Development of Wind in Flow Measurement System Using 9-Beam Nacelle Lidar

Abstract

This paper reports on wind inflow measurements performed using a nine-beam nacelle lidar. Various nacelle lidar systems have been used for the measurements of wind inflow to realize high-performance wind turbines. The measurement of a two-beam nacelle lidar used as a simple measurement system has been compared with those of a nacelle anemometer and a met-mast. The 10-min-averaged data obtained from the two-beam nacelle lidar have good measurement accuracy, but the lidar is unable to measure wind shear. Monitoring of wind in-flow for multimegawatt wind turbines requires an advanced lidar system that can measure wind shear. Further, there is a lack of observation reports on measurements using the two-beam nacelle lidar under strong turbulence conditions. In this study, the authors evaluated the measurement characteristics of a nine-beam nacelle lidar installed on a 300-kW wind turbine. This nacelle lidar could measure radial wind speeds in nine directions; further, horizontal wind speeds were measured using a three-beam system. The use of three beams led to a considerably higher availability of the lidar in comparison to the availability when using two beams. This lidar also could measure wind speed uniformity in a transverse direction by using three beams. To discriminate the lidar measurement data in terms of their quality, some filtering indexes for these data were proposed. Continuous and reliable monitoring of wind shear could be achieved by filtering the measured data.