A power plant that uses electricity from a variety of natural sources to produce electricity. Power plants can be divided into: thermal power plants, hydroelectric power plants, nuclear power plants, geothermal power plants, tidal power plants, wind power plants, and solar power plants. Currently playing a leading role in the power system are fire, hydro and atomic power plants.
Hydroelectric power plants use the kinetic energy and potential energy of water flow to produce electric energy, referred to as hydropower plants. The size of the water flow and the level of the water head determine the amount of water flow energy. From the point of view of energy conversion, the process is: water energy → mechanical energy → electrical energy. The production method to achieve this energy conversion is generally to build a dam on the upper reaches of the river, raise the water level to create a higher head; and construct corresponding hydraulic facilities to effectively obtain concentrated water flow. Water is introduced into the turbine of the hydropower plant through the diversion tank, which drives the turbine to rotate, and the water energy is converted into the rotating mechanical energy of the turbine. A generator directly connected to the turbine converts mechanical energy into electrical energy and is boosted into the grid by the electrical system of the power plant.
When building a powerful hydropower plant, consider improving navigation and land irrigation and ecological balance. Hydropower plants are classified into diversion type, dam type and hybrid hydropower plants according to power plant structure and hydropower development mode; runoff type and reservoir type hydropower plants are classified according to power plant performance and water flow regulation degree; , dam internal hydropower plant; classified by ground type, underground hydropower station according to the host layout.
The construction cost of hydropower plants is high, and the power generation is limited by hydrological and meteorological conditions, but the cost of electricity is low, and it has comprehensive benefits of water conservancy. The turbine can be adapted to the power system load change from start-up to full load, so the hydropower plant can be used for system frequency modulation, peak shaving and load backup.
Thermal power plants use the chemical energy of coal, oil, natural gas or other fuels to produce electricity, referred to as thermal power plants. From the point of view of energy conversion, the basic process is: chemical energy → thermal energy → mechanical energy → electrical energy. Thermal power plants in most countries of the world are dominated by coal. The pulverized coal and air are suspended in the furnace space of the power plant boiler and subjected to intense mixing and oxidative combustion, and the chemical energy of the fuel is converted into heat energy. The heat energy is transmitted to the high-pressure water medium in the boiler by means of radiation and heat convection, and the preheating, vaporization and superheating processes of the water are completed in stages, so that the water becomes a high-pressure and high-temperature superheated water vapor. The water vapor is controlled to be sent to the steam turbine through the pipeline, and the steam turbine realizes the conversion of the steam heat energy to the rotating mechanical energy. The high-speed rotating turbine rotor is powered by a coupling to drive the generator, and the electrical energy is boosted into the grid by the electrical system of the power plant.
Thermal power plants can be classified into coal-fired, fuel-fired, gas-fired, and waste-fired thermal power plants according to fuel categories; they can be classified into condensing power plants and thermal power plants according to their power plant functions. A condensing power plant is a power plant that is simply used to generate electricity. It is generally built near a fuel base or a mining area, and the generated electric energy is sent to the load center by a high-voltage transmission line. This eliminates the long-distance transportation of fuel, improves the efficiency of energy transmission, and prevents the pollution of coal ash to the urban environment. The condensing power plant built near the fuel base or mining area, also known as the Hangkou Power Plant, is the main direction for the construction of large thermal power plants in the future. A thermal power plant is a power plant that generates both electricity and heat. Because the heating network cannot be too long, it is generally built near thermal energy users in large industrial areas.
The fuel of a thermal power plant is a consumable energy source. The combustion of fuel produces environmental pollution, and the cost of electric energy is higher than that of a hydropower plant. However, the initial investment of thermal power plants is smaller than that of hydropower plants, and the layout is more flexible. The installed capacity can be determined according to needs. Turbine generator set operation control is more complicated, and the opening and closing time is long. Therefore, it is easy to bring basic load and intermediate load in the power system, and it is not easy to serve as a peak load that changes greatly in the system. Otherwise, not only the coal consumption will increase but also the unit life will be shortened. .
Atomic power plants use nuclear energy to produce electricity, also known as nuclear power plants. There is a strong bond between the various nuclei of the nucleus (neutrons and protons). When heavy nuclear splitting and light nuclear polymerization are carried out, huge energy is released, called nuclear energy. At present, the technology is relatively mature, and the scale is put into operation. It is only an atomic power plant that produces nuclear energy from nuclear energy released by fission. From the point of view of energy conversion, it is a process of conversion from heavy nuclear fission nuclear energy → thermal energy → mechanical energy → electric energy.
