in physics

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

11th grade students A

MOU school number 85

Catherine.

Abstract plan.

Introduction.

1. Production of electricity.

1. types of power plants.

2. alternative sources of energy.

2. Power transmission.

transformers.

3. Use of electricity.

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 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.

To date, 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 electricity 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 were predominantly distributed. 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 a 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 with a special heat extraction turbine installed on it with steam extraction. 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, and the other part, which has a high temperature and pressure, is taken from the intermediate stage of the turbine and used for heat supply. The condensate is pumped 7 through the deaerator 8 and then fed by the 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.

Thermal stations with gas turbine(GTPS), steam-gas(PGPP) and diesel plants.

Gas is burned in the combustion chamber of the GTPP or liquid fuel; 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 peak electrical loads. 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 shaft generator.

Modern steam turbines for thermal power plants are very advanced, high-speed, highly economical machines with a long service life. Their power in the warhead 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 gradually decrease.

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 with the hot waste 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 the 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.

Napor HPP is created by the concentration of the fall of the river in the used area by the dam, or derivation, or dam and derivation together. The main power equipment of the hydroelectric power station is located in the building of the hydroelectric power station: 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. Switchgears 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. At the building of the HPP or inside it, an assembly site is created for the assembly and repair of various equipment and for auxiliary maintenance operations of the HPP.

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 upper and lower pool ), 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 rate 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(more than 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 for the use of water resources and the concentration of pressure, HPPs are usually divided into channel, near-dam, diversion pump and non-pressure diversion, mixed, pumped storage And tidal.

In channel and dam hydroelectric power plants, the pressure of water 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 HPPs 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 the hydrostatic water pressure to the HPP building. In this case, the type dam The hydroelectric power station, in which the pressure front is blocked by a dam throughout, the building of the hydroelectric power station is located behind the dam, adjacent to the downstream.

Other kind of layout near the dam The hydroelectric power station corresponds to mountainous conditions with relatively low river flows.

IN derivational Hydroelectric concentration of the fall of the river is created by means of 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 PSP to accumulate energy is based on the fact that the free electric energy in the power system in a certain period of time is used by the PSP units, which, operating in the 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 basin enters the pressure pipeline and rotates the hydraulic units operating in the current generator mode).

PES convert the energy of sea tides into electrical energy. The electric power of tidal hydropower plants, due to some features associated with the periodic nature of the tides, can be used in power systems only 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 compared to fuel and energy resources is their continuous renewal. Therefore, the construction of hydroelectric power stations, despite the significant, specific capital investments per 1 kW installed capacity and long construction periods have been and are 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 fission of the nuclei 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(mainly 233U, 235U, 239Pu). 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 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 production, there is a tendency in the world to a 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.

A schematic diagram of a nuclear power plant with a water-cooled nuclear reactor 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. The 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 circulation of the circuit, devices for reloading nuclear fuel, systems of special ventilation, emergency cooling, etc.

To protect nuclear power plant 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 vapors, due to the presence of leaks from the circuit, are removed from the unattended premises of the NPP by a special ventilation system, in which, to exclude the possibility of atmospheric pollution, purification filters and holding gas holders are provided. The dosimetric control service monitors the compliance with the radiation safety rules by the NPP personnel.

Availability of biological shielding, special ventilation and emergency cooling systems, and dosimetric control service makes it possible to completely protect NPP maintenance personnel from the harmful effects of radioactive exposure.

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 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 almost equal to the capacity of an average hydroelectric power station, however, the installed capacity utilization factor at nuclear power plants (80%) significantly exceeds this indicator at hydroelectric power plants or thermal power plants.

There are practically no significant shortcomings of nuclear power plants under normal operating conditions. However, it is impossible not to notice the danger of nuclear power plants in case of 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 sources of energy.

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 pilot plants and stations will help to solve not only technical, but also economic problems.

Wind energy.

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

Today, wind-powered engines cover only one thousandth of the world's energy needs. Therefore, aircraft builders who are able to choose the most appropriate blade profile and explore it in a wind tunnel are involved in the creation of wind wheel structures - 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.

Earth energy.

Since ancient times, people have known about the elemental manifestations of the gigantic energy lurking in the sub-earth globe. The memory of mankind keeps legends about catastrophic volcanic eruptions that claimed millions human lives that unrecognizably changed the appearance of many places on Earth. 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, 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 sources 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.

Power transmission.

Transformers.

