Production, transmission and use of electricity. Production, transmission and distribution of electrical energy

Types of power plants Thermal (TPP) - 50% Thermal (TPP) - 50% Hydroelectric power station (HPP) % Hydroelectric power station (HPP) % Nuclear (NPP) - 15% Nuclear (NPP) - 15% Alternative sources Alternative energy sources - 2 – 5% (solar energy, fusion energy, tidal energy, wind energy) energy - 2 – 5% (solar energy, fusion energy, tidal energy, wind energy)

Electric current generator The generator converts mechanical energy into electrical energy The generator converts mechanical energy into electrical energy The generator action is based on the phenomenon of electromagnetic induction The generator action is based on the electromagnetic induction phenomenon

The frame with current is the main element of the generator. The rotating part is called ROTOR (magnet). The rotating part is called ROTOR (magnet). The stationary part is called the STATOR (frame) The stationary part is called the STATOR (frame) When the frame rotates, the magnetic flux penetrating the frame changes in time, as a result of which an induced current appears in the frame

Electricity transmission Power transmission lines (PTL) are used to transmit electricity to consumers. When transmitting electricity over a distance, losses occur due to heating of the wires (Joule-Lenz law). Ways to reduce heat loss: 1) Reduce the resistance of the wires, but increase their diameter (heavy - difficult to hang, and expensive - copper). 2) Reducing the current by increasing the voltage.

The impact of thermal power plants on the environment TPPs lead to thermal air pollution with fuel combustion products. Hydroelectric power stations lead to flooding of vast territories that are taken out of land use. Nuclear power plant - can lead to the release of radioactive substances.

The main stages of production, transmission and consumption of electricity 1.Mechanical energy is converted into electrical energy using generators at power plants. 1.Mechanical energy is converted into electrical energy using generators in power plants. 2. Electrical voltage is increased to transmit electricity over long distances. 2. Electrical voltage is increased to transmit electricity over long distances. 3. Electricity is transmitted at high voltage through high-voltage power lines. 3. Electricity is transmitted at high voltage through high-voltage power lines. 4. When distributing electricity to consumers, the electrical voltage is reduced. 4. When distributing electricity to consumers, the electrical voltage is reduced. 5. When electricity is consumed, it is converted into other types of energy - mechanical, light or internal. 5. When electricity is consumed, it is converted into other types of energy - mechanical, light or internal.

I Introduction
II Electricity production and use
1. Electricity generation
1.1 Generator
2. Electricity use
III Transformers
1. Purpose
2. Classification
3. Device
4. Characteristics
5. Modes
5.1 Idling
5.2 Short circuit mode
5.3 Load mode
IV Electricity 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 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. Electricity production and use

1. Electricity generation

Electricity generation is the production of electricity by converting it from other types of energy using special technical devices.
To generate electricity use:
An electric generator is 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 a coolant or convert it into electricity.
Electricity is generated at power plants: thermal, hydraulic, nuclear, solar, geothermal, wind and others.
Almost all power plants of industrial importance use the following scheme: the energy of the primary energy carrier, using 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 plant, hydroelectric power station, nuclear power plant
Thermal power plants (TPPs) play a leading role in the electric power industry of many countries.
Thermal power plants require huge amounts of organic fuel, but its reserves are decreasing, and the cost is constantly increasing due to increasingly complex production conditions and transportation distances. Their fuel utilization rate is quite low (no more than 40%), and the volume of waste that pollutes the environment is large.
Economic, technical, economic and environmental factors do not allow thermal power plants to be considered a promising way to generate electricity.
Hydroelectric power plants (HPP) are the most economical. Their efficiency reaches 93%, and the cost of one kWh is 5 times cheaper than other methods of generating electricity. They use an inexhaustible source of energy, are serviced by a minimum number of workers, and are well regulated. In terms of the size and power of individual hydroelectric power stations and units, our country occupies a leading position in the world.
But the pace of development is hampered by significant costs and construction time due to the remoteness of hydroelectric power station construction sites from large cities, lack of roads, difficult construction conditions, subject to the influence of seasonality of river regimes, large areas of valuable riverine lands are flooded by reservoirs, large reservoirs negatively impact the environmental situation, powerful hydroelectric power stations can only be built in places where appropriate 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 the 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 during 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 shut them down or start them up), and technologies for processing radioactive waste have not been developed.
Nuclear energy has grown into one of the leading sectors of the national economy and continues to develop rapidly, ensuring safety and environmental cleanliness.

1.1 Generator

An electric generator is a device in which non-electrical types 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 induced EMF, in which the conductor moves in a magnetic field, moving up or down, is very inconvenient for practical use. Therefore, generators use not linear, 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 alternating current 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 using 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 induced emf arising in the frame is equal to:

where is the amplitude of the induced emf.
Another quantity that characterizes the generator is the current strength, expressed by the formula:

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

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

2. Electricity use

Power supply for industrial enterprises. Industrial enterprises consume 30-70% of the electricity generated as part of the electrical power system. The significant variation in industrial consumption is determined by the industrial development and climatic conditions of different countries.
Power supply for electrified transport. Rectifier substations of electric transport on direct current (urban, industrial, intercity) and step-down substations of intercity electric transport on alternating current are supplied with electricity from the electrical networks of the EPS.
Electricity supply for municipal and household consumers. This group of buildings includes a wide range of buildings located in residential areas of cities and towns. These are residential buildings, administrative buildings, educational and scientific institutions, shops, healthcare buildings, cultural buildings, public catering, etc.

III. Transformers

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

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, Hungarian scientists M. Deri, O. Blati, K. Tsipernovsky developed single-phase industrial transformers with a closed magnetic circuit. In 1889-1891. M.O. Dolivo-Dobrovolsky proposed a three-phase transformer.

1. Purpose

Transformers are widely used in various fields:
For transmission and distribution of electrical energy
Typically, in power plants, alternating current generators produce electrical energy at voltages 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, transformers are installed at each power plant to increase the voltage.
The distribution of electrical energy between industrial enterprises, populated areas, in cities and rural areas, as well as within industrial enterprises, is carried out via overhead and cable lines, at voltages of 220, 110, 35, 20, 10 and 6 kV. Consequently, transformers must be installed in all distribution nodes, reducing the voltage to 220, 380 and 660 V.
To provide the required circuit for switching on valves in converter devices and matching 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, electrical 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. (instrument transformers)

2. Classification

Transformer classification:

By purpose: general power (used in power transmission and distribution lines) and special applications (furnaces, rectifiers, 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.
According to the number of windings per phase: two-winding, three-winding, multi-winding (more than three windings).
According to the winding design: with concentric and alternating (disc) windings.

3. Device

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

The principle of a single-phase two-winding transformer
The magnetic core is the magnetic system of the transformer, through which the main magnetic flux is closed.
When an alternating voltage is applied to the primary winding, an emf of the same frequency is induced in the secondary winding. If you connect some electrical receiver 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 depends to some relatively small extent on the load.

