Electricity production plays a huge role in the world these days. She is the core state economy any country. Huge amounts of money are invested annually in the production and use of electricity and scientific research related to this. In everyday life, we are constantly faced with its action, so a modern person must have an idea of the basic processes of its production and consumption.
Electricity is produced from other types of electricity using special devices. For example, from kinetic. For this purpose, a generator is used - a device that converts mechanical work into electrical energy.
Other existing methods its production is, for example, the conversion of light radiation by photocells or a solar battery. Or electricity production by chemical reaction. Or using the potential of radioactive decay or coolant.
It is produced at power plants, which can be hydraulic, nuclear, thermal, solar, wind, geothermal, etc. Basically, they all work according to the same scheme - thanks to the energy of the primary carrier, a certain device generates mechanical (rotation energy), which is then transferred to a special generator, where electric current is generated.
The production and distribution of electricity in most countries is carried out through the construction and operation of thermal power plants - thermal power plants. Their operation requires a large supply of organic fuel, the conditions for its extraction are becoming more complicated from year to year, and the cost is increasing. The fuel efficiency coefficient in thermal power plants is not too high (within 40%), and the amount of environmentally polluting waste is large.
All these factors reduce the prospects of this production method.
The most economical production of electricity is from hydropower plants (HPP). Their efficiency reaches 93%, the cost of 1 kW/h is five times cheaper than other methods. The natural energy source of such stations is practically inexhaustible, the number of workers is minimal, and they are easy to manage. Our country is a recognized leader in the development of this industry.
Unfortunately, the pace of development is limited by the serious costs and long construction times of hydroelectric power stations associated with their remoteness from large cities and highways, the seasonal regime of rivers and difficult operating conditions.
In addition, giant reservoirs worsen the environmental situation - they flood valuable lands around the reservoirs.
Nowadays, the production, transmission and use of electricity is carried out by nuclear power plants - NPPs. They are designed on almost the same principle as thermal ones.
Their main advantage is the small amount of fuel required. A kilogram of enriched uranium is equivalent in productivity to 2.5 thousand tons of coal. That is why nuclear power plants can theoretically be built in any area, regardless of the availability of nearby fuel resources.
Currently, the reserves of uranium on the planet are much greater than those of mineral fuel, and the impact of nuclear power plants on the environment is minimal, provided there is trouble-free operation.
A huge and serious drawback of nuclear power plants is the likelihood of a terrible accident with unpredictable consequences, which is why very serious safety measures are required for their uninterrupted operation. In addition, the production of electricity at nuclear power plants is difficult to regulate - it will take several weeks both to start them and to completely stop them. And there are practically no technologies for recycling hazardous waste.
The production and transmission of electricity is possible thanks to an electric generator. This is a device for converting any type of energy (thermal, mechanical, chemical) into electrical energy. The principle of its operation is based on the process of electromagnetic induction. EMF is induced in a conductor that moves in a magnetic field and crosses its magnetic lines of force. Thus, the conductor can serve as a source of electricity.
The basis of any generator is a system of electromagnets that form a magnetic field and conductors that cross it. Most of all alternating current generators are based on the use of rotating magnetic field. Its stationary part is called the stator, and the moving part is called the rotor.
A transformer is an electromagnetic static device designed to convert one current system into another (secondary) using electromagnetic induction.
The first transformers in 1876 were proposed by P. N. Yablochkov. In 1885, Hungarian scientists developed industrial single-phase devices. In 1889-1891. The three-phase transformer was invented.
The simplest single-phase transformer consists of a steel core and a pair of windings. They are used for the distribution and transmission of electricity, because power plant generators produce it at voltages from 6 to 24 kW. It is beneficial to transfer it when large values(from 110 to 750 kW). For this purpose, step-up transformers are installed at power plants.
Its lion's share goes to supplying electricity to industrial enterprises. Manufacturing consumes up to 70% of all electricity generated in the country. This figure varies significantly for individual regions depending on climatic conditions and the level of industrial development.
Another expense item is the supply of electric vehicles. Urban, intercity, and industrial electric transport substations using direct current operate from EPS power grids. For AC transport, step-down substations are used, which also consume power from power plants.
Another sector of electricity consumption is utilities. The consumers here are buildings in residential areas of any settlements. These are houses and apartments, administrative buildings, shops, educational, scientific, cultural, healthcare, catering etc.
Production, transmission and use of electricity are the three pillars of the industry. Moreover, transferring the received power to consumers is the most difficult task.
It “travels” mainly through power lines - overhead power lines. Although cable lines are beginning to be used more and more often.
Electricity is generated by powerful units of giant power plants, and its consumers are relatively small receivers scattered over a vast territory.
There is a tendency to concentrate power due to the fact that with their increase, the relative costs of constructing power plants, and therefore the cost of the resulting kilowatt-hour, decrease.
A number of factors influence the decision to locate a large power plant. This is the type and quantity of available resources, accessibility of transportation, climatic conditions, inclusion in a single energy system, etc. Most often, power plants are built far from large centers of energy consumption. The efficiency of its transmission over considerable distances affects the successful operation of a single energy complex over a vast territory.
The production and transmission of electricity must occur with a minimum amount of losses, main reason of which - heating of the wires, i.e. increase internal energy conductor. To maintain power transmitted over long distances, it is necessary to proportionally increase the voltage and reduce the current in the wires.
Mathematical calculations show that the amount of heating losses in wires is inversely proportional to the square of the voltage. That is why electricity is transmitted over long distances using power lines - high-voltage power lines. Between their wires the voltage amounts to tens, and sometimes hundreds of thousands of volts.
Power plants located close to each other are combined into a single energy system using power lines. Electricity production in Russia and its transmission are carried out through a centralized energy network, which includes a huge number of power plants. Unified system control guarantees a constant supply of electricity to consumers.
How was a unified electrical network formed in our country? Let's try to look into the past.
Until 1917, electricity production in Russia was carried out at an insufficient pace. The country lagged behind its developed neighbors, which negatively affected the economy and defense capability.
After October Revolution The project for the electrification of Russia was developed by the State Commission for the Electrification of Russia (abbreviated as GOELRO), headed by G. M. Krzhizhanovsky. More than 200 scientists and engineers collaborated with her. Control was carried out personally by V.I. Lenin.