You have purchased a ZIL refrigerator. The seller warned you that the refrigerator is designed for a mains voltage of 220 V. Do you have a mains voltage of 127 V in your house. Not at all. You just have to make an additional cost and purchase a transformer.

Transformer- a very simple device that allows you to both increase and decrease the voltage. AC conversion is carried out with the help of transformers. For the first time, transformers were used in 1878 by the Russian martyr 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 winding, 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.

Fig.1 Fig.2

The diagram of the device of a transformer with two windings is shown in Figure 2, and the conventional designation adopted for it is in Figure. 3.

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 eV 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= Ф0сosωt, then

e = ω Ф0sinω t, or

e =Esinω t,

Where E\u003d ω Ф0 - the amplitude of the EMF in one turn.

In the primary winding having n1 turns, total induction emf e1 is equal to p1e.

In the secondary winding, there is a total emf. e2 is equal to p2e, Where p2 is the number of turns of this winding.

Hence it follows that

e1 e2 = p1p2. (1)

Amount of voltage u1 , applied to the primary winding, and the EMF e1 should be equal to the voltage drop in the primary winding:

u1 + e1 = i1 R1 , Where R1 is the active resistance of the winding, and i1 is the current in it. This equation follows directly from the general equation. Usually the active resistance of the winding is small and the term i1 R1 can be neglected. That's why

u1 ≈ -e1 . (2)

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

u2 ≈ - e2 . (3)

Since the instantaneous values ​​of the EMF e1 And e2 change in phase, then their ratio in formula (1) can be replaced by the ratio of effective values E1 AndE2 these EMFs or, taking into account equalities (2) and (3), the ratio of the effective values ​​of the voltages U 1 and U 2 .

U 1 /U 2 = E1 / E2 = n1 / n2 = 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 u2 ≈ - e2 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 I1 = U 2 I2, (5)

Where I1 And I2 - the effective values ​​of the force in the primary and secondary windings.

Hence it follows that

U 1 /U 2 = I1 / I2 . (6)

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

Due to the inevitable energy losses due to 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, apart from 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, having previously turned the battery’s direct current into alternating current using a breaker. It is easy to figure that, up to the loss of energy used to heat the transformer, the current decreases with increasing voltage, 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 when converting voltage. In a sheet material, eddy currents will play a lesser role than in a continuous one.

At home you deal 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.

Power transmission

Electricity consumers are everywhere. It is produced in relatively few places close to sources of fuel and water resources. Therefore, there is a need 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 economically 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 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 losses are small.

For the direct use of electricity in the motors of the electric drive of machine tools, 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, the territory covered by the electrical network is getting wider. The scheme of transmission and distribution of electricity is shown in the figure.

Electric 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.

Use of electricity.

The use of electric power in various fields of science.

The twentieth century has become a century when science invades all spheres of society: economics, 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 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.

Most of the scientific developments begin with theoretical calculations. But if in the nineteenth century these calculations were made using pen and paper, then in the age of scientific and technological 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) that work on electrical energy, the most convenient for its transmission over a distance and use. But if computers were originally used for scientific calculations, now computers have come to life from science.

Now they are used in all spheres of human activity: for recording and storing information, creating archives, preparing and editing texts, performing drawing and graphic works, 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 of the microprocessor in 1971 - a microelectronic logic device built into various devices to control their operation.

Microprocessors 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. Arobots - "intellectuals" of the third generation will "see", "feel", "hear". Scientists and engineers among the most priority areas of application of robots name nuclear energy, space exploration, transport, trade, warehousing, medical care, waste processing, development of the wealth of the ocean floor. 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 more efficient methods and new energy-saving technological processes.

But let's get back to science. All new theoretical developments are verified experimentally after calculations on a computer. And, as a rule, at this stage, research is carried out with the help of physical measurements, chemical analyzes, etc. Here, the instruments of scientific research are diverse - numerous measuring instruments, accelerators, electron microscopes, magnetic resonance tomographs, etc. The main part of these experimental science instruments operate on electric 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 has not bypassed the sphere of management. With the development of scientific and technical revolutions, the expansion of production and non-production spheres of human activity, management begins to play an increasingly important role in improving their efficiency. From a kind of art, until recently based on experience and intuition, today management has turned into a science. The science of management, of the general laws of receipt, storage, transmission and processing of 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 gigantically increased flows of information, the energy source 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 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 society of an industrial type. 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;

· the 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 runs on electric energy. High electricity consumption is typical for such energy-intensive industries as metallurgy, aluminum and machine building industries.

Household electricity.

