Wind direction tracking
The yaw drive is, a mechanism or a technical system for the rotor of a horizontal axis wind turbine , a windmill or wind turbine to the wind align (old name: "krühen"). This can be either by human power (with the help of a cod-end ) by the force of the wind itself or by servomotors (also azimuth drive or yaw motors called) take place, as is customary in wind turbines.
Adjustment by the wind
Alignment by the wind itself can be done, for example, by means of a simple wind vane for small systems or by means of an auxiliary wind turbine, known as a side wheel or wind rose. The latter is common with Holländermühlen (cap windmills).
The axis of rotation of the side wheel is arranged on the rotatable cap of the mill transversely to the axis of the main wind wheel and drives a worm , which engages in teeth on the lower ring of the turntable which carries the cap. If the side wheel is turned by the wind blowing across it, it sets the gear and thus the whole canopy in motion. The self-locking of the gear prevents frequent changes of direction.
The slewing ring is designed as a slip ring or roller slewing ring and protected from the weather by an apron. A multi-stage gear transmission instead of a worm drive made it possible to have a more easily accessible, internal toothing of the slewing ring.
External power adjustment
External power-operated actuating systems determine the wind direction via sensors , so-called wind direction transmitters , and control electric servomotors. In order to avoid vibrations of the system around the vertical axis, the mostly several servomotors are braced against each other or the entire bearing is locked with a brake when it is not in motion. When moving around the vertical axis, strong moments of resistance ( gyroscopic forces ) act on the rotor and the rest of the structure. The wind direction tracking in modern wind turbines is therefore slow and strongly damped.
In the long run, constantly tracking the wind direction would result in cable connections to the tower becoming twisted. The system control ensures untwisting if necessary. So every now and then you can see a carousel ride, with a gondola turn taking around 10 to 20 minutes. So that this can be done in weak or calm winds, a movement of three to four revolutions of the nacelle is sufficient.
literature
- Robert Gasch , Jochen Twele (Hrsg.): Wind power plants. Basics, design, planning and operation. 9th updated edition. Springer, Wiesbaden 2016, ISBN 978-3-658-12360-4 .
- Erich Hau: Wind turbines - basics, technology, use, economy. 5th edition. Springer, Berlin / Heidelberg 2014, ISBN 978-3-642-28876-0 .
- Alois Schaffarczyk (Ed.): Introduction to wind energy technology. Munich 2012, ISBN 978-3-446-43032-7 .