In 1920, the “Electrification Plan of the RSFSR” was prepared, designed for 10-15 years. It included the restoration of the previous energy system and the construction of 30 new power plants equipped with modern turbines and boilers. The main idea of the plan is to use gigantic domestic hydropower resources. Electrification and radical reconstruction of the entire national economy were envisaged. The emphasis was on the growth and development of the country's heavy industry.
Since 1947, the USSR has become Europe's first and world's second producer of electricity. It was thanks to the plan that GOELRO was formed in as soon as possible the entire domestic economy. The production and consumption of electricity in the country has reached a qualitatively new level.
Fulfillment of the plan became possible thanks to a combination of several important factors: high level the country's scientific personnel, the material potential of Russia preserved from pre-revolutionary times, the centralization of political and economic power, the ability of the Russian people to believe in the “tops” and embody the proclaimed ideas.
The plan proved the effectiveness of the Soviet system of centralized power and government.
In 1935, the adopted program was implemented and exceeded. 40 power plants were built instead of the planned 30, and almost three times more capacity was introduced than was provided for according to the plan. 13 power plants with a capacity of 100 thousand kW each were built. The total capacity of Russian hydroelectric power stations was about 700,000 kW.
During these years, the largest objects of strategic importance were erected, such as the world famous Dnieper hydroelectric power station. In terms of total indicators, the Unified Soviet Energy System surpassed similar systems in the most developed countries of the New and Old Worlds. Electricity production in European countries in those years lagged significantly behind the USSR indicators.
If before the revolution there was practically no electricity in the villages of Russia (small power plants installed by large landowners do not count), then with the implementation of the GOELRO plan thanks to the use of electricity agriculture received a new impetus for development. Electric motors appeared in mills, sawmills, and grain cleaning machines, which contributed to the modernization of the industry.
In addition, electricity became firmly established in the everyday life of townspeople and villagers, literally tearing “dark Russia” out of the darkness.
Khokhlova Kristina
Presentation on the topic "Production, transmission and use of electrical energy"
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Presentation Production, transmission and use of electrical energy Kristina Khokhlova, 11th grade, Municipal Educational Institution-Secondary School No. 64
Presentation plan Electricity generation Types of power plants Alternative energy sources Electricity transmission Electricity use
There are several types of power plants: Types of power plants TPP HPP NPP
Thermal power plant (TPP), a power plant that generates electrical energy as a result of the conversion of thermal energy released during the combustion of fossil fuels. In thermal power plants, the chemical energy of the fuel is converted first into mechanical energy and then into electrical energy. The fuel for such a power plant can be coal, peat, gas, oil shale, and fuel oil. The most economical are large thermal steam turbine power plants. Most thermal power plants in our country use coal dust as fuel. To generate 1 kWh of electricity, several hundred grams of coal are consumed. In a steam boiler, over 90% of the energy released by the fuel is transferred to steam. In the turbine, the kinetic energy of the steam jets is transferred to the rotor. The turbine shaft is rigidly connected to the generator shaft. TPP
TPPs TPPs are divided into: Condensing power plants (CHES) They are designed to generate only electrical energy. Large CPPs of regional significance are called state district power plants (SDPPs). combined heat and power plants (CHP) producing, in addition to electrical energy, thermal energy in the form hot water and a couple.
Hydroelectric station (HPP), a complex of structures and equipment through which the energy of water flow is converted into electrical energy. A hydroelectric power station consists of a sequential chain of hydraulic structures that provide the necessary concentration of water flow and the creation of pressure, and energy equipment that converts the energy of water moving under pressure into mechanical rotational energy, which, in turn, is converted into electrical energy. The pressure of a hydroelectric power station is created by the concentration of the fall of the river in the area being used by a dam, or diversion, or a dam and diversion together. hydroelectric power station
Power of hydroelectric power stations Hydroelectric power stations are also divided into: The power of hydroelectric power stations depends on the pressure, water flow used in hydraulic turbines, and the efficiency of the hydraulic unit. For a number of reasons (due to, for example, seasonal changes in the water level in reservoirs, fluctuations in the load of the power system, repairs of hydraulic units or hydraulic structures, etc.), the pressure and flow of water continuously change, and, in addition, the flow changes when regulating the power of a hydroelectric power station. high-pressure (over 60 m) medium-pressure (from 25 to 60 m) low-pressure (from 3 to 25 m) Medium (up to 25 MW) Powerful (over 25 MW) Small (up to 5 MW)
A special place among hydroelectric power plants is occupied by: Pumped storage power plants (PSPPs) The ability of PSPPs to accumulate energy is based on the fact that free electrical energy in the power system for a certain period of time is used by pumped storage power plants, which, operating in pump mode, pump water from the reservoir into the upper storage pool. During peak load periods, the accumulated energy is returned to the power system. Tidal power plants (TPPs) TPPs convert the energy of sea tides into electricity. The electricity of tidal hydroelectric power stations, due to some features associated with the periodic nature of the ebb and flow of tides, can be used in energy systems only in conjunction with the energy of regulating power plants, which make up for the power failures of tidal power stations within days or months.
The heat that is released in the reactor as a result of the chain reaction of fission of the nuclei of some heavy elements is then converted into electricity in the same way as in conventional thermal power plants (TPPs). Unlike thermal power plants that run on fossil fuels, nuclear power plants run on nuclear fuel (based on 233U, 235U, 239Pu). It has been established that the world's energy resources of nuclear fuel (uranium, plutonium, etc.) significantly exceed the energy resources of natural reserves of organic fuel (oil, coal, natural gas etc.). In addition, it is necessary to take into account the ever-increasing volume of coal and oil consumption for technological purposes in the global chemical industry, which is becoming a serious competitor to thermal power plants. nuclear power plant
Nuclear power plants Most often, 4 types of thermal neutron reactors are used at nuclear power plants: graphite-water reactors with a water coolant and a graphite moderator, heavy-water with a water coolant and heavy water as a moderator, water-water with ordinary water as a moderator and coolant, graffito-gas with a gas coolant and a graphite moderator.
