What is used to produce electricity. Production, transmission and consumption of electrical energy

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 Khokhlova Kristina, grade 11, secondary school No. 64

Presentation plan Electricity generation Types of power plants Alternative sources energy 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. At thermal power plants, the chemical energy of the fuel is converted first into mechanical and then into electrical energy. The fuel for such a power plant can be coal, peat, gas, oil shale, fuel oil. The most economical are large thermal steam turbine power plants. Most of the thermal power plants in our country use coal dust as fuel. It takes several hundred grams of coal to generate 1 kWh of electricity. 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 subdivided into: Condensing (CPP) They are designed to generate only electrical energy. Large IESs of district significance are called state district power plants (GRES). combined heat and power plants (CHP) producing, in addition to electricity thermal energy as hot water and couple.

Hydroelectric power station (HPP), a complex of structures and equipment through which the energy of the flow of water is converted into electrical energy. The hydroelectric power station consists of a series of hydraulic structures that provide the necessary concentration of water flow and create pressure, and power 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 used section by a dam, or by a derivation, or by a dam and a derivation together. hydroelectric power station

HPP power HPPs are also subdivided into: HPP power depends on the pressure, water flow used in hydro turbines, and the efficiency of the hydroelectric unit. For a number of reasons (due to, for example, seasonal changes in the water level in reservoirs, variability in the load of the power system, repair of hydroelectric units or hydraulic structures, etc.), the pressure and flow of water are constantly changing, and, in addition, the flow changes when regulating the power of the HPP. high-pressure (more than 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 HPPs is occupied by: Hydrostorage power plants (PSPPs) Electric Energy is used by pumped storage power plants, 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 grid. Tidal power plants (TPP) TPPs convert the energy of sea tides into electricity. The electric power of tidal hydroelectric power plants, due to some features associated with the periodic nature of the tides, can only be used in power systems in conjunction with the energy of regulating power plants, which compensate for power failures of tidal power plants during the day or months.

The heat released in the reactor as a result of chain reaction nuclear fission of some heavy elements, then, just as in conventional thermal power plants (TPPs), it is converted into electricity. Unlike thermal power plants operating on fossil fuels, nuclear power plants operate 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 natural resources organic, fuel (oil, coal, natural gas and etc.). In addition, it is necessary to take into account the ever-increasing volume of consumption of coal and oil for technological purposes of the world economy. chemical industry, which is becoming a serious competitor to thermal power plants. nuclear power station

NPP Most often, NPPs use 4 types of thermal neutron reactors: graphite-water reactors with a water coolant and a graphite moderator heavy water reactors with a water coolant and heavy water as a moderator water-water reactors with ordinary water as a moderator and coolant graffito-gas reactors with a gas coolant and a graphite moderator

The choice of the predominantly used type of reactor is determined mainly by the accumulated experience in the reactor carrier, 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 blowers that circulate the coolant, pipelines and valves for the circulation of the circuit, devices for reloading nuclear fuel, special ventilation systems, emergency cooling systems, etc. To protect NPP personnel from radiation exposure, the reactor is surrounded by biological protection, the main material for which is concrete, water, serpentine sand. The reactor circuit equipment must be completely sealed. nuclear power station

Alternative energy sources. Solar energy Solar energy is one of the most material-intensive types of energy production. The large-scale use of solar energy entails a gigantic increase in the need for materials, and, consequently, for labor resources for the extraction of raw materials, their enrichment, the production of materials, the manufacture of heliostats, collectors, other equipment, and their transportation. Wind energy The energy of moving air masses is enormous. The reserves of wind energy are more than a hundred times greater than the reserves of hydropower of all the rivers of the planet. Winds blow constantly and everywhere on earth. Climatic conditions allow the development of wind energy in a vast area. 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 space heating, 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 quite low-power, was built in 1904 in the small Italian town of Larderello. Gradually, the capacity of the power plant grew, more and more new units came 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.

Sun energy Air energy Earth energy

Electricity transmission Electricity consumers are everywhere. It is produced in relatively few places close to sources of fuel and water resources. Therefore, it becomes necessary to transmit electricity over distances sometimes reaching hundreds of kilometers. But the transmission of electricity over long distances is associated with notable losses. The fact is that, flowing through power lines, the current heats them. In accordance with the Joule-Lenz law, the energy spent on heating the wires of the line is determined by the formula: Q \u003d I 2 Rt where R is the line resistance. With a long line, power transmission can become generally uneconomical. To reduce losses, you can increase the area of ​​the cross section of the wires. But with a decrease in R by a factor of 100, the mass must also be increased by a factor of 100. 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, a decrease in current by a factor of 10 reduces the amount of heat released in the conductors by 100 times, i.e., the same effect is achieved as from a hundredfold weighting of the wire. Therefore, step-up transformers are installed at large power plants. The transformer increases the voltage in the line as much as it reduces the current. The power loss in this case is small. 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 the uninterrupted supply of energy to consumers, regardless of their location.

