DunoAir: Components of a wind turbine
Cutting-edge wind turbines for grid-connected power generation are high-tech units consisting essentially of 50 to 150 m tall tower structures, the nacelle with mechanical equipment and the rotor with horizontal axis and three rotor blades.
The foundation is the link between the tower and the subsoil and bears all the static and dynamic loads arising from the wind turbine. The foundations of our Enercon wind turbines are circular and consist of a steel mesh that is lined with concrete. The circular shape has the advantage that the effect of the forces is the same for all wind directions and the volume of concrete and steel to be installed is demonstrably reduced. Filling the foundation with the excavated soil from the excavation pit additionally makes it possible to ensure stability even with a smaller diameter.
The tower is the largest and heaviest part of the wind turbine. Enercon produces towers which are between 50 and 150 m tall and weigh several hundred tonnes. Among other things, the height of the tower is crucial to the yield situation at a location. The higher the tower, the lower the loads due to turbulence and the higher the wind speeds. We are therefore moving towards ever-increasing hub heights with which higher yields can be achieved.
Tubular concrete structures which are transported to the site in segments and assembled in situ are the preferred tower design for our Enercon wind turbines.
The green stripes at the foot of the mast are another special feature of the Enercon towers. The various shades of green are used to better integrate the towers into the natural landscape.
The rotor “captures” the wind’s energy and passes it on to the drivetrain. The rotor hub connects the rotor blades to the rest of the system and transmits the power to the rotor shaft. In our wind turbines, braking of the turbine is also controlled via the rotor blades. The blade angle adjustment (pitch control) makes it possible to limit the power output of the turbines at high wind speeds. The position of each individual rotor blade in relation to the wind can be controlled using so-called pitch motors, thus actively controlling the aerodynamics. This has become necessary because the rotor blades used nowadays with lengths of 35 to over 60 m develop very high forces that are no longer manageable with mechanical brakes.
The modified blade geometry, which also uses the inner part of the rotor disc surface and thus increases its efficiency, is particularly important in the Enercon rotor blade concept. The blade tips are also optimised with regard to noise emission and energy yield.
The nacelle is located on the top of the tower and houses the whole machine set of a wind turbine. The central component is the drivetrain which, in the case of our Enercon turbines, consists of rotor hub, rotor shaft with bearing and generator. Enercon wind turbines have the characteristic egg shape to accommodate the large annular generator in the nacelle. The nacelle is rotatably mounted on the tower due to the necessary yaw control and can be rotated by so-called azimuth motors. They are used to rotate the wind turbine optimally into the prevailing wind direction. From a purely visual point of view, the wind turbines planned by DunoAir can be identified by the blue company logo on the nacelle.
DunoAir plans to use only the gearless concept of the Enercon wind turbines in its wind farms. In gearless wind turbines, the rotor directly drives a large-diameter special synchronous generator (an annular generator). This annular generator is directly connected to the hub of the wind turbine and turns slowly at a rotor speed of 6 to 20 revolutions per minute. The output voltage and frequency of this multi-pole synchronous generator vary with the speed and are converted for transfer to the grid via an intermediate DC circuit with inverter.
In contrast to gear-driven wind turbines, the gearless wind turbines which we use in our plans have fewer moving parts and hardly any mechanics, thus guaranteeing less material wear and longer lifetimes. Maintenance, oil changes and repairs to the gearbox also become superfluous. The only disadvantage of the gearless wind turbine concept is the size and weight of the annular generator which is considerably larger and heavier than a traditional synchronous generator.