The choice of the predominantly used reactor type is determined mainly by the accumulated experience in the carrier reactor, as well as the availability of the necessary industrial equipment, raw material reserves, etc. The reactor and its servicing systems include: the reactor itself with biological protection, heat exchangers, pumps or gas-blowing units that circulate the coolant, pipelines and fittings for the circulation circuit, devices for reloading nuclear fuel, special ventilation systems, emergency cooling, etc. To protect nuclear power plant personnel from radiation exposure, the reactor is surrounded by biological shielding, the main materials for which are concrete, water, and serpentine sand. The reactor circuit equipment must be completely sealed. nuclear power plant
Alternative energy sources. Solar energy Solar energy is one of the most material-intensive types of energy production. Large-scale use of solar energy entails a gigantic increase in the need for materials, and, consequently, in labor resources for the extraction of raw materials, their enrichment, obtaining materials, manufacturing heliostats, collectors, other equipment, and their transportation. Wind energy The energy of moving air masses is enormous. Wind energy reserves are more than a hundred times greater than the hydroelectric energy reserves of all the rivers on the planet. Winds blow constantly and everywhere on earth. Climatic conditions allow the development of wind energy over a vast territory. Through the efforts of scientists and engineers, a wide variety of designs of modern wind turbines have been created. Earth energy Earth energy is suitable not only for heating premises, as is the case in Iceland, but also for generating electricity. Power plants using hot underground springs have been operating for a long time. The first such power plant, still very low-power, was built in 1904 in the small Italian town of Larderello. Gradually, the power of the power plant grew, more and more new units were put into operation, new sources of hot water were used, and today the power of the station has already reached an impressive value of 360 thousand kilowatts.
Solar energy Air energy Earth energy
Electricity transmission Electricity consumers are everywhere. It is produced in relatively few places close to sources of fuel and hydro resources. Therefore, there is a need to transmit electricity over distances sometimes reaching hundreds of kilometers. But transmitting electricity over long distances is associated with noticeable losses. The fact is that as current flows through power lines, it heats them up. In accordance with the Joule-Lenz law, the energy spent on heating the line wires is determined by the formula: Q= I 2 Rt where R is the line resistance. At long length power transmission lines may become generally unprofitable. To reduce losses, you can increase the cross-sectional area of the wires. But when R decreases by 100 times, the mass must also be increased by 100 times. Such consumption of non-ferrous metal should not be allowed. Therefore, energy losses in the line are reduced in another way: by reducing the current in the line. For example, reducing the current by 10 times reduces the amount of heat released in the conductors by 100 times, i.e., the same effect is achieved as from making the wire a hundred times heavier. That's why step-up transformers are installed at large power plants. The transformer increases the voltage in the line by the same amount as it decreases the current. The power losses are small. Electric power stations in a number of regions of the country are connected by high-voltage transmission lines, forming a common power grid to which consumers are connected. Such an association is called a power system. The power system ensures uninterrupted supply of energy to consumers regardless of their location.
The use of electricity in various fields of science Science directly influences the development of energy and the scope of application of electricity. About 80% of the GDP growth in developed countries is achieved through technical innovation, the bulk of which is related to the use of electricity. Everything new in industry, agriculture and everyday life comes to us thanks to new developments in various branches of science. Most scientific developments begins with theoretical calculations. But if in the 19th century these calculations were made with the help of pen and paper, then in the age of STR (scientific and technological revolution) all theoretical calculations, selection and analysis of scientific data, and even linguistic analysis literary works are made using computers (electronic computers), which operate on electrical energy, which is most convenient for transmitting it over a distance and using it. But if initially computers were used for scientific calculations, now computers have come from science to life. Electronization and automation of production are the most important consequences of the “second industrial” or “microelectronic” revolution in the economies of developed countries. Science in the field of communications and communications is developing very rapidly. Satellite communications are no longer used only as a means of international communication, but also in everyday life - satellite antennas not uncommon in our city. New means of communication, for example, fiber technology, can significantly reduce energy losses in the process of transmitting signals over long distances. Completely new means of obtaining information, storing it, processing it and transmitting it, together forming a complex information structure, have been created.
Use of electricity in production Modern society It is impossible to imagine production activities without electrification. Already at the end of the 80s, more than 1/3 of all energy consumption in the world was carried out in the form of electrical energy. By the beginning of the next century, this share may increase to 1/2. This increase in electricity consumption is primarily associated with an increase in its consumption in industry. The bulk of industrial enterprises operate on electrical energy. High electricity consumption is typical for energy-intensive industries such as metallurgy, aluminum and mechanical engineering.
Use of electricity in everyday life Electricity in everyday life is an integral assistant. Every day we deal with her, and, probably, we can no longer imagine our life without her. Remember the last time your lights were turned off, that is, there was no electricity coming to your house, remember how you swore that you didn’t have time to do anything and you needed light, you needed a TV, a kettle and a bunch of other electrical appliances. After all, if we are de-energized forever, then we will simply return to those ancient times when food was cooked over a fire and they lived in cold wigwams. A whole poem can be dedicated to the importance of electricity in our lives, it is so important in our lives and we are so accustomed to it. Although we no longer notice that it is coming into our homes, when it is turned off, it becomes very uncomfortable.
Thank you for your attention
in physics
on the topic “Production, transmission and use of electricity”
11th grade A students
Municipal educational institution No. 85
Catherine.
Abstract plan.
Introduction.
1. Electricity production.
1. types of power plants.
2. alternative sources energy.
2. Electricity transmission.
3. Electricity use.
Introduction.
The birth of energy occurred several million years ago, when people learned to use fire. Fire gave them warmth and light, was a source of inspiration and optimism, a weapon against enemies and wild animals, remedy, an assistant in agriculture, a food preservative, a technological aid, etc.
The wonderful myth of Prometheus, who gave fire to people, appeared in Ancient Greece much later, after many parts of the world had mastered methods of quite sophisticated handling of fire, its production and extinguishing, preservation of fire and rational use of fuel.
For many years, fire was maintained by burning plant energy sources (wood, shrubs, reeds, grass, dry algae, etc.), and then it was discovered that it was possible to use fossil substances to maintain fire: coal, oil, shale, peat.
Today, energy remains the main component of human life. It makes it possible to create various materials, is one of the main factors in the development of new technologies. Simply put, without mastering various types energy, a person is not able to fully exist.
Electricity production.
Types of power plants.
Thermal power plant (TPP), a power plant that generates electrical energy as a result of the conversion of thermal energy released during the combustion of fossil fuels. The first thermal power plants appeared at the end of the 19th century and became widespread. In the mid-70s of the 20th century, thermal power plants were the main type of power plants.
In thermal power plants, the chemical energy of the fuel is converted first into mechanical energy and then into electrical energy. The fuel for such a power plant can be coal, peat, gas, oil shale, and fuel oil.
