LIDAR Wind Speed Measurements of Evolving Wind Fields

Abstract

Light Detection and Ranging (LIDAR) systems are able to measure the speed of incoming wind before it interacts with a wind turbine rotor. These preview wind measurements can be used in feedforward control systems designed to reduce turbine loads. However, the degree to which such preview-based control techniques can reduce loads by reacting to turbulence depends on how accurately the incoming wind field can be measured. Past studies have assumed Taylor's frozen turbulence hypothesis, which implies that turbulence remains unchanged as it advects downwind at the mean wind speed. With Taylor's hypothesis applied, the only source of wind speed measurement error is distortion caused by the LIDAR. This study introduces wind evolution, characterized by the longitudinal coherence of the wind, to LIDAR measurement simulations to create a more realistic measurement model. A simple model of wind evolution is applied to a frozen wind field used in previous studies to investigate the effects of varying the intensity of wind evolution. Simulation results show the combined effects of LIDAR errors and wind evolution for realistic turbine-mounted LIDAR measurement scenarios.

Application of simulated lidar scanning patterns to constrained Gaussian turbulence fields for load validation

“…As a result, the lidar measurements represent spatially averaged samples of the wind speed, 12 which in principle can be taken into account by applying constraints on multiple points per lidar measurement. The size of the measurement volume and the maximum possible measurement frequency depends on the lidar technology: 13 Continuous-wave lidars normally can measure with very high frequency, but the measurement volume increases with the focusing distance. For example, the probe length for the ZephIR 300 commercial continuous-wave lidar is 0.07 m at a 10 m measurement distance, and 7 m at a 100 m measurement distance.…”

Upwind preview to a horizontal axis wind turbine: a wind tunnel and field‐scale study

“…Researchers are now developing new ways of mitigating loading damage caused by wind gusts and continual variations of turbulence intensities by employing updated control logics, new blade designs and incoming flow forecasting. Wind turbine control designs include a wide spectrum of implementations, ranging from pitch control, to smart rotors and active flow control, which combines incoming flow measurements with new control algorithms. All these techniques address the problem of maintaining high energy production while reducing the effect of wind gusts on the mechanical and structural components of the turbine.…”

“…Wind turbine control designs include a wide spectrum of implementations, ranging from pitch control, [3][4][5][6] to smart rotors and active flow control, [7][8][9] which combines incoming flow measurements with new control algorithms. [10][11][12] All these techniques address the problem of maintaining high energy production while reducing the effect of wind gusts on the mechanical and structural components of the turbine. Unfortunately, extreme wind events occurring in the operating range of wind turbines are not perceived by the feedback control in the majority of current utility-turbines, which, in fact, does not allow the prediction of instantaneous turbine loads; 13 this is why recent advancements in remote sensing technology, e.g., forward-facing light detection and ranging (LiDAR) devices mounted on utility-scale turbines, are envisioned to monitor the incoming wind conditions as an input to the control system.…”

Infragravity Wave Generation by Wind Gusts

“…LIght Detection And Ranging measurements show that the wind speeds are highly correlated between two points lying in the mean wind direction. This correlation quickly decays as the angle between the mean direction and the two points increases (Simley et al, ).…”