Electricity is an indispensable assistant in everyday life. Every day we deal with it, and, probably, we cannot 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 need light, you need a TV, kettles 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 lives can be a whole poem, it is so important in our lives and we are so used to it. Although we no longer notice that it comes to our homes, but when it is turned off, it becomes very uncomfortable.

Appreciate the 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. Ellion L., Wilkons U ... Physics. Moscow: Nauka.

4. KoltunM. The world of physics. Moscow.

5. Sources of energy. Facts, problems, solutions. Moscow: Science and technology.

6. Non-traditional sources of energy. Moscow: Knowledge.

7. Yudasin L.S. Energy: problems and hopes. Moscow: Enlightenment.

8. Podgorny A.N. Hydrogen energy. Moscow: Nauka.

« Physics - Grade 11 "

Power generation

Electricity is produced at power stations mainly with the help of electromechanical induction generators.
There are two main types of power plants: thermal and hydroelectric.
These power plants differ in engines that rotate the rotors of generators.

At thermal power plants, the source of energy is fuel: coal, gas, oil, fuel oil, oil shale.
The rotors of electric generators are driven by steam and gas turbines or internal combustion engines.

Thermal steam turbine power plants - TPPs the most economical.

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.
Steam turbine generators are very fast: the number of revolutions of the rotor is several thousand per minute.

The efficiency of heat engines increases with an increase in the initial temperature of the working fluid (steam, gas).
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.

Thermal power plants - CHP allow a significant part of the energy of the exhaust steam to be used in industrial enterprises and for domestic needs.
As a result, the CHP efficiency reaches 60-70%.
In Russia, thermal power plants provide about 40% of all electricity and supply hundreds of cities with electricity.

On hydroelectric power plants - HPPs the potential energy of water is used to rotate the rotors of the generators.

The rotors of electric generators are driven by hydraulic turbines.
The power of such a station depends on the pressure created by the dam and the mass of water passing through the turbine every second.

Hydroelectric power plants provide about 20% of all electricity generated in our country.

Nuclear power plants - nuclear power plants in Russia they provide about 10% of electricity.

Electricity use

The main consumer of electricity is industry - 70% of the electricity produced.
Transport is also a major consumer.

Most of the electricity used is now converted into mechanical energy, because. almost all mechanisms in industry are driven by electric motors.

Electricity transmission

Electricity cannot be conserved on a large scale.
It must be consumed immediately upon receipt.
Therefore, there is a need to transmit electricity over long distances.

The transmission of electricity is associated with noticeable losses, since the electric current heats the wires of power lines. In accordance with the Joule-Lenz law, the energy spent on heating the wires of the line is determined by the formula

Where
R- line resistance,
U- transmitted voltage,
R- power of the current source.

With very long lines, power transmission can become uneconomical.
It is practically very difficult to significantly reduce the resistance of the line R, therefore, it is necessary to reduce the current strength I.

Since the power of the current source P is equal to the product of the current I and the voltage U, in order to reduce the transmitted power, it is necessary to increase the transmitted voltage in the transmission line.

For this, step-up transformers are installed at large power plants.
The transformer increases the voltage in the line as many times as it reduces the current.

The longer the transmission line, the more advantageous it is to use a higher voltage. Alternating current generators are tuned to voltages not exceeding 16-20 kV. Higher voltage would require complex special measures to isolate the windings and other parts of the generators.

This is achieved using step-down transformers.

The decrease in voltage (and, accordingly, the increase in current strength) is carried out in stages.

At very high voltage between the wires, a discharge can begin, leading to energy losses.
The permissible amplitude of the alternating voltage must be such that, for a given cross-sectional area of ​​the wire, the energy loss due to the discharge is negligible.

Power stations are connected by high-voltage transmission lines, forming a common electrical network to which consumers are connected.
Such an association, called a power system, makes it possible to distribute the loads of energy consumption.
The power system ensures uninterrupted power supply to consumers.
Now the Unified Energy System of the European part of the country is operating in our country.

Electricity use

The need for electricity is constantly increasing both in industry, in transport, in scientific institutions, and in everyday life. This need can be met in two main ways.

The first is the construction of new powerful power plants: thermal, hydraulic and nuclear.
However, the construction of a large power plant requires several years and high costs.
In addition, thermal power plants consume non-renewable natural resources: coal, oil and gas.
At the same time, they cause great damage to the balance on our planet.
Advanced technology makes it possible to meet energy needs in a different way.

The second is the efficient use of electricity: modern fluorescent lamps, lighting savings.

Great hopes are placed on obtaining energy by means of controlled thermonuclear reactions.

