Wind turbines are made of three visible components; the tower, the box on top of the tower called the nacelle and the three blades, that can extend to over 80m in length. Often wind turbines are grouped together to form wind farms, which help to power our national electricity grid. The blades of the turbine rotate when the wind blows at speeds as low as 6-7 miles per hour.
Most modern turbines have blades that can rotate on their own axis to create resistance and can be feathered to prevent the turbines rotating during very high wind speeds to prevent damage to the turbine. The turbine can also rotate the nacelle and the blades to face into the oncoming wind, optimising efficiency. The rotating turbines blades are attached to a hub that turns a low speed shaft, located inside the nacelle. When the low speed shaft turns, it is connected to a gearbox that increases the rotational speed by about 100 times and transfers this to a high-speed shaft, which spins very quickly. An electrical generator is connected to the high-speed shaft which transforms this kinetic energy into electrical energy. Generators transform the kinetic energy into electrical energy by rotating a large electromagnet close to stationary coils.
The movement of the magnetic field induces a current in the coils. The electrical energy is sent through electrical cables down the tower, to a transformer that raises the voltage coming from the generator, from 690V to between 11-33kV. This minimises energy losses as energy is distributed to the national grid, to power homes, hospitals, schools, offices and more. The turbine transformer then directs the electrical current through underground cables to the wind farm control building and substation where the voltage may, for some windfarms, be further stepped up to 66kV or even 132kV. The output of the wind farm is measured at this point and the electricity is sent into the grid via infrastructure such as cables and overhead lines.
Find out more about wind farm developments by looking at our projects page: www.banksgroup.co.uk/renewablesprojects