Transformer symbol:
a) - transformer with a steel core, b) - transformer with a ferrite core

4. Transformer characteristics

The rated power of a transformer is the power for which it is designed.
Rated primary voltage is the voltage for which the primary winding of the transformer is designed.
Rated secondary voltage - the voltage at the terminals of the secondary winding, resulting from the no-load condition of the transformer and the rated voltage at the terminals of the primary winding.
Rated currents are determined by the corresponding rated power and voltage values.
The highest rated voltage of a 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 is a rated voltage that is intermediate between the highest and lowest rated voltage of the transformer windings.

5. Modes

5.1 Idling

No-load mode is the operating mode 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, resulting in an alternating magnetic flux appearing in the core. Φ , penetrating both windings. Since Φ is the same in both windings of the transformer, then the change Φ leads to the appearance of the same induced emf in each turn of the primary and secondary windings. Instantaneous value of induced 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 induced 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 a resistor, is very small compared to ε 1, and therefore for effective voltage values in the primary U 1 and secondary U 2 windings the following expression will be valid:

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

5.2 Short circuit mode

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

A short circuit of a 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 rated one. Therefore, in circuits with transformers, protection is provided that, in the event of a short circuit, automatically turns off the transformer.

It is necessary to distinguish between two short circuit modes:

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

The 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.

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

Where U 1nom- rated primary voltage.

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

5.3 Load mode

Load mode of a transformer - operating mode of a transformer in the presence of currents in at least two of its main windings, each of which is closed to an external circuit, and currents flowing in two or more windings in no-load mode are not taken into account:

If 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 Φ 2, 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 are decreasing. 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 flow Φ 2. Equilibrium is restored again at almost the same value of the total flow.

IV. Electricity transmission

Transferring electricity from power plants to consumers is one of the most important tasks in the energy sector.
Electricity is transmitted primarily through overhead AC power lines (OLTs), although there is a trend towards increasing use of cable 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 electrical receivers distributed over a large area. The trend towards concentration of generating capacities is explained by the fact that with their growth, the relative costs of constructing 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 capabilities, natural conditions, the ability to operate as part of a unified energy system, etc. Often such power plants turn out to be significantly remote from the main centers of electricity consumption. The operation of unified electrical power systems covering vast territories depends on the efficiency of transmitting electricity over distances.
It is necessary to transfer electricity from 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 time t in the conductor by resistance R when current passes I, equals:

From the formula it follows that to reduce the heating of the wires it is necessary to reduce the current 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 influence of gravity, especially during snowfall. In addition, as the thickness of the wires increases, their cost increases, and they are made of a relatively expensive metal - copper. Therefore, a more effective way to minimize energy losses during electricity transmission is to reduce the current 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 current multiplied by the voltage:

Consequently, to maintain the power transmitted over long distances, it is necessary to increase the voltage by the same amount as the current in the wires was reduced:

It follows from the formula that at constant values of transmitted current power and wire resistance, heating losses in the wires are inversely proportional to the square of the network voltage. Therefore, to transmit electricity over distances of several hundred kilometers, high-voltage power lines (power lines) 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 a power grid. The Unified Energy System of Russia includes a huge number of power plants controlled from a single center and ensures an uninterrupted supply of electricity to consumers.

V. GOELRO

1. History

GOELRO (State Commission for 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.

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

By the end of 1920, the commission had done a lot of work and prepared the “Electrification Plan of the RSFSR” - a volume of 650 pages of text with maps and diagrams of electrification of areas.
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 the electric power industry, 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 boilers and turbines that were large for that time.
One of the main ideas of the plan was the widespread use of the country's huge hydropower resources. A radical reconstruction based on the electrification of all sectors of the country's national economy and mainly the growth of heavy industry and the rational distribution of industry throughout the country were envisaged.
The implementation of the GOELRO plan began in difficult conditions of the Civil War and economic ruin.

Since 1947, the USSR has ranked 1st in Europe and 2nd in the world in 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 drawing up and implementation of the GOELRO plan became possible 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 in one hand of all economic and political power, its strength and will, as well as 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 in conditions of strictly centralized government and predetermined the development of this system for many decades.

2. Results

By the end of 1935, the electrical construction program was exceeded 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, among the regional power plants there were 13 power plants with 100 thousand kW each.

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 reached almost 700 thousand kW.
The largest hydroelectric power station in the world at that time, the Dnieper hydroelectric station, Svirskaya 3rd, Volkhovskaya, etc., were built. At the highest point of its development, the Unified Energy System of the USSR was superior in many respects to the energy systems of developed countries in Europe and America.

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

Electricity began to be used in agriculture: in mills, feed 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 sq. 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 methodological complex. /AND. M. Kogol, G. P. Dubovitsky, V. N. Borodyanko, V. S. Gun, N. V. Klinachev, V. V. Krymsky, A. Ya. Ergard, V. A. Yakovlev; Edited by N.V. Klinachev. - Chelyabinsk, 2006-2008.
Electrical systems, vol. 3 - Energy transmission by alternating and direct current of high voltage, M., 1972.

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Essay

in physics

on the topic “Production, transmission and use of electricity”

11th grade A students

Municipal educational institution No. 85

Catherine.

Teacher:

2003

Abstract plan.

Introduction.

1. Power generation.

1. types of power plants.

2. alternative energy sources.

2. Electricity transmission.

transformers.

Introduction.

The birth of energy occurred several million years ago, when people learned to use fire. Fire gave them warmth and light, was a source of inspiration and optimism, a weapon against enemies and wild animals, a remedy, an assistant in agriculture, a food preservative, a technological tool, etc.

The wonderful myth of Prometheus, who gave fire to people, appeared in Ancient Greece much later, after many parts of the world had mastered methods of quite sophisticated handling of fire, its production and extinguishing, preservation of fire and rational use of fuel.

For many years, fire was maintained by burning plant energy sources (wood, shrubs, reeds, grass, dry algae, etc.), and then it was discovered that it was possible to use fossil substances to maintain fire: coal, oil, shale, peat.

Today, energy remains the main component of human life. It makes it possible to create various materials and is one of the main factors in the development of new technologies. Simply put, without mastering various types of energy, a person is not able to fully exist.

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.

In thermal power plants, the chemical energy of the fuel is converted first into mechanical energy and then into electrical energy. The fuel for such a power plant can be coal, peat, gas, oil shale, and fuel oil.

Thermal power plants are divided into condensation(IES), designed to generate only electrical energy, and combined heat and power plants(CHP), producing, in addition to electrical energy, thermal energy in the form of hot water and steam. Large CPPs of regional significance are called state district power plants (SDPPs).