The use of electricity in various fields of science Science directly affects the development of energy and the scope of electricity. About 80% of GDP growth in developed countries is achieved through technical innovations, most of which are related to the use of electricity. Everything new in the industry, Agriculture and life comes to us thanks to new developments in various industries science. Most of scientific developments starts with theoretical calculations. But if in the 19th century these calculations were made using pen and paper, then in the age of scientific and technical revolution (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, the most convenient for its transmission to a distance and use. But if initially computers were used for scientific calculations, now computers have come to life from science. Electronicization 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 used not only as a means of international communication, but also in everyday life - satellite dishes not uncommon in our city.New means of communication, such as fiber technology, can significantly reduce the loss of electricity in the process of transmitting signals over long distances.Completely new means of obtaining information, its accumulation, processing and transmission have been created, which together form a complex information structure.

Use of electricity in production Modern society impossible to imagine without electrification production activities. Already at the end of the 1980s, 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 proportion may increase to 1/2. Such an increase in electricity consumption is primarily associated with an increase in its consumption in industry. Main part industrial enterprises runs on electrical energy. High electricity consumption is typical for energy-intensive industries such as metallurgy, aluminum and engineering industries.

Use of electricity in everyday life Electricity in everyday life is an essential assistant. Every day we deal with it, and, probably, we can no longer imagine our life without it. Remember the last time you turned off the light, that is, your house did not receive electricity, remember how you swore that you didn’t have time for 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 on a fire and lived in cold wigwams. The importance of electricity in our life can be covered with a whole poem, it is so important in our life and we are so used to it. Although we no longer notice that she comes to our homes, but when she is turned off, it becomes very uncomfortable.

Thank you for your attention

Electrical energy is produced at different scales power stations, mainly with the help of induction electromechanical generators.

Power generation

There are two main types of power plants:

1. Thermal.

2. Hydraulic.

This division is caused by the type of motor that turns the generator rotor. AT thermal power plants use fuel as an energy source: coal, gas, oil, oil shale, fuel oil. The rotor is driven by steam gas turbines.

The most economical are thermal steam turbine power plants (TPPs). Their maximum efficiency reaches 70%. This is taking into account the fact that the exhaust steam is used in industrial enterprises.

On the hydroelectric power plants the potential energy of water is used to rotate the rotor. The rotor is driven by hydraulic turbines. The power of the station will depend on the pressure and mass of water passing through the turbine.

Electricity use

Electrical energy is used almost everywhere. Of course, most of the electricity produced comes from industry. In addition, transport will be a major consumer.

Many railway lines have long switched to electric traction. Lighting of dwellings, city streets, industrial and domestic needs of villages and villages - all this is also a large consumer of electricity.

A huge part of the electricity received is converted into mechanical energy. All mechanisms used in industry are driven by electric motors. There are enough consumers of electricity, and they are everywhere.

And electricity is produced only in a few places. The question arises about the transmission of electricity, and over long distances. When transmitting over long distances, there is a lot of power loss. Mainly, these are losses due to heating of electrical wires.

According to the Joule-Lenz law, the energy spent on heating is calculated by the formula:

Since it is almost impossible to reduce the resistance to an acceptable level, it is necessary to reduce the current strength. To do this, increase the voltage. Usually there are step-up generators at the stations, and step-down transformers at the end of the transmission lines. And already from them energy disperses to consumers.

The need for electrical energy is constantly increasing. There are two ways to meet demand for increased consumption:

1. Construction of new power plants

2. Use of advanced technology.

Efficient use of electricity

The first way is costly. a large number construction and financial resources. It takes several years to build one power plant. In addition, for example, thermal power plants consume a lot of non-renewable natural resources and harm the natural environment.

