Among the most popular prospective renewable energy sectors, wind energy occupies a special place. A modern kinetic wind turbine takes advantage of the power of air currents by converting it into energy. To do this, one can select among the industrial and domestic models that can be applied both by enterprises and private households.
The Wind Turbine Device
Industrial turbines are sophisticated large constructions, while domestic models usually include a few components. A common construction has the below parts:
- alternator (the speed of airflows determines power);
- vanes (they convey rotation to the generator shaft, so they are usually assembled with transmission boxes and rotor speed leveling feature);
- windmill mast, to which the vanes are fixed (the higher these parts are, the more energy they can receive);
- batteries that store energy, which allows it to be used with little or no airflow;
- controller — a transformer of alternating voltage received from the generator into direct voltage, which is used to charge the battery;
- ATS — an auto-switching system that links the generator with other energy sources (for example, the power grid);
- wind direction sensor — this detail simplifies for the vanes the process of finding the airflow;
- inverter — this part is used for transferring direct current from accumulators into alternating voltage, applied in electrical communications.
The Principle of Operation of the Wind Turbine
The principle of work of the wind turbine is based on the conversion of the wind kinetic energy into mechanical energy of the rotor, which is then converted into electricity. The force of the wind sets the blades in motion, which, through a special drive, makes the rotor rotate. Due to the presence of a stator winding, mechanical energy is converted into electric current. The aerodynamic features of the propellers make it possible to quickly turn the generator turbine.
Further, the rotational force is converted into electricity, which is accumulated in the battery. The stronger the airflow, the faster the blades spin, producing more energy. Since the operation of the turbine is based on the maximum use of an alternative source of energy, one side of the blades is rounded, the other is relatively flat. When the airflow passes along the rounded side, a vacuum is created pulling it to the side. This creates energy, which makes the blades spin.
During their turns, the propellers also rotate the axle connected to the generator rotor. When twelve magnets attached to the rotor rotate in the stator, an alternating electric current is created that has the same frequency as in ordinary room outlets. Alternating current is easy to generate and transmit over long distances, but cannot be accumulated. To do this, it has to be converted into direct current. This is done by an electronic circuit inside the turbine.
If the airflow moves at a speed of 45 km/h, the turbine generates 400 watts of electricity. A special device controls the charging of the battery. As the charge decreases, the rotation of the blades slows down. When the battery is completely discharged, the blades begin to rotate again. In this way, charging is maintained at a certain level. The more powerful the airflow, the more electricity the turbine can generate.
All wind turbines work in the same way. First, the alternating voltage obtained from the wind pressure is converted into direct current. This charges the battery. The inverter then produces alternating current again.
Wind Turbine Types
There are two types of turbines available:
- Horizontal axis wind turbines (HAWT). The top of the shaft is directed downwind. Since they have to be directed towards the wind, smaller turbines are guided by blades mounted. They are also equipped with gearboxes to speed up the slow rotation to make it strong enough for the turbine of a generator.
- Vertical Axis Wind Turbines (VAWT). They are placed vertically to the ground. The blades of such a turbine are long, usually arched. Due to the vertical arrangement of the rotor drive shaft, H-shaped turbines catch the wind blowing in any direction, and they do not need to change the rotor position when the direction of airflows changes.
A large wind turbine is easy and cheap to maintain. Wind power plants can reduce dependence on fossil fuels, water resources, and nuclear reactors to generate electricity, so technologies for using wind energy will continue to develop.