Spinner anemometer - best practice. Version 1

Spinner anemometry is used to measure traceable and calibrated wind speed, yaw misalignment and inflow angle. Free wind speed may be measured by application of a spinner wind speed transfer function. Spinner anemometer free wind speed measurements are used in power performance measurements according to the standard IEC61400-12-2 on use of nacelle anemometry. An improved procedure, developed specifically for power performance measurements with spinner anemometry, without considering the use of nacelle anemometry, is the aim of this document. The best practice description for spinner anemometry provides procedures for mounting, calibrations, measurements and uncertainty calculation. As such it could provide input to a separate IEC standard on wind speed, yaw misalignment and inflow angle measurements with spinner anemometry. This best practice procedure for wind measurements is used in the PTP demo project for power performance measurements on 90 wind turbines. The experience from the measurements will be used to demonstrate and support the further development of the best practice procedures.