Ground motions induced by wind turbines

Abstract

Wind flow transfers forces to the wind turbine's rotor blades. These then set the rotor in motion. The hub and the gearbox, where present, transfer this rotational energy to the generator for conversion into electrical power. All the rotating components have significant mass and are located at the head of a slender, elastic load‐bearing tower in which they induce dynamic effects. The resulting vibrations, generated at the upper end of the tower, are modified by the dynamic properties of the tower structure and pass through the foundations into the ground. Broadband seismometers record these ground vibrations not only directly adjacent to the wind turbine but also at greater distances of (up to) several kilometers from the turbine. We are aware that local residents and opponents of wind power consider that these vibration phenomena bear potential negative health effects. In the context of this paper, seismic vibrations were measured at the foundation of a 2 MW reference turbine. These seismic signals were compared to numerical simulations. Based on this, we explain the physical background. In the past, any ground vibrations measured have usually been attributed exclusively to the excitation frequencies from the rotor. However, the investigations presented here show that the structural properties of the tower structure significantly influence the type and intensity of the vibrations induced in the ground and dominate the ground motion amplitudes. Finally, we show that the targeted use of absorbers can significantly reduce the vibrations induced in the ground.

Joint Analysis of Resident Complaints, Meteorological, Acoustic, and Ground Motion Data to Establish a Robust Annoyance Evaluation of Wind Turbine Emissions

“…In addition to airborne sound pressure waves, WTs induce elastic waves due to the coupling of their foundation with the ground [32]. These ground motions cause recordable signals and have been the subject of many seismological studies in recent years [33e39].…”

“…Therefore, WT-induced ground motions are studied extensively. Natural vibrations of WTs are related to the eigen modes of the WT tower and blades [32,40], and the blade-passing frequency (BPF) and its multiples (e.g., Refs. [32,34,41]).…”

“…Natural vibrations of WTs are related to the eigen modes of the WT tower and blades [32,40], and the blade-passing frequency (BPF) and its multiples (e.g., Refs. [32,34,41]). While the latter are proportional in frequency to the rotation rate of the WT, natural vibrations are of constant frequency but increase in amplitude with faster rotation.…”

Simulation of ground motion emissions from wind turbines in low mountain ranges: implications for amplitude decay prediction

“…The vibration emissions are linked to the excited eigenmodes of the WT towers [Nagel et al, 2021, Zieger et al, 2020 and occur mainly at frequencies below 10 Hz.…”

Accurate Estimation of Effective Wind Speed for Wind Turbine Control Using Linear and Nonlinear Kalman Filters

“…On other hand, the nonlinear system will be achieved by considering the tower shadow effect. In fact, implanting the tower shadow effect to the WTS will introduce a link between the wind acceleration and the square of the rotor speed [36][37]. Therefore, the model becomes more realistic, effective and nonlinear.…”