Thermal power plants are divided into condensation(IES), designed to generate only electrical energy, and combined heat and power plants(CHP), producing, in addition to electrical energy, thermal energy in the form of hot water and steam. Large CPPs of regional significance are called state district power plants (SDPPs).
The simplest schematic diagram of a coal-fired IES is shown in the figure. Coal is fed into the fuel bunker 1, and from it into the crushing unit 2, where it turns into dust. Coal dust enters the furnace of a steam generator (steam boiler) 3, which has a system of tubes in which chemically purified water, called feed water, circulates. In the boiler, the water is heated, evaporated, and the resulting saturated steam is brought to a temperature of 400-650 °C and, under a pressure of 3-24 MPa, enters steam turbine 4 through a steam line. Steam parameters depend on the power of the units.
Thermal condensing power plants have low efficiency (30-40%), since most of the energy is lost with flue gases and condenser cooling water. It is advantageous to build CPPs in close proximity to fuel production sites. In this case, electricity consumers may be located at a considerable distance from the station.
Combined heat and power plant differs from a condensing station by having a special heating turbine installed on it with steam extraction. At a thermal power plant, one part of the steam is completely used in the turbine to generate electricity in the generator 5 and then enters the condenser 6, and the other, having a higher temperature and pressure, is taken from the intermediate stage of the turbine and is used for heat supply. The condensate is supplied by pump 7 through the deaerator 8 and then by the feed pump 9 to the steam generator. The amount of steam taken depends on the thermal energy needs of enterprises.
Coefficient useful action CHP reaches 60-70%. Such stations are usually built near consumers - industrial enterprises or residential areas. Most often they run on imported fuel.
Thermal stations with gas turbine(GTPP), steam-gas(PHPP) and diesel plants.
Gas or liquid fuel is burned in the combustion chamber of a gas turbine power plant; combustion products with a temperature of 750-900 ºС enter a gas turbine that rotates an electric generator. The efficiency of such thermal power plants is usually 26-28%, power - up to several hundred MW . GTPPs are usually used to cover electrical load peaks. The efficiency of PGES can reach 42 - 43%.
The most economical are large thermal steam turbine power plants (abbreviated TPP). Most thermal power plants in our country use coal dust as fuel. To generate 1 kWh of electricity, several hundred grams of coal are consumed. In a steam boiler, over 90% of the energy released by the fuel is transferred to steam. In the turbine, the kinetic energy of the steam jets is transferred to the rotor. The turbine shaft is rigidly connected to the generator shaft.
Modern steam turbines for thermal power plants are very advanced, high-speed, highly economical machines with a long service life. Their power in a single-shaft version reaches 1 million 200 thousand kW, and this is not the limit. Such machines are always multi-stage, that is, they usually have several dozen disks with working blades and the same number, in front of each disk, of groups of nozzles through which a stream of steam flows. The pressure and temperature of the steam gradually decrease.
It is known from a physics course that the efficiency of heat engines increases with increasing initial temperature of the working fluid. Therefore, the steam entering the turbine is brought to high parameters: temperature - almost 550 ° C and pressure - up to 25 MPa. The efficiency of thermal power plants reaches 40%. Most of the energy is lost along with the hot exhaust steam.
Hydroelectric station (hydroelectric power station), a complex of structures and equipment through which the energy of water flow is converted into electrical energy. A hydroelectric power station consists of a series circuit hydraulic structures, providing the necessary concentration of water flow and creating pressure, and energy equipment that converts the energy of water moving under pressure into mechanical rotational energy, which, in turn, is converted into electrical energy.
The pressure of a hydroelectric power station is created by the concentration of the fall of the river in the area used by the dam, or derivation, or a dam and diversion together. The main power equipment of the hydroelectric power station is located in the hydroelectric power station building: in the turbine room of the power plant - hydraulic units, auxiliary equipment, automatic control and monitoring devices; in the central control post - operator-dispatcher console or auto operator of a hydroelectric power station. Increasing transformer substation It is located both inside the hydroelectric power station building and in separate buildings or in open areas. Switchgears often located in an open area. A hydroelectric power plant building can be divided into sections with one or more units and auxiliary equipment, separated from adjacent parts of the building. An installation site is created at or inside the hydroelectric power station building for the assembly and repair of various equipment and for auxiliary operations for the maintenance of the hydroelectric power station.
According to installed capacity (in MW) distinguish between hydroelectric power stations powerful(over 250), average(up to 25) and small(up to 5). The power of a hydroelectric power station depends on the pressure (the difference between the levels of the upstream and downstream ), water flow used in hydraulic turbines and the efficiency of the hydraulic unit. For a number of reasons (due to, for example, seasonal changes in the water level in reservoirs, fluctuations in the load of the power system, repairs of hydraulic units or hydraulic structures, etc.), the pressure and flow of water continuously change, and, in addition, the flow changes when regulating the power of a hydroelectric power station. There are annual, weekly and daily cycles of hydroelectric power station operation.
Based on the maximum used pressure, hydroelectric power stations are divided into high-pressure(more than 60 m), medium-pressure(from 25 to 60 m) And low-pressure(from 3 to 25 m). On lowland rivers pressures rarely exceed 100 m, in mountainous conditions, a dam can create pressures of up to 300 m and more, and with the help of derivation - up to 1500 m. The division of hydroelectric power stations according to the pressure used is of an approximate, conditional nature.
According to the pattern of water resource use and pressure concentration, hydroelectric power stations are usually divided into channel , dam , diversion with pressure and non-pressure diversion, mixed, pumped storage And tidal .
In run-of-river and dam-based hydroelectric power plants, the water pressure is created by a dam that blocks the river and raises the water level in the upper pool. At the same time, some flooding of the river valley is inevitable. Run-of-river and dam-side hydroelectric power stations are built both on lowland high-water rivers and on mountain rivers, in narrow compressed valleys. Run-of-river hydroelectric power stations are characterized by pressures up to 30-40 m.
At higher pressures, it turns out to be inappropriate to transfer hydrostatic water pressure to the hydroelectric power station building. In this case the type is used dam A hydroelectric power station, in which the pressure front is blocked along its entire length by a dam, and the hydroelectric power station building is located behind the dam, is adjacent to the tailwater.
Another type of layout dammed The hydroelectric power station corresponds to mountain conditions with relatively low river flows.