The simplest schematic diagram of a coal-fired IES is shown in the figure. Coal is fed into the fuel bunker 1, and from it into the crushing unit 2, where it turns into dust. Coal dust enters the furnace of a steam generator (steam boiler) 3, which has a system of tubes in which chemically purified water, called feed water, circulates. In the boiler, the water is heated, evaporated, and the resulting saturated steam is brought to a temperature of 400-650 °C and, under a pressure of 3-24 MPa, enters steam turbine 4 through a steam line. Steam parameters depend on the power of the units.

Thermal condensing power plants have low efficiency (30-40%), since most of the energy is lost with flue gases and condenser cooling water. It is advantageous to build CPPs in close proximity to fuel production sites. In this case, electricity consumers may be located at a considerable distance from the station.

Combined heat and power plant differs from a condensing station by the special heating turbine installed on it with steam extraction. At a thermal power plant, one part of the steam is completely used in the turbine to generate electricity in the generator 5 and then enters the condenser 6, and the other, having a higher temperature and pressure, is taken from the intermediate stage of the turbine and is used for heat supply. The condensate is supplied by pump 7 through the deaerator 8 and then by the feed pump 9 to the steam generator. The amount of steam taken depends on the thermal energy needs of enterprises.

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

Thermal stations with gas turbine(GTPP), steam-gas(PHPP) and diesel plants.

Gas or liquid fuel is burned in the combustion chamber of a gas turbine power plant; combustion products with a temperature of 750-900 ºС enter a gas turbine that rotates an electric generator. The efficiency of such thermal power plants is usually 26-28%, power - up to several hundred MW . GTPPs are usually used to cover electrical load peaks. The efficiency of PGES can reach 42 - 43%.

The most economical are large thermal steam turbine power plants (abbreviated TPP). Most thermal power plants in our country use coal dust as fuel. To generate 1 kWh of electricity, several hundred grams of coal are consumed. In a steam boiler, over 90% of the energy released by the fuel is transferred to steam. In the turbine, the kinetic energy of the steam jets is transferred to the rotor. The turbine shaft is rigidly connected to the generator shaft.

Modern steam turbines for thermal power plants are very advanced, high-speed, highly economical machines with a long service life. Their power in a single-shaft version reaches 1 million 200 thousand kW, and this is not the limit. Such machines are always multi-stage, that is, they usually have several dozen disks with working blades and the same number, in front of each disk, of groups of nozzles through which a stream of steam flows. The pressure and temperature of the steam gradually decrease.

It is known from a physics course that the efficiency of heat engines increases with increasing initial temperature of the working fluid. Therefore, the steam entering the turbine is brought to high parameters: temperature - almost 550 ° C and pressure - up to 25 MPa. The efficiency of thermal power plants reaches 40%. Most of the energy is lost along with the hot exhaust steam.

Hydroelectric station (hydroelectric power station), a complex of structures and equipment through which the energy of water flow is converted into electrical energy. A hydroelectric power station consists of a series circuit hydraulic structures, providing the necessary concentration of water flow and creating pressure, and energy equipment that converts the energy of water moving under pressure into mechanical rotational energy, which, in turn, is converted into electrical energy.

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

According to installed capacity (in MW) distinguish between hydroelectric power stations powerful(over 250), average(up to 25) and small(up to 5). The power of a hydroelectric power station depends on the pressure (the difference between the levels of the upstream and downstream ), water flow used in hydraulic turbines and the efficiency of the hydraulic unit. For a number of reasons (due to, for example, seasonal changes in the water level in reservoirs, fluctuations in the load of the power system, repairs of hydraulic units or hydraulic structures, etc.), the pressure and flow of water continuously change, and, in addition, the flow changes when regulating the power of a hydroelectric power station. There are annual, weekly and daily cycles of hydroelectric power station operation.

Based on the maximum used pressure, hydroelectric power stations are divided into high-pressure(more than 60 m), medium-pressure(from 25 to 60 m) And low-pressure(from 3 to 25 m). On lowland rivers pressures rarely exceed 100 m, in mountainous conditions, a dam can create pressures of up to 300 m and more, and with the help of derivation - up to 1500 m. The division of hydroelectric power stations according to the pressure used is of an approximate, conditional nature.

According to the pattern of water resource use and pressure concentration, hydroelectric power stations are usually divided into channel, dam, diversion with pressure and non-pressure diversion, mixed, pumped storage And tidal.

In run-of-river and dam-based hydroelectric power plants, the water pressure is created by a dam that blocks the river and raises the water level in the upper pool. At the same time, some flooding of the river valley is inevitable. Run-of-river and dam-side hydroelectric power stations are built both on lowland high-water rivers and on mountain rivers, in narrow compressed valleys. Run-of-river hydroelectric power stations are characterized by pressures up to 30-40 m.

At higher pressures, it turns out to be inappropriate to transfer hydrostatic water pressure to the hydroelectric power station building. In this case the type is used dam A hydroelectric power station, in which the pressure front is blocked along its entire length by a dam, and the hydroelectric power station building is located behind the dam, is adjacent to the tailwater.

Another type of layout dammed The hydroelectric power station corresponds to mountain conditions with relatively low river flows.

IN derivational Hydroelectric power station concentration of the river fall is created through diversion; Water at the beginning of the used section of the river is diverted from the river bed by a conduit with a slope significantly less than the average slope of the river in this section and with straightening the bends and turns of the channel. The end of the diversion is brought to the location of the hydroelectric power station building. Waste water is either returned to the river or supplied to the next diversion hydroelectric power station. Diversion is beneficial when the river slope is high.

A special place among hydroelectric power stations is occupied by pumped storage power plants(PSPP) and tidal power plants(PES). The construction of pumped storage power plants is driven by the growing demand for peak power in large energy systems, which determines the generating capacity required to cover peak loads. The ability of pumped storage power plants to accumulate energy is based on the fact that the electrical energy free in the power system for a certain period of time is used by pumped storage power plant units, which, operating in pump mode, pump water from the reservoir into the upper storage pool. During load peaks, the accumulated energy is returned to the power system (water from the upper pool enters the pressure pipeline and rotates hydraulic units operating as a current generator).

PES convert the energy of sea tides into electricity. The electricity of tidal hydroelectric power stations, due to some features associated with the periodic nature of the ebb and flow of tides, can be used in energy systems only in conjunction with the energy of regulating power plants, which make up for the power failures of tidal power stations within days or months.

The most important feature of hydropower resources compared to fuel and energy resources is their continuous renewability. The absence of fuel requirement for hydroelectric power plants determines the low cost of electricity generated by hydroelectric power plants. Therefore, the construction of hydroelectric power stations, despite significant specific capital investments by 1 kW installed capacity and long construction periods were and are given great importance, especially when this is associated with the placement of electricity-intensive industries.

