitored using Doppler lidar include wind and turbulence profiles, turbulence intensity, nighttime evolution of low-level jet and jet properties (speed, height, direction), wind and directional shear across the rotor heights.

The study will focus on 1) deviations of observed wind profiles from logarithmic or power law profiles, 2) understanding how variation in stability affects the difference between measured and extrapolated wind profiles across the entire layer of turbine operations, and 3) analysis of directional shear as a function of stability.