On turbulence models and lidar measurements for wind turbine control

Liang Dong,Eric Simley,Wai Hou Lio

doi:10.5194/wes-6-1491-2021

Liang Dong, Eric Simley + Show 1 more

Open Access

https://doi.org/10.5194/wes-6-1491-2021

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Abstract

Abstract. To provide comprehensive information that will assist in making decisions regarding the adoption of lidar-assisted control (LAC) in wind turbine design, this paper investigates the impact of different turbulence models on the coherence between the rotor-effective wind speed and lidar measurement. First, the differences between the Kaimal and Mann models are discussed, including the power spectrum and spatial coherence. Next, two types of lidar systems are examined to analyze the lidar measurement coherence based on commercially available lidar scan patterns. Finally, numerical simulations have been performed to compare the lidar measurement coherence for different rotor sizes. This work confirms the association between the measurement coherence and the turbulence model. The results indicate that the lidar measurement coherence with the Mann turbulence model is lower than that with the Kaimal turbulence model. In other words, the potential value creation of LAC based on simulations during the wind turbine design phase, evaluated using the Kaimal turbulence model, will be diminished if the Mann turbulence model is used instead. In particular, the difference in coherence is more significant for larger rotors. As a result, this paper suggests that the impacts of different turbulence models should be considered uncertainties while evaluating the benefits of LAC.

Highlights

Turbine-mounted lidar sensors provide preview information about the inflow wind to be used for improving wind turbine control, which is referred to as wind-turbine-integrated lidar-assisted control (LAC)
Three commonly used simulated measurement quality metrics for LAC application are defined in Simley et al (2018): magnitude-squared coherence between the true rotoreffective wind speed (REWS) and the lidar-based estimate, mean square error (MSE) between the true REWS and the lidar-based estimate, and MSE between the generator speed and the rated generate speed
The specific objective of this study is to investigate the impact of different turbulence models recommended by the International Electrotechnical Commission (IEC) standards on the lidar measurement coherence, especially for large rotor sizes, whereby the analysis can shed light on how to reasonably evaluate LAC benefits during the wind turbine design phase

Summary

Introduction

Turbine-mounted lidar sensors provide preview information about the inflow wind to be used for improving wind turbine control, which is referred to as wind-turbine-integrated lidar-assisted control (LAC). The topic of the optimal lidar scan pattern for wind energy applications is critical for the widespread deployment of LAC. Three commonly used simulated measurement quality metrics for LAC application are defined in Simley et al (2018): magnitude-squared coherence between the true rotoreffective wind speed (REWS) and the lidar-based estimate, mean square error (MSE) between the true REWS and the lidar-based estimate, and MSE between the generator speed and the rated generate speed. The correlation between the REWS measured by the lidar and experienced by the rotor has been discussed in Haizmann et al (2015), Simley et al (2012) and Schlipf et al (2013a), in which the magnitude-squared coherence is suggested as a key metric to quantify the measurement quality.

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