Generation of electrical energy Electric current is generated in generators-devices that convert energy of one form or another into electrical energy. The predominant role in our time is played by electromechanical induction generators. alternating current. There mechanical energy is converted into electrical energy. Electric current is generated in generators-devices that convert energy of one form or another into electrical energy. The predominant role in our time is played by electromechanical induction alternators. There mechanical energy is converted into electrical energy. The generator consists of The generator consists of permanent magnet, which creates a magnetic field, and a winding in which a variable EMF is induced. a permanent magnet that creates a magnetic field, and a winding in which an alternating EMF is induced.

Transformers A TRANSFORMER is a device that converts alternating current of one voltage into alternating current of another voltage at a constant frequency. In the simplest case, the transformer consists of a closed steel core, on which two coils with wire windings are put on. That of the windings that is connected to an alternating voltage source is called primary, and the one to which the "load" is connected, that is, devices that consume electricity, is called secondary. The action of the transformer is based on the phenomenon electromagnetic induction.

Electricity generation Electricity is produced in large and small power plants mainly by means of electromechanical induction generators. There are several types of power plants: thermal, hydroelectric and nuclear power plants. NPP HPP Thermal power plants

Electricity use The main consumer of electricity is industry, which accounts for about 70% of electricity produced. Transport is also a major consumer. All large quantity railway lines to be converted to electric traction. Almost all villages and villages receive electricity from state-owned power plants for industrial and domestic needs. About a third of the electricity consumed by industry is used for technological purposes (electric welding, electric heating and melting of metals, electrolysis, etc.).

Electricity transmission Energy transmission is associated with significant losses: electricity heats the wires of power lines. With very long lines, power transmission can become uneconomical. Since the current power is proportional to the product of the current strength and voltage, in order to maintain the transmitted power, it is necessary to increase the voltage in the transmission line. Therefore, step-up transformers are installed at large power plants. They increase the voltage in the line as much as they reduce the current strength. For direct use of electricity, step-down transformers are installed at the ends of the line. Step-up transformer Step-down transformer Step-down transformer Step-down transformer To consumer Generator 11 kV 110 kV 35 kV 6 kV Transmission line Transmission line Transmission line 35 kV 6 kV 220 V

Effective use Electricity Demand for electricity is constantly increasing. This need can be met in two ways. The most natural and at first glance the only way is the construction of new powerful power plants. But TPPs consume non-renewable Natural resources, and also cause great damage to the ecological balance on our planet. Hi-tech allow you to meet your energy needs in a different way. Priority should be given to increasing the efficiency of electricity use, rather than increasing the capacity of power plants.

abstract

in physics

on the topic "Production, transmission and use of electricity"

11th grade A students

MOU school number 85

Catherine.

Teacher:

2003

Abstract plan.

Introduction.

1. Power generation.

1. types of power plants.

2. alternative energy sources.

2. Electricity transmission.

• transformers.

3.

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, technological tool etc.

The beautiful myth of Prometheus, who gave people fire, appeared in Ancient Greece much later than in many parts of the world, methods of rather sophisticated handling of fire, its production and extinguishment, fire conservation and rational use of fuel were mastered.

For many years, the 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 the 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 of energy, a person is not able to fully exist.

Power generation.

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.

At thermal power plants, the chemical energy of the fuel is converted first into mechanical and then into electrical energy. The fuel for such a power plant can be coal, peat, gas, oil shale, 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 heat energy in the form of hot water and steam. Large IESs of district significance are called state district power plants (GRES).

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 plant 2, where it turns into dust. Coal dust enters the furnace of the steam generator (steam boiler) 3, which has a system of pipes in which chemically purified water, called feed water, circulates. In the boiler, the water heats up, evaporates, and the resulting saturated steam is brought to a temperature of 400-650 ° C and, under a pressure of 3-24 MPa, enters the steam turbine 4 through the steam pipeline. The steam parameters depend on the power of the units.

Thermal condensing power plants have a low efficiency (30-40%), since most of the energy is lost with flue gases and condenser cooling water. It is advantageous to build IES in the immediate vicinity of fuel extraction sites. At the same time, consumers of electricity can be located at a considerable distance from the station.

combined heat and power plant differs from the condensing station by a special heat and power turbine with steam extraction installed on it. At the CHPP, one part of the steam is completely used in the turbine to generate electricity in the generator 5 and then enters the condenser 6, while the other part, which has a high temperature and pressure, is taken from the intermediate stage of the turbine and used for heat supply. Condensate pump 7 through the deaerator 8 and then feed pump 9 is fed into the steam generator. The amount of steam extracted depends on the needs of enterprises for thermal energy.

