Spinner Anemometry – Best Practice. Version 2

Spinner anemometry is used to measure traceable and calibrated measurements of wind conditions at the rotor centre, including horizontal wind speed, yaw misalignment and flow inclination angle. This best practice for spinner anemometry wind measurements provides procedures for mounting, calibrations, measurements and uncertainty calculation. The spinner anemometer wind speed measurement can be converted to “free wind speed” (i.e. a speed that is not affected by turbine induction) by applying a transfer function. Wind measurements with spinner anemometry may be used for a range of applications, including the mentioned free wind measurements, or measurements for control purposes. This report focuses on wind measurements for power performance according to the current IEC 61400-12-2 standard (and the expected IEC 61400-50-1, with identical contents but scope limited to wind measurements only), including improved methods alternative to the standard. This report could provide support to a revision of the last mentioned standard or a separate IEC standard on wind speed, yaw misalignment and inflow angle measurements with spinner anemometry. The best practice document was used in EUDP’s PTP demonstration project for power performance measurements on 77 wind turbines. The experience from these measurements was used to demonstrate and develop the best practice procedures.