The Earth’s atmosphere is an enormous and inexhaustible source of energy. The constant movement of air masses has a gigantic kinetic energy, the true extent of which can only be guessed. It is enough to consider the effects of any hurricane or just a squall of wind to get an idea of the scale of available energy reserves, the use of which is still at a minimal level.
The availability of more efficient ways to produce electricity has limited research activity in this area, which has been restarted relatively recently. The shortage of hydrocarbon sources and the fuel and energy crisis are forcing a rethinking of alternative options for power generation, with wind power as a leader.
Wind energy at the service of a human being
Nowadays there are full-fledged power stations, which produce electrical energy with the help of wind flows. There is quite a lot of them, about 20 thousand of such stations worldwide. However, it is not enough to say that man has conquered the wind energy and is using it quite effectively. Despite the significant amount of energy obtained, the capabilities of wind energy are still far from ideal.
Existing installations have insufficient efficiency due to difficult operating conditions and inability to regulate air flows. Their irregularity is one of the key reasons holding back the development of the industry. Ongoing research in this area gives a limit value of the efficiency of wind turbines – 59.3%, which is much higher than the actual values, but not enough in general.
The understanding of the importance and great potential of wind energy in society is constantly strengthening. China and India have achieved great success in this field, having the most powerful wind power plants today.
The peculiarity of the industry is the renewable nature of the energy source, the possibility of endless use of the resource. In this respect, wind power is the most sustainable in comparison to other ways of generating electricity.
Research and development is constantly being conducted, and its intensity has recently increased markedly. Completely new models are emerging, using techniques that are different from those currently in use. The activity of the designers and researchers is in itself a sign of the growing importance of wind power and a guarantee that the number of wind turbines will increase in the future.
In order to transform the kinetic energy of the wind into electrical energy, the appropriate equipment must be used. The most common device for conversion is a wind turbine generator. This is a unit consisting of several units that perform the tasks of receiving, transmitting and converting the energy of the wind flow into electricity.
There are many variants of the design of wind turbines, performing the same function with the help of an impeller with blades. The difference in all types of design is in the direction of the axis of rotation and in the design of the rotating assembly – the rotor.
Wind turbines are divided into two large groups that have a different location of the axis of rotation:
The most effective are considered horizontal devices, resembling an airplane propeller. The flow of wind, acting on the blades, is used as much as possible, almost without loss. In this case, there is a constant need to correct the position of the axis depending on the wind direction, which forces the use of additional devices and appliances. The simplest and most effective among them is the tail stabilizer, similar to the tail of the aircraft, which automatically sets the wind turbine in the wind.
Vertical designs have an important advantage – independence from the wind direction. At the same time, the efficiency of such devices is somewhat lower, because the flow simultaneously affects both the working and the reverse side of the blades, creating a balancing force. It stops the rotation of the rotor, forcing to resort to various design tricks. For example, various shrouds are used to cover the back sides of the blades.
Also, there are external structures which cover the access of the flow to the back of the blades, straightening devices, directing the flow in the desired direction, etc.
Practical results have shown the greatest efficiency of horizontal installations as part of industrial power plants and the benefit of using vertical structures for power supply of individual households.
Principles of operation of a wind turbine generator
Wind generator is a unit consisting of several units. They perform separate tasks, being links in a chain of successive changes in the type of energy.
- Air flow, interacting with the impeller of the wind turbine, makes it rotate
- the shaft motion is transmitted to a generator, which generates an electric current
- The generator sends the voltage to the battery through the rectifier and charges it
- the level of charge is monitored by a special device – a controller which cuts the power and turns it on again as needed
- The charge is transferred from the accumulator to the inverter, which transforms the obtained current to the appropriate level and transmits it to the consumers
Small devices sometimes work according to a simplified scheme, supplying voltage directly from the generator to consumers. This is possible to power water pumps or site lighting, greenhouses, etc.
Performance of the wind turbine depends on the parameters of the generator itself, the size and design of the impeller. In addition, an important parameter is the prevailing wind speed in the region, which provides the basic mode of rotation of the rotor and determines the performance of the entire complex.