The efficiency of CHP reaches 60-70%. Such stations are usually built near consumers - industrial enterprises or residential areas. Most often they work on imported fuel.

Significantly less widespread thermal stations With gas turbine(GTPS), steam-gas(PGES) and diesel plants.

Gas or liquid fuel is burned in the GTPP combustion chamber; combustion products with a temperature of 750-900 ºС enter the gas turbine that rotates the 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 SGPP can reach 42 - 43%.

The most economical are large thermal steam turbine power plants (TPPs for short). Most thermal power plants in our country use coal dust as fuel. It takes several hundred grams of coal to generate 1 kWh of electricity. 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 jet of steam flows. The steam pressure and temperature are gradually reduced.

From the course of physics it is known that the efficiency of heat engines increases with an increase in the initial temperature of the working fluid. Therefore, the steam entering the turbine is brought to high parameters: the temperature is almost up to 550 ° C and the pressure is up to 25 MPa. The efficiency of TPP 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 the water flow is converted into electrical energy. HPP consists of a series circuit hydraulic structures, providing the necessary concentration of water flow and the creation of pressure, and power equipment that converts the energy of water moving under pressure into mechanical energy of rotation, which, in turn, is converted into electrical energy.

The head of the hydroelectric power station is created by the concentration of the fall of the river in the used section by the dam, or derivation, or dam and derivation together. The main power equipment of the HPP is located in the HPP building: in the engine room of the power plant - hydraulic units, auxiliary equipment, automatic control and monitoring devices; in the central control post - the operator-dispatcher console or hydroelectric power plant operator. Boosting transformer substation located both inside the power plant building and in separate buildings or in open areas. Distribution devices often located in an open area. The power plant building can be divided into sections with one or more units and auxiliary equipment, separated from adjacent parts of the building. An assembly site is created at the building of the HPP or inside it for the assembly and repair of various equipment and for auxiliary maintenance operations of the HPP.

By installed capacity(in MW) distinguish between hydroelectric power stations powerful(St. 250), medium(up to 25) and small(up to 5). The power of the hydroelectric power station depends on the pressure (the difference between the levels of the upstream and downstream ), the flow rate of water 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, variability in the load of the power system, repair of hydroelectric units or hydraulic structures, etc.), the head and flow of water are constantly changing, and, in addition, the flow changes when regulating the power of the HPP. There are annual, weekly and daily cycles of the HPP operation mode.

According to the maximum used pressure, HPPs are divided into high-pressure(over 60 m), medium pressure(from 25 to 60 m) and low-pressure(from 3 to 25 m). On flat rivers, the pressure rarely exceeds 100 m, in mountainous conditions, through the dam, it is possible to create pressures up to 300 m and more, and with the help of derivation - up to 1500 m. The subdivision of the hydroelectric power station according to the pressure used is approximate, conditional.

According to the scheme of use of water resources and the concentration of pressure, HPPs are usually divided into channel, near-dam, diversion with pressure and non-pressure derivation, mixed, pumped storage and tidal.

In run-of-river and near-dam HPPs, the water pressure is created by a dam that blocks the river and raises the water level in the upstream. At the same time, some flooding of the river valley is inevitable. Run-of-river and near-dam hydroelectric power stations are built both on low-lying high-water rivers and on mountain rivers, in narrow compressed valleys. Run-of-river HPPs are characterized by heads up to 30-40 m.

At higher pressures, it turns out to be impractical to transfer hydrostatic water pressure to the power plant building. In this case, the type dam The hydroelectric power station, in which the pressure front is blocked by a dam throughout its entire length, and the building of the hydroelectric power station is located behind the dam, adjoins the downstream.

Another kind of layout near the dam The hydroelectric power station corresponds to mountainous conditions with relatively low river flow rates.

AT derivational Hydroelectric concentration of the fall of the river is created through derivation; water at the beginning of the used section of the river is diverted from the river channel by a conduit, with a slope significantly less than the average slope of the river in this section and with straightening of the bends and turns of the channel. The end of the derivation is brought to the location of the HPP building. Waste water is either returned to the river or fed to the next diversion HPP. Derivation is beneficial when the slope of the river is high.

A special place among HPPs is occupied by pumped storage power plants(PSPP) and tidal power plants(PES). The construction of a pumped storage power plant is due to the growing demand for peak power in large energy systems, which determines the generating capacity required to cover peak loads. The ability of the pumped storage power plant 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 the pumped storage units, which, operating in the pump mode, pump water from the reservoir into the upper storage pool. During load peaks, the accumulated energy returns to the power system (water from the upper basin enters penstock and rotates hydraulic units operating in the current generator mode).