Priority should be given to increasing the efficiency of electricity use, rather than increasing the capacity of power plants.

I Introduction
II Production and use of electricity
1. Power generation
1.1 Generator
2. Electricity use
III Transformers
1. Appointment
2. Classification
3. Device
4. Characteristics
5. Modes
5.1 Idling
5.2 Short circuit mode
5.3 Load mode
IV Power transmission
V GOELRO
1. History
2. Results
VI List of references

I Introduction

Electricity, one of the most important types of energy, plays a huge role in the modern world. It is the core of the economies of states, determining their position in the international arena and the level of development. Huge sums of money are invested annually in the development of scientific industries related to electricity.
Electricity is an integral part of everyday life, so it is important to have information about the features of its production and use.

II. Production and use of electricity

1. Power generation

Electricity generation is the production of electricity by converting it from other types of energy using special technical devices.
To generate electricity use:
Electric generator - an electrical machine in which mechanical work is converted into electrical energy.
A solar battery or photocell is an electronic device that converts the energy of electromagnetic radiation, mainly in the light range, into electrical energy.
Chemical current sources - the conversion of part of chemical energy into electrical energy, through a chemical reaction.
Radioisotope sources of electricity are devices that use the energy released during radioactive decay to heat the coolant or convert it into electricity.
Electricity is generated at power plants: thermal, hydraulic, nuclear, solar, geothermal, wind and others.
Practically at all power plants of industrial importance, the following scheme is used: the energy of the primary energy carrier with the help of a special device is first converted into mechanical energy of rotational motion, which is transferred to a special electrical machine - a generator, where electric current is generated.
The main three types of power plants: thermal power plants, hydroelectric power plants, nuclear power plants
The leading role in the electric power industry of many countries is played by thermal power plants (TPPs).
Thermal power plants require a huge amount of fossil fuel, while its reserves are declining, and the cost is constantly increasing due to increasingly difficult conditions for extraction and transportation distances. The fuel utilization factor in them is quite low (no more than 40%), and the volumes of waste polluting the environment are large.
Economic, technical, economic and environmental factors do not allow us to consider thermal power plants as a promising way to generate electricity.
Hydropower plants (HPP) are the most economical. Their efficiency reaches 93%, and the cost of one kWh is 5 times cheaper than with other methods of generating electricity. They use an inexhaustible source of energy, are serviced by a minimum number of workers, and are well regulated. Our country occupies a leading position in the world in terms of the size and capacity of individual hydroelectric stations and units.
But the pace of development is hindered by significant costs and construction time, due to the remoteness of HPP construction sites from large cities, the lack of roads, difficult construction conditions, are affected by the seasonality of the river regime, large areas of valuable riverine lands are flooded by reservoirs, large reservoirs negatively affect the environmental situation, powerful HPPs can only be built where the corresponding resources are available.
Nuclear power plants (NPPs) operate on the same principle as thermal power plants, i.e., the thermal energy of steam is converted into mechanical energy of rotation of the turbine shaft, which drives a generator, where mechanical energy is converted into electrical energy.
The main advantage of nuclear power plants is the small amount of fuel used (1 kg of enriched uranium replaces 2.5 thousand tons of coal), as a result of which nuclear power plants can be built in any energy-deficient areas. In addition, the reserves of uranium on Earth exceed the reserves of traditional mineral fuel, and with trouble-free operation of nuclear power plants, they have little impact on the environment.
The main disadvantage of nuclear power plants is the possibility of accidents with catastrophic consequences, the prevention of which requires serious safety measures. In addition, nuclear power plants are poorly regulated (it takes several weeks to completely stop or turn them on), and technologies for processing radioactive waste have not been developed.
Nuclear power has grown into one of the leading sectors of the national economy and continues to develop rapidly, ensuring safety and environmental friendliness.

1.1 Generator

An electric generator is a device in which non-electrical forms of energy (mechanical, chemical, thermal) are converted into electrical energy.
The principle of operation of the generator is based on the phenomenon of electromagnetic induction, when an EMF is induced in a conductor moving in a magnetic field and crossing its magnetic lines of force. Therefore, such a conductor can be considered by us as a source of electrical energy.
The method of obtaining an induced emf, in which the conductor moves in a magnetic field, moving up or down, is very inconvenient in its practical use. Therefore, generators use not rectilinear, but rotational movement of the conductor.
The main parts of any generator are: a system of magnets or, most often, electromagnets that create a magnetic field, and a system of conductors that cross this magnetic field.
An alternator is an electrical machine that converts mechanical energy into AC electrical energy. Most alternators use a rotating magnetic field.

