Production of electricity transmission Its use. Production and use of electrical energy - knowledge hypermarket

I administration
II production and use of electricity
1. Generation of electricity
1.1 Generator
2. Use of electricity
III transformers
1. Purpose
2. Classification
3. Device
4. Characteristics
5. Modes
5.1 idle stroke
5.2 Short Circuit Mode
5.3 Load mode
IV Electricity Transmission
V Goro.
1. History
2. Results
VI List of References

I. Introduction

Electricity, one of the most important species Energy, plays a huge role in modern world. It is a rod economies of states, determining their position in the international arena and the level of development. Huge amounts of money are invested annually into the development of scientific sectors related to electricity.
Electricity is an integral part everyday lifeTherefore, it is important to own information about the peculiarities of its production and use.

II. Production and use of electricity

1. Generation of electricity

Electricity generation - electricity generation by converting it from other types of energy using special technical devices.
To generate electricity use:
The electrical generator is an electrical machine in which the mechanical work is converted into electrical energy.
Sunny battery or photocell - electronic device that converts energy electromagnetic radiation, mostly light range, in electrical energy.
Chemical current sources - transformation of a portion of chemical energy into electrical, by means of a chemical reaction.
Radioisotope sources of electricity - devices using the energy released during radioactive decay, for heating the coolant or transforming it into electricity.
Electricity is produced in power plants: thermal, hydraulic, atomic, solar, geothermal, wind and others.
Almost all power plants with industrial importance are used as follows: The energy of the primary energy carrier using a special device is completely transformed into the mechanical energy of the rotational motion, which is transmitted to a special electrical machine - the generator where it is produced electricity.
Major three types of power plants: TPP, HPP, NPP
The leading role in the electric power industry of many countries is played by thermal power plants (TPP).
Thermal power plants require a huge amount of organic fuel, its reserves are reduced, and the cost is constantly increasing due to all the complicated conditions for the production and range of transportation. The fuel use coefficient in them is quite low (no more than 40%), and the volume of waste polluting environment, Great.
Economic, technical and economic and environmental factors Do not allow to consider thermal power plants by a perspective method for producing electricity.
Hydropower installation (HPP) are the most economical. Their efficiency reaches 93%, and the cost of one kWh is 5 times cheaper than with other methods for generating electricity. They use an inexhaustible source of energy, serviced by the minimum number of workers, are well regulated. The largest and power of individual hydropower plants and aggregates, our country occupies leading position in the world.
But the pace of development is constrained by the considerable costs and terms of construction, due to the remoteness of the construction of hydroelectric power plants from large cities, lack of roads, difficult construction conditions, are influenced by seasonality of river regime, reservoirs are flooded with large squares valuable lands, large reservoirs negatively affect the environmental situation, powerful hydropower plants can only be built in places of availability of relevant resources.
Nuclear power plants (NPP) work according to one principle with thermal power plants, i.e., there is a transformation of steam thermal energy into the mechanical energy of rotation of the turbine shaft, which leads to the generator, where the mechanical energy is transformed into electrical.
The main advantage of NPPs is a 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, uranium reserves on Earth exceed the reserves of traditional mineral fuels, and during the trouble-free operation, NPPs are slightly affected by the environment.
The main disadvantage of NPP is the possibility of accidents with catastrophic consequences, to prevent major security measures required. In addition, nuclear power plants are poorly regulated (for their full stop or inclusion takes several weeks), radioactive waste processing technologies have not been developed.
Nuclear energy has grown into one of the leading industries. national economy And continues to develop rapidly, ensuring safety and environmental purity.

1.1 Generator

The electrical generator is a device in which non-electrical types of energy (mechanical, chemical, thermal) are converted into electrical energy.
The principle of the generator is based on the phenomenon electromagnetic inductionwhen in the conductor moving in a magnetic field and crosses its magnetic power lines, EMF is induced consequently, such a conductor can be considered as a source electrical Energy.
The method of obtaining an induced EMF in which the conductor moves in a magnetic field, moving up or down, is very uncomfortable with its practical use. Therefore, the generators use not straightforward, but the rotational motion of the conductor.
The main parts of all generator are: a system of magnets or most often electromagnets creating a magnetic field, and a system of conductors crossing this magnetic field.
Generator alternating current - Electrical machine transforming mechanical energy into the electrical energy of alternating current. Most alternating current generators use a rotating magnetic field.

When rotating the frame changes magnetic flow Through it, therefore, EDC is induced in it. Since with the help of the current collector (rings and brushes), the frame is connected to an external electrical circuit, an electric current occurs in the frame and external circuit.
With uniform rotation of the frame, the angle of rotation varies by law:

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

where S. - Frame area.
Under the law of electromagnetic induction, Faraday EMF induction, which occurs in the frame is equal to:

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

where i. - current at any time, I M. - current strength amplitude (maximum module value of current value), φ C. - Shift phases between fluctuations of current and voltage strength.
The electrical voltage on the clamps of the generator is changing according to a sinusodal or cosine law:

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

2. Use of electricity

Electricity supply of industrial enterprises. Industrial enterprises consume 30-70% of electricity generated as part of an electric power system. A significant scatter of industrial consumption is determined by the industrial development and climatic conditions of various countries.
Electrified electricity supply. Rectifiable electrical transport substations on constant current (urban, industrial, intercity) and lowering PS long-distance electric vehicles on alternating current are powered by electricity from electrical networks EES.
Power supply of utility consumer services. This group of PE includes a wide range of buildings located in residential areas of cities and settlements. These are residential buildings, administrative and management buildings, educational and scientific institutions, shops, health care buildings, cultural and mass purposes, catering etc.

