Identification of torsional frequencies of a large rotor blade based on measurement and simulation data

Abstract

With increasing size of wind turbines, the aerodynamic and structural properties of the rotor blades become more and more important. However, studies investigating the torsional properties using measurement data and simulation results on full-size turbines are still scarce. In this study, torsional measurements are carried out on a large wind turbine with a rotor diameter of 180 m and compared with model results. In this study, torsional measurements on a large wind turbine with a rotor diameter of 180 m are conducted and compared with model results. Torsional parameters of a rotor blade are identified using two different measurement methods, the first based on strain gauges and the second based on accelerometers. Both methods show frequencies that can be associated with the natural frequencies of the two first torsional modes of the rotor blade. To extract the natural frequencies and to reduce external effects, a manual pitching procedure is evaluated. Here, the first two natural frequencies associated with torsional modes can be identified. In a second step, the behaviour of the blade during power production is investigated and compared with the simulation results.

Detecting abnormal small-scale events by nacelle lidar at the AD8-180 prototype turbine

“…The raw measurements have been filtered using a validity-signal from the manufacturer, an accepted value range (2 m s −1 ≤ V LoS ≤ 30 m s −1 ), a rolling despiking algorithm (window length of 100 s, maximal variation of ±4 • σ V LoS around the median) and a maximal step size of ±15 m s −1 . Strain gauges have been installed at the root of all three blades, providing access to blade flapwise (FW) and edgewise (EW) root bending moments (RBM) at 100 Hz [7].…”

Constrained synthetic wind fields from high-resolution 3D WindScanner measurements

“…This contribution utilizes the comprehensive dataset of the Testfeld BHV around the AD8-180 prototype wind turbine. Various wind and load measurements were previously conducted at the site [10,11,12]. An IEC-compliant meteorological mast with wind vanes, cup and highfrequency 3D ultrasonic anemometers at a height of 25 m, 55 m and 110 m above ground level was installed at a distance of 400 m and a direction of 189 • from the turbine.…”

Comparison of Drivetrain Vibration Response During Field Operation and on a Nacelle Test Bench

“…The field test infrastructure also included an IEC-compliant met mast as well as several types of wind lidar instruments to measure the wind flow in front and behind the turbine. More details on the field measurement setup and the test site can be found in [9], [10], and [11].…”