Wind energy is far from a new branch of energy supply, however, in the current conditions, it is acquiring ever 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 successes in using individual engineering solutions suggest that in the near future there will also be a single unified structural model. At the moment, the world uses several types of wind power plants, each of which has its own strengths.
General principle of operation of wind generators
Like most modern alternative energy sources, the wind generator operates due to the force acting as a result of the natural process. We are talking about wind flows resulting from the uneven heating of the earth's surface by the Sun. Almost all wind turbines operate according to the following principle: air flows rotate the wheel on a special shaft with blades, thus transmitting torque to a generator or battery pack. In conditions of stability and sufficient force of air movement, windmills for generating electricity are able to provide a coefficient of performance at the level of 45-50%. Just the inconstancy of the wind and its strength is due to the wide variety of designs of wind generators, which are calculated including on the basis of specific climatic conditions of use.
What are the main advantages of wind generators?
Evaluating the performance of windmills 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 power itself is not only renewable, but also available for storage and processing.
- Economic benefit. Unambiguous assessments regarding specific economic indicators cannot yet be due to the variety of systems working with different performance. But we can talk about outstanding results that demonstrate individual projects. For example, how much is a kilowatt of electricity from a large offshore windmill? We can talk about a range of 2-12 rubles. per 1 kWh
- Ecological cleanliness. The operation of wind power stations does not provide for harmful emissions polluting the atmosphere.
- Compactness. Installing a wind turbine, even in an industrial format, cannot be compared with traditional power plants. This is largely due to the autonomy and independence of such systems from auxiliary communications and resources.
Horizontal axis generators
The structural scheme of such windmills provides for the presence of an electric generator, gearbox, blades and a tower with a bed. The configuration of the blades is implemented in such a way that the air flows into the funnel, creating a torsion moment. An important condition for the operation of such windmills to generate electricity is the ability to adapt to the characteristics of the movement of flows (direction and force). For this design, they are provided with mechanisms for turning and tilting the blades with respect to the earth's surface. In the most developed models, automatic controllers are also used. As for the implementation of the wind wheel, then more often in horizontal schemes a three-blade configuration is used. Moreover, in order to increase the productivity of generators, engineers strive to increase the size of the functional receiving part, which, for example, explains the current trend of the 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 control of the installation. That is, during operation, a wind turbine with a vertical axis does not adapt to the movement of flows. This feature of the interaction with the air masses simultaneously reduces the voltage in the blades of the wind generator and reduces gyroscopic loads. A generator with a gearbox forming the engine of the installation can be located at the base of the tower of the structure without the risk of damage or failure. But why, with the described advantages, vertical installations did not displace fully horizontal windmills? Unfortunately, such models have significant disadvantages. Since the wind wheel does not focus on wind flows and always works in a narrow range of energy capture ranges, the generator’s performance is logically reduced. Therefore, to maintain sufficient power of vertical windmills requires their massive use with coverage of large areas, which is not always possible.
Designs based on the Daria rotor
Wind-driven generators with a vertical impeller arrangement are based on a Savonius or Darier rotor circuit. But this group also has its own variations and modern modifications. The most promising development of recent times is Gorlov’s helicoidal turbine, created in 2001. It is a kind of continuation of the Darier rotor concept, but in a more optimized form. Spiral vertical blades allow you to generate energy from the flows of water and air with minimal activity. Today, such generators are used both on specialized wind farms and as part of hydroelectric power plants.
Amplifier wind generators
Also, in some way, the continuation of the classic designs of windmills, but adjusted for the current high-tech operating conditions. Modifications with current 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 grooves collect flows over a large area, orienting them to one point of direction and thereby increasing the speed of the blade system. The difficulty of using wind power plants with current amplifiers is that they require the use of an additional element 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 economically justified.
Gearless wind generators
In line with the idea of structural optimization, a variant of a wind-driven installation devoid of a gearbox appeared. Instead, an annular channel provided with an internal metal rod is used. This ring is mounted around the rotor rim. It also houses a group of magnets that interacts with a metal rod, thereby contributing to the generation of current. The productivity of wind power plants without a gearbox with a rotor diameter of about 200 cm can reach 1500 kWh per year. The principal advantage of this design can be called a reduction in energy losses naturally occurring in the operation of generators provided with gearboxes. But you have to pay for this dignity with the limitations of high-speed modes. In order for the installation to enter the optimal workflow, a flow rate of at least 2 m / s is required.
Features of industrial wind generators
Industrial windmills have two fundamental differences - large sizes and high power capacity. Both advantages and disadvantages of stations of this type arise from these features. As for the construction, it’s enough to say that the height of modern industrial windmills can reach 150-200 m, and the max of the blades - more than 100 m. To maintain such a massive structure, large-scale construction work is underway on the construction of the foundation site. High power also requires more sophisticated functional infrastructure. So, to control the process of energy conversion, wind generator controllers are used to ensure that the current charge of the battery pack is taken into account. In addition, in the electrical equipment of such installations, inverters and short-circuit protection systems are provided.
Features of household wind generators
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 not more than 10 m, capable of operating at a power of 0.5-5 kW. As a passive source of energy for household appliances or individual groups of electrical devices, this option justifies itself. However, large-scale compact wind power plants are also used today by large companies to power production facilities. On the basis of mini-windmill farms, quite efficient and reliable systems are formed that can compete with high-power single generators.
Features of marine wind generators
The popularity of this type of windmill is due to several advantages over stations that are located on land. Mainly, it is about more stable working conditions, since in the distance from the coastline the wind flows do not meet obstacles. At the same time, the designs of marine-type wind power plants 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 generator structures with building frames
There is also a very promising group of windmills that literally integrate into the buildings of high-rise buildings. This solution has two advantages - favorable conditions for the “reception” of flows and a reduction in the way of electricity delivery, since consumers inside the building usually act as the final source of supply. At the moment, the integration of wind power plants of this type is often done using special aerodynamic cylinders that are mounted on the roofs of skyscrapers. The concept of mini-propellers, which can even be placed in any part of a high construction site, is also developing. The devices literally integrate into the walls, after which they are connected to a common energy supply system, producing a small but stable amount of energy.
Conclusion
In recent years, interest in wind generators has increased significantly in Russia. Periodically, in various regions large stations with a capacity of up to 30-50 MW are commissioned. For our country, windmills are especially useful for the reason that they allow you 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 farms is also actively developing. In Russia, individual power systems with a capacity of 1-5 kW began to be very popular. At the same time, the 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 structures. 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 tendencies of transition to alternative energy in the whole world are likely to spur and Russian industry to actively develop such directions.