How do Wind Turbines work ?

How do Wind Turbines work ?


Windmills have been assisting mankind to convert the energy contained in wind to many other useful forms for the last two
thousand years. Today’s wind turbines are capable of
converting a great amount of energy in the wind into electricity. This is due to the blades which are
developed using state-of-the-art aerodynamic analysis and the other
performance-enhancing equipment. In this video we will explore these
different set of technology in a simple yet scientific way. First, let’s get into its basic working If the blowing wind can turn the wing, we
will receive electricity from the generator that is attached to it. However, how does the blowing wind turn the wing ? Let’s have a close look at the blade. The Blade has a lot of airfoil
cross-sections consisting of different sizes and shapes from the root to tip. The simple airfoil technology makes the
wind turbine blade turn. That means that a lift force is produced
when a fluid moves over an airfoil. This way the wind turbine achieves the
basic rotation we are accustomed to seeing. Just as in a moving train you experience things relatively, the
moving wind turbine blade also experiences the wind relatively. For the moving blade the relative wind
velocity is as shown. Therefore the wind turbine blade is
positioned in a tilted manner in order to align with the relative wind
speed. As the blade velocity increases 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 tip. However this rotation cannot be directly
coupled to a generator. Because the wind turbine blades
typically turn at a very low rate of rpm due to the issues of the noise and
mechanical strength. Considering this low-speed rotation we
cannot produce any meaningful electricity frequency
from a generator. So before connecting to the generator
the speed is increased in a gearbox. The gearbox uses a planetary gear set
arrangement to achieve the high speed ratio. A break also sits in the nacelle. The function of the brake is to arrest
wind blade rotation during excessively windy conditions Consequently the electricity that is passed through the cables towards the
base where a step-up transformer is situated. The wind turbine should face the wind normally for maximum power extraction. But the wind direction can change at any time. A velocity sensor on the top of the nacelle measures the
wind speed and direction. The deviation in the wind’s direction is sent to an electronic controller which in
turn sends an appropriate signal to the yawing mechanism to correct the error. You can see how the yaw motors turn the nacelle. Thus the wind turbine will always be aligned with the wind
direction: According to the wind speed the relative
velocity anggle of the wind also changes. A blade tilting mechanism tilts the blades and guarantees a proper alignment
of the blade with the relative velocity. Thus the blades are always at the
optimum angle of attack with the relative wind flow. Efficiency of the wind turbine is the
really interesting topic. To gain a good insight into wind turbine
efficiency assume that you are measuring wind speed at upstream and downstream
over wind turbine. You can note that the wind speed at the downstream is much smaller than
the upstream. This is because the blades absorb some kinetic energy from the wind. The same amount of energy is converted as mechanical power of the
wind turbine. It is interesting to note that a wind turbine absorbs 100 percent of the
available kinetic energy only if the downstream wind speech
becomes zero. However zero wind speed at downstream is a physically impossible condition. This cartoon animation clearly depicts
this fact. Zero downstream speed simply means the whole flow is stock. This physical reality of the flow
demands a certain amount of exit wind speed. That means that there is a theoretically
maximum efficiency a wind turbine can achieve. This limit is known as Betz’s limit. Essentially it means that no wind
turbine in the world can ever cross the efficiency limit of 59.3
percent. We hope you have now developed a good
inside of the operation a wind turbines. Thank You !