IN derivational Hydroelectric power station concentration of the river fall is created through diversion; Water at the beginning of the used section of the river is diverted from the river bed by a conduit with a slope significantly less than the average slope of the river in this section and with straightening the bends and turns of the channel. The end of the diversion is brought to the location of the hydroelectric power station building. Waste water is either returned to the river or supplied to the next diversion hydroelectric power station. Diversion is beneficial when the river slope is high.
A special place among hydroelectric power stations is occupied by pumped storage power plants(PSPP) and tidal power plants(PES). The construction of pumped storage power plants is driven by the growing demand for peak power in large energy systems, which determines the generating capacity required to cover peak loads. The ability of pumped storage power plants to accumulate energy is based on the fact that the electrical energy free in the power system for a certain period of time is used by pumped storage power plant units, which, operating in pump mode, pump water from the reservoir into the upper storage pool. During load peaks, the accumulated energy is returned to the power system (water from the upper pool enters the pressure pipeline and rotates hydraulic units operating as a current generator).
PES convert the energy of sea tides into electricity. The electricity of tidal hydroelectric power stations, due to some features associated with the periodic nature of the ebb and flow of tides, can be used in energy systems only in conjunction with the energy of regulating power plants, which make up for the power failures of tidal power stations within days or months.
The most important feature of hydropower resources compared to fuel and energy resources is their continuous renewability. The absence of fuel requirement for hydroelectric power plants determines the low cost of electricity generated by hydroelectric power plants. Therefore, the construction of hydroelectric power stations, despite significant specific capital investments by 1 kW installed capacity and long construction periods were and are given great importance, especially when this is associated with the placement of electricity-intensive industries.
Nuclear power plant (NPP), a power plant in which atomic (nuclear) energy is converted into electrical energy. The energy generator at a nuclear power plant is a nuclear reactor. The heat that is released in the reactor as a result of a chain reaction of fission of the nuclei of some heavy elements is then converted into electricity in the same way as in conventional thermal power plants (TPPs). Unlike thermal power plants that run on fossil fuels, nuclear power plants run on nuclear fuel(based on 233 U, 235 U, 239 Pu). It has been established that the world's energy resources of nuclear fuel (uranium, plutonium, etc.) significantly exceed the energy resources of natural reserves of organic fuel (oil, coal, natural gas, etc.). This opens up broad prospects for meeting rapidly growing fuel demands. In addition, it is necessary to take into account the ever-increasing volume of coal and oil consumption for technological purposes in the global chemical industry, which is becoming a serious competitor to thermal power plants. Despite the discovery of new deposits of organic fuel and the improvement of methods for its production, there is a tendency in the world towards a relative increase in its cost. This creates the most difficult conditions for countries with limited reserves of fossil fuels. The need is obvious rapid development nuclear energy, which already occupies a prominent place in the energy balance of a number of industrial countries around the world.
A schematic diagram of a nuclear power plant with a water-cooled nuclear reactor is shown in Fig. 2. Heat released in core reactor coolant, is taken in by water from the 1st circuit, which is pumped through the reactor by a circulation pump. Heated water from the reactor enters the heat exchanger (steam generator) 3, where it transfers the heat received in the reactor to the water of the 2nd circuit. The water of the 2nd circuit evaporates in the steam generator, and steam is formed, which then enters the turbine 4.
Most often, 4 types of thermal neutron reactors are used at nuclear power plants:
1) water-water with ordinary water as a moderator and coolant;
2) graphite-water with water coolant and graphite moderator;
3) heavy water with water coolant and heavy water as a moderator;
4) graffito - gas with gas coolant and graphite moderator.
The choice of the predominantly used reactor type is determined mainly by the accumulated experience in the carrier reactor, as well as the availability of the necessary industrial equipment, raw material reserves, etc.
The reactor and its servicing systems include: the reactor itself with biological protection , heat exchangers, pumps or gas-blowing units that circulate the coolant, pipelines and fittings for the circulation circuit, devices for reloading nuclear fuel, special ventilation systems, emergency cooling systems, etc.
To protect nuclear power plant personnel from radiation exposure, the reactor is surrounded by biological shielding, the main materials for which are concrete, water, and serpentine sand. The reactor circuit equipment must be completely sealed. A system is provided to monitor places of possible coolant leaks; measures are taken to ensure that leaks and breaks in the circuit do not lead to radioactive emissions and contamination of the nuclear power plant premises and the surrounding area. Radioactive air and a small amount of coolant vapor, due to the presence of leaks from the circuit, are removed from unattended rooms of the nuclear power plant by a special ventilation system, in which purification filters and holding gas tanks are provided to eliminate the possibility of air pollution. The compliance with radiation safety rules by NPP personnel is monitored by the dosimetry control service.
The presence of biological protection, special ventilation and emergency cooling systems and a radiation monitoring service makes it possible to completely protect NPP operating personnel from the harmful effects of radioactive radiation.
Nuclear power plants, which are the most modern look power plants have a number of significant advantages over other types of power plants: under normal operating conditions they do not pollute at all environment, do not require connection to a source of raw materials and, accordingly, can be placed almost anywhere. New power units have a capacity almost equal to that of an average hydroelectric power station, but the installed capacity utilization factor at a nuclear power plant (80%) significantly exceeds this figure for a hydroelectric power station or thermal power plant.
NPPs have practically no significant disadvantages under normal operating conditions. However, one cannot fail to notice the danger of nuclear power plants under possible force majeure circumstances: earthquakes, hurricanes, etc. - here old models of power units pose a potential danger of radiation contamination of territories due to uncontrolled overheating of the reactor.
Alternative energy sources.
Solar energy.
IN lately interest in the problem of using solar energy has increased sharply, because the potential possibilities of energy based on the use of direct solar radiation are extremely high.
The simplest solar radiation collector is a blackened metal (usually aluminum) sheet, inside of which there are pipes with a liquid circulating in it. Heated by solar energy absorbed by the collector, the liquid is supplied for direct use.
Solar energy is one of the most material-intensive types of energy production. Large-scale use of solar energy entails a gigantic increase in the need for materials, and, consequently, in labor resources for the extraction of raw materials, their enrichment, obtaining materials, manufacturing heliostats, collectors, other equipment, and their transportation.
So far, electrical energy generated by the sun's rays is much more expensive than that obtained by traditional methods. Scientists hope that the experiments they will conduct at pilot installations and stations will help solve not only technical, but also economic problems.
Wind energy.
