Understanding of the Offshore Wind Resource up to High Altitudes (≤ 315 m)
van der Werff, P.A.
In order to better understand North Sea wind conditions, analyses were performed on wind speed and direction measurements by light-detection and ranging (lidar) at eight offshore measurement locations distributed throughout the North Sea. Lidar enabled measurement of the North Sea wind conditions at relatively high altitudes (i.e. ≤ 315 m) and therefore was used to examine vertical profiles of wind shear and veer. The greatest wind shear was observed with south-westerly wind directions and high wind speeds, and in general wind direction veered (i.e. increased in magnitude) with height. The wind speed distribution as defined by the Weibull probability distribution was also determined at each measurement location and height. Measurement-site wind speed distributions exhibited inter-annual variability and varied as a function of height and proximity to the coast. The Weibull scale parameter on average increased with height, while the Weibull shape parameter decreased with height. Vertical tendencies in the Weibull scale parameter were expected (i.e. wind speed on average increases with height); however, vertical tendencies in the Weibull shape parameter were nontrivial. This reduction in the Weibull shape parameter with height indicates that although the winds become less turbulent with height, the range of possible wind speeds is greater at higher altitudes (i.e. wider distribution). Further, correlation in wind speed and direction between lidar measurement locations was determined in order to examine the potential applicability of measurement-correlate predict methods within the North Sea. Analyses conclude with a comparison of the lidar wind speed measurements to wind data produced by the KNW-atlas. KNW atlas wind speed comparisons were made to lidar data at LEG, HKZA, and HKZB and overall, the KNW atlas compares well with these measurements.
To reference this document use:
TNO 2018 R11592