When the frame rotates, the magnetic flux through it changes, so an EMF is induced in it. Since the frame is connected to an external electrical circuit with the help of a current collector (rings and brushes), an electric current arises in the frame and the external circuit.
With uniform rotation of the frame, the angle of rotation changes according to the law:

The magnetic flux through the frame also changes over time, its dependence is determined by the function:

Where S− frame area.
According to Faraday's law of electromagnetic induction, the EMF of induction that occurs in the frame is:

where is the amplitude of the EMF of induction.
Another value that characterizes the generator is the current strength, expressed by the formula:

Where i is the current strength at any given time, I m- the amplitude of the current strength (the maximum value of the current strength in absolute value), φ c- phase shift between fluctuations in current and voltage.
The electrical voltage at the generator terminals varies according to a sinusoidal or cosine law:

Almost all generators installed in our power plants are three-phase current generators. In essence, each such generator is a connection in one electric machine of three alternating current generators, designed in such a way that the EMF induced in them are shifted relative to each other by one third of the period:

2. Electricity use

Power supply of industrial enterprises. Industrial enterprises consume 30-70% of the electricity generated as part of the electric power system. A significant variation in industrial consumption is determined by the industrial development and climatic conditions of various countries.
Power supply of electrified transport. DC electric transport rectifier substations (urban, industrial, intercity) and step-down substations of long-distance electric transport on alternating current are powered by electricity from the electrical networks of the EPS.
Power supply of household consumers. This group of PE includes a wide range of buildings located in residential areas of cities and towns. These are residential buildings, buildings for administrative and managerial purposes, educational and scientific institutions, shops, buildings for health care, cultural purposes, public catering, etc.

III. transformers

Transformer - a static electromagnetic device having two or more inductively coupled windings and designed to convert one (primary) alternating current system into another (secondary) alternating current system by means of electromagnetic induction.

Transformer device diagram

1 - primary winding of the transformer
2 - magnetic circuit
3 - secondary winding of the transformer
F- direction of magnetic flux
U 1- voltage on the primary winding
U 2- voltage on the secondary winding

The first transformers with an open magnetic circuit were proposed in 1876 by P.N. Yablochkov, who used them to power an electric "candle". In 1885, the Hungarian scientists M. Deri, O. Blaty, K. Zipernovsky developed single-phase industrial transformers with a closed magnetic circuit. In 1889-1891. M.O. Dolivo-Dobrovolsky proposed a three-phase transformer.

1. Appointment

Transformers are widely used in various fields:
For transmission and distribution of electrical energy
Typically, at power plants, alternating current generators generate electrical energy at a voltage of 6-24 kV, and it is profitable to transmit electricity over long distances at much higher voltages (110, 220, 330, 400, 500, and 750 kV). Therefore, at each power plant, transformers are installed that increase the voltage.
The distribution of electrical energy between industrial enterprises, settlements, in cities and rural areas, as well as within industrial enterprises, is carried out via overhead and cable lines, at a voltage of 220, 110, 35, 20, 10 and 6 kV. Therefore, transformers must be installed in all distribution nodes that reduce the voltage to 220, 380 and 660 V.
To provide the desired circuit for switching on valves in converter devices and to match the voltage at the output and input of the converter (converter transformers).
For various technological purposes: welding (welding transformers), power supply of electrothermal installations (electric furnace transformers), etc.
For powering various circuits of radio equipment, electronic equipment, communication and automation devices, household appliances, for separating electrical circuits of various elements of these devices, for matching voltage, etc.
To include electrical measuring instruments and some devices (relays, etc.) in high voltage electrical circuits or in circuits through which large currents pass, in order to expand the measurement limits and ensure electrical safety. (measuring transformers)

2. Classification

Transformer classification:

• By appointment: general power (used in power transmission and distribution lines) and special applications (furnace, rectifier, welding, radio transformers).
• By type of cooling: with air (dry transformers) and oil (oil transformers) cooling.
• According to the number of phases on the primary side: single-phase and three-phase.
• According to the shape of the magnetic circuit: rod, armored, toroidal.
• By the number of windings per phase: two-winding, three-winding, multi-winding (more than three windings).
• According to the design of the windings: with concentric and alternating (disk) windings.

3. Device

The simplest transformer (single-phase transformer) is a device consisting of a steel core and two windings.

