what is a wind turbine and how does it
generate electricity
wind power components accidents wind
turbines are devices that convert the
winds kinetic energy into electrical
energy we can simply describe the wind
as moving air caused by differences in
atmospheric pressure between different
regions of our planet differences in
atmospheric pressure arise as a result
of temperature differences when the air
moves from a high pressure region into a
low pressure region we feel the moving
air as wind on the other hand we can
describe wind energy as the process in
which wind is used to generate
mechanical energy or electricity since
the beginnings of civilization man has
always took advantage of wind energy
from the simple sailboats to the
grinding of grain with wind mills up to
the actual production of electricity
thanks to the wind energy converters
also known as wind turbines there are
different types and different sizes of
wind turbines in this video we will
focus on the most common horizontal axis
turbines we'll find out which are the
main components of this particular type
of wind turbine we will understand how
these devices are able to transform wind
energy into electric current we'll see
why wind turbines don't have more than
three blades through the observation of
their airfoil shape and we will also see
what are the main causes of accidents
that occur during the operation of these
devices the first wind turbines were
built towards the end of the 19th
century with the aim of supplying
electricity to small isolated villages
in the following years the gradual
structural and technological
improvements of these devices allowed
the creation of real wind farms entirely
dedicated to the production of
electricity nowadays there are about 26
companies in the world specialized in
the production of wind
turbines. JAES besides being a
qualified partner for some of the most
important wind turbine manufacturers is
constantly engaged in the supply of all
those spare parts necessary for the
production assembly repair and
maintenance of wind turbines as we
already mentioned at the beginning of this video
wind turbines transform mechanical
energy into electrical energy the wind
energy caught by the wind turbines is in
fact transferred thanks to a mechanical
shaft to a generator the generator
transforms the rotation energy into
electrical energy which in turn is
transferred to a transformer usually
placed at the base of the wind tower the
transformer acts as a link between the
wind turbines and distribution grid it
steps up the low output voltage from the
generator to higher distribution voltage
level let's take a look at the various
components of a wind turbine this is the
tower one of the most important parts it
represents the supporting structure of
the wind turbine and has the function of
absorbing the vibrations generated by
the rotary motion of the blade these are
the blades which are aerodynamically
optimized to capture the maximum power
from the wind and transfer it to the
rotor hub each blade is usually 20
meters or more in length depending on
the power level the rotor is the
rotating part of the wind turbine the
rotor hub holds the wind turbine blades
while connected to the gearbox via the
low-speed shaft here we can find the
pitch control system thanks to the pitch
control blades are turned in their
longitudinal access to change the angle
of attack according to the wind
directions this mechanism also blocks
the rotation of the rotor when the wind
is too strong or too weak the nacelle is
instead the enclosure of the wind
turbine that houses all of the
generating components including
the gearbox the braking system and the
generator but also the pitch control
system and the yaw system which is
responsible for the orientation of the
wind turbine rotor towards the wind an
anemometer placed at the rear of the
nacelle
in fact constantly detects the wind
direction whenever there's a change in
wind direction the a nanami terse ends a
signal to the yaw system that provides
to rotate the entire nacelle and
consequentially the rotor and the blades
to meet the wind at the best angle but
now let's see in detail what happens
when the wind turbine goes into action
the blades start to turn when the wind
reaches the so-called cut in wind speed
that is the point at which the turbine
starts generating electricity from
turning the rotor is connected to the
drive shaft which rotates inside the
nacelle the rotational energy of the
drive shaft is transformed into
electrical energy by the generator a
generator is in fact a device that uses
electromagnetic induction to produce
electrical voltage one of the main
elements of the power transmission of
the wind turbine is the speed multiplier
since the rotor blade rotation is low
the speed multiplier inside the gearbox
is used with the aim to reach higher
levels of the rotational speed needed by
the electric generator in order to
produce the electrical power most wind
farms are also equipped with inverters
that convert direct current into
alternating current at 220 volts making
it suitable for grid feeding or
self-consumption if the wind speed
increases there will be a gradual
increased in the instantaneous power of
the turbine until reaching the rated
wind speed that is the wind speed in
which the generator reaches its rated
power output as the speed increases
above the rated wind speed the forces on
the turbine structure continue to rise
and at some point there is a risk of
damage to the rotor as a result the
braking system is employed to bring the
rotor to a standstill this is called the
cut out speed and is usually around 25
m/s we've already said that the turbines
blades start to turn when they're hit by
the wind if we look closely we can
notice that the blade has a lot of
airfoil cross sections consisting of
different sizes and shapes from the root
to tip the teardrop shape of the blade
is very similar to the aerodynamics of
the wing of the aircraft which we've
already discussed in our previous video
in that case the airflow hitting the
wing followed precise trajectories
allowing the molecules of the lower
surface to have a higher density than
those of the upper surface the
difference in pressure between the two
parts allowed the wing and
consequentially the whole aircraft to
lift up also in this case the lifting
process of the wind turbine blades is
very similar thanks to the pitch control
mechanism the blade is tilted in order
to be always aligned with the airflow
when the blade speed is increased to the
tip the relative wind speed becomes more
inclined towards the tip this means that
a continuous twist is given to the blade
from the root to the tip by observing
the operating principle of wind turbines
we may be led to believe that a turbine
with many more blades is more powerful
than one with three two or even a single
blade this conclusion has some truth
more blades allow you to achieve more
power but the more blades there are on a
wind turbine the higher will be the
torque which is the force that creates
rotation and thus lower the rotational
speed because of the increased drag
caused by wind flow resistance so a wind
turbine with many blades will be more
powerful but less efficient than one
with less blades a wind turbine with
three blades placed at
120 degrees from each other represents a
good compromise between power and
efficiency a turbine with four blades
means more weight and therefore more
costs also a wind turbine with two
blades will obtain similar performances
but would require bigger dimensions and
therefore higher costs we have seen so
far that the design and implementation
of a wind turbine involves a series of
structural choices that are not directly
linked to the power of the wind turbine
but take into account factors such as
costs maintenance noise pollution
landscape assessment and many others
maintenance still represents a
fundamental element for the correct
functioning of these devices
unfortunately many accidents still occur
if regular maintenance activities are
not carried out the causes of these
accidents can be mainly attributed to
fires related to the malfunctioning of
internal components or lubrication
system damage caused when foreign
objects make impact with the blades
bad weather conditions or Thunderbolts
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