Wind turbine cooling technologies - Wind Power Generation and Wind Turbine Design - page 614

As shown in Fig. 1, a wind turbine working in a parallel operation is mainly
comprised of an impeller, a nacelle, a pylon, a foundation and an electric trans-
former. Among these components, the impeller is wind collecting device, includ-
ing blades and hub. It can convert wind power at a certain height to mechanical
energy, representing as shaft rotation at a low speed but with high torque. The
nacelle, comprised of a gearbox, a generator and control systems, is the core com-
ponent of the wind turbine where the mechanical movement is accelerated, then
converted to electric energy with modulated frequency to meet the demands of
parallel operation. The pylon and foundation are mostly used to support the nacelle
and impeller to a certain height and ensure the safe operation. The function of the
electric transformer is to perform the voltage regulation to the output electricity so
as to transfer power effi ciently.
To sum up, the operating procedure of a wind turbine is as follows: the impeller
rotating under the wind force action drives the main shaft in the nacelle to rotate
simultaneously. This movement is then accelerated in the gearbox, and supplies
the high-speed revolution for the generator rotor by connecting with high-speed
shaft. The rotor cuts the magnetic lines of force, and thus produces electric energy.
With the increasing unit capacity of wind turbines, the length of impeller blades
and the height of pylon are gradually increased for the purpose of capturing more
wind energy.
2 Heat dissipating components and analysis
It is well known from the operation principle mentioned in Section 1, the nacelle
is the core component for a wind generating set and also the concentrated area of
heat production in the operating process. The confi guration of the nacelle is shown
in Fig. 2, and the mechanisms of heat production for different components are
explained as follows.
Figure 1: Sketch of a wind turbine generator connecting to power system: 1, impeller;
2, nacelle; 3, pylon; 4, foundation; 5, transformer.