Function
A number of auxiliary systems facilitate ongoing unattended operation of the wind turbine for the vast majority of the time, and support planned maintenance, which typically should be only on an annual basis.
What it costs*
The nacelle auxiliary systems cost varies significantly for different nacelle layouts.
Who supplies them
Brake: Siegerland, Stromag and Svendborg.
Cooling: Hydac and Windsyn.
Air conditioning: Cotes.
Anemometry: FT Technologies, Gill Instruments, Kipp & Zonen, NRG Systems, Orga, Thies, Vaisala and Vector Instruments.
Fire protection: Danfoss, Firetrace and Minimax.
Uninterruptible power supply (UPS): AKI Power Systems.
Internal service crane: Effer, Hiab, Liftra and Palfinger Marine.
Key facts
Typically, a mechanical brake is mounted at the rear of the gearbox [T.1.4]. Primary braking of the wind turbine in the event of an emergency is achieved by pitching the blades. In some cases also electrodynamic braking is used but a mechanical brake is also present, frequently with a hydraulically applied calliper acting on a disk.
A rotor lock enables locking of the rotor in a fixed position for maintenance activities. Typically, for large turbines it consists of a peg-and-hole arrangement with manual or automatic hydraulic actuation engaging one or more pegs with holes on the front flange of the main shaft [T.1.3].
A large offshore turbine is about 92-94% efficient in converting kinetic energy in the rotor to electrical energy, requiring at times up to 1 MW of heat to be dissipated from gearbox, generator and electrical system.
To protect all nacelle components from corrosion, the nacelle is well sealed and the whole area is served by a local air conditioning system.
Mounted on the roof of the nacelle is typically a sonic anemometer measuring wind speed and direction.
Frequently, fire protection systems are provided in order to sense and suppress fire in different areas of the turbine. Within electrical panels, nitrogen is used. In open spaces such as the nacelle, spray systems are employed. The fire protection systems have separate control and condition monitoring from the turbine controllers.
To facilitate orderly shutdown of the turbine under grid loss conditions, UPS systems are used to power the control, safety and emergency systems and provide emergency lighting in the tower to facilitate safe exit of personnel. In some cases, UPS power is required in order to ensure requirements for rotor warning lights on the tips of blades continue to operate for an agreed period.
The internal service crane for a large turbine is designed to lift key turbine components during maintenance activities, typically up to 10 t. The crane is controlled wirelessly and operates through cut-outs in the nacelle cover to lower components to the access platform.
What’s in it
- Brake
- Rotor lock
- Cooling
- Anemometry
- Fire protection
- UPS
- Internal service crane