STF uncertainty analysis in an offshore site. PTP Deliverable D7.2

The “Performance Transparency Project” (PTP), project partners ROMO Wind and DTU, focuses on demonstrating spinner anemometers accuracy and precision for power performance measurements (the relevant measurement standard is IEC 61400-12-2). Spinner anemometers measure wind speed, yaw misalignment and inflow angle at the rotor centre. They require a Spinner Transfer Function (STF) to obtain “free” (of turbine induction) wind speeds.

STF uncertainties, to a great extent, are determined by the uncertainties of the instruments used to obtain them. These instruments have different uncertainty sources (e.g. calibrations, mounting, instrument sensitivities to environmental variables, etc), and the procedures to obtain them are described in standards and best practices. One of the main goals of PTP is to study the applicability of STF: from one turbine to another, and from one wind farm to another – both consisting of the same turbine types and operation modes; and to obtain a suitable uncertainty due to the STF application or transfer. To estimate this uncertainty, STFs from different turbine types and different terrain types were analysed in PTP. This report summarizes the analysis results from an offshore site, based on the work done by DNV-GL (project 3rd party consultant), and work by ROMO Wind and DTU.

The Performance Transparency Project (PTP) was sponsored by EUDP under the name “Large Spinner Anemometer Performance Demonstration Project” with the EUDP Journal number: 64016-0059.