The principle of the device of a single-phase two-winding transformer
The magnetic core is the magnetic system of the transformer, through which the main magnetic flux closes.
When an alternating voltage is applied to the primary winding, an EMF of the same frequency is induced in the secondary winding. If an electrical receiver is connected to the secondary winding, then an electric current arises in it and a voltage is established at the secondary terminals of the transformer, which is somewhat less than the EMF and to some relatively small extent depends on the load.

Symbol of the transformer:
a) - a transformer with a steel core, b) - a transformer with a ferrite core

4. Characteristics of the transformer

• The rated power of a transformer is the power for which it is designed.
• Rated primary voltage - the voltage for which the primary winding of the transformer is designed.
• Rated secondary voltage - the voltage at the terminals of the secondary winding, obtained when the transformer is idling and the rated voltage at the terminals of the primary winding.
• Rated currents are determined by the respective power and voltage ratings.
• The highest rated voltage of the transformer is the highest of the rated voltages of the transformer windings.
• The lowest rated voltage is the smallest of the rated voltages of the transformer windings.
• Average rated voltage - rated voltage, which is intermediate between the highest and lowest rated voltage of the transformer windings.

5. Modes

5.1 Idling

Idle mode - the mode of operation of the transformer, in which the secondary winding of the transformer is open, and alternating voltage is applied to the terminals of the primary winding.

A current flows in the primary winding of a transformer connected to an alternating current source, as a result of which an alternating magnetic flux appears in the core Φ penetrating both windings. Since Φ is the same in both windings of the transformer, the change Φ leads to the appearance of the same induction EMF in each turn of the primary and secondary windings. Instantaneous value of induction emf e in any turn of the windings is the same and is determined by the formula:

where is the amplitude of the EMF in one turn.
The amplitude of the induction EMF in the primary and secondary windings will be proportional to the number of turns in the corresponding winding:

Where N 1 And N 2- the number of turns in them.
The voltage drop across the primary winding, like across a resistor, is very small compared to ε 1, and therefore for the effective values ​​of the voltage in the primary U 1 and secondary U 2 windings, the following expression will be true:

K- transformation ratio. At K>1 step-down transformer, and when K<1 - повышающий.

5.2 Short circuit mode

Short circuit mode - a mode when the outputs of the secondary winding are closed by a current conductor with a resistance equal to zero ( Z=0).

A short circuit of the transformer under operating conditions creates an emergency mode, since the secondary current, and therefore the primary one, increases several tens of times compared to the nominal one. Therefore, in circuits with transformers, protection is provided that, in the event of a short circuit, automatically turns off the transformer.

Two modes of short circuit must be distinguished:

Emergency mode - when the secondary winding is closed at the rated primary voltage. With such a circuit, the currents increase by a factor of 15–20. The winding is deformed, and the insulation is charred. Iron also burns. This is hard mode. Maximum and gas protection disconnects the transformer from the network in case of an emergency short circuit.

An experimental short circuit mode is a mode when the secondary winding is short-circuited, and such a reduced voltage is supplied to the primary winding, when the rated current flows through the windings - this is U K- short circuit voltage.

Under laboratory conditions, a test short circuit of the transformer can be carried out. In this case, expressed as a percentage, the voltage U K, at I 1 \u003d I 1nom designate u K and is called the short circuit voltage of the transformer:

Where U 1nom- rated primary voltage.

This is the characteristic of the transformer, indicated in the passport.

5.3 Load mode

The load mode of the transformer is the mode of operation of the transformer in the presence of currents in at least two of its main windings, each of which is closed to an external circuit, while currents flowing in two or more windings in idle mode are not taken into account:

If a voltage is connected to the primary winding of the transformer U 1, and connect the secondary winding to the load, currents will appear in the windings I 1 And I 2. These currents will create magnetic fluxes Φ 1 And Φ2 directed towards each other. The total magnetic flux in the magnetic circuit decreases. As a result, the EMF induced by the total flow ε 1 And ε 2 decrease. RMS voltage U 1 remains unchanged. Decrease ε 1 causes an increase in current I 1:

With increasing current I 1 flow Φ 1 increases just enough to compensate for the demagnetizing effect of the flux Φ2. Equilibrium is restored again at practically the same value of the total flow.

IV. Electricity transmission

The transmission of electricity from the power plant to consumers is one of the most important tasks of the energy industry.
Electricity is transmitted predominantly via AC overhead transmission lines (TL), although there is a trend towards an increasing use of cable lines and DC lines.