The energy of moving air masses is enormous. Wind energy reserves are more than a hundred times greater than the hydroelectric energy reserves of all the rivers on the planet. Winds blow constantly and everywhere on earth. Climatic conditions allow the development of wind energy over a vast territory.
But today, wind engines supply just one thousandth of the world's energy needs. Therefore, aircraft specialists who know how to select the most appropriate blade profile and study it in a wind tunnel are involved in creating the designs of the wind wheel, the heart of any wind power plant. Through the efforts of scientists and engineers, a wide variety of designs of modern wind turbines have been created.
Energy of the Earth.
People have long known about the spontaneous manifestations of gigantic energy hidden in the depths of the globe. The memory of mankind contains legends about catastrophic volcanic eruptions that claimed millions of human lives and changed the appearance of many places on Earth beyond recognition. The power of the eruption of even a relatively small volcano is colossal; it is many times greater than the power of the largest power plants created by human hands. True, there is no need to talk about the direct use of the energy of volcanic eruptions; people do not yet have the ability to curb this rebellious element.
The Earth's energy is suitable not only for heating premises, as is the case in Iceland, but also for generating electricity. Power plants using hot underground springs have been operating for a long time. The first such power plant, still very low-power, was built in 1904 in the small Italian town of Larderello. Gradually, the power of the power plant grew, more and more new units were put into operation, new sources of hot water were used, and today the power of the station has already reached an impressive value of 360 thousand kilowatts.
Electricity transmission.
Transformers.
You purchased a ZIL refrigerator. The seller warned you that the refrigerator is designed for a mains voltage of 220 V. And in your house the mains voltage is 127 V. A hopeless situation? Not at all. You just have to make an additional expense and purchase a transformer.
Transformer- a very simple device that allows you to both increase and decrease voltage. The conversion of alternating current is carried out using transformers. Transformers were first used in 1878 by the Russian scientist P. N. Yablochkov to power the “electric candles” he invented, a new light source at that time. P. N. Yablochkov’s idea was developed by Moscow University employee I. F. Usagin, who designed improved transformers.
The transformer consists of a closed iron core, on which two (sometimes more) coils with wire windings are placed (Fig. 1). One of the windings, called the primary winding, is connected to an alternating voltage source. The second winding, to which the “load” is connected, i.e., instruments and devices that consume electricity, is called secondary.
The operation of a transformer is based on the phenomenon of electromagnetic induction. When alternating current passes through the primary winding, an alternating magnetic flux appears in the iron core, which excites an induced emf in each winding. Moreover, the instantaneous value of the induced emf e V any turn of the primary or secondary winding according to Faraday’s law is determined by the formula:
e = - Δ F/ Δ t
If F= Ф 0 сosωt, then
e = ω Ф 0 sin ω t , or
e = E 0 sin ω t ,
Where E 0 = ω Ф 0 - amplitude of the EMF in one turn.
In the primary winding, which has n 1 turns, total induced emf e 1 equal to p 1 e.
In the secondary winding there is a total emf. e 2 equal to p 2 e, Where n 2- the number of turns of this winding.
It follows that
e 1 e 2 = n 1 n 2 . (1)
Sum voltage u 1 , applied to the primary winding, and EMF e 1 should be equal to the voltage drop in the primary winding:
u 1 + e 1 = i 1 R 1 , Where R 1 - active resistance of the winding, and i 1 - current strength in it. This equation follows directly from the general equation. Usually the active resistance of the winding is small and i 1 R 1 can be neglected. That's why
u 1 ≈ -e 1 . (2)
When the secondary winding of the transformer is open, no current flows in it, and the following relationship holds:
u 2 ≈ - e 2 . (3)
Since the instantaneous values of the emf e 1 And e 2 change in phase, then their ratio in formula (1) can be replaced by the ratio of effective values E 1 And E 2 of these EMFs or, taking into account equalities (2) and (3), the ratio of effective voltage values U 1 and U 2 .
U 1 /U 2 = E 1 / E 2 = n 1 / n 2 = k . (4)
Magnitude k called the transformation ratio. If k>1, then the transformer is step-down, when k <1 - increasing
When the secondary winding circuit is closed, current flows in it. Then the ratio u 2 ≈ - e 2 is no longer fulfilled exactly, and accordingly the connection between U 1 and U 2 becomes more complex than in equation (4).
According to the law of conservation of energy, the power in the primary circuit must be equal to the power in the secondary circuit:
U 1 I 1 = U 2 I 2, (5)
Where I 1 And I 2 - effective values of force in the primary and secondary windings.
It follows that
U 1 /U 2 = I 1 / I 2 . (6)
This means that by increasing the voltage several times using a transformer, we reduce the current by the same amount (and vice versa).
Due to the inevitable energy losses due to heat release in the windings and iron core, equations (5) and (6) are satisfied approximately. However, in modern powerful transformers, the total losses do not exceed 2-3%.
In everyday practice we often have to deal with transformers. In addition to those transformers that we use willy-nilly due to the fact that industrial devices are designed for one voltage, and the city network uses another, we also have to deal with car bobbins. The bobbin is a step-up transformer. To create a spark that ignites the working mixture, a high voltage is required, which we obtain from the car battery, after first converting the direct current of the battery into alternating current using a breaker. It is not difficult to understand that, up to the loss of energy used to heat the transformer, as the voltage increases, the current decreases, and vice versa.
Welding machines require step-down transformers. Welding requires very high currents, and the welding machine's transformer has only one output turn.
You probably noticed that the transformer core is made from thin sheets of steel. This is done so as not to lose energy during voltage conversion. In sheet material, eddy currents will play a smaller role than in solid material.
At home you are dealing with small transformers. As for powerful transformers, they are huge structures. In these cases, the core with windings is placed in a tank filled with cooling oil.
Electricity transmission
Electricity consumers are everywhere. It is produced in relatively few places close to sources of fuel and hydro resources. Therefore, there is a need to transmit electricity over distances sometimes reaching hundreds of kilometers.
But transmitting electricity over long distances is associated with noticeable losses. The fact is that as current flows through power lines, it heats them up. In accordance with the Joule-Lenz law, the energy spent on heating the wires of the line is determined by the formula
where R is the line resistance. With a large line length, energy transmission may become generally unprofitable. To reduce losses, you can, of course, follow the path of reducing the resistance R of the line by increasing the cross-sectional area of the wires. But to reduce R, for example, by 100 times, you need to increase the mass of the wire also by 100 times. It is clear that such a large consumption of expensive non-ferrous metal cannot be allowed, not to mention the difficulties of fastening heavy wires on high masts, etc. Therefore, energy losses in the line are reduced in another way: by reducing the current in the line. For example, reducing the current by 10 times reduces the amount of heat released in the conductors by 100 times, i.e., the same effect is achieved as from making the wire a hundred times heavier.
