Wind energy is far from a new branch of energy supply, however, in the current conditions, it is becoming more and more pronounced features of a promising direction for further development. It is still difficult to talk about universal concepts for the technical implementation of wind generators, but progress in the use of individual engineering solutions suggests that a single unified structural model will appear in the near future. At the moment, several types of wind turbines are used in the world, each of which has its own strengths.
General principle of operation of wind turbines
Like most modern alternative energy sources, the wind turbine operates due to the force acting as a result of a natural process. We are talking about wind flows resulting from uneven heatingearth's surface by the sun. Almost all wind turbines work according to the following principle: air flows rotate the wheel on a special shaft with blades, thus transmitting torque to the generator or battery pack. In conditions of stability and sufficient force of air movement, windmills for generating electricity are able to provide an efficiency of 45-50%. It is precisely the variability of the wind and its strength that determines the wide variety of designs of wind turbines, which are also calculated based on specific climatic conditions of use.
What are the main advantages of wind turbines?
Evaluate the efficiency of wind turbines can be both in comparison with traditional energy sources, and against the background of generators running on renewable free resources. The most pronounced advantages of such systems, which give hope for their successful development in the future, are the following factors:
- Wind energy itself is not only renewable, but also available for accumulation and processing.
- Economic benefit. Unambiguous assessments regarding specific economic indicators cannot yet be due to the variety of systems operating with different performance. But we can talk about the outstanding results demonstrated by individual projects. For example, how much does a kilowatt of electricity from a large offshore windmill cost? We can talk about the range of 2-12 rubles. for 1 kWh.
- Eco-friendly. The operation of wind turbines does not provide for harmfulair pollutant emissions.
- Compact. Installing a windmill, even in an industrial format, cannot be compared with traditional power stations. This is largely due to the autonomy and independence of such systems from auxiliary communications and resources.
Horizontal Axis Generators
The design scheme of such windmills provides for the presence of an electric generator, gearbox, blades and a tower with a frame. The configuration of the blades is implemented in such a way that the air flows into the funnel, which creates a torsion moment. An important condition for the operation of such windmills for generating electricity is the ability to adapt to the characteristics of the movement of flows (direction and strength). For this, the structures are provided with mechanisms for turning and tilting the blades in relation to the earth's surface. In the most developed models, controllers with automatic control are also used. As for the implementation of the wind wheel, the three-bladed configuration is more often used in horizontal schemes. Moreover, in order to increase the performance of generators, engineers tend to increase the size of the functional receiving part, which, for example, explains the current trend of transition from plastic and light metals to expensive composite elements in the manufacture of structures.
Vertical Axis Generators
Such generators have a significant advantage over horizontal structures,which consists in the absence of the need for additional means of monitoring and controlling the installation. That is, in the process of operation, a windmill with a vertical axis does not adjust in any way to the movement of flows. This feature of interaction with air masses simultaneously reduces the voltage in the wind generator blades and reduces gyroscopic loads. The geared generator that forms the engine of the unit can be located at the base of the tower structure without the risk of damage or failure. But why, with the described advantages, vertical installations did not replace completely horizontal windmills? Unfortunately, these models also have significant disadvantages. Since the wind wheel is not guided by wind flows and always operates in a narrow range of energy capture ranges, the performance of the generator is logically reduced. Therefore, to maintain sufficient power of vertical windmills, their mass use covering large areas is required, which is not always possible.
Designs based on the Darrieus rotor
Wind turbine generators with vertical impeller are based on the Savonius or Darrieus rotor design. But this group also has its own variations and modern modifications. The most promising recent development is the Gorlov helicoid turbine, created in 2001. It is a kind of continuation of the Darrieus rotor concept, but in a more optimized form. Spiral vertical blades allow energy to be generated from water and air flows with minimal activity. Today these generatorsare used both in specialized wind farms and as part of hydroelectric power plants.