The need to transmit electricity over a distance is due to the fact that electricity is generated by large power plants with powerful units, and is consumed by relatively low-power power consumers distributed over a large area. The trend towards the concentration of generating capacities is explained by the fact that with their growth, the relative costs for the construction of power plants decrease and the cost of generated electricity decreases.
The placement of powerful power plants is carried out taking into account a number of factors, such as the availability of energy resources, their type, reserves and transportation possibilities, natural conditions, the ability to work as part of a single energy system, etc. Often, such power plants turn out to be significantly remote from the main centers of electricity consumption. The operation of unified electric power systems covering vast territories depends on the efficiency of electric power transmission over a distance.
It is necessary to transfer electricity from the places of its production to consumers with minimal losses. The main reason for these losses is the conversion of part of the electricity into the internal energy of the wires, their heating.

According to the Joule-Lenz law, the amount of heat Q, released during the time t in the conductor by resistance R during the passage of current I, equals:

It follows from the formula that in order to reduce the heating of the wires, it is necessary to reduce the current strength in them and their resistance. To reduce the resistance of the wires, increase their diameter, however, very thick wires hanging between power line supports can break under the action of gravity, especially during snowfall. In addition, with an increase in the thickness of the wires, their cost increases, and they are made of a relatively expensive metal - copper. Therefore, a more effective way to minimize energy losses in the transmission of electricity is to reduce the current strength in the wires.
Thus, in order to reduce the heating of wires when transmitting electricity over long distances, it is necessary to make the current in them as small as possible.
The current power is equal to the product of the current strength and voltage:

Therefore, in order to save power transmitted over long distances, it is necessary to increase the voltage by the same amount as the current strength in the wires was reduced:

From the formula it follows that at constant values ​​of the transmitted power of the current and the resistance of the wires, the heating losses in the wires are inversely proportional to the square of the voltage in the network. Therefore, to transmit electricity over distances of several hundred kilometers, high-voltage power lines (TL) are used, the voltage between the wires of which is tens, and sometimes hundreds of thousands of volts.
With the help of power lines, neighboring power plants are combined into a single network, called the power system. The Unified Energy System of Russia includes a huge number of power plants controlled from a single center and provides uninterrupted power supply to consumers.

V. GOELRO

1. History

GOELRO (State Commission for the Electrification of Russia) is a body created on February 21, 1920 to develop a project for the electrification of Russia after the October Revolution of 1917.

More than 200 scientists and technicians were involved in the work of the commission. G.M. headed the commission. Krzhizhanovsky. The Central Committee of the Communist Party and personally V. I. Lenin daily directed the work of the GOELRO commission, determined the main fundamental provisions of the country's electrification plan.

By the end of 1920, the commission had done an enormous amount of work and prepared the Plan for the Electrification of the RSFSR, a volume of 650 pages of text with maps and schemes for the electrification of regions.
The GOELRO plan, designed for 10-15 years, implemented Lenin's ideas of electrifying the entire country and creating a large industry.
In the field of electric power economy, the plan consisted of a program designed for the restoration and reconstruction of the pre-war electric power industry, the construction of 30 regional power stations, and the construction of powerful regional thermal power plants. It was planned to equip the power plants with large boilers and turbines for that time.
One of the main ideas of the plan was the widespread use of the country's vast hydropower resources. Provision was made for a radical reconstruction on the basis of the electrification of all branches of the national economy of the country, and primarily for the growth of heavy industry, and the rational distribution of industry throughout the country.
The implementation of the GOELRO plan began in the difficult conditions of the Civil War and economic devastation.

Since 1947, the USSR has been ranked first in Europe and second in the world in terms of electricity production.

The GOELRO plan played a huge role in the life of our country: without it, it would not have been possible to bring the USSR into the ranks of the most industrially developed countries in the world in such a short time. The implementation of this plan shaped the entire domestic economy and still largely determines it.

The drafting and implementation of the GOELRO plan became possible and solely due to a combination of many objective and subjective factors: the considerable industrial and economic potential of pre-revolutionary Russia, the high level of the Russian scientific and technical school, the concentration of all economic and political power, its strength and will, and also the traditional conciliar-communal mentality of the people and their obedient and trusting attitude towards the supreme rulers.
The GOELRO plan and its implementation proved the high efficiency of the state planning system under conditions of rigidly centralized power and predetermined the development of this system for many decades to come.

2. Results

By the end of 1935, the electrical construction program had been overfulfilled by several times.

Instead of 30, 40 regional power plants were built, at which, together with other large industrial stations, 6,914 thousand kW of capacity were commissioned (of which 4,540 thousand kW were regional, almost three times more than according to the GOELRO plan).
In 1935, there were 13 power plants of 100,000 kW among the regional power plants.