Nuclear power plant (NPP), a power plant in which atomic (nuclear) energy is converted into electrical energy. The energy generator at a nuclear power plant is a nuclear reactor. The heat that is released in the reactor as a result of the chain reaction of fission of the nuclei of some heavy elements is then converted into electricity in the same way as in conventional thermal power plants (TPPs). Unlike thermal power plants that run on fossil fuels, nuclear power plants run on nuclear fuel(based on 233 U, 235 U, 239 Pu). It has been established that the world's energy resources of nuclear fuel (uranium, plutonium, etc.) significantly exceed the energy resources of natural reserves of organic fuel (oil, coal, natural gas, etc.). This opens up broad prospects for meeting rapidly growing fuel demands. In addition, it is necessary to take into account the ever-increasing volume of coal and oil consumption for technological purposes in the global chemical industry, which is becoming a serious competitor to thermal power plants. Despite the discovery of new deposits of organic fuel and the improvement of methods for its production, there is a tendency in the world towards a relative increase in its cost. This creates the most difficult conditions for countries with limited reserves of fossil fuels. 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 around the world.

A schematic diagram of a nuclear power plant with a water-cooled nuclear reactor is shown in Fig. 2. Heat released in core reactor coolant, is absorbed by water from the 1st circuit, which is pumped through the reactor by a circulation pump. Heated water from the reactor enters the heat exchanger (steam generator) 3, where it transfers the heat received in the reactor to the water of the 2nd circuit. The water of the 2nd circuit evaporates in the steam generator, and steam is formed, which then enters the turbine 4.

Most often, 4 types of thermal neutron reactors are used at nuclear power plants:

1) water-water with ordinary water as a moderator and coolant;

2) graphite-water with water coolant and graphite moderator;

3) heavy water with water coolant and heavy water as a moderator;

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

The choice of the predominantly used 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 material reserves, etc.

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

To protect nuclear power plant personnel from radiation exposure, the reactor is surrounded by biological shielding, the main materials for which are concrete, water, and serpentine sand. The reactor circuit equipment must be completely sealed. A system is provided to monitor places of possible coolant leaks; measures are taken to ensure that leaks and breaks in the circuit do not lead to radioactive emissions and contamination of the nuclear power plant premises and the surrounding area. Radioactive air and a small amount of coolant vapor, due to the presence of leaks from the circuit, are removed from unattended rooms of the nuclear power plant by a special ventilation system, in which purification filters and holding gas tanks are provided to eliminate the possibility of air pollution. The compliance with radiation safety rules by NPP personnel is monitored by the dosimetry control service.

Nuclear power plants, which are the most modern type of power plants, have a number of significant advantages over other types of power plants: under normal operating conditions, they do not pollute the environment at all, do not require connection to a source of raw materials and, accordingly, can be located almost anywhere. New power units have a capacity almost equal to that of an average hydroelectric power station, but the installed capacity utilization factor at a nuclear power plant (80%) significantly exceeds this figure for a hydroelectric power station or thermal power plant.

NPPs have practically no significant disadvantages under normal operating conditions. However, one cannot fail to notice the danger of nuclear power plants under possible force majeure circumstances: earthquakes, hurricanes, etc. - here old models of power units pose a potential danger of radiation contamination of territories due to uncontrolled overheating of the reactor.

Alternative energy sources.

Energy of sun.

Recently, interest in the problem of using solar energy has increased sharply, because the potential possibilities of energy based on the use of direct solar radiation are extremely high.

The simplest solar radiation collector is a blackened metal (usually aluminum) sheet, inside of which there are pipes with a liquid circulating in it. Heated by solar energy absorbed by the collector, the liquid is supplied for direct use.

Solar energy is one of the most material-intensive types of energy production. Large-scale use of solar energy entails a gigantic increase in the need for materials, and, consequently, in labor resources for the extraction of raw materials, their enrichment, obtaining materials, manufacturing heliostats, collectors, other equipment, and their transportation.

So far, electrical energy generated by the sun's rays is much more expensive than that obtained by traditional methods. Scientists hope that the experiments they will conduct at pilot installations and stations will help solve not only technical, but also economic problems.

Wind energy.

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

But today, wind engines supply just one thousandth of the world's energy needs. Therefore, aircraft specialists who know how to select the most appropriate blade profile and study it in a wind tunnel are involved in creating the designs of the wind wheel, the heart of any wind power plant. Through the efforts of scientists and engineers, a wide variety of designs of modern wind turbines have been created.

Energy of the Earth.

People have long known about the spontaneous manifestations of gigantic energy hidden in the depths of the globe. The memory of mankind contains legends about catastrophic volcanic eruptions that claimed millions of human lives and changed the appearance of many places on Earth beyond recognition. The power of the eruption of even a relatively small volcano is colossal; it is many times greater than the power of the largest power plants created by human hands. True, there is no need to talk about the direct use of the energy of volcanic eruptions; people do not yet have the ability to curb this rebellious element.

The Earth's energy is suitable not only for heating premises, as is the case in Iceland, but also for generating electricity. Power plants using hot underground springs have been operating for a long time. The first such power plant, still very low-power, was built in 1904 in the small Italian town of Larderello. Gradually, the power of the power plant grew, more and more new units were put into operation, new sources of hot water were used, and today the power of the station has already reached an impressive value of 360 thousand kilowatts.

Electricity transmission.

Transformers.

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

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

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

The operation of a transformer is based on the phenomenon of electromagnetic induction. When alternating current passes through the primary winding, an alternating magnetic flux appears in the iron core, which excites an induced emf in each winding. Moreover, the instantaneous value of the induced emf 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= Ф 0 сosωt, then

e = ω Ф 0sinω t, or

e =E 0 sinω t ,

Where E 0 = ω Ф 0 - amplitude of the EMF in one turn.

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

In the secondary winding there is a total emf. e 2 equal to p 2 e, Where n 2- the number of turns of this winding.

It follows that

e 1 e 2 = n 1 n 2. (1)

Sum voltage u 1 , applied to the primary winding, and EMF e 1 should be equal to the voltage drop in the primary winding:

u 1 + e 1 = i 1 R 1 , Where R 1 - active resistance of the winding, and i 1 - current strength in it. This equation follows directly from the general equation. Usually the active resistance of the winding is small and i 1 R 1 can be neglected. That's why

u 1 ≈ - e 1. (2)

When the secondary winding of the transformer is open, no current flows in it, and the following relationship holds:

u 2 ≈ - e 2 . (3)

Since the instantaneous values of the emf e 1 And e 2 change in phase, then their ratio in formula (1) can be replaced by the ratio of effective values E 1 AndE 2 of these EMFs or, taking into account equalities (2) and (3), the ratio of effective voltage values U 1 and U 2 .

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

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

When the secondary winding circuit is closed, current flows in it. Then the ratio u 2 ≈ - e 2 is no longer fulfilled exactly, and accordingly the connection between U 1 and U 2 becomes more complex than in equation (4).

According to the law of conservation of energy, the power in the primary circuit must be equal to the power in the secondary circuit:

U 1 I 1 = U 2 I 2, (5)

Where I 1 And I 2 - effective values of force in the primary and secondary windings.

It follows that

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

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

Due to the inevitable energy losses due to heat release in the windings and iron core, equations (5) and (6) are satisfied approximately. However, in modern powerful transformers, the total losses do not exceed 2-3%.