III. Transformers

Transformer - static electromagnetic devicehaving two or more Inductive-related windings and intended for conversion by means of electromagnetic induction of one (primary) AC system to another (secondary) AC system.

Transformer device diagram

1 - Primary transformer winding
2 - Magnetic Line
3 - Secondary transformer winding
F. - direction of the magnetic flux
U 1. - Voltage on the primary winding
U 2. - Voltage on the secondary winding

The first transformers with open magnetic core suggested in 1876 P.N. Apples, which applied them to power the electric "candle". In 1885, Hungarian scientists M. Deri, O. Blati, K. Typernovsky developed single-phase industrial transformers with a closed magnetic circuit. In 1889-1891 M.O. Dolo-Dobrovolsky offered a three-phase transformer.

1. Purpose

Transformers are widely used in various fields:
For transmission and distribution of electrical energy
Usually, in power plants, alternators are produced by electrical energy at a voltage of 6-24 kV, and electricity to transmit electricity to long distances is beneficial with significantly large stresses (110, 220, 330, 400, 500, and 750 kV). Therefore, at each power plant, there are transformers that increase the voltage.
The distribution of electrical energy between industrial enterprises, settlements, in cities and rural areas, as well as inside industrial enterprises are produced by air and cable lines, at a voltage of 220, 110, 35, 20, 10 and 6 kV. Therefore, in all distribution nodes, transformers lowering voltage to a value of 220, 380 and 660 V. must be installed.
To provide schema Enable valves in converting devices and voltage matching and input of the converter (converter transformers).
For various technological purposes: Welding ( welding transformers), power supply electrothermal installations (electrical transformers), etc.
To power the various chains of radio equipment, electronic equipment, communication devices and automation, electrical appliances, for separating electrical circuits of various elements of the specified devices, to coordinate the voltage, etc.
To include electrical instruments and some devices (relays, etc.) into high voltage electrical circuits or in the circuit on which large currents are passing, in order to expand the measurement limits and ensuring electrical safety. (measuring transformers)

2. Classification

Transformers classification:

For the purpose: Power General (used in the transmission lines and distribution of electricity) and special use (furnace, rectifier, welding, radio transformers).
By type of cooling: with air (dry transformers) and oily (oil transformers) with cooling.
By the number of phases on the primary side: single-phase and three-phase.
On the form of a magnetic pipeline: rod, armor, toroidal.
By the number of windings on the phase: two-winding, three-winding, multi-winding (more than three windings).
By the design of the windings: with concentric and alternating (disk) windings.

3. Device

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

Principle of the device of a single-phase two-winding transformer
The magnetic core is a magnetic transformer system, which closes the main magnetic flux.
When applied to the primary winding of alternating voltage, the secondary winding is induced by the same frequency. If you connect some electrical receipt to the secondary winding, then there is an electric current in it and a voltage is installed on the secondary clamps of the transformer, which is somewhat less than the EDC and in some relatively low degreely depends on the load.

Conditional transformer designation:
a) - a transformer with a steel core, b) - a transformer with a core from ferrite

4. Characteristics of the transformer

The rated power of the transformer is the power to which it is designed.
Nominal primary voltage - voltage on which the primary transformer winding is calculated.
Nominal secondary voltage - voltage at the clips of the secondary winding, resulting in idle transformer and rated voltage on the primary winding clips.
Nominal currents are determined by the corresponding rated power and voltage values.
The highest nominal voltage of the transformer is the largest of the nominal voltages of the transformer winding.
The lower rated voltage is the smallest of the nominal voltages of the transformer winding.
The average rated voltage is the rated voltage, which is intermediate between the highest and lower rated voltage of the transformer winding.

5. Modes

5.1 idle stroke

The idling mode is the mode of operation of the transformer, at which the secondary winding of the transformer is open, and an alternating voltage is applied to the primary winding clamps.

In the primary winding of the transformer connected to the source of alternating current flow, as a result of which an alternating magnetic flux appears in the core. Φ Putting both windings. Since φ is the same in both windings of the transformer, the change Φ it leads to the appearance of the same EMF induction in each twist of primary and secondary windings. Instant EMF induction e. In any turn of the windings equally and determined by the formula:

where is the amplitude of EDS in one turn.
The amplitude of EMF induction 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 on the primary winding, as on the resistor, is very small, compared to ε 1.and therefore for existing voltage values \u200b\u200bin the primary U 1. and secondary U 2. The windings will be fair to the following expression:

K. - Transformation coefficient. For K.\u003e 1 reduced transformer, and when K.<1 - повышающий.

5.2 Short Circuit Mode

The short circuit mode is the mode when the outlook outputs are closed by a conductor with a resistance equal to zero ( Z.=0).

A short circuit of the transformer under operating conditions creates emergency mode, as the secondary current, and therefore, the primary increases in several tens of times compared with the nominal. Therefore, in circuits with transformers, it is possible to protect the transformer in the short circuit, the transformer automatically turns off.

It is necessary to distinguish between two short circuit modes:

Emergency mode - when the secondary winding is closed at nominal primary voltage. With such a closure, currents increase in 15¸ 20 times. The winding is deformed, and the insulation is charred. Iron also burns. This is a hard mode. The maximum and gas protection shuts off the transformer from the network during emergency short circuit.

The prototype of short circuit mode is the mode when the secondary winding is closed, and such a reduced voltage is supplied to the primary winding when the rated current proceeds - this U K. - Short circuit voltage.

In laboratory conditions, you can conduct a test short circuit of the transformer. In addition, the stress expressed in percent U K., P. I 1 \u003d i 1 denote u K. and called the short circuit voltage of the transformer