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Case study Wind generation

Wind turbines are being used increasingly to harness the naturally produced energy generated by wind. The turbines use a three-bladed rotor with slender, tapered aerofoil sections that can be adjusted to optimise performance, according to wind speeds or to stop the machine by stalling or turning out of the wind. The rotor is fixed on the end of a horizontal shaft, attached to the support tower, which drives a gearbox. This in turn drives a smaller shaft at higher speeds inside a generator. The rotor is upwind of the tower to avoid the shock waves to the rotor that would otherwise occur as each blade passes the lee of the tower.

The voltage from a wind turbine is only 690 volts – a small multiple of household voltage – so it is increased via transformers to make it suitable for transmission to the local grid.

The rotor, shaft, gearbox and generator, and sometimes the first transformer, are located in a housing, called a nacelle, on the top of the tower. The nacelle is turned on a platform at the top of the tower so as to face the wind. The tower is usually made of tubular steel sections but occasionally a lattice (like a transmission pylon) or hollow concrete tower is used. The whole system is controlled by computers within each tower, which continually adjust the blade pitch and monitor for faults, operating hours and power output. The computers are also linked to a control centre, where all machines can be monitored and controlled remotely.

All of International Power’s wind turbines are of the types described above, made by leading manufacturers. Mostly they have been acquired after construction, and the operations and maintenance is generally contracted out to a combination of the original developers and manufacturers. International Power does, however, still take an active role in the management of its wind farm portfolio and is one of the world’s leading owners of wind turbines.