Following a brief decline in 2013, the global wind power industry is now looking stronger than ever. A record year in 2014 saw annual installations cross the 50 GW mark and as the world continues recognize wind energy as one of the most important sources of renewable energy, 2015 is set to be just as strong.
At Trelleborg we have been working with the wind energy sector since the first British installation in the 1990’s without a single failure. Building on this experience we take a look at the key considerations when managing wind turbine vibrations.
The effects of vibrations
Excessive vibrations not only impact wind farm performance but also the life cycle of the turbines. Untamed vibrations result in material fatigue, component and weld failure, reduced life cycle of components and most importantly, reduced power quality.
In addition, the noise and vibrations generated by the wind turbines can have a negative effect on the environment, in particular with farm animals and local residents. Fear of such environmental impacts have been known to halt an installation all together.
Fortunately for turbine OEMs there are a range of solutions available. Mounting generators on vibration mounts such as the Cushyfloat, reduces vibration amplitude, lowers structure borne noise and improves equipment life. Originally designed for use with marine engines, the Cushyfloat is a compact low-profile mounting, combining three way control of suspended equipment. Supporting large static deflections, the design incorporates bump and rebound control features to limit excessive movement. The top metal cover provides protection against oil contamination and the protective finishing resists corrosion attacks and thrust from the rotor blades.
Large isolators such as heavy duty sandwich mounts and bushes sit between the gearbox, nacelle and tower to block the noise path, reduce stress on expensive equipment and eliminate strong vibrations that could cause structural damage.
Spherilastik bearings work by allowing the rotor blades to tilt on its hub, so counteracting the see-saw motion caused by gusting wind. In addition to acting as a resilient spherical joint, the compact, precisely formulated rubber/metal component also keeps vibration to a minimum. Spherilastik bearings are designed for un-lubricated, maintenance-free operation and have a long track record in demanding applications where a high duty bearing of compact size is required. The bearing not only suppresses noise and vibration but also provides articulation, helping to reduce bending forces on the turbine shaft, gearbox, tower and foundations, which can therefore be lighter and less expensive.
With the rapid expansion of the industry, Trelleborg Industrial AVS’ expertise in the design of custom solutions has come to play an increasing role. We now frequently design complex isolation systems that will bring a windfarm’s overall noise levels within specified and environmentally acceptable norms. In one typical package, a combination of Spherilastik and Metalastik Cushyfloats achieve a reduction of 4 dBA in structure-borne noise.
Selecting the right anti-vibration solution
The first step in selecting the correct vibration isolator starts with collecting key structural information such as dimensions, weight, mounting locations, vibration characteristics and environmental requirements such as chemical exposure and operating temperatures.
As the drive train is typically mounted at the top of a 100 meter tower, one of the most important features is that the anti-vibration component must work reliably over an extended period to reduce the need for maintenance. Other features to consider are resistance to oils and weather related stress, the ease of installation and its overall ability to reduce noise and vibration.
At Trelleborg, we provide a complete end-to-end service. Providing technical support from mount selection all the way through testing and validation to installation and post service support. Our dedicated team of application engineers have the knowledge to analyze the situation and recommend suitable anti-vibration solutions. We also provide design testing and validation to demonstrate that the isolators meets the customer’s exact requirements.
To find out more about isolating vibrations in wind farm technology contact our specialist team.