Presentations | WindEurope Technology Workshop 2024

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A comprehensive investigation on dynamic Wind Turbine Power Curve (WTPC) by the Nacelle-Mounted Lidar (NML)

Zhi Liang, Application Manager, Vaisala


Predicting the power output of wind turbines for a given set of climatic conditions is a fundamental challenge in wind energy resource assessment (Lee et all, 2020) and the fluctuating wind brings challenges to evaluate the true Wind Turbine Power Curve (WTPC). Traditionally, the Meteorological Mast (Met Mast) have been the conventional and standard solution for WTPC. However, the field measurements and simulations increasingly show that the anemometer is easily affected by the mast itself (Shin et al., 2019). Nowadays, Nacelle-mounted lidar (NML) technology is increasingly used for WTPC and is widely accepted by wind turbine manufactures, certification societies and wind farm operators (Wagner et al., 2014). The newly release of IEC 61400-50-3 provides industrial guidelines on use the NML as an IEC-complaint technology (IEC, 2022). One pilot project to comply with this IEC standard are conducted on a flat wind farm in the US. An IEC met mast is located 290 meters in front of the testing wind turbine to measure free wind speed at hub height of 89 meters, while an NML is mounted on the top of the nacelle of wind turbine to measure wind speed in front of the rotor. The results of field measurement show that the wind speed accuracy of NML is consistent with the Met Mast, the correlation coefficient is 0.994, and the slope and offset by linear regression are 0.979 and 0.084, respectively; the scattering points of WTPC by NML are more concentrated, and NML is always measuring the wind speed exactly in front of the wind turbine during the yawing of the wind turbine, which is better representative of the wind speed. The AEP range evaluated by Met Mast and NML are respectively [3592h, 4265h] and [3739h, 4252h]. Since the NML dispersion interval for wind speed measurement is included inside the ones of Met Mast, the overall uncertainty of NML is smaller than that of Met Mast. NML has less uncertainty for the measurement of PPT and has higher accuracy. Further investigation for the WTPC is conducted by analysing the measurement at Line Of Sights (LOSs) of NML and the difference at LOSs reveals the complexity of spatial wind field. The wind sector is selected from 170 to 190 degree, when LOS1 is close at Meet Mast. Two scenarios for the WTPC comparison are according to the wind speed difference from LOS0 to LOS1: if LOS0>LOS1, positive; if LOS0

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WindEurope Technology Workshop 2024