PES convert the energy of sea tides into electrical energy. The electric power of tidal hydroelectric power plants, due to some features associated with the periodic nature of the tides, can only be used in power systems in conjunction with the energy of regulating power plants, which compensate for power failures of tidal power plants during the day or months.

The most important feature of hydropower resources in comparison with fuel and energy resources is their continuous renewal. The lack of need for fuel for HPPs determines the low cost of electricity generated at HPPs. Therefore, the construction of hydroelectric power stations, despite significant, specific capital investments per 1 kW installed capacity and long construction time, was and is of great importance, especially when it is associated with the location of electrically intensive industries.

Nuclear power plant (NPP), a power plant in which atomic (nuclear) energy is converted into electrical energy. The power 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 nuclear fission of some heavy elements, then, just like in conventional thermal power plants (TPPs), is converted into electricity. Unlike thermal power plants operating on fossil fuels, nuclear power plants operate on nuclear fuel(based on 233 U, 235 U, 239 Pu). It has been established that the world 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 the rapidly growing demand for fuel. In addition, it is necessary to take into account the ever-increasing consumption of coal and oil for the technological purposes of 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 extraction, the world tends to relative increase in its cost. This creates the most difficult conditions for countries with limited reserves of fossil fuels. There is an obvious need for the rapid development of nuclear energy, which already occupies a prominent place in the energy balance of a number of industrial countries of the world.

Schematic diagram of a nuclear power plant with nuclear reactor, having water cooling, is shown in fig. 2. Heat generated in core reactor coolant, is taken in by water of 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. Water from 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 a water coolant and heavy water as a moderator;

4) graffito - gas with a gas coolant and a graphite moderator.

The choice of the predominantly used type of reactor is determined mainly by the accumulated experience in the carrier reactor, as well as the availability of the necessary industrial equipment, raw materials, etc.

The reactor and its supporting systems include: the reactor itself with biological protection , heat exchangers, pumps or gas-blowing installations that circulate the coolant, pipelines and fittings for the circulation of the circuit, devices for reloading nuclear fuel, systems of special ventilation, emergency cooling, etc.

To protect NPP personnel from radiation exposure, the reactor is surrounded by biological protection, the main material for which are concrete, water, serpentine sand. The reactor circuit equipment must be completely sealed. A system is provided for monitoring the places of possible leakage of the coolant, measures are taken so that the appearance of leaks and breaks in the circuit does not lead to radioactive emissions and pollution of the NPP 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 NPP premises special system ventilation, in which, to exclude the possibility of air pollution, cleaning filters and holding gas holders are provided. The dosimetric control service monitors the compliance with the radiation safety rules by the NPP personnel.

NPPs, 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 absolutely do not pollute environment, do not require binding to the source of raw materials and, accordingly, can be placed almost anywhere. The new power units have a capacity of almost equal power average HPP, however, the installed capacity utilization factor at nuclear power plants (80%) significantly exceeds that of HPPs or TPPs.

There are practically no significant drawbacks of nuclear power plants 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.

Energy of sun.

Recently, interest in the problem of using solar energy has increased dramatically, because the potential for energy based on the use of direct solar radiation is extremely high.

The simplest collector of solar radiation 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. The large-scale use of solar energy entails a gigantic increase in the need for materials, and, consequently, for labor resources for the extraction of raw materials, their enrichment, the production of materials, the manufacture of heliostats, collectors, other equipment, and their transportation.

So far, the electrical energy generated by the sun's rays is much more expensive than that obtained by traditional methods. The scientists hope that the experiments that they will carry out at experimental facilities and stations will help to solve not only technical but also economic problems.

wind energy.

The energy of moving air masses is enormous. The reserves of wind energy are more than a hundred times greater than the reserves of hydropower of all the rivers of the planet. Winds blow constantly and everywhere on earth. Climatic conditions allow the development of wind energy in a vast area.

But these days, wind-powered engines cover only one-thousandth of the world's energy needs. That is why the design of the wind wheel, the heart of any wind power plant, involves aircraft builders who are able to choose the most appropriate blade profile and study it in a wind tunnel. Through the efforts of scientists and engineers, a wide variety of designs of modern wind turbines have been created.

Earth energy.