In everyday practice we often have to deal with transformers. In addition to those transformers that we use willy-nilly due to the fact that industrial devices are designed for one voltage, and the city network uses another, we also have to deal with car bobbins. The bobbin is a step-up transformer. To create a spark that ignites the working mixture, a high voltage is required, which we obtain from the car battery, after first converting the direct current of the battery into alternating current using a breaker. It is not difficult to understand that, up to the loss of energy used to heat the transformer, as the voltage increases, the current decreases, and vice versa.

Welding machines require step-down transformers. Welding requires very high currents, and the welding machine's transformer has only one output turn.

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

At home you are dealing with small transformers. As for powerful transformers, they are huge structures. In these cases, the core with windings is placed in a tank filled with cooling oil.

Electricity transmission

Electricity consumers are everywhere. It is produced in relatively few places close to sources of fuel and hydro resources. Therefore, there is a need to transmit electricity over distances sometimes reaching hundreds of kilometers.

But transmitting electricity over long distances is associated with noticeable losses. The fact is that as current flows through power lines, it heats them up. In accordance with the Joule-Lenz law, the energy spent on heating the line wires is determined by the formula

where R is the line resistance. With a large line length, energy transmission may become generally unprofitable. To reduce losses, you can, of course, follow the path of reducing the resistance R of the line by increasing the cross-sectional area of the wires. But to reduce R, for example, by 100 times, you need to increase the mass of the wire also by 100 times. It is clear that such a large consumption of expensive non-ferrous metal cannot be allowed, not to mention the difficulties of fastening heavy wires on high masts, etc. Therefore, energy losses in the line are reduced in another way: by reducing the current in the line. For example, reducing the current by 10 times reduces the amount of heat released in the conductors by 100 times, i.e., the same effect is achieved as from making the wire a hundred times heavier.

Since current power is proportional to the product of current and voltage, to maintain the transmitted power, it is necessary to increase the voltage in the transmission line. Moreover, the longer the transmission line, the more profitable it is to use a higher voltage. For example, in the high-voltage transmission line Volzhskaya HPP - Moscow, a voltage of 500 kV is used. Meanwhile, alternating current generators are built for voltages not exceeding 16-20 kV, since a higher voltage would require more complex special measures to be taken to insulate the windings and other parts of the generators.

That's why step-up transformers are installed at large power plants. The transformer increases the voltage in the line by the same amount as it reduces the current. The power losses are small.

To directly use electricity in the electric drive motors of machine tools, in the lighting network and for other purposes, the voltage at the ends of the line must be reduced. This is achieved using step-down transformers. Moreover, usually a decrease in voltage and, accordingly, an increase in current occurs in several stages. At each stage, the voltage becomes less and less, and the territory covered by the electrical network becomes wider. The diagram of transmission and distribution of electricity is shown in the figure.

Electric power stations in a number of regions of the country are connected by high-voltage transmission lines, forming a common power grid to which consumers are connected. Such an association is called a power system. The power system ensures uninterrupted supply of energy to consumers regardless of their location.

Electricity use.

The use of electrical power in various fields of science.

The twentieth century has become the century when science invades all spheres of social life: economics, politics, culture, education, etc. Naturally, science directly influences the development of energy and the scope of application of electricity. On the one hand, science contributes to expanding the scope of application of electrical energy and thereby increases its consumption, but on the other hand, in an era when the unlimited use of non-renewable energy resources poses a danger to future generations, the urgent tasks of science are the development of energy-saving technologies and their implementation in life.

Let's look at these questions using specific examples. About 80% of the growth in GDP (gross domestic product) of developed countries is achieved through technical innovation, the main part of which is related to the use of electricity. Everything new in industry, agriculture and everyday life comes to us thanks to new developments in various branches of science.

Now they are used in all areas of human activity: for recording and storing information, creating archives, preparing and editing texts, performing drawing and graphic work, automating production and agriculture. Electronicization and automation of production are the most important consequences of the “second industrial” or “microelectronic” revolution in the economies of developed countries. The development of complex automation is directly related to microelectronics, a qualitatively new stage of which began after the invention in 1971 of the microprocessor - a microelectronic logical device built into various devices to control their operation.

Microprocessors have accelerated the growth of robotics. Most of the robots currently in use belong to the so-called first generation, and are used for welding, cutting, pressing, coating, etc. The second generation robots that are replacing them are equipped with devices for recognizing the environment. And third-generation “intelligent” robots will “see,” “feel,” and “hear.” Scientists and engineers name nuclear energy, space exploration, transport, trade, warehousing, medical care, waste processing, and the development of the riches of the ocean floor among the highest priority areas for using robots. The majority of robots operate on electrical energy, but the increase in electricity consumption by robots is offset by a decrease in energy costs in many energy-intensive production processes due to the introduction of more rational methods and new energy-saving technological processes.

But let's get back to science. All new theoretical developments after computer calculations are tested experimentally. And, as a rule, at this stage, research is carried out using physical measurements, chemical analyzes, etc. Here, the tools of scientific research are diverse - numerous measuring instruments, accelerators, electron microscopes, magnetic resonance imaging, etc. The bulk of these instruments of experimental science are powered by electrical energy.

Science in the field of communications and communications is developing very rapidly. Satellite communications are no longer used only as a means of international communication, but also in everyday life - satellite dishes are not uncommon in our city. New means of communication, such as fiber technology, can significantly reduce energy losses in the process of transmitting signals over long distances.

Science has not bypassed the sphere of management. As scientific and technological progress develops and the production and non-production spheres of human activity expand, management begins to play an increasingly important role in increasing their efficiency. From a kind of art, which until recently was based on experience and intuition, management today has turned into a science. The science of management, the general laws of receiving, storing, transmitting and processing information is called cybernetics. This term comes from the Greek words “helmsman”, “helmsman”. It is found in the works of ancient Greek philosophers. However, its rebirth actually occurred in 1948, after the publication of the book “Cybernetics” by the American scientist Norbert Wiener.

Before the start of the “cybernetic” revolution, there was only paper computer science, the main means of perception of which was the human brain, and which did not use electricity. The "cybernetic" revolution gave birth to a fundamentally different one - machine informatics, corresponding to the gigantically increased flows of information, the source of energy for which is electricity. Completely new means of obtaining information, its accumulation, processing and transmission have been created, which together form a complex information structure. It includes automated control systems (automated control systems), information data banks, automated information databases, computer centers, video terminals, copying and phototelegraph machines, national information systems, satellite and high-speed fiber-optic communication systems - all this has unlimitedly expanded the scope of electricity use.

Many scientists believe that in this case we are talking about a new “information” civilization, replacing the traditional organization of an industrial-type society. This specialization is characterized by the following important features:

· widespread use of information technology in material and non-material production, in the field of science, education, healthcare, etc.;

· the presence of a wide network of various data banks, including public ones;

· turning information into one of the most important factors in economic, national and personal development;

· free circulation of information in society.

