Summary report describing current state-of-the-art developments on efficiency determination methods for wind turbines and nacelles in the field and on test benches respectively, their traceability, and general methods for direct and indirect efficiency determination

This report has been produced within the EMPIR project entitled Traceable Mechanical and Electrical Power Measurement for Efficiency Determination of Wind Turbines or 19ENG08 WindEFCY. More information about this collaborative research project can be found on the project’s website https://www.ptb.de/empir2020/windefcy/home/. This report aims to investigate the multitude of influencing variables and the changing boundary conditions for measurements to determine the efficiency of wind turbines. Moreover, through a systematic comparison of direct and indirect efficiency determination methods for rotating electrical machines, the challenges for designing an efficiency determination procedure for nacelles and their components on test benches is examined.