Traceable efficiency determination of a 2.75 MW nacelle on a test bench

Abstract

In this paper, the efficiency of a 2.75 MW nacelle drivetrain on a test bench was determined traceably at various load points. For this purpose, so-called transfer standards for mechanical and electrical power measurement were additionally installed and integrated into the nacelle drivetrain. As torque measurement contributes greatly to the overall uncertainty, the static torque calibration was expanded to include additional influences present under rotation. An overall system efficiency of 89% was measured in the high torque and high speed range. The relative expanded measurement uncertainty for efficiency determination was between 0.30% and 0.72% over the entire operating range. Both the efficiency and the relative expanded measurement uncertainty were calculated for each operating point.

Validation of a traceable efficiency determination method for wind turbines with a focus on measurement uncertainty

“…It was introduced by (Deprez et al, 2010), (Stockman et al, 2010), and (Vanhooydonck et al, 2010). In an iso-efficiency map, the efficiency is a function of rotational speed n and torque T, with rotational speed plotted on the abscissa and torque on the ordinate (Song et al, 2023). With this new method, the efficiency is determined directly by measuring all input and output variables.…”

“…The same procedure is used in test benches for wind turbines. A more detailed analysis of occurring influences and further explanations concerning the need to determine the zero signal can be found in (Song et al, 2023).…”

“…This serves to average the signals over many more revolutions within the defined time intervals compared to the low-speed shaft of the DUT. Similarly, signal averaging in an NTB is also considered over an integer number of drive train revolutions when measuring torque on the LSS as described in (Song et al, 2023).…”

“…Torque averaging was conducted by marking the shaft at 12 positions separated by 30° intervals and incrementally rotating the shaft in the operational direction to each position and holding the shaft stationary there for 60 seconds. A comprehensive explanation of this procedure is provided in the referenced paper (Song et al, 2023).…”

“…Due to the rotational motion, measurements are also subject to disturbances, which can in turn lead to instabilities in the torque measurement. A comprehensive analysis of these challenges has been extensively documented in (Song et al, 2023).…”