中文版
ENGLISH
| Principle and significance of wind power generation |
| Release time:2023-02-28 09:03:03| Viewed： |
Wind has long been used by people - mainly through windmills to pump water and grind flour. Now, people are interested in how to use wind to generate electricity.
Wind is a new energy with great potential. People may recall that at the beginning of the 18th century, a violent wind swept Britain and France, destroying 400 wind mills, 800 houses, 100 churches, and more than 400 sailboats. Thousands of people were injured and 250000 trees were uprooted. In the case of tree pulling alone, the wind generated 10 million horsepower (7.5 million kilowatts; one horsepower equals 0.75 kilowatts) in a few seconds! It has been estimated that there are about 10 billion kilowatts of wind resources available for power generation on the earth, almost 10 times the amount of hydropower generation in the world today. At present, the energy obtained by burning coal every year in the world is only one third of the energy provided by wind in one year. Therefore, both at home and abroad attach great importance to the use of wind power to generate electricity and develop new energy.
The attempt to use wind power generation began as early as the beginning of this century. In the 1930s, Denmark, Sweden, the Soviet Union and the United States successfully developed some small wind power plants by applying the rotor technology of the aviation industry. This kind of small wind turbine is widely used in windy islands and remote villages, and the cost of electricity generated by it is much lower than that of small internal combustion engines. However, the power generation at that time was relatively low, mostly below 5 kilowatts.
At present, it is understood that 15, 40, 45100, 225 kW wind turbines have been produced abroad. In January 1978, the United States built a 200-kilowatt wind turbine in Clayton, New Mexico. Its blade diameter is 38 meters, and its power generation capacity is enough for 60 households. In the early summer of 1978, the wind power plant put into operation on the west coast of the Jutland Peninsula in Denmark had a power generation capacity of 2000 kilowatts. The windmill was 57 meters high. 75% of the power generation capacity was sent to the power grid, and the rest was supplied to a nearby school.
In the first half of 1979, the United States built the world's largest windmill for power generation in the Blue Ridge Mountains of North Carolina. The windmill is ten stories high, and its steel blades are 60 meters in diameter; The blades are installed on a tower building, so the windmill can rotate freely and obtain power from any direction; When the wind speed is above 38 kilometers per hour, the power generation capacity can also reach 2000 kilowatts. Because the average wind speed in this hilly area is only 29 kilometers per hour, the windmill cannot move completely. It is estimated that even if it operates only half the year round, it can meet the power demand of 1% to 2% in seven counties in North Carolina.
How to use wind power to generate electricity?
We convert the kinetic energy of wind into mechanical energy, and then convert mechanical energy into electrical energy, which is wind power generation. The devices needed for wind power generation are called wind turbines. This kind of wind turbine can be divided into three parts: wind turbine (including tail rudder), generator and tower. (Large-scale wind power stations basically have no tail rudder, and generally only small (including household type) will have tail rudder
The wind wheel is an important component that converts the kinetic energy of the wind into mechanical energy. It consists of two (or more) propeller-shaped impellers. When the wind blows to the blades, the aerodynamic power generated on the blades drives the wind wheel to rotate. The blade material requires high strength and light weight. At present, it is mostly made of glass fiber reinforced plastics or other composite materials (such as carbon fiber). (Now there are some vertical wind turbines, s-type rotating blades, etc., whose functions are the same as those of conventional propeller blades
Because the speed of the wind wheel is relatively low, and the size and direction of the wind force often change, which makes the speed unstable; Therefore, before driving the generator, it is necessary to add a gear box to increase the speed to the rated speed of the generator, and then add a speed regulating mechanism to keep the speed stable, and then connect it to the generator. In order to keep the wind wheel always aligned with the wind direction to obtain maximum power, it is also necessary to install a tail rudder similar to a wind vane at the rear of the wind wheel.
The tower is the frame supporting the wind wheel, tail rudder and generator. It is generally built relatively high in order to obtain a larger and more uniform wind force and have sufficient strength. The tower height depends on the impact of ground obstacles on wind speed and the diameter of wind wheel, which is generally within the range of 6-20 meters.
The role of the generator is to transfer the constant speed obtained by the wind turbine to the power generation mechanism for uniform operation through speed increase, thus converting mechanical energy into electrical energy.
How strong the wind can generate electricity?
Generally speaking, level 3 wind is valuable. However, from the economic and reasonable point of view, the wind speed is more than 4 meters per second to be suitable for power generation. It is measured that when the wind speed is 9.5 meters per second, the output power of a 55 kW wind turbine generator unit is 55 kW; When the wind speed is 8 meters per second, the power is 38 kW; When the wind speed is 6 meters per second, it is only 16 kilowatts; When the wind speed is 5 meters per second, it is only 9.5 kilowatts. It can be seen that the greater the wind, the greater the economic benefits.
In China, there are many successful small and medium-sized wind power plants in operation.
China is extremely rich in wind resources. The average wind speed in most areas is more than 3 meters per second, especially in the northeast, northwest, southwest plateau and coastal islands; In some places, more than one third of the year is windy. In these areas, the development of wind power generation is very promising.
|
