Model of the 4MW test rig and measuring ranges of the multi-component transducer Copyright: © CWD


Lukas Schmitz © Copyright: CWD


+49 241 80 90869



Improving the precision of measurements on wind turbine system test rigs

The development process of new and more powerful wind turbines (WT) is accompanied by extensive tests to ensure high reliability. The tests are carried out on system test rigs. Numerous test rigs ranging from 1 MW to 30 MW are currently operating or under construction worldwide. With the help of test rigs, cause-and-effect relationships, e.g. in the occurrence of damage, can be reproduced and understood in an economically reproducible manner. This enables remedial measures to be developed.

Failures in the drive train of WT, especially gearbox and main bearing damage, cause more than 39% of the downtimes of a WT. Failures result in long downtimes and costly repairs. The input loads of the drive train have a decisive influence on gearbox and main bearing failures. The input loads can be divided into the torsional load (torque), which can be converted into energy, and the parasitic non-torsional loads (NTL). The NTL are applied to the powertrain by hydraulic load units. The amount of NTL applied is calculated from the pressure of the hydraulic cylinders. Inaccuracies occur due to simplified assumptions. The measurement of the torque usually takes place in front of the hydraulic load units to prevent crosstalk of the parasitic loads on the torque measurement. However, the position of the measurement point also leads to measurement inaccuracies as losses in the load unit cannot be taken into account.

The inaccurate determination of input loads on system test rigs results in the inability to simulate or record load conditions with sufficient accuracy. This means, for example, that critical operating states and relevant system behaviour cannot be clearly identified. As a result, optimisation potential in the development process is not fully exploited.

As part of the ErWind project, CWD, Renk Test System and Manner Sensortelemetrie are working together to develop, test and verify a multi-component transducer that is directly integrated into the force and moment flow of the test specimen. This will significantly improve the accuracy of the measurement of applied loads.

  Project flow diagram Copyright: © CWD

First, a sensor concept is systematically selected and optimised. The aim of the optimisation is to maximise the measurement accuracy of the sensor, which is achieved by minimising the crosstalk between the different measurement variables. In view of the trend towards ever larger rotor diameters and increasing turbine power, the scalability of the multi-component transducer for future power classes of WT and test rigs is also taken into account.

Based on the sensor concept, a multi-component transducer will be designed, manufactured and then tested on CWD's 4 MW test rig. The development of the multi-component transducer for all six degrees of freedom includes a new type of telemetry for precise time synchronisation of measurement systems. Furthermore, an automated recording of characteristic curves and characteristic curve fields for the computational real-time compensation of crosstalk effects is made possible.

In summary, a multi-component transducer with low crosstalk behaviour and high measurement accuracy is being developed in the project. Through the precise determination of input loads on test rigs, simulation models can be validated and critical operating conditions can be better identified.


01.11.2022 - 31.10.2025

Project partners:

MANNER Sensortelemetrie GmbH Renk Test System GmbH

Project funded by:

Federal Ministry for Economic Affairs and Climate Action

Project promoted by:

Projektträger Jülich