Before the revolution, the capacity of the largest power plant in Russia (1st Moscow) was only 75 thousand kW; there was not a single large hydroelectric power station. By the beginning of 1935, the total installed capacity of hydroelectric power stations had reached almost 700,000 kW.
The largest at that time in the world, the Dnieper hydroelectric power station, Svirskaya 3rd, Volkhovskaya, etc. were built. At the highest point of its development, the Unified Energy System of the USSR in many respects surpassed the energy systems of the developed countries of Europe and America.

Electricity was practically unknown in the villages before the revolution. Large landowners installed small power plants, but their numbers were few.

Electricity began to be used in agriculture: in mills, fodder cutters, grain cleaning machines, and sawmills; in industry, and later - in everyday life.

List of used literature

Venikov V. A., Long-distance power transmission, M.-L., 1960;
Sovalov S. A., Power transmission modes 400-500 kv. EES, M., 1967;
Bessonov, L.A. Theoretical foundations of electrical engineering. Electric circuits: textbook / L.A. Bessonov. - 10th ed. — M.: Gardariki, 2002.
Electrical engineering: Educational and methodical complex. /AND. M. Kogol, G. P. Dubovitsky, V. N. Borodianko, V. S. Gun, N. V. Klinachev, V. V. Krymsky, A. Ya. Ergard, V. A. Yakovlev; Edited by N.V. Klinacheva. - Chelyabinsk, 2006-2008.
Electrical systems, v. 3 - Power transmission by alternating and direct current of high voltage, M., 1972.

Sorry, nothing was found.

Electrical energy is produced at various scales of 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. IN 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 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 method requires the expenditure of a large number of 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.

ELECTRODYNAMICS

The phenomenon of electromagnetic induction is the occurrence of electric current in a closed circuit when any change in magnetic flux through the surface bounded by this contour.

Alternating current- it is an electric current whose strength varies in some way with time.

Transformer- is a device for stepping up or stepping down an alternating voltage.

1. Production:

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.

2. Transfer:

A transformer is a device that allows you to both increase and decrease voltage. AC conversion is carried out using transformers. The transformer consists of a closed iron core, on which two (sometimes more) coils with wire windings are put on. 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.

3. Consumption:

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 also 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. 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 the city.

Problems of power saving. Russia has huge prospects for energy saving and at the same time is one of the most wasteful countries in the world. Energy saving directly depends on the rational use of existing energy resources. Huge energy losses are characteristic of housing and communal services. According to experts, about 70% of heat loss occurs due to the negligent attitude of consumers. Batteries without power regulation are often installed in apartments, as a result of which they work at full capacity and residents have to open windows to reduce the temperature in the room. In order to realize the energy saving potential in the housing and communal services, it is planned to introduce widespread introduction of metering devices, move to mandatory energy efficiency standards for new and reconstructed buildings, modernize the heat supply systems of buildings and structures, introduce energy-saving lighting systems, introduce energy-saving devices and technologies at boiler houses, sewage treatment plants, water utility enterprises, granting budgetary organizations the right to dispose of funds saved as a result of the implementation of energy saving projects for up to 5 years, and more.

Safety precautions in handling electric current. A current from 25 V is considered dangerous for a person. In this situation, it is necessary to clearly distinguish between voltage and current strength. It's the last one that kills. For example: blue sparks of static discharges have a voltage of 7000 V, but negligible power, while the voltage of an outlet of 220 V, but with a current of 10-16 A, can cause death. Moreover, the passage of a current with a force of 30-50 mA through the heart muscle can already cause fibrillation (flutter) of the heart muscle and reflex cardiac arrest. How this will end is quite clear. If the current does not touch the heart (and the paths of electricity in the human body are very bizarre), then its effect can cause paralysis of the respiratory muscles, which also does not bode well.

Electromagnetic field and electromagnetic waves.Electromagnetic field- a special form of matter, through which the interaction between electrically charged particles is carried out.

electromagnetic wave- the process of electromagnetic field propagation in space.

Velocity of electromagnetic waves. Wavelength is the quotient of speed divided by frequency.

Principles of radio communication. The principles of radio communication are as follows. An alternating high-frequency electric current created in a transmitting antenna causes a rapidly changing electromagnetic field in the surrounding space, which propagates in the form of an electromagnetic wave. Reaching the receiving antenna, an electromagnetic wave induces an alternating current in it of the same frequency at which the transmitter operates.