Figure 26 Hydraulic pitch actuators (rest of pitch system not visible), © MHI Vestas Offshore Wind.
Function
The pitch system uses hydraulic actuators to adjust pitch angle of the blades.
Who supplies them
Bosch Rexroth, Fritz Schur and Hydratech Industries.
Key facts
Hydraulic actuation uses linear hydraulic cylinders, typically controlled by proportional valves. These actuators are generally trunnion-mounted to the hub and a plate fixed to the inner (rotating) ring of the blade bearing.
Maximum pressures are about 250 bar and total system mass is of the order of 3 t.
Back-up energy to facilitate safety shutdown even without grid power is provided by accumulators.
The main hydraulic tank is normally located in the Nacelle [T.1], with pressure and return lines passing through the Gearbox [T1.4] and the main shaft along with control signal and control power cables.
What’s in it
- Power pack
- Hydraulic actuators
- Rotating union
- Manifold blocks
- Accumulators
- Hoses
- Electrical slip rings