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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING How modern wind turbines deal with the vagaries of the wind. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Alternative energy sources In pre-revolutionary Russia there was no industry producing wind turbines; they were built only in a handicraft way. But the idea of the best, most profitable use of wind energy originated in Russia. The great Russian scientist, "father of Russian aviation", Professor N. E. Zhukovsky (1847-1921) also created the theoretical foundations of the wind turbine. His remarkable works found practical application only under the Soviet regime. On the initiative of N. E. Zhukovsky and with the support of V. I. Lenin, in 1918 the Central Aero-Hydrodynamic Institute (TsAGI) was organized in Moscow. Here the first domestic high-speed wind turbines were built. Based on the work of prof. N. E. Zhukovsky, his students prof. V. P. Vetchinkin (1888-1950), Honored Worker of Science and Technology prof. G. X. Sabinin and prof. N. V. Krasovsky developed the theoretical foundations for the design of high-quality modern wind turbines, and prof. E. M. Fateev developed the foundations for their correct exploitation in agriculture. Soviet designers created original and still unsurpassed in their qualities high-speed wind turbines with a power from several tens of watts to several thousand kilowatts. Factory-made all-metal wind turbines, in contrast to the considered wood-metal wind power plants, have special devices to deal with the "whims" of the wind. Everyone knows that the wind can change its direction and speed several times a day. The simplest drum wind turbines had a wind energy receiver, which was rigidly, once and for all, installed in any one position. Carousel and rotary wind turbines are operational in any wind direction, but they, like drum-type wind turbines, are not protected from possible damage in strong winds "The simplest windmill can only work normally in the presence of a person. A person must monitor the wind and set the wind wheel in the right position in time. If the windmill is large, then at least two people are needed to set the wheel in the wind, if it does not have a special gate ( the simplest machine for lifting loads). With the further development of the technology of building wind turbines, they began to strive to use the power of the wind not only to rotate the wind wheel, but also to automatically install it against the wind, as can be seen from a conventional weather vane showing the direction of the wind. To do this, to the rear parts of the swivel head began to attach a tail, consisting of a long rod or a special truss with a surface at the end, which is called tail plumage (see Fig. rice. 24).
If the wind changed its direction, the tail automatically turned its head. The wind wheel was again installed in the forehead to the wind. So there was a simple device for turning the wind wheel into the wind without human intervention. In modern wind turbines, the tails are calculated so that they begin to turn the head with the wind wheel into the wind when its direction changes by an angle of about 10 degrees. To turn the heads of large wind turbines, tail plumage is sometimes made in the form of two or three vertical surfaces set parallel at a certain distance from each other (see Fig. 27). In other systems of wind turbines, the role of the tail is performed by the wind wheel itself. It sets itself upwind as soon as the wind changes its direction. To do this, the wind wheel is not placed in front of the tower, but behind the tower. In this case, the wheel, like a weather vane, automatically follows the wind. With large wind wheel sizes, sharp tail turns can cause wing breakage. Therefore, with the help of tails, only small wind wheels with diameters up to 18 meters are usually installed in the wind. The most common devices consist of two multi-blade wind wheels placed on the back of the head truss. Such devices are called windroses. Windroses are located so that if the wind blows against the impeller, they are located edge to the direction of the wind and stand motionless. When the wind blows from the side, the windroses come into motion and, by means of a transmission mechanism, turn the head with the wind wheel into the wind until it is strictly against the wind (Fig. 26). At this time, the windroses will once again be positioned edge to the wind and stop until the wind changes its direction again.
Other ingenious devices are used to turn the large wind wheels of modern high-speed wind turbines into the wind. In any wind, they gently and smoothly bring the wind wheel into the wind. Typically, thrust mechanisms rotate the head relative to the tower at a very low speed, one complete revolution in a few minutes. In large wind turbines, the head is set into the wind using an electric motor controlled by a small weather vane. When the wind direction changes, the weather vane turns and closes the electric line, automatically turning on the electric motor. The electric motor will stop only when the line is disconnected. And this will happen when the weather vane is located along the air flow, and the wind wheel - in the forehead to the wind. These are the main devices in modern wind turbines for automatically turning the wind wheel into the wind. However, the wind can change not only its direction, but also its speed. Consequently, the force of pressure on the wind wheel also changes. As the wind speed increases, the number of revolutions of the wind wheel increases. They can reach high values. This is dangerous not only for the strength of the wheel, but also for the entire installation and the machines attached to it. To avoid this, modern wind turbines are equipped with special devices that come into action at high wind speeds. They make sure that with a further increase in the wind, the number of revolutions of the wind wheel does not increase, and in the event of a storm it stops. The simplest method of limiting the speed of a wind wheel is that, with wind at a certain speed, it begins to partially go out from under the wind. As the wind speed increases, the wind wheel rotates through an increasingly significant angle, and during a storm it is located edge to the air flow and stops. At the same time, the control springs are stretched or a special load is lifted, which, when the wind speed decreases, again bring the wind wheel into the wind. Speed control by bringing the entire wind wheel out of the wind is usually used only for low-speed wind turbines with small wind wheels. To control the speed of large high-speed wind turbines, it is not the wind wheels that are brought out from under the wind, but separate wings or their end parts, equal to 1/4 or 1/8 of the total length of the wing. At present, the most perfect is the regulation of high-speed wind turbines with the help of special streamlined surfaces - stabilizers, which are attached to the rotary parts of the wings on racks. The stabilizers are controlled by centrifugal weights located inside the wings. Loads are very sensitive to changes in the speed of the wind wheel, and consequently, to wind speed. A slight movement of centrifugal weights causes the stabilizers to turn, on which the force from the headwind arises, turning the tips of the blades like a small rudder turns a large boat. When the turning parts of the wings come out from under the wind, the number of revolutions of the wind wheel decreases. This original regulation was developed by Soviet scientists and designers under the guidance of Prof. G. X. Sabinina and prof. N. V. Krasovsky. It is used in most modern high-speed wind turbines with a capacity of 10 to 1000 kilowatts. Inventor A. G. Ufimtsev and prof. V. P. Vetchinkin proposed to regulate the speed of the wind wheels of high-speed wind turbines by removing the wings from under the wind due to the pressure of the air flow on them. In a strong wind, the wings, like weathercocks, can rotate relative to the axes of the flaps, freely passing the air flow. The necessary uniformity of the rotation of the wind wheel with this regulation is achieved due to the operation of the so-called inertial accumulator, in other words, the flywheel included in the transmission. Rotating rapidly, the battery disk absorbs excess energy when the wind speed increases and gives this energy to the working machines when the wind speed decreases. Such regulation is established, for example, for wind turbines 1-D-18 of the Ufimtsev-Vetchinkin system (Fig. 27).
In small high-speed wind turbines, the rotation of the wings is carried out due to additional centrifugal forces that arise on special loads attached to the wings near the wind wheel shaft. This device, the simplest in execution and very original in design, was proposed by the laureate V. S. Shamanin. These are the main automatic mechanisms of modern vane wind turbines, with the help of which the wind wheels are installed in the wind and keep the set speed at high wind speeds. Author: Karmishin A.V.
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