Vibration Reduction with Passive and Active Dampers

Vibrations play a vital role regarding wind turbine fatigue. They cannot be avoided completely, therefore they have to be controlled and reduced as much as possible.

Unwanted vibrations occur in almost all industries and applications. As experts for vibrations and acoustics, we have vast experience in the field of vibration reduction and with our extensive knowledge of structural mechanics and dynamics, we have specialized in solving vibration problems.

In addition to conventional measures, such as detuning, we provide a wide range of passive and active absorber concepts, which we successfully apply to  various industries. Tuned mass dampers are mounted directly on the vibrating structure – if possible, very close to the affected area – and have a vibration-reducing effect.

If we are already involved in the product development process, we work out solutions mainly by means of FE simulation and measurements. If damping devices are considered as an option for vibration optimization in the design process, they can be conveniently integrated in the structural design. Also for existing structures with an excessively high level of vibration, damping devices are an effective option to solving the problem.

Within the wind energy sector, we offer customized solutions in the field of low-frequency structural vibrations and structure-borne sound. The reduction of structural vibrations is usually intended to reduce mechanical stress, the reduction of structure-borne sound is intended to reduce tonal sound radiations.


Measurement of Vibrations on Wind Turbines

We support you with the vast experience of our highly specialized measuring engineers. Using our comprehensive equipment, we design your individual measurement campaign from planning and instrumentation up to long-term monitoring with daily or weekly reports.

Our measuring equipment includes:

  • Data acquisition system with more than 200 channels, e.g. for acceleration, sound, power, strain gauge or further physical parameters (incl. long-term recording)
  • Wide range of acceleration sensors, microphones, strain gauge technology and various meteorological masts
  • Experimental modal analysis with shakers of all performance classes
  • Laser vibrometry
  • Recording system for meteorological data
  • Proven data transfer technology between rotating (hub, blade) and stationary components (nacelle, tower)

With our electrodynamic shaker systems for universal vibration excitation, it is also possible to analyze the dynamic properties of structures.

In the field of Individual Measuring Systems, we cooperate with our partner Micromega.

Reduction of Gearbox Tonalities with Active or Passive Damping Devices

Vibrations in the gearbox of a wind turbine can cause tonalities (noise with a fixed frequency, e.g. whistling noise). These tonalities are particularly unpleasant for people and thus they have to be specifically considered in the evaluation of noise emissions. In accordance with legal standards, surcharges are therefore assigned to the determined sound power level of the wind turbine. With this surcharge, the authorized limits for noise emissions or the contractually agreed noise levels may be exceeded.

Therefore, tonalities have to be reduced. In the wind energy sector, Wölfel has many years of experience in the application of active and passive absorbers, which compensate the vibrations at their source before they can spread. This is achieved by precisely applied counter-vibrations.

By moving the black dots you can calculate your individual payback period with our interactive tool:



Amortisation after


not possible

Noise-reduced operation of your WTG can massively reduce the yield of your wind farm. With ADD.Sound you minimize tonality and can return to the normal operation mode. This calculation includes all costs including installation.

With more than 1.000 systems in the market, we are proud to be the technology leader in the field of active damping devices for the reduction of gearbox tonalities.

  • ADD.Sound compensates several orders of tonal gearbox vibrations at variable speed (over the entire speed range of the wind turbine)
  • One active absorber ADD.Sound each is mounted on the torque supports (can also be retrofitted; small installation space required)
  • A compact control cabinet is installed in the nacelle
  • Due to the speed-adaptive control algorithm, ADD.Sound generates active forces which eliminate the tonal excitation forces in the gearbox
  • Tonal sound is cancelled over the entire range of speed (broadband effect, simultaneous compensation of several tonalities)

Solution for mastering tonalities with fixed frequency: Passive damper – TMD.Sound

  • Compensation of one order of tonal gearbox vibrations at one fixed speed (mostly the rated speed of the wind turbine)
  • One passive absorber TMD.Sound each is mounted on the torque supports (can also be retrofitted)
  • TMD.Sound is exactly adjusted to the tonality frequency at rated speed
  • TMD.Sound applies a force that is exactly opposite to the excitation
  • Tonal sound at rated speed is cancelled – no energy supply is required

TMD.Tower – Damper for Vibration Reduction at the Tower

Low-frequency vibrations of the entire wind turbine generator (WTG) can cause high stresses on the tower. These stresses can significantly reduce the lifetime of the tower structure. Furthermore, if the vibrations are too high in the assembly state, e.g. the installation of the rotor blades may become impossible or may only be carried out in a narrow time frame due to weather conditions. Resonant vibrations in particular can be (cost-)effectively reduced by tuned mass dampers.

In bridge construction, dampers have long been tried and tested. Wölfel has designed and delivered dampers for bridges already in the 1970s. In the wind energy sector, the demand for dampers has continuously increased over the past few years.

The following scenarios, in which a TMD.Tower can be used, have emerged:

  • Resonance case due to rotor speed and higher harmonics: When starting a WTG, often a resonance is passed through or the WTG should be operated in such a way that the excitations from the rotor (1P, 2P or 3P etc.) are close to a natural frequency of the WTG.
  • Excitation by periodic vortex shedding: At certain wind speeds, vortices can periodically detach from the tower of a WTG. Typically, this can become critical for WTGs in the assembled state (without nacelle or rotor blades) or for slender WTGs with a low second tower bending natural frequency.
  • Wave excitation in offshore WTGs: Wave excitation can become critical if the first natural frequency of a WTG is very low because the energy of the wave excitation is particularly high at these frequencies. The trend towards more and more powerful WTGs in greater water depths and the retention of the monopile foundation concept intensify this problem.

Depending on the type of wind turbine and the overall context, it has to be assessed whether the expected vibrations are problematic and which solution is the most suitable for vibration reduction.

The passive dampers used by Wölfel are characterized by a high robustness. Tailored to the specific application, we offer individually adapted dampers to successfully solve the respective problem.

Our service portfolio as an experienced partner – from planning to delivery of the final damper

  • Support in the conception of the WTG
  • Concept development for different variants/series of WTGs
  • Detailed design including relevant aspects, such as:
    • Component selection
    • Selection and design of the optimal damping concept
    • Braking or locking mechanism
    • Optional frequency adjustment
    • Thermal proof
    • Complete documentation, including proof of structural integrity etc.
    • Support with any necessary certifications
    • Prototype construction
    • Experimental verification
    • Serial delivery

Particularly notable is the direct contact within a cooperation with LISEGA, which makes it possible to provide large production capacities of the highest quality at short notice.

Case Studies

Case Study "TMD.Tower prevents vortex induced tower vibrations" 944.34 KB
Case Study "TMD.Tower prevents vortex induced tower vibrations"

Today’s slender and high wind turbine towers are increasingly subject to vibrations, which are typically caused by wind and wave loads or rotor imbalances. A leading german wind turbine OEM requested for Wölfel to develop and manufacture a solution for vortex induced vibrations (VIV) in the 2nd tower bending mode for turbines in wind farms across the world. The aim is to reduce critical fatigue loads during vortex shedding events. Relatively high tower frequencies above one hertz, a cost efficient design and fast delivery are only some of the challenges within this project.

Please contact us personally


We would be pleased to support you in solving your problem concerning "Wind turbine vibrations" and advise you on questions regarding our system and service offerings in the areas of structural health monitoring, vibration reduction, sound and noise as well as structural design.

Dr.-Ing. Georg Enß

+49 40 524715-262

Timo Klaas

+49 40 524715-265

Dipl.-Ing. Bernd Wölfel