Engine & Turbine Technology
Braking ideas for yaw and pitch of wind turbines
Brakes are key at several locations on a wind turbine. Regardless of size, a turbine structure will require rotor brakes, yaw control brakes and blade pitch control brakes.
Los frenos son fundamentales en distintos puntos de una turbina eólica. Independientemente de su tamaño, una estructura de turbina precisa frenos de rotor, frenos de control de guiñada y frenos de control de cabeceo.
Bremsen sind die Schlüsselkomponenten an bestimmten Stellen einer Windturbine. Unabhängig von der Größe benötigt der Turbinenaufbau Rotor-, Azimut- und Pitch-Steuerungsbremsen.
W
ith requirements for clean energy placing the focus ever more strongly on wind turbines, getting the greatest possible output
from a given installation is becoming more and more important. Te amount of useful energy that a turbine can extract from the wind is proportional to the total area which the blades of the turbine will sweep. It is no surprise, then, to see that wind turbine structures are growing steadily bigger. But this places ever greater loads and stresses on the associated mechanical power transmission components in general, and on the brakes in particular. Brakes for wind turbines call for higher
cycle rates, higher loads, greater reliability and often in more compact packages than those on conventional factory equipment. Consider, too, that they must operate automatically in installations that are largely unmanned, often in remote areas that makes access for maintenance both difficult and costly. Tey must operate reliably in some of the most challenging environmental conditions – often subject to extremes of humidity or temperature. Tey must ensure absolute reliability when located in areas as diverse as offshore sites in salt atmospheres or desert sites subject to dust. Brakes are key at several locations on a wind
turbine. Regardless of size, a turbine structure will require rotor brakes, yaw control brakes and blade pitch control brakes – all with specific design considerations.
Emergency braking Rotor brakes control overspeed, and provide parking and emergency braking. Altra Industrial Motion company Twiflex has considerable expertise in the supply of rotor brakes for the very largest wind turbines. Sales and Marketing Director Jon Cooksley comments: “Almost all wind turbine rotor brakes are of the fail-to-safe design, being spring-applied and hydraulically released. Tey incorporate powerful springs which directly, or through an independently mounted thruster, apply force to press each brake liner against a disc. Te brakes
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Fig. 1. Warner ERS series brakes are high torque, electrically released, spring engaged, static holding brakes ideal for pitch brake applications.
Rotor brakes can be mounted on the low speed rotor shaft, on the high-speed generator shaft, and in some cases on both shafts. Low speed shaft braking is relatively straightforward in that a large disc brake, with a large friction lining area, is easy to accommodate. But wind turbine applications require a very high braking torque. So, generally speaking, the most cost-effective position for the brake is on the high-speed shaft between the gearbox and the generator, where the high ratio of the gearbox means a large reduction in output torque. However, placing the brake on the high speed
are released by compressing the springs with high pressure hydraulic oil supplied from a power pack.”
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