Bonfiglioli drives wind farm

Electrical switching & drive systems & components

4th Quarter 2010 Electrical switching & drive systems & components

Alpha Ventus, the world’s biggest offshore wind farm, was recently commissioned off the German island of Borkum in the North Sea.

The wind farm consists of 12 towers between 148 and 155 metres in height, each generating 5 MW of electricity. It is expected to generate enough electricity to power 500 000 homes.

Bonfiglioli was the preferred partner for this major €250 million development, and supplied the yaw drives that orient the wind turbine nacelles and the pitch drives that adjust the angle of attack of the blades. Bonfiglioli has been producing motion control systems for wind turbines since 1985 and has a market share of over 30%.

A tall order

The harsh environment and high power output of the turbines called for reliable, high performance components. Orientation of the nacelle (yaw) and blades (pitch) had to be constantly adjusted to achieve optimum exposure and to derive adequate torque for the blades. It was also important to avoid dangerous overspeed conditions occurring in strong winds and to prevent side gusts from subjecting the mast to damaging oscillations. To control these risks, the nacelle and blades were required to rotate intelligently around their axes to assume the position required by the control system.

Fresh thinking

Fresh thinking was needed to meet these load requirements. The outcome had to be lightweight and compact but no compromise could be made when it came to solid design and long service life of the components. The design also had to be to be maintenance and service friendly.

The Bonfiglioli solution

Bonfiglioli, which produces equipment for some of the world’s most sophisticated applications, was able to achieve this through the introduction of two new drive systems. Bonfiglioli Trasmital 700T series planetary gearboxes were selected, driven by Bonfiglioli series brake motors and controlled by Bonfiglioli Vectron inverters (AgilE, Active or Active Cube series). Together these provided vector speed and torque control.

Pitch drive

The pitch drive controls the angle adjustment of each of the blades through three independent systems. To withstand the high stress duty cycle, Bonfiglioli introduced the 711 T3F gearbox, together with a special P200 motor adaptor. It had the following main features:

* A reinforced final stage planet carrier, designed after test and simulation.

* Higher capacity pinion and final stage output bearings which enhanced safety and improved reliability.

Yaw drive

The yaw drive moves the nacelle to the optimum position and holds it there. This is performed by electric geared motors. To meet the need for a compact solution, Bonfiglioli introduced a new gearbox, the 716 T4U, together with the BN 160M FD motor. In addition to the features listed above, this system had:

* A reinforced final drive to improve torque delivery without an increase in blade dimensions.

* A supported pinion to increase stiffness and performance while keeping the compact design.

For more information contact Robert Rohman, Bonfiglioli, +27 (0)11 608 2030, [email protected], www.bonfiglioli.co.za

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Bonfiglioli drives wind farm

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