Wind generators with flux amplifiers
Also, in some way, a continuation of the classic designs of windmills, but adjusted for the current high-tech operating conditions. Modifications with flow amplifiers are distinguished by the presence of one or more gutters, which are designed to concentrate air flows. Aerodynamic cone-shaped elements in the form of those same gutters collect flows over a large area, orienting them to one direction point and thereby increasing the speed of the blade system. The difficulty of using wind turbines with flux amplifiers is that they require the use of an additional elemental group. Moreover, it is possible to achieve a significant increase in productivity in such systems only by connecting auxiliary energy sources, which is not always justified economically.
Gearless wind turbines
In line with the idea of structural optimization, a variant of a wind power plant without a gearbox has also appeared. Instead, an annular channel is used, provided with an internal metal rod. This ring is installed around the rotor rim. A group of magnets is also located here, which interacts with a metal rod, thereby contributing to the generation of current. The performance of wind turbines without a gearbox with a rotor diameter of about 200 cm can reach 1500 kWhin year. The principal advantage of this design is the reduction of energy losses naturally occurring in the operation of generators provided with gearboxes. But you have to pay for this advantage with speed limits. In order for the unit to enter into an optimal workflow, a flow velocity of at least 2 m/s is required.
Features of industrial wind turbines
Industrial windmills have two fundamental differences - large size and high power output. Both advantages and disadvantages of stations of this type come from these features. As for the structure, it is enough to say that the height of modern industrial windmills can reach 150-200 m, and the blade span can be more than 100 m. High power also requires the complexity of the functional infrastructure. So, to control the process of energy conversion, wind generator controllers are used, which ensure that the current charge of the battery pack is taken into account. In addition, the electrical stuffing of such installations includes inverters and short circuit protection systems.
Features of household wind turbines
The simplest windmills can not only be used at home, but also assembled by hand. As a rule, these are small-sized installations with a height of no more than 10 m, capable of operating at a power of 0.5-5 kW. As a passive energy source for household appliancesor individual groups of electrical devices, this option justifies itself. However, compact wind turbines are used in large numbers today by large companies to power production facilities. On the basis of mini-windmill farms, sufficiently productive and reliable systems are formed that can compete with high-power single generators.
Features of offshore wind turbines
The popularity of this type of windmills is due to several advantages over stations that are located on land. This is mainly about more stable working conditions, since the wind flows are not obstructed away from the coastline. At the same time, the structures of offshore wind turbines are divided into two groups - supporting and floating. The first are installed in shallow water with a classic support in the ground under water. Floating stations, respectively, have their own floating platform with fixation by means of anchors and other marine devices.
Combination of wind turbine structures with building frames
There is also a very promising group of windmills that are literally integrated into the hulls of high-rise buildings. This solution has two advantages - favorable conditions for the "reception" of flows and a reduction in the path of delivery of electricity, since the final source of supply is usually the consumers inside the building. At the moment, the integration of wind turbines of this type is more often done usingspecial aerodynamic cylinders that are mounted on the roofs of skyscrapers. The concept of mini-propellers is also being developed, which can be placed in any part of a tall construction site. The devices are literally integrated into the walls, after which they are connected to the general power supply system, giving out a small but stable amount of energy.
In recent years, interest in wind turbines has increased significantly in Russia. Large stations with a capacity of up to 30-50 MW are put into operation periodically in different regions. For our country, windmills are especially useful because they allow us to provide energy to remote regions where at the moment there is no possibility of organizing other means of energy supply. The segment of small wind power plants is also actively developing. In Russia, individual power systems with a capacity of 1-5 kW have become very popular. At the same time, developers do not refuse to combine the principles of operation of windmills with internal combustion engines. Successes in this direction are demonstrated, in particular, by wind-diesel designs. It is still difficult to say how much wind energy will be in demand in Russia in the coming decades, since the positions of traditional energy sources are still strong. But the trends in the transition to alternative energy around the world are likely to spur the Russian industry to actively explore such areas.