Such a transition from an industrial society to an “information civilization” became possible largely thanks to the development of energy and the provision of a convenient type of energy for transmission and use - electrical energy.

Electricity in production.

Modern society cannot be imagined without the electrification of production activities. Already at the end of the 80s, more than 1/3 of all energy consumption in the world was carried out in the form of electrical energy. By the beginning of the next century, this share may increase to 1/2. This increase in electricity consumption is primarily associated with an increase in its consumption in industry. The bulk of industrial enterprises operate on electrical energy. High electricity consumption is typical for energy-intensive industries such as metallurgy, aluminum and mechanical engineering.

Electricity in the home.

Electricity is an essential assistant in everyday life. We deal with her every day, and we probably can’t imagine our life without her. Remember the last time your lights were turned off, that is, there was no electricity coming to your house, remember how you swore that you didn’t have time to do anything and you needed light, you needed a TV, a kettle and a bunch of other electrical appliances. After all, if we were to lose power forever, we would simply return to those ancient times when food was cooked over fires and we lived in cold wigwams.

A whole poem can be dedicated to the importance of electricity in our lives, it is so important in our lives and we are so accustomed to it. Although we no longer notice that it is coming into our homes, when it is turned off, it becomes very uncomfortable.

Appreciate electricity!

Bibliography.

1. Textbook by S.V. Gromov “Physics, 10th grade”. Moscow: Enlightenment.

2. Encyclopedic dictionary of a young physicist. Compound. V.A. Chuyanov, Moscow: Pedagogy.

3. Ellion L., Wilcons W.. Physics. Moscow: Science.

4. Koltun M. World of Physics. Moscow.

5. Energy sources. Facts, problems, solutions. Moscow: Science and Technology.

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

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

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

in physics

on the topic “Production, transmission and use of electricity”

11th grade A students

Municipal educational institution No. 85

Catherine.

Abstract plan.

Introduction.

1. Electricity production.

1. types of power plants.

2. alternative energy sources.

2. Electricity transmission.

transformers.

3. Electricity use.

Introduction.

Power generation.

Types of power plants.

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

Thermal stations with gas turbine(GTPP), steam-gas(PHPP) and diesel plants.

According to the pattern of water resource use and pressure concentration, hydroelectric power stations are usually divided into channel , dam , diversion with pressure and non-pressure diversion, mixed, pumped storage And tidal .

Another type of layout dammed The hydroelectric power station corresponds to mountain conditions with relatively low river flows.

in physics

on the topic “Production, transmission and use of electricity”

11th grade students A

Municipal educational institution No. 85

Catherine.

Abstract plan.

Introduction.

1. Electricity production.

1. types of power plants.

2. alternative energy sources.

2. Transmission of electricity.

transformers.

3. Use of electricity.

Introduction.

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 by 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.

The simplest schematic diagram of a coal-fired IES is shown in the figure. Coal is fed into the fuel bunker 1, and from it into the crushing unit 2, where it turns into dust. Coal dust enters the furnace of a steam generator (steam boiler) 3, which has a system of tubes in which chemically purified water, called feedwater, circulates. In the boiler, the water is heated, evaporated, and the resulting saturated steam is brought to a temperature of 400-650 °C and, under a pressure of 3-24 MPa, enters steam turbine 4 through a steam line. The steam parameters depend on the power of the units.

Thermal condensing power plants have low efficiency (30-40%), since most of the energy is lost with flue gases and condenser cooling water. It is advantageous to construct IES in close proximity to fuel production sites. In this case, electricity consumers may be located at a considerable distance from the station.

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

The efficiency factor of thermal power plants reaches 60-70%. Such stations are usually built near consumers - industrial enterprises or residential areas. Most often they operate on imported fuel.

Thermal stations with gas turbine(GTPP), steam-gas(PHPP) and diesel plants.

Gas or liquid fuel is burned in the combustion chamber of a gas turbine power plant; combustion products at a temperature of 750-900 ºС enter a gas turbine that rotates an electric generator. The efficiency of such thermal power plants is usually 26-28%, the power is up to several hundred MW . GTPPs are usually used to cover peak electrical loads. The efficiency of PGES can reach 42 - 43%.

Modern steam turbines for thermal power plants are very advanced, high-speed, highly economical machines with a long service life. Their power in the new version reaches 1 million 200 thousand kW, and this is not the limit. Such machines are always multi-stage, that is, they usually have several dozen disks with working blades and the same number, in front of each disk, of groups of nozzles through which a stream of steam flows. The pressure and temperature of the steam gradually decrease.

It is known from a physics course that the efficiency of heat engines increases with increasing initial temperature of the working fluid. Therefore, the steam entering the turbine is brought to high parameters: temperature - almost 550 ° C and pressure - up to 25 MPa. The efficiency factor of thermal power plants reaches 40%. Most of the energy is lost along with the hot exhaust steam.

NaporHES is created by the concentration of the fall of the river in the area used by the dam, or derivation, or a dam and diversion together. The main power equipment of the hydroelectric power station is located in the hydroelectric power station building: in the machine room of the power plant - hydraulic units, auxiliary equipment, automatic control and monitoring devices; in the central control post - operator-dispatcher console or auto operator of a hydroelectric power station. Increasing transformer substation located both inside the hydroelectric power station building and in separate buildings or open areas. Switchgears often located in an open area. A hydroelectric power station building can be divided into sections with one or more units and auxiliary equipment, separated from adjacent parts of the building. An installation site for the assembly and repair of various equipment and for auxiliary operations for servicing the hydroelectric power station is created at or within the building of a hydroelectric power station.

Installed power (in MW) distinguish between hydroelectric power stations powerful(over 250), average(up to 25) and small(up to 5). The power of a hydroelectric power station depends on the pressure (the difference between the levels of the upstream and downstream ), water flow used in hydraulic turbines and the efficiency of the hydraulic unit. For a number of reasons (due to, for example, seasonal changes in the water level in reservoirs, fluctuations in the load of the power system, repairs of hydraulic units or hydraulic structures, etc.), the pressure and flow of water are constantly changing, and, in addition, the flow changes when regulating the power of a hydroelectric power station. There are annual, weekly and daily cycles of hydroelectric power station operation.

Based on the maximum used pressure, hydroelectric power stations are divided into high-pressure(more than 60 m), medium-pressure(from 25 to 60 m) And low-pressure(from 3 to 25 m). On lowland rivers pressures rarely exceed 100 m, in mountain conditions, the dam can create pressures of up to 300 m most, and with the help of derivation - up to 1500 m. The division of hydroelectric power stations according to the pressure used is of an approximate, conditional nature.

Based on the use of water resources and pressure concentration, hydroelectric power stations are usually divided into channel, dam, diversion with pressure and free-flow diversion, mixed, pumped storage And tidal.