Depending on the type of nuclear reactor, atomic power generation can be classified into gas-cooled reactors, modified gas-cooled reactors, pressurized water reactors, boiling water reactors, and heavy water reactors. Due to the strong radiation of heavy nuclear fission, the nuclear power plant is divided into two parts: nuclear island and power generation, which are strictly separated by safety protection facilities. The important equipment in the nuclear island part is the “heavy nuclear fission reactorâ€, which functions as a thermal power plant. Boiler equipment. The fuel used in the reactor is mostly metal uranium, and the energy released by fission of 1 kg of uranium is equal to the energy released when 2 700 t of standard coal is completely burned. The thermal energy generated by uranium fission is continuously carried out by the circulating coolant, and in the steam generator, the water is heated into water vapor with a certain pressure and temperature (without radioactivity), and the steam promotes the turbine generator and There is no essential difference between other equipment and thermal power plants.
The uranium enrichment, heavy water production and waste fuel treatment technologies in nuclear power plants are complex and have large investments. However, nuclear power plants consume less energy, and the cost of electricity is 30% to 40% lower than that of thermal power plants. The larger the installed capacity, the more economical the average investment in a single kilowatt. Since the nuclear power plant generator maintains a constant output and can fully utilize the technical and economic benefits, it is most suitable for the basic load part of the power system.
The power station of the train power station is installed in a mobile power station on a special railway vehicle. It can be quickly transferred to any location that the railway can reach as required, and emergency power is supplied to the area.
The construction power plant is used for the construction of railways, industrial and mining projects, and power plants during field operations. Generally refers to small power plants that use diesel generators.
The captive power plant acts as an emergency backup power source within the power system's power supply range, or where the power system does not reach it, and some power plants used by mobile users. Diesel generator sets are generally used as power generation equipment.
Development Status In 1949, there were only a handful of small and medium-sized power plants in China, and the total installed capacity of power generation equipment in the country ranked 21st in the world at that time. At the end of 2002, the total installed capacity of China's power generation equipment reached 353 million kW, and the annual power generation reached 164 billion kW, ranking second in the world. Among them, the installed capacity has exceeded 350 million kW from 100 million kW at the end of 1987 to the end of 2002. It took only 15 years before and after, which is rare in the history of world power development. In 1988, the total installed capacity of Gezhouba Hydropower Plant reached 2,715 MW. In 1989, the first Chinese-made 600MW thermal power generating unit was put into commercial operation. At present, China's thermal power installed capacity accounts for about 75% of the total installed capacity, and hydropower installed capacity accounts for about 24% of the total installed capacity. However, the nuclear power industry started late, and the nuclear installed capacity only accounts for 1% of the total installed capacity. The 300MW pressurized water 碓 nuclear power unit designed, manufactured, installed and commissioned by itself was first connected to the power grid of Qinshan Nuclear Power Plant in Zhejiang Province in 1991, achieving zero breakthrough in nuclear power plants. The 2×9 00MW pressurized water 碓 nuclear power unit was introduced. In 1994, it was put into operation at the Daya Bay Nuclear Power Plant in Guangdong. Its installation, commissioning and operation management have reached the world's advanced level. It is China's largest nuclear power plant, marking China's nuclear power industry has entered a new stage of development.
Energy and the environment are the subject of increasing concern around the world. At present, there are more than 450 nuclear power plants connected to the grid, accounting for 17% of the world's power generation capacity. Nuclear power development will focus on safety, reliability and efficiency. The trend of thermal power generation is to develop large-capacity and efficient gas turbine generator sets, and develop and use new ones. Efficient combustion, coal gasification and other technologies.
According to the development goal of China's electric power industry, the plan is to develop 300MW, 600MW thermal power units, further develop 800MW, 1 000MW and 1 300MW large generating units, build a batch of large-scale thermal power plants of 4 000 MW to 5000 MW, and determine nuclear power to press water. The heap is the main development technology development route. The development of stand-alone capacity has recently reached 600,000 levels and has gradually reached the goal of one million. In the future, the development policy of China's power industry is to "optimize the structure of thermal power, vigorously develop hydropower, properly develop nuclear power, develop various new energy sources according to local conditions, and pay equal attention to development and conservation." The construction of the Yangtze River Three Gorges hydraulic hub project with an installed capacity of 18 200MW will be taken as the leader, adhere to the water construction policy of rolling, basin, cascade and comprehensive development to accelerate the pace of hydropower plant construction; accelerate the construction of a large number of large areas in coastal and fuel-deficient areas. Nuclear Power Plant. Let China's power industry move toward a healthy development path of low energy consumption, low environmental pollution, and efficient operation.
Mini Circuit breakers, also named as the air switch which have a short for arc extinguishing device. It is a switch role, and also is a automatic protection of low-voltage electrical distribution. Its role is equivalent to the combination of switch. Fuse. Thermal Relay and other electrical components. It mainly used for short circuit and overload protection. Generally, According to the poles, mini Circuit breaker can be divided into 1P , 1P+N , 2P, 3P and 4P.
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