Figure 18 Yaw system, © MHI Vestas Offshore Wind.
Function
The yaw system orients the nacelle to the wind direction during operation.
What it costs*
The yaw system cost varies significantly for different nacelle layouts.
Who supplies them
ABB, Bonfiglioli, Bosch Rexroth and VEM.
Key facts
The yaw system typically consists of about 10 geared electric motors mounted on the nacelle bedplate [T.1.1], with gear mounted on their shaft acting on the toothed inner ring of the yaw bearing [T.1.9]. Each drive has mass up to 1 t and typically has ratio 200-300:1.
To avoid constant varying loading on the drives, a series of about 10 calliper brakes are hydraulically applied to hold the yaw bearing in position, except when movement is required. Even during movement (which may be the order of a few degrees every few minutes in order to align the nacelle to the wind direction), the yaw brakes act to damp movement.
Sensors measure the position of the nacelle and limit switches prevent over-twisting of the cables down the tower.
What’s in it
- Yaw motors and associated gearboxes
- Yaw brakes, sensors