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

At higher pressures, it turns out to be inappropriate to transfer hydrostatic water pressure to the hydroelectric power station building. In this case the type is used dam A hydroelectric power station in which the pressure front is blocked along its entire length by a dam, the building of the hydroelectric power station is located behind the dam, adjacent to the downstream.

Another type of layout dammed The hydroelectric power station corresponds to mountain conditions with relatively low river flows.

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

A special place among hydroelectric power stations is occupied by pumped storage power plants(PSPP) and tidal power plants(PES). The construction of pumped storage power plants is 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 pumped storage power plants to accumulate energy is based on the fact that free electrical energy in the energy system for a certain period of time is used by pumped storage power plant units, which, operating in pump mode, pump water from the reservoir into the upper storage pool. During peak load periods, the accumulated energy is returned to the power system (water from the upper basin enters the pressure pipeline and rotates hydraulic units operating in current generator mode).

The most important feature of hydropower resources compared to fuel and energy resources is their continuous renewability. The absence of the need for fuel for hydroelectric power plants determines the low cost of electricity generated at hydroelectric power stations. Therefore, the construction of hydroelectric power stations, despite the significant specific capital investments of 1 kW installed capacity and long construction periods were and are given great importance, especially when this is associated with the placement of electrically intensive industries.

Nuclear power plant (NPP), a power plant in which atomic (nuclear) energy is converted into electrical energy. The energy generator at a nuclear power plant is a nuclear reactor. The heat that is released in the reactor as a result of a chain reaction of nuclear fission of some heavy elements is then converted into electricity, just like in conventional thermal power plants (TPPs). Unlike thermal power plants that run on fossil fuels, nuclear power plants run on nuclear fuel(mainly 233U, 235U, 239Pu). It has been established that the world's energy resources of nuclear fuel (uranium, plutonium, etc.) significantly exceed the energy resources of natural reserves of organic fuel (oil, coal, natural gas, etc.). This opens up broad prospects for meeting rapidly growing fuel needs. In addition, it is necessary to take into account the ever-increasing volume of coal and oil consumption for technological purposes in the global chemical industry, which is becoming a serious competitor to thermal power plants. Despite the discovery of new deposits of organic fuel and the improvement of methods for its extraction, there is a tendency in the world towards a relative increase in its cost. This creates the most difficult conditions for countries with limited reserves of fossil fuels. 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 around the world.

The 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 absorbed by water from the 1st circuit, which is pumped through the reactor by a circulation pump. Heated water from the reactor enters the heat exchanger (steam generator) 3, where it transfers the heat received in the reactor to the water of the 2nd circuit. The water of the 2nd circuit evaporates in the steam generator, and steam is formed, which then enters the turbine 4.

Most often, 4 types of thermal neutron reactors are used at nuclear power plants:

1) water-water with ordinary water as a moderator and coolant;

2) graphite-water with water coolant and graphite moderator;

3) heavy water with water coolant and heavy water as a moderator;

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

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

To protect nuclear power plant personnel from radiation exposure, the reactor is surrounded by biological protection, the main materials for which are concrete, water, and serpentine sand. The reactor circuit equipment must be completely sealed. A system is provided to monitor places of possible coolant leakage; measures are taken to ensure that leaks and breaks in the circuit do not lead to radioactive emissions and contamination of the nuclear power plant premises and the surrounding area. Radioactive air and a small amount of coolant vapor, caused by leaks from the circuit, are removed from unattended rooms of the nuclear power plant by a special ventilation system, in which cleaning filters and holding gas tanks are provided to eliminate the possibility of air pollution. The compliance with radiation safety rules by NPP personnel is monitored by the dosimetry control service.

The presence of biological protection, special ventilation and emergency cooling systems and a dosimetric monitoring service makes it possible to completely protect NPP operating personnel from the harmful effects of radioactive radiation.

Nuclear power plants, which are the most modern type of power plants, have a number of significant advantages over other types of power plants: under normal operating conditions, they do not pollute the environment at all, do not require connection to a source of raw materials and, accordingly, can be located almost anywhere. New power units have a capacity almost equal to the capacity of an average hydroelectric power station, however, the installed capacity utilization factor at a nuclear power plant (80%) significantly exceeds this figure for a hydroelectric power station or thermal power plant.

Nuclear power plants practically do not have any significant disadvantages under normal operating conditions. However, one cannot fail to notice the danger of nuclear power plants under possible force majeure circumstances: earthquakes, hurricanes, etc. - here, old models of power units pose a potential danger of radiation contamination of territories due to uncontrolled overheating of the reactor.

Alternative energy sources.

Energy of sun.

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

The simplest solar radiation collector is a blackened metal (usually aluminum) sheet, inside of which there are pipes with liquid circulating in it. Heated by solar energy absorbed by the collector, the liquid is supplied for direct use.

Wind energy.

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

Nowadays, wind engines cover only one thousandth of the world's energy needs. Therefore, aircraft construction specialists who know how to select the most appropriate blade profile and study it in a wind tunnel are involved in creating the design of the wind wheel, the heart of any wind power plant. Through the efforts of scientists and engineers, a wide variety of designs of modern wind turbines have been created.

Energy of the Earth.

Since ancient times, people have known about the spontaneous manifestations of gigantic energy hidden in the earth’s surface. The memory of mankind preserves legends about catastrophic volcanic eruptions that claimed millions of human lives and changed the appearance of many places on Earth beyond recognition. The power of the eruption of even a relatively small volcano is colossal; it is many times greater than the power of the largest power plants created by human hands. True, there is no need to talk about the direct use of the energy of volcanic eruptions; people do not yet have the ability to curb this rebellious element.

Transmission of electricity.

Transformers.

Transformer- a very simple device that allows you to both increase and decrease the voltage. The conversion of alternating current is carried out using transformers. Transformers were first 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 Moscow University employee I. F. Usagin, who designed improved transformers.

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

Fig.1 Fig.2

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

The action of the transformer is based on the phenomenon of electromagnetic induction. When alternating current passes through the primary winding, an alternating magnetic flux appears in the iron core, which excites the induced emf in each winding. Moreover, the instantaneous value of the induced 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= Ф0соsωt, then

e = ω Ф0sinω t, or

e =Esinω t,

Where E=ω Ф0 is the amplitude of the EMF in one turn.

In the primary winding, which has p1 turns, total induced emf e1 equal to p1e.

There is a total EMF in the secondary winding. e2 equal to p2e, Where n2- the number of turns of this winding.

It follows that

e1 e2 = n1n2. (1)

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

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

u1 ≈ -e1 . (2)

When the secondary winding of the transformer is open, no current flows in it, and the following relation holds:

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 the effective values E1 AndE2 of these EMFs or, taking into account equalities (2) and (3), the ratio of effective voltage values U 1 and U 2 .

U 1 /U 2 = E1 / E2 = n1 / n2 = k. (4)

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

When the circuit of the secondary winding is closed, current flows in it. Then the ratio u2 ≈ - e2 is no longer fulfilled exactly, and accordingly the connection between U 1 and U 2 becomes more complex than in equation (4).