Since current power is proportional to the product of current and voltage, to maintain the transmitted power, it is necessary to increase the voltage in the transmission line. Moreover, the longer the transmission line, the more profitable it is to use a higher voltage. For example, in the high-voltage transmission line Volzhskaya HPP - Moscow, a voltage of 500 kV is used. Meanwhile, alternating current generators are built for voltages not exceeding 16-20 kV, since a higher voltage would require more complex special measures to be taken to insulate the windings and other parts of the generators.
That's why step-up transformers are installed at large power plants. The transformer increases the voltage in the line by the same amount as it reduces the current. The power losses are small.
To directly use electricity in the electric drive motors of machine tools, in the lighting network and for other purposes, the voltage at the ends of the line must be reduced. This is achieved using step-down transformers. Moreover, usually a decrease in voltage and, accordingly, an increase in current occurs in several stages. At each stage, the voltage becomes less and less, and the territory covered by the electrical network becomes wider. The diagram of transmission and distribution of electricity is shown in the figure.
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Electric power stations in a number of regions of the country are connected by high-voltage transmission lines, forming a common power grid to which consumers are connected. Such an association is called a power system. The power system ensures uninterrupted supply of energy to consumers regardless of their location.
Electricity use.
The use of electrical power in various fields of science.
The twentieth century has become the century when science invades all spheres of social life: economics, politics, culture, education, etc. Naturally, science directly influences the development of energy and the scope of application of electricity. On the one hand, science contributes to expanding the scope of application of electrical energy and thereby increases its consumption, but on the other hand, in an era when the unlimited use of non-renewable energy resources poses a danger to future generations, the urgent tasks of science are the development of energy-saving technologies and their implementation in life.
Let's look at these questions using specific examples. About 80% of the growth in GDP (gross domestic product) of developed countries is achieved through technical innovation, the main part of which is related to the use of electricity. Everything new in industry, agriculture and everyday life comes to us thanks to new developments in various branches of science.
Most scientific developments begin with theoretical calculations. But if in the 19th century these calculations were made using pen and paper, then in the age of STR (scientific and technological revolution) all theoretical calculations, selection and analysis of scientific data, and even linguistic analysis of literary works are done using computers (electronic computers), which operate on electrical energy, which is most convenient for transmitting it over a distance and using it. But if initially computers were used for scientific calculations, now computers have come from science to life.
Now they are used in all areas of human activity: for recording and storing information, creating archives, preparing and editing texts, performing drawing and graphic work, automating production and agriculture. Electronicization and automation of production are the most important consequences of the “second industrial” or “microelectronic” revolution in the economies of developed countries. The development of complex automation is directly related to microelectronics, a qualitatively new stage of which began after the invention in 1971 of the microprocessor - a microelectronic logical device built into various devices to control their operation.
Microprocessors have accelerated the growth of robotics. Most of the robots currently in use belong to the so-called first generation, and are used for welding, cutting, pressing, coating, etc. The second generation robots that are replacing them are equipped with devices for recognizing the environment. And third-generation “intellectual” robots will “see,” “feel,” and “hear.” Scientists and engineers name nuclear energy, space exploration, transport, trade, warehousing, medical care, waste processing, and the development of the riches of the ocean floor among the highest priority areas for using robots. The majority of robots operate on electrical energy, but the increase in electricity consumption by robots is offset by a decrease in energy costs in many energy-intensive production processes due to the introduction of more rational methods and new energy-saving technological processes.
But let's get back to science. All new theoretical developments after computer calculations are tested experimentally. And, as a rule, at this stage, research is carried out using physical measurements, chemical analyzes, etc. Here, the tools of scientific research are diverse - numerous measuring instruments, accelerators, electron microscopes, magnetic resonance imaging, etc. The bulk of these instruments of experimental science are powered by electrical energy.
Science in the field of communications and communications is developing very rapidly. Satellite communications are no longer used only as a means of international communication, but also in everyday life - satellite dishes are not uncommon in our city. New means of communication, such as fiber technology, can significantly reduce energy losses in the process of transmitting signals over long distances.
Science has not bypassed the sphere of management. As scientific and technological progress develops and the production and non-production spheres of human activity expand, management begins to play an increasingly important role in increasing their efficiency. From a kind of art, which until recently was based on experience and intuition, management today has turned into a science. The science of management, the general laws of receiving, storing, transmitting and processing information is called cybernetics. This term comes from the Greek words “helmsman”, “helmsman”. It is found in the works of ancient Greek philosophers. However, its rebirth actually occurred in 1948, after the publication of the book “Cybernetics” by the American scientist Norbert Wiener.
Before the start of the “cybernetic” revolution, there was only paper computer science, the main means of perception of which was the human brain, and which did not use electricity. The "cybernetic" revolution gave birth to a fundamentally different one - machine informatics, corresponding to the gigantically increased flows of information, the source of energy for which is electricity. Completely new means of obtaining information, its accumulation, processing and transmission have been created, which together form a complex information structure. It includes automated control systems (automated control systems), information data banks, automated information databases, computer centers, video terminals, copying and phototelegraph machines, national information systems, satellite and high-speed fiber-optic communication systems - all this has unlimitedly expanded the scope of electricity use.
Many scientists believe that in this case we are talking about a new “information” civilization, replacing the traditional organization of an industrial-type society. This specialization is characterized by the following important features:
· widespread use of information technology in material and non-material production, in the field of science, education, healthcare, etc.;
· the presence of a wide network of various data banks, including public ones;
· turning information into one of the most important factors in economic, national and personal development;
· free circulation of information in society.
Such a transition from an industrial society to an “information civilization” became possible largely thanks to the development of energy and the provision of a convenient type of energy for transmission and use - electrical energy.
Electricity in production.
Modern society cannot be imagined without the electrification of production activities. Already at the end of the 80s, more than 1/3 of all energy consumption in the world was carried out in the form of electrical energy. By the beginning of the next century, this share may increase to 1/2. This increase in electricity consumption is primarily associated with an increase in its consumption in industry. The bulk of industrial enterprises operate on electrical energy. High electricity consumption is typical for energy-intensive industries such as metallurgy, aluminum and mechanical engineering.