Since ancient times, people have known about the elemental manifestations of gigantic energy lurking in the depths the globe. The memory of mankind keeps legends about catastrophic volcanic eruptions that claimed millions of human lives, unrecognizably changed the appearance of many places on Earth. The power of the eruption of even a relatively small volcano is colossal, it many times exceeds 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, so far people do not have the opportunity to curb this recalcitrant element.

The energy of the Earth is suitable not only for space heating, 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 quite low-power, was built in 1904 in the small Italian town of Larderello. Gradually, the capacity of the power plant grew, more and more new units came 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 have 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 stalemate? Not at all. Just have to do additional cost and buy a transformer.

Transformer- a very simple device that allows you to both increase and decrease the voltage. AC conversion is carried out using transformers. For the first time, transformers were used in 1878 by the Russian scientist P.N. Yablochkov to power the “electric candles” he invented, a new light source at that time. The idea of ​​P. N. Yablochkov was developed by I. F. Usagin, an employee of Moscow University, who designed improved transformers.

The transformer consists of a closed iron core, on which two (sometimes more) coils with wire windings are put on (Fig. 1). One of the windings, called the primary, is connected to an AC voltage source. The second winding, to which the "load" is connected, i.e. devices and devices that consume electricity, is called secondary.

The action of the transformer is based on the phenomenon of electromagnetic induction. When an alternating current passes through the primary winding, an alternating magnetic flux appears in the iron core, which excites the induction EMF in each winding. Moreover, the instantaneous value of the induction emf ein any turn of the primary or secondary winding according to Faraday's law is determined by the formula:

e = -Δ F/Δ t

If a F= Ф 0 сosωt, then

e = ω Ф 0sinω t, or

e =E 0 sinω t ,

where E 0 \u003d ω Ф 0 - the amplitude of the EMF in one turn.

In the primary winding, which has p 1 turns, total induction emf e 1 is equal to n 1 e.

There is total EMF in the secondary winding. e 2 is equal to n 2 e, where p 2 is the number of turns of this winding.

Hence it follows that

e 1 e 2 \u003d n 1 n 2. (1)

Sum of voltage u 1 , applied to the primary winding, and the 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 is the active resistance of the winding, and i 1 is the current in it. This equation follows directly from the general equation. Usually the active resistance of the winding is small and a member i 1 R 1 can be neglected. That's why

u 1 ≈ - e 1. (2)

When the secondary winding of the transformer is open, the current does not flow in it, and the relation takes place:

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 andE 2 these EMF or, taking into account equalities (2) and (3), the ratio of the effective voltage values ​​U 1 and U 2 .

U 1 /U 2 = E 1 / E 2 = n 1 / n 2 = k. (4)

Value k called the transformation ratio. If k>1, then the transformer is step-down, with k<1 - increasing.

When the circuit of the secondary winding is closed, current flows in it. Then the relation u 2 ≈ - e 2 is no longer satisfied 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 the force in the primary and secondary windings.

Hence it follows that

U 1 /U 2 = I 1 / I 2 . (6)

This means that by increasing the voltage several times with the help of a transformer, we reduce the current by the same amount (and vice versa).

Due to the inevitable energy losses for heat generation in the windings and the iron core, equations (5) and (6) are approximately fulfilled. However, in modern high-power transformers, the total losses do not exceed 2-3%.

In everyday practice, you 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 another is used in the city network, besides them, we have to deal with car reels. The bobbin is a step-up transformer. To create a spark that ignites the working mixture, a high voltage is required, which we get from the car battery, after first turning the battery’s direct current into alternating current using a breaker. It is easy to see 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 transformer of the welding machine has only one output turn.

You probably noticed that the core of the transformer is made from thin sheets of steel. This is done in order not to lose energy during voltage conversion. In sheet material, eddy currents will play a lesser 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

Consumers of electricity are everywhere. It is produced in relatively few places close to sources of fuel and water resources. Therefore, it becomes necessary to transmit electricity over distances sometimes reaching hundreds of kilometers.

But the transmission of electricity over long distances is associated with significant losses. The fact is that, flowing through power lines, the current heats them. 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 long line, power transmission can become generally uneconomical. 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 ​​\u200b\u200bthe wires. But to reduce R, for example, by a factor of 100, the mass of the wire must also be increased by a factor of 100. It is clear that such a large expenditure of expensive non-ferrous metal cannot be allowed, not to mention the difficulties of fixing 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, a decrease in current by a factor of 10 reduces the amount of heat released in the conductors by 100 times, i.e., the same effect is achieved as from a hundredfold weighting of the wire.

