Torque Measurement in the MNm range

Overview

The overall aim of this project is to provide traceability for torque measurements in the MNm range for nacelle test benches. Such a development will support the wind energy industry by significantly improving testing conditions. Within the framework of this project, existing nacelle test benches will be reviewed, multi-component effects of superimposed forces and bending moments will be investigated and novel traceable calibration methods will be developed.

Need

Based on EU Directive “2009/28/EC of the European Parliament and of the Council of 23 April 2009 on the promotion of the use of energy from renewable sources” Article 3, all European countries have to set overall national targets for the use of renewable energy sources. One of the main pillars in the new energy mix in most countries is onshore and offshore wind energy. In particular offshore wind turbine generators (WTGs) are able to provide a very predictable and steady electricity flow which might eventually be used as part of the base load in the electricity grid. To fulfil this important role in energy production, highly reliable power production is extremely important. The growing market in the field of wind energy has already led to the construction of several nacelle test benches to support the development of WTGs. These nacelle test benches all work in the MW power range where torques occur in the MNm range. However, it is not currently possible to trace torque measurements in that range to torque standards. The largest torque standard at PTB in Germany covers a maximum torque of 1.1 MNm. The traceability of torque measurements is important in order to be able to reliably verify the quality of the measurements and thus the quality of the test object, in this case, mostly WTGs. Nacelle tests are needed in order to be able to predict the performance of a WTG during its lifetime. Moreover, a growth in the capacity of WTGs from the current 6 MW to 20 MW is possible by 2050. Extensive testing of prototype WTGs will ensure successful development with high reliability. To address the needs for traceability in large nacelle test benches, this project focuses on the development of transfer standards for torque measurement using nacelle test benches for WTG in the MNm range which can also withstand the high non-torque loading present in such facilities.

Objectives

The specific scientific and technological objectives of the project are to:

Review existing nacelle test benches and their boundary conditions. The review will include the range of loads that can be applied and the dimensions of the test bench, as well as existing methods of torque measurement and calibration and the levels of uncertainty achieved. (WP1)
Develop novel traceable calibration methods for torque values in nacelle test benches in the form of transfer standards for the range above 1 MN m. In order to enable the multi-use of transfer standards a unified approach for several nacelle test benches will be applied. Two different approaches will be used in the project: a commercial torque transducer will be used with an extrapolation procedure for the MNm range (WP2) and a force lever system will be designed to directly reach the MNm range (WP4).
Investigate the effect of multi-component loading on the measurement of torque. In particular, cross-talk effects, in the case of 6-component loading (3 directional forces, 2 directional bending, torque), will be studied to describe effects on the torque measurements which occur in large nacelle test benches. (WP3)
Develop a calibration procedure for large nacelle test benches. The calibration procedure will enable the traceability of torque loads up to 20 MN m and will include an uncertainty model that considers cross-talk effects. (WP5)

Official project homepage

Duration:

01.09.2015 - 30-08.2018

Associated companies: