Comparison of wind turbine power curves using cup anemometer and pulsed doppler light detection and ranging systems

Abstract

To clarify the difference in the wind turbine power curves obtained by cup anemometer and light detection and ranging (LIDAR) measurements, an investigation was experimentally performed in the Haengwon wind farm on Jeju Island, South Korea. A LIDAR mounted on the nacelle of a 1.5-MW test wind turbine was used with a met mast and a ground LIDAR positioned at a distance of 2.5 times the rotor diameter from the turbine. The wind speed data obtained by each instrument were compared through linear regression analysis. The rotor equivalent wind speed (REWS) was derived from a cup anemometer and ground LIDAR measurements in accordance with the International Electrotechnical Commission (TEC) standard 61400-12-1, 2nd edition. The scatter plots were drawn using the wind data measured by each instrument and compared in terms of the standard deviation. The power curves drawn from the REWS and nacelle LIDAR measurements were compared with that from the cup anemometer measurements according to IEC 61400-12-1, 1st edition. To quantitatively identify the difference in the power curves, the relative error was calculated using the cup anemometer power curve as a reference. Consequently, the relative error for the power output in the bin interval of 0.5 m/s before the rated wind speed was high, whereas that after the rated was close to 0 %. The relative errors for the power curve from the REWS and the nacelle LIDAR measurements were −0.37 % and 3.01 % on average, respectively.