Since the current power is proportional to the product of the current strength and voltage, in order 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. So, 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 the adoption of more complex special measures to isolate the windings and other parts of the generators.

Therefore, step-up transformers are installed at large power plants. The transformer increases the voltage in the line as much as it reduces the current. The power loss in this case is small.

For the direct use of electricity in the motors of the electric drive 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 strength occurs in several stages. At each stage, the voltage is getting smaller, and the area covered by the electrical network is getting wider. The scheme of transmission and distribution of electricity is shown in the figure.

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 the uninterrupted supply of energy to consumers, regardless of their location.

The use of electricity.

The use of electric power in various fields of science.

The 20th century has become a century when science invades all spheres of society: economy, politics, culture, education, etc. Naturally, science directly affects the development of energy and the scope of electricity. On the one hand, science contributes to the expansion of the scope 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 development of energy-saving technologies and their implementation in life become topical tasks of science.

Let's consider these questions on specific examples. About 80% of GDP growth (gross domestic product) in developed countries is achieved through technical innovation, most 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.

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. Electronization 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 integrated automation is directly related to microelectronics, a qualitatively new stage of which began after the invention in 1971 of the microprocessor - a microelectronic logic device built into various devices to control their operation.

Microprocessors have accelerated the growth of robotics. Most of the robots in use today belong to the so-called first generation, and are used in welding, cutting, pressing, coating, etc. The second-generation robots that replace them are equipped with devices for recognizing the environment. And robots - "intellectuals" of the third generation will "see", "feel", "hear". Scientists and engineers call nuclear energy, space exploration, transport, trade, warehousing, medical care, waste processing, and the development of the wealth of the ocean floor among the most priority areas for the use of robots. The majority of robots run on electrical energy, but the increase in robot electricity consumption is offset by the reduction in energy costs in many energy-intensive manufacturing processes through the introduction of smarter methods and new energy-saving technological processes.

But back to science. All new theoretical developments are verified experimentally after computer calculations. And, as a rule, at this stage, research is carried out using physical measurements, chemical analyzes, etc. Here, scientific research tools are diverse - numerous measuring instruments, accelerators, electron microscopes, magnetic resonance tomographs, etc. Most of these instruments of experimental science run on electrical energy.

Science in the field of communications and communications is developing very rapidly. Satellite communication is used not 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 the loss of electricity in the process of transmitting signals over long distances.

Science and the sphere of management did not bypass. As the scientific and technological revolution develops, the production and non-production spheres of human activity expand, management begins to play an increasingly important role in improving their efficiency. From a kind of art, until recently based on experience and intuition, management has now become 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 writings of ancient Greek philosophers. However, its new birth actually took place in 1948, after the publication of the book "Cybernetics" by the American scientist Norbert Wiener.

Before the beginning 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 rise to a fundamentally different - 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 bases, computer centers, video terminals, copiers and telegraph machines, nationwide 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 of 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 use;

transformation of information into one of the most important factors of 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 due to the development of energy and the provision of a convenient type of energy in 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 1980s, 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 proportion may increase to 1/2. Such an increase in electricity consumption is primarily associated with an increase in its consumption in industry. The main part of industrial enterprises works on electric energy. High electricity consumption is typical for energy-intensive industries such as metallurgy, aluminum and engineering industries.

Electricity in the home.

Electricity in everyday life is an essential assistant. Every day we deal with it, and, probably, we can no longer imagine our life without it. Remember the last time you turned off the light, that is, your house did not receive electricity, remember how you swore that you didn’t have time for 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 on a fire and lived in cold wigwams.

The importance of electricity in our life can be covered with a whole poem, it is so important in our life and we are so used to it. Although we no longer notice that she comes to our homes, but when she is turned off, it becomes very uncomfortable.

Appreciate electricity!

Bibliography.

1. Textbook by S.V. Gromov "Physics, Grade 10". Moscow: Enlightenment.

2. Encyclopedic Dictionary of a Young Physicist. Compound. V.A. Chuyanov, Moscow: Pedagogy.

3. Allion L., Wilcons W.. Physics. Moscow: Nauka.

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: Nauka.

K category: Electric installation work

Production of electrical energy

Electrical energy (electricity) is the most advanced form of energy and is used in all spheres and branches of material production. Its advantages include the possibility of transmission over long distances and conversion into other types of energy (mechanical, thermal, chemical, light, etc.).

