Wind Turbines

8 Basic concepts of wind turbines

wind  turbines
wind farm

 

The need for wind energy in the energy system is to replace fossil fuel-based electricity generation to combat climate change on a global scale, but also to mitigate environmental concerns which are more on a regional or a local scale, which is associated with. Fossil fuel-fired power plants emission of particles, nitrogen oxides, or sulfur oxides.

Wind energy is also increasing the security of the energy supply of our energy system because it is a domestic fuel that we don’t need to import from politically unstable regions of the globe. It is cost-competitive It would be traditional power generation and it provides local employment and regional economic development. It can be installed very fast compared to conventional power plants.
 

#1. Considerable Elements we need  for  choosing  wind turbines

Wind speeds

 
Wind turbines are classified according to the wind speeds they are supposed to cross.
The categories of wind turbines are determined according to the specifications of the photoelectric committee IEC 61400 on the basis of three factors
  1. Average wind speed on site ( Vave )
  2. The maximum speed of a storm for 50 years (V50)
  3. The disturbance rate of the “standard deviation” in the change of wind speed is attributed to a record speed of 15 meters per second, and all the speeds are measured at the height of the feather pin (I15).
 
The value of the average speed contributes to choosing the quality of the turbine, but the level of turbulence plays an important role in determining the quality of the turbines (according to the real speeds).
Turbines are classified according to speeds into five types arranged according to the Latin numbers (I, II, III, IV, V)
 
 

Properties of the site

 
 
The more the site has a flat topographic nature and cool climate the better is for creating wind farms. And take into account the nature of the areas surrounding the site as this has an impact on increasing or decreasing the wind speed and the locations closest to the water surfaces are better because the friction force of the air with the water surface is weaker and therefore does not interfere with wind speed.
 
Avoid protected or populated areas and if the area is populated the residents should accept the idea of ​​creating wind farms.

 

How does the wind turbine work?

 

The production of electricity by a wind turbine is carried out by the transformation of the kinetic energy of the wind into electrical energy. Many stages  Are necessary to this transformation, which calls upon very diverse technologies.

 

The transformation of energy by the blades

The blades of a wind turbine operate on the principle of an airplane the pressure difference between the two faces of the blade creates an aerodynamic force, setting the rotor in motion by the transformation of the kinetic energy of the wind into mechanical energy.

The acceleration of the rotational movement thanks to the multiplier

The blades rotate at a relatively slow speed, of the order of 5 to 15 revolutions per minute, especially slower than the wind turbine is large. Most generators need spinning at very high speed (1000 to 2000 rpm) to generate electricity.

This is why the slow movement of the rotor is accelerated by a multiplier.

Electricity production by the generator

The mechanical energy transmitted by the multiplier is transformed into energy electricity by the generator. The generator rotor rotates at high speed and produces electricity at a voltage of around 690 volts.

Treatment of electricity by the converter and the transformer


This electricity cannot be used directly; she is treated with a converter, then its voltage is increased to 20,000 volts by a transformer.
The electricity is then routed through a buried cable to a transformer station, to be injected into the electricity network, then distributed to the most relatives.

#2.The main factors affecting the amount of energy produced by the wind

 

Wind speed

 

The resulting energy is proportional to the cube of the wind speed, so the higher the wind speed, the more the energy produced will be three times greater
 

Air density

 

 
The relationship of density with wind power is a direct relationship, The colder the location the higher the density of air. As a result, the amount of energy in the wind increases.
The higher the site temperature, the higher the air density.
 
 

Swept area

 

The rotation zone, that is to say, the circular zone through which the air passes: the larger the circulation zone, the greater the volume of air that strikes the turbine, and therefore the energy resulting increases.



Types of wind speeds

 
Cut in: is the speed at which the turbine starts to generate energy
Cut out: is the speed at which the turbine stops generating power
rated: The speed at which the turbine begins to generate a constant amount of energy.

Nominal values

Cut in Speed =4 m/s nominal
The cut of Speed=25 m/s nominal

#3.Seven Top  wind turbines Manufacturers  in the world

 
  • Danmark   Vestas.
  • Spain   Gamesa‬‬ .
  • GermanyEnercon.
  • GermanyNordex‬‬ .
  • USA   General electric.
  • India  Suzlon.
  • ChinaGoldwind.

#4.Wind turbines maintenance

 
The life of the turbine is estimated at 20 years, and this will only be achieved by performing the necessary maintenance operations to ensure that the turbine is operating during this period. Maintenance is classified into three sections.
 

1- Preventive maintenance

Preventive maintenance is within specific programs according to the manufacturer’s instructions and includes the following:
 
  • Maintenance of transformers through testing of measuring and cleaning devices 
  • Container maintenance « Maintenance of oil circuits, hydraulic »
  • Blades cleaning.

 

2-Corrective maintenance

 
Fixing sudden breakdowns, through which the system checks for any sudden breakdowns and adopts the appropriate procedures.

 

3-Predictive maintenance

 

Maintenance is done through remote monitoring devices to monitor the state of the turbine through measurements on temperature on all internal components, which can detect faults before they occur and know their causes.

Read also: Victoria Polytechnic University introduced a Diploma in Maintenance of Wind Generators
source: Vestas

How controllers restart the wind turbine after the malfunction?

 
The turbine is automatically restarted from the main control room through remote control devices through the exchange of data with the data room for each turbine. The remote restart will be directly from the main room or indirectly after ensuring the possibility of restarting in the following cases:
 
  • Network setup malfunctions where remote operation is restarted after network stability.
  • The defective temperature in control panels and oils as a result of the continuous rotation of the turbine
  • Manual stopping due to maintenance, loss of connection to control rooms, or lack of turbine response to some orders and calculation errors.
In the case of heavy dependencies, clogged filters, or oil circles being turned off, in this case, remote operation is not permitted.
 
 

#5.The big wind farm in the world

 

 The largest wind farm in the world in the state of Texas, USA, which contains more than 400 turbines with a production capacity of 770 megawatts.

#6.The big wind farm in Africa and the Middle East


The Zaafarana farm in Egypt is considered the largest farm in Africa with an area of ​​156 square kilometers, and thus, Egypt will be the first Arab and African to produce electric energy from wind energy with a capacity of 550 MW, followed by Morocco with 286 MW, then Tunisia, then Algeria.

 

#7.Types of wind farms

Wind farms are divided into two parts:
 
  • Major wind farms from 100 MW to above

These farms are found in abundance in China and North America, because of the vast areas suitable for placing large projects

 
  • Small wind farms from 1 to 50 MW

There are many of these farms in Europe and Denmark as a result of the lack of free areas of the population in Europe, and this does not mean that major projects do not exist, but most are small farms.

 

#8.The negative impact of wind stations on the lands


The production of electricity through wind farms requires the occupation of large lands, so an area of kilometer square of wind turbines can produce 9 megawatts while one kilometer square of solar panels can produce 40 to 50 megawatts.
Thanks to the development of forecasting techniques and satellites, it has become easy to monitor the location of winds and their speed, which has made it possible to set up all major projects based on the data provided by modern surveillance and the error rate has been reduced to 5 or 4%.

In addition to this, many countries are looking to use renewable energy to meet their energy needs in order to reduce the pressure on traditional and impure sources by relying on wind power, which is the first clean source approved to produce electricity around the world.

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