久久久人妻一区精品久久久,最新国产福利片在线观看,亚洲欧美v人片在线观看,u久久免费看黄a级毛片

　　1、 History and principle of wind power generation:

　　At the beginning of the 18th century, a violent gale swept across Britain and France, destroying 400 wind mills, 800 houses, 100 churches and more than 400 sailing boats. Thousands of people were injured and 250000 trees were uprooted. As far as tree pulling is concerned, the wind produces 10 million horsepower (7.5 million kilowatts; one horsepower equals 0.75 kilowatts) in a few seconds! Some people have estimated that the wind power resources available for power generation on the earth are about 10 billion kilowatts, almost 10 times of the world's hydroelectric power. At present, only one third of the energy provided by wind in a year is obtained by burning coal every year in the world. Therefore, both at home and abroad attach great importance to the use of wind power generation and the development of new energy.

　　The attempt to use wind power has already begun as early as the beginning of this century. In the 1930s, Denmark, Sweden, the Soviet Union and the United States successfully developed some small-scale wind power generation devices by applying the rotor technology of the aviation industry. This kind of small-scale wind turbine is widely used in windy islands and remote villages, and its power cost is much lower than that of small-scale internal combustion engine. However, at that time, the power generation was relatively low, mostly under 5kW.

　　At present, it is understood that 15, 40, 45100225 kW wind turbines have been produced abroad. In January 1978, the U.S. built a 200 kilowatt wind turbine in Clayton, New Mexico, with a blade diameter of 38 meters, generating enough electricity 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 generated 2000 kilowatts of electricity, with 57 meters of windmills. 75% of the electricity generated 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 the diameter of the steel blade of the windmill is 60 meters; the blade is installed on a tower building, so the windmill can rotate freely and get power from any direction; when the wind speed is more than 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 windmills can't move completely. It is estimated that even if it operates only half the time of the year, it will be able to meet 1-2% of the electricity demand of seven counties in North Carolina.

　　How to use wind power to generate electricity?

　　We turn the kinetic energy of wind into mechanical energy, and then mechanical energy into electrical energy, which is wind power generation. The devices needed for wind power generation are called wind turbines. The wind turbine can be divided into three parts: wind wheel (including tail rudder), generator and tower. (large wind power plants basically have no tail rudder, generally only small (including domestic type) will have tail rudder)

　　The wind wheel is an important part of converting the kinetic energy of wind into mechanical energy. It consists of two (or more) propeller shaped impellers. When the wind blows to the blade, the generated gas on the blade drives the wind wheel to rotate. The material of paddle blade 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 often change, which makes the speed unstable; therefore, before driving the generator, it is necessary to add a gearbox to increase the speed to the rated speed of the generator, add a speed regulating mechanism to keep the speed stable, and then connect to the generator. In order to keep the wind wheel always in line with the wind direction for maximum power, a tail rudder similar to the wind vane should be installed at the back of the wind wheel.

　　The tower is the framework supporting wind wheel, tail rudder and generator. It is generally built high, in order to get a larger and more uniform wind, but also have enough strength. The height of the tower depends on the impact of ground obstacles on the wind speed and the diameter of the wind wheel, generally within 6-20 meters.

　　The function of the generator is to transfer the constant speed obtained by the wind wheel to the generating mechanism for uniform operation through speed up, thus transforming the mechanical energy into electrical energy.

　　How much wind can generate electricity?

　　Generally speaking, the level 3 wind has the use value. However, from an economic and reasonable point of view, wind speed greater than 4 meters per second is suitable for power generation. According to the measurement, when the wind speed is 9.5 meters per second, the output power of a 55 kW wind turbine 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, only 16 kW; and when the wind speed is 5 meters per second, only 9.5 kW. 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 generation devices in operation.

　　China is 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 time of a year is windy days. In these areas, the development of wind power is very promising.