Posters

Abstract

The wind flow complexity is almost the largest source of uncertainty for the Annual Energy Production (AEP) of the operational wind farm. Turbulence Intensity (TI) reveals the complexity of wind flow, and TI is widely used as one important wind-related parameter in many applications, such as the load estimation of Wind Turbine Generator (WTG), the verification of Power Performance Testing (PPT), and the micro-siting of WTGs. Nowadays, Nacelle-mounted lidar (NML) is increasingly used for the wind flow measurement, thanks to its high measurement accuracy and its easy deployment, especially in the offshore wind farm or under harsh scenarios. This study adopts a new testing setup to study the TI measurement of NML at multiple ranges: (1)The NML is installed on the ground of the testing site with a small tilt-up angle; (2)One Laser beam is shouted towards the Meteorological Mast (Met Mast) to compare the measurement at the location of Met Mast; (3)The measurements at multiple ranges along this laser beam are used to study the TI profile of Atmospheric Boundary Layer (ABL). This study proves that wind lidar measures TI accurately at multiple distances, which brings benefits not only to the application of wind farm operation, but also to the research of wind field in Atmospheric Boundary Layer. IEC 61400-50-3 describes two approaches to calibrate wind lidar with Met Mast: (1) the white box comparison is to compare the immediate measurement (Radial Wind Speed and TI) of one laser beam with met mast; (2) the black box comparison is to compare the wind speed at certain height, reconstructed by 4 laser beams. This study uses the white box comparison to directly compare the TI of one laser beam with Met Mast. One WindCube Nacelle is deployed at 481m from the Met Mast and one LOS shouts toward the cup anemometer at 30-m height. In this lidar setup, the wind speed and TI are measured by multiple range gates at different heights. First, the wind speed and TI between NML and Met Mast is compared: (1) the fitting formula of wind speed is Y=0.993X-0.078, with a good correlation coefficient of 0.998; (2) the fitting formula of TI is Y=0.971X+0.003, with a good correlation coefficient of 0.971. Furthermore, TI vertical profile is investigated, and the parameterized model is proposed. The vertical distribution of wind speed and TI is studied. The averaged TI profile is 𝑇𝐼=0.64×𝐻𝑒𝑖𝑔ℎ𝑡^0.43, with a low RMSE of 0.01. This study verifies the TI measurement of wind lidar, uses a new testing setup and proposes one parameterized model of TI profile. The vertical distribution of TI by NML is studied here: (1) The measurement of wind speed and TI is very accurate; (2) The parameterized scheme of TI profile by this study is 𝑇𝐼=0.64×𝐻𝑒𝑖𝑔ℎ𝑡^0.43; (3) The low RMSE of 0.01 reveals the parameterized model is very presentative. The wind lidar can measure the wind speed and TI at multiple distances, which provides very useful information for the research on the vertical structure of wind field of Atmospheric Boundary Layer.