According to the law of conservation of energy, the power in the primary circuit must be equal to the power in the secondary circuit:

U 1 I1 = U 2 I2, (5)

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

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 the same number of times (and vice versa).

In everyday practice, we often have to deal with transformers. In addition to those transformers that we use willy-nilly due to the fact that industrial devices are designed for one voltage, and the city network uses another, we also have to deal with car bobbins. The bobbin is a step-up transformer. To create a spark that ignites the working mixture, a high voltage is required, which we obtain from a car battery, after first converting the battery's direct current into alternating current using a breaker. It is not difficult to understand that, up to the loss of energy used to heat the transformer, as the voltage increases, the current strength decreases, and vice versa.

Welding machines require step-down transformers. Welding requires very high currents, and the welding machine's transformer has only one output turn.

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

where R is the line resistance. With a large line length, energy transmission may become generally unprofitable. To reduce losses, you can, of course, follow the path of reducing the resistance R of the line by increasing the cross-sectional area of the wires. But to reduce R, for example, by 100 times, you need to increase the mass of the wire by 100 times. It is clear that such a large expenditure of expensive non-ferrous metal cannot be allowed, not to mention the difficulties of securing heavy wires on high masts, etc. Therefore, energy losses in the line are reduced in another way: by reducing the current in the line. For example, reducing the current by 10 times reduces the amount of heat released in the conductors by 100 times, i.e., the same effect is achieved as from making the wire a hundred times heavier.

Since current power is proportional to the product of current and voltage, to maintain the transmitted power it is necessary to increase the voltage in the transmission line. Moreover, the longer the transmission line, the more profitable it is to use a higher voltage. For example, in the high-voltage transmission line Volzhskaya HPP - Moscow, a voltage of 500 kV is used. Meanwhile, alternating current generators are built at voltages not exceeding 16-20 kV, since higher voltages would require more complex special measures to be taken to insulate the windings and other parts of the generators.

That’s why step-up transformers are installed at large power plants. The transformer increases the voltage in the line by the same amount as it decreases the current. The loss of power is small.

For direct use of electricity in electric drive motors of machine tools, lighting networks and for other purposes, the voltage at the ends of the line must be reduced. This is achieved using step-down transformers. Moreover, usually a decrease in voltage and, accordingly, an increase in current occurs in several stages. At each stage, the voltage becomes less and less, the territory covered by the electrical network becomes wider. The power transmission and distribution diagram is shown in the figure.

Electric power stations in a number of regions of the country are connected by high-voltage transmission lines, forming a common power grid to which consumers are connected. Such an association is called an energy system. The energy system ensures uninterrupted supply of energy to consumers regardless of their location.

Use of electricity.

Use of electric power in various fields of science.

The twentieth century became the century when science invades all spheres of society: economics, politics, culture, education, etc. Naturally, science directly influences the development of energy and the scope of application of electricity. On the one hand, science contributes to expanding the scope of application of electrical energy and thereby increases its consumption, but on the other hand, in an era when the unlimited use of non-renewable energy resources poses a danger to future generations, the urgent tasks of science are the development of energy-saving technologies and their implementation in life.

Most scientific developments begin with theoretical calculations. But if in the 19th century these calculations were made with the help of pen and paper, then in the age of STR (scientific and technological revolution) all theoretical calculations, selection and analysis of scientific data, and even linguistic analysis of literary works are done using computers (electronic computers), which operate on electrical energy, most convenient for transmitting it over a distance and using it. But if computers were initially used for scientific calculations, now computers have come to life from 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 complex automation is directly related to microelectronics, a qualitatively new stage of which began after the invention in 1971 of the microprocessor - a microelectronic logical device built into various devices to control their operation.

Microprocessors have accelerated the growth of robotics. Most of the robots currently in use are of the so-called first generation, and are used for welding, cutting, pressing, coating, etc. The second-generation robots that replace them are equipped with devices for recognizing the environment. Robotic “intellectuals” of the third generation will “see”, “feel”, “hear”. Scientists and engineers name nuclear energy, space exploration, transport, trade, warehousing, medical care, waste processing, and the development of ocean resources among the most priority areas of application of robots. The majority of robots operate on electrical energy, but the increase in electricity consumption by robots is offset by a reduction in energy consumption in many energy-intensive production processes due to the introduction of more rational methods and new energy-saving technological processes.

But let's return to science. All new theoretical developments, after computer calculations, are tested experimentally. And, as a rule, at this stage, research is carried out using physical measurements, chemical analyzes, etc. Here, the instruments of scientific research are diverse - numerous measuring instruments, accelerators, electron microscopes, magnetic resonance imaging scanners, etc. The bulk of these instruments of experimental science operate on electrical energy.

Science has not bypassed the sphere of management. As scientific and technological progress develops and the production and non-production spheres of human activity expand, management begins to play an increasingly important role in increasing their efficiency. From a kind of art, which until recently was based on experience and intuition, management has recently turned into a science. The science of management, the general laws of receiving, storing, transmitting and processing information is called cybernetics. This term comes from the Greek words “helmsman”, “helmsman”. It is found in the works of ancient Greek philosophers. However, its rebirth actually occurred in 1948, after the publication of the book “Cybernetics” by the American scientist Norbert Wiener.

Before the start of the “cybernetic” revolution, there was only paper computer science, the main means of perception of which was the human brain, and which did not use electricity. The “cybernetic” revolution gave birth to a fundamentally different one - machine informatics, corresponding to the gigantically increased flows of information, the energy source for which is electricity. Completely new means of obtaining information, its accumulation, processing and transmission were created, together forming a complex information structure. It includes automated control systems (automated control systems), information data banks, automated information databases, computer centers, video terminals, copying and phototelegraph machines, national information systems, satellite and high-speed fiber-optic communication systems - all this has unlimitedly expanded the scope of electricity use.

· widespread use of information technology in material and non-material production, in the field of science, education, healthcare, etc.;

· the presence of a wide network of various data banks, including public ones;

· turning information into one of the most important factors of economic, national and personal development;

· free circulation of information in society.

Electricity in production.

Electricity in the home.

Electricity is an integral assistant in everyday life. Every day we deal with her, and, probably, we can no longer imagine our life without her. Remember the last time your lights were turned off, that is, there was no electricity coming to your house, remember how you swore that you didn’t have time to do anything and you needed light, you needed a TV, kettles and a bunch of other electrical appliances. After all, if we were to lose power forever, we would go back to those ancient times when food was cooked over fires and we lived in cold wigwams.

A whole poem can be devoted to the importance of electricity in our lives, it is so important in our lives and we are so accustomed to it. Although we no longer notice that it comes into our homes, when it 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. Ellion L., Wilkons U... Physics. Moscow: Science.

4. KoltunM. World of physics. Moscow.

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

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

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

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