Electricity in the home.
Electricity is an essential assistant in everyday life. Every day we deal with her, and, probably, we can no longer imagine our life without her. Remember the last time your lights were turned off, that is, there was no electricity coming to your house, remember how you swore that you didn’t have time to do anything and you needed light, you needed a TV, a kettle and a bunch of other electrical appliances. After all, if we were to lose power forever, we would simply return to those ancient times when food was cooked over fires and we lived in cold wigwams.
A whole poem can be dedicated to the importance of electricity in our lives, it is so important in our lives and we are so accustomed to it. Although we no longer notice that it is coming into our homes, when it is turned off, it becomes very uncomfortable.
Appreciate electricity!
List of used literature.
1. Textbook by S.V. Gromov “Physics, 10th grade”. Moscow: Enlightenment.
2. Encyclopedic dictionary of a young physicist. Compound. V.A. Chuyanov, Moscow: Pedagogy.
3. Ellion L., Wilkons U.. Physics. Moscow: Science.
4. Koltun M. World of Physics. Moscow.
5. Energy sources. Facts, problems, solutions. Moscow: Science and Technology.
6. Non-traditional energy sources. Moscow: Knowledge.
7. Yudasin L.S.. Energy: problems and hopes. Moscow: Enlightenment.
8. Podgorny A.N. Hydrogen energy. Moscow: Science.
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Introduction.
The birth of energy occurred several million years ago, when people learned to use fire. Fire gave them warmth and light, was a source of inspiration and optimism, a weapon against enemies and wild animals, a remedy, an assistant in agriculture, a food preservative, a technological tool, etc.
The wonderful myth of Prometheus, who gave fire to people, appeared in Ancient Greece much later, after many parts of the world had mastered methods of quite sophisticated handling of fire, its production and extinguishing, preservation of fire and rational use of fuel.
For many years, fire was maintained by burning plant energy sources (wood, shrubs, reeds, grass, dry algae, etc.), and then it was discovered that it was possible to use fossil substances to maintain fire: coal, oil, shale, peat.
Today, energy remains the main component of human life. It makes it possible to create various materials and is one of the main factors in the development of new technologies. Simply put, without mastering various types of energy, a person is not able to fully exist.
Electricity production.
Types of power plants.
Thermal power plant (TPP), a power plant that generates electrical energy as a result of the conversion of thermal energy released during the combustion of organic fuel. The first thermal power plants appeared at the end of the 19th century and became widespread. In the mid-70s of the 20th century, thermal power plants were the main type of power plants.
In thermal power plants, the chemical energy of the fuel is converted first into mechanical energy and then into electrical energy. The fuel for such a power plant can be coal, peat, gas, oil shale, and fuel oil.
Thermal power plants are divided into condensing power plants (CHPs), designed to generate only electrical energy, and combined heat and power plants (CHPs), which produce, in addition to electricity, thermal energy in the form of hot water and steam. Large CPPs of regional significance are called state district power plants (SDPPs).
The simplest schematic diagram of a coal-fired IES is shown in the figure. Coal is fed into the fuel bunker 1, and from it into the crushing unit 2, where it turns into dust. Coal dust enters the furnace of a steam generator (steam boiler) 3, which has a system of tubes in which chemically purified water, called feed water, circulates. In the boiler, the water is heated, evaporated, and the resulting saturated steam is brought to a temperature of 400-650 °C and, under a pressure of 3-24 MPa, enters steam turbine 4 through a steam line. Steam parameters depend on the power of the units.
Thermal condensing power plants have low efficiency (30-40%), since most of the energy is lost with flue gases and condenser cooling water. It is advantageous to build CPPs in close proximity to fuel production sites. In this case, electricity consumers may be located at a considerable distance from the station.
A combined heat and power plant differs from a condensing station by having a special heating turbine installed on it with steam extraction. At a thermal power plant, one part of the steam is completely used in the turbine to generate electricity in the generator 5 and then enters the condenser 6, and the other, having a higher temperature and pressure, is taken from the intermediate stage of the turbine and is used for heat supply. The condensate is supplied by pump 7 through the deaerator 8 and then by the feed pump 9 to the steam generator. The amount of steam taken depends on the thermal energy needs of enterprises.
The efficiency of thermal power plants reaches 60-70%. Such stations are usually built near consumers - industrial enterprises or residential areas. Most often they run on imported fuel.
Thermal stations with gas turbine (GTPP), combined cycle (CGPP) and diesel plants have become significantly less widespread.
Gas or liquid fuel is burned in the combustion chamber of a gas turbine power plant; combustion products with a temperature of 750-900 ºС enter a gas turbine that rotates an electric generator. The efficiency of such thermal power plants is usually 26-28%, the power is up to several hundred MW. GTPPs are usually used to cover electrical load peaks. The efficiency of PGES can reach 42 - 43%.
The most economical are large thermal steam turbine power plants (abbreviated TPP). Most thermal power plants in our country use coal dust as fuel. To generate 1 kWh of electricity, several hundred grams of coal are consumed. In a steam boiler, over 90% of the energy released by the fuel is transferred to steam. In the turbine, the kinetic energy of the steam jets is transferred to the rotor. The turbine shaft is rigidly connected to the generator shaft.
Modern steam turbines for thermal power plants are very advanced, high-speed, highly economical machines with a long service life. Their power in a single-shaft version reaches 1 million 200 thousand kW, and this is not the limit. Such machines are always multi-stage, that is, they usually have several dozen disks with working blades and the same number, in front of each disk, of groups of nozzles through which a stream of steam flows. The pressure and temperature of the steam gradually decrease.
It is known from a physics course that the efficiency of heat engines increases with increasing initial temperature of the working fluid. Therefore, the steam entering the turbine is brought to high parameters: temperature - almost 550 ° C and pressure - up to 25 MPa. The efficiency of thermal power plants reaches 40%. Most of the energy is lost along with the hot exhaust steam.
Hydroelectric station (HPP), a complex of structures and equipment through which the energy of water flow is converted into electrical energy. A hydroelectric power station consists of a sequential chain of hydraulic structures that provide the necessary concentration of water flow and the creation of pressure, and energy equipment that converts the energy of water moving under pressure into mechanical rotational energy, which, in turn, is converted into electrical energy.
