ContiTech Makes Wind Turbines Efficient And Quiet

Less noise and longer service life thanks to rubber

Wind turbines are subject to high loads. They therefore need resilient bearings to cope with vibrations. This helps minimise environmental noise pollution, on the one hand, and increases component life, on the other – with simplified construction and maintenance. ContiTech offers a wide range of advanced solutions for this purpose.

Rubber/metal composites from ContiTech’s SCHWINGMETALL® and MEGI® product series reduce the propagation of shock vibrations and solid-borne noise vibrations to the environment and reduce the impact of ambient vibrations on sensitive equipment. Not only does the rubber/metal connection cushion and insulate, it also has a damping effect at the same time – as a function of the rubber material chosen. The use of metallic materials entails significantly higher costs for these functions .

Rubber/metal takes on complex tasks as mounts in wind turbines

The SCHWINGMETALL® and MEGI® mounting elements meet the complex requirements relating to load absorption, impact and vibration insulation and damping critical resonances in stressed components. At the same time they offer the necessary level of qualitative reliability.

“The rubber/metal components enable flexible mount systems where previously there was no option but to use rigid mounts, for example for key functional components such as the shaft case and control cabinet in the rotor’s gondola and hub,” explains Thomas Knickelmann, Industry Manager ContiTech Vibration Control. “A flexible mount here increases security of operation, improves damping and ensures durability while requiring minimum maintenance input.”

Other applications includes the acoustic decoupling of the gondola housing with dome mounts which will remain in position, and mounts for gearboxes and the generators. The components provide optimum absorption of the axial and radial loads.

Elastomer competence from ContiTech

ContiTech Vibration Control has decades of experience in the manufacture of elastomer products for particular needs. As a development partner, the company offers customised support in the manufacture of tailored mount systems for wind turbines. The company provides a one-stop shop for development and manufacture from the initial query through to series production. The customers benefit both from Vibration Control’s elastomer expertise and also from synergies within the ContiTech Group of Companies, e.g. in terms of testing technology or materials development throughout the process – i.e. from the technical specification stage via computer simulation and development to sample production, field trials and testing and finally to series production. “This means we are capable of manufacturing elastomers which are precisely tailored to the specific demands for the required components,“ explains Knickelmann.

The latest proof of ContiTech Vibration Control’s development skills comes in the form of a novel mount system with optimised properties for gearboxes in wind power generators in the 1.5 to 2.9 MW class. The gearbox mount is designed such that it can also fit in turbines already in operation.

Active absorbers – as variable as wind power itself

ContiTech’s development engineers are also currently working on innovative mount systems which respond actively to the forces acting on a wind turbine. “The forces are as changeable as the wind itself,” declares Dr. Hans-Jürgen Karkosch, Head of Preliminary R&D, ContiTech Vibration Control, in outlining the problem. “Active absorption systems can provide the optimum means of counteracting this. They enable a high level of vibration compensation in the turbine.”

The principle of ContiTech’s active absorber is based on the use of electrical energy with which opposed vibrations are specifically generated by an actuator. These vibrations are then  fed, for example, into components in the wind turbine gondola which are subject to especially high loads. “This counterphase compensation is used to specifically reduce the transmission of troublesome vibrations to a particular structure,” according to Karkosch.

The principle of active vibration compensation in wind turbines.

ContiTech’s active absorber system is made up of four components: the actuator to compensate for the load – ContiTech owns the decisive patent for an electromagnetic actuator – the electronic control unit, a power amplifier and an acceleration sensor. The vibrations, which are transmitted to elements of the wind turbine via the mount, are measured by means of a sensor and routed to an electronic control unit. Together with the amplifier, this has to modify the sensor signal such that the actuator generates a vibration which has the same amplitude but is phase-displaced by 180 degrees. “This enables a troublesome excitation source to be equalised. Audible frequencies become quieter, and vibrations are significantly reduced.” To ensure an adequate compensatory effect, the actuator’s counter-vibration must be generated with an accuracy of ± 5 degrees in its phase and ± 0.5 dB in its amplitude throughout the operating range (20 – 800 Hz).

One of the key parts of the active absorber is the electronic control unit in which specially developed control algorithms are implemented. Fine adjustment of the system is handled by an autotuning function. Depending on the application, a control unit can actuate one or more actuators simultaneously. ContiTech Vibration Control is able to call on the expertise of other divisions within the company group with regard to development of the control unit and the sensors

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