A study of mechanical torque measurement on the wind turbine drive train—ways and feasibilities

Abstract

The signal of the drive train mechanical torque can be a very informative input for new technologies on the wind turbine, helping further reducing the cost of energy. However, measuring the mechanical torque is not an easy task even during a test campaign on a prototype. In case of the long‐term measurement for operational purpose of use on the turbine, it is often considered as technically and economically not feasible. This paper discusses possible ways of the torque measurement and presents a test campaign where two different methods of torque measurement are conducted. One of the methods measures the shear strain signal using strain gauges at one section of the turbine main shaft. The other method measures the torsional deformation between two positions of the drive train, with an incremental encoder measuring the angular position of the drive train at each position. The tests are conducted on an 8‐MW wind turbine drive train under tests on the nacelle test bench “DyNaLab” of Fraunhofer IWES. During the tests, different load steps of torque and other load components are applied to the drive train. The measurement results from both measuring methods are presented and analysed. In the end, technical and economical feasibilities are discussed for both methods of torque measurement; some suggestions are also given respectively.

Proposals for a practical calibration method for mechanical torque measurement on the wind turbine drive train under test on a test bench

“…With r(t) being considered as a source of uncertainty, the expression can be simplified to Equation (16).…”

“…Another contributor is the so‐called "cross‐talk" effect, which means that the load in other directions exert an influence on the torque measurement. Despite the effort and common methods available for the compensation against cross‐talk, a satisfactory compensation is usually very difficult on a wind turbine . Fortunately, in some cases, the transient value of the measurement is of less interest, for example, in a stable operation on the test bench.…”

“…Despite the effort and common methods available for the compensation against cross-talk, 15 a satisfactory compensation is usually very difficult on a wind turbine. 16 Fortunately, in some cases, the transient value of the measurement is of less interest, for example, in a stable operation on the test bench. The torque can then be determined by the mean of a period of time, or more precisely the mean value of an integer number of revolutions.…”

Input torque measurements for wind turbine gearboxes using fiber-optic strain sensors

“…These drawbacks have limited the use of such measurements to laboratory environments (Guo et al, 2017), validation and certification of experimental wind turbines, and troubleshooting exercises (Rosinski and Smurthwaite, 2010). More recently, Zhang et al (2018) explored different alternatives to measure torque in wind turbine drivetrains and added that a long-term measurement of torque is considered to be nonpractical or economically not feasible.…”

A FEM-Based Optimization Method for Driving Frequency of Contactless Magnetoelastic Torque Sensors in Steel Shafts

“…Measuring the torque in mechanical shafts made of steel is a common challenge found in various industrial applications. Some examples of these applications include marine propulsion systems [ 1 , 2 ], turbine generators [ 3 , 4 , 5 ], robotics [ 6 , 7 , 8 , 9 , 10 ], and automotive [ 11 , 12 , 13 , 14 ] and electromobility applications [ 15 , 16 , 17 ]. Due to the rotation of a mechanical shaft under normal working conditions, powering a typical strain-gauge based torque sensor while collecting data is very challenging [ 3 ].…”