The generator is similar to a dynamo, in which the rotational movement is converted into electricity. The electricity thus generated is converted to high voltage by a transformer in the wind turbine. The electricity is then transported to the mainland by a cable.
The upper part of the wind turbine is known as the nacelle. The gearbox, generator and transformer are all located in the nacelle. This nacelle is fixed as a pivot on top of the tower, so the nose cone of the wind turbine can always be turned to the optimal wind direction. The rotor blades of the wind turbine can be adjusted to take more, or less, advantage of the wind. In this way the power generated by the wind can be regulated. The turbine can be shut down by turning the blades completely away from the wind.
Inside the lower part of the wind turbine tower there is a computer that manages all the control signals. This computer determines whether it is safe to generate electricity.
Finally, on the mainland there is a computer that can monitor remotely the state of the turbine, such as the generated power, and that can also override the control.
Maintenance of the wind turbines at sea
The wind turbines need maintenance once a year. This maintenance is planned to take place in periods when the wind is less strong. At those times the wind farm is more easily accessible by sea and we lose the least revenue.
It takes two days to carry out maintenance on a wind turbine, using a team of three or four people. The maintenance staff go by boat to the turbines. To reduce the maintenance period, several teams are deployed simultaneously.
The maintenance of the turbines includes carrying out inspections, lubricating rotating parts and replacing worn parts. You can compare maintaining a turbine with servicing a car, as far as the activities involved are concerned. A car is serviced roughly every 20,000 kilometres. Those 20,000 km equate to 400 operating hours of a wind turbine.
A wind turbine can run for a total of 8760 hours a year, depending on the wind of course.
In addition to the planned maintenance, it is likely that a turbine will have to be visited 3 or 4 times a year to repair a breakdown. In this case, a team of 2 people will visit the turbine to be able to work safely.
Maintenance is carried out once a year on the foundations of the turbines, the undersea cables and the transformer sub-station. This maintenance consists principally of visual inspections and underwater video recordings.