Electrical energy is generated at special enterprises - power stations that convert other types of energy into electrical energy: chemical, fuel, water, wind, solar, nuclear.

The ability to transmit electricity over long distances makes it possible to build power plants near fuel locations or on high-water rivers, which is more economical than transporting large amounts of fuel to power plants located near electricity consumers.

Depending on the type of energy used, there are thermal, hydraulic, nuclear power plants. Power plants that use wind energy and the heat of sunlight are still low-power sources of electricity that do not have industrial significance.

Thermal power plants use thermal energy obtained by burning solid fuels (coal, peat, oil shale), liquid (fuel oil) and gaseous (natural gas, and blast-furnace and coke oven gas) in boiler furnaces.

Thermal energy is converted into mechanical energy by the rotation of the turbine, which is converted into electrical energy in a generator connected to the turbine. The generator becomes a source of electricity. Thermal power plants are distinguished by the type of primary engine: steam turbine, steam engine, internal combustion engine, locomobile, gas turbine. In addition, steam turbine power plants are divided into condensing and cogeneration. Condensing stations supply consumers only with electrical energy. The exhaust steam goes through a cooling cycle and, turning into condensate, is again fed into the boiler.

The supply of consumers with thermal and electrical energy is carried out by heating stations, called combined heat and power plants (CHP). At these stations, thermal energy is only partially converted into electrical energy, and is mainly spent on supplying industrial enterprises and other consumers located in the immediate vicinity of power plants with steam and hot water.

Hydroelectric power plants (HPPs) are built on rivers, which are an inexhaustible source of energy for power plants. They flow from highlands to lowlands and are therefore capable of doing mechanical work. Hydroelectric power stations are built on mountain rivers using the natural pressure of water. On flat rivers, the pressure is artificially created by the construction of dams, due to the difference in water levels on both sides of the dam. Hydro turbines are the primary engines in hydroelectric power plants, in which the energy of the water flow is converted into mechanical energy.

Water rotates the impeller of the hydroturbine and the generator, while the mechanical energy of the hydroturbine is converted into electrical energy generated by the generator. The construction of a hydroelectric power station, in addition to the task of generating electricity, also solves a complex of other tasks of national economic importance - improving the navigation of rivers, irrigating and watering arid lands, improving water supply to cities and industrial enterprises.

Nuclear power plants (NPPs) are classified as thermal steam turbine stations that do not operate on fossil fuels, but use as an energy source the heat obtained in the process of nuclear fission of nuclear fuel (fuel) atoms - uranium or plutonium. At nuclear power plants, the role of boiler units is performed by nuclear reactors and steam generators.

Power supply to consumers is carried out mainly from electrical networks that combine a number of power plants. Parallel operation of power plants on a common electrical network provides a rational distribution of the load between power plants, the most economical generation of electricity, better use of the installed capacity of stations, increasing the reliability of power supply to consumers and supplying them with electricity with normal quality indicators in terms of frequency and voltage.

The need for unification is caused by the unequal load of power plants. Consumer demand for electricity changes dramatically not only during the day, but also at different times of the year. In winter, electricity consumption for lighting increases. In agriculture, electricity is needed in large quantities in summer for field work and irrigation.

The difference in the degree of loading of the stations is especially noticeable with a significant distance between the areas of electricity consumption from each other in the direction from east to west, which is explained by the difference in the timing of the onset of hours of morning and evening load maxima. In order to ensure the reliability of power supply to consumers and to make better use of the power of power plants operating in different modes, they are combined into energy or electrical systems using high-voltage electrical networks.

The set of power plants, power lines and heat networks, as well as receivers of electric and heat energy, connected into one whole by the commonality of the regime and the continuity of the process of production and consumption of electric and thermal energy, is called the energy system (energy system). The electrical system, consisting of substations and transmission lines of various voltages, is part of the power system.

The energy systems of individual regions, in turn, are interconnected for parallel operation and form large systems, for example, the unified energy system (UES) of the European part of the USSR, the unified systems of Siberia, Kazakhstan, Central Asia, etc.

Combined heat and power plants and factory power plants are usually connected to the power grid of the nearest power system via generator voltage lines of 6 and 10 kV or higher voltage lines (35 kV and higher) through transformer substations. The transmission of energy generated by powerful regional power plants to the power grid for supplying consumers is carried out via high voltage lines (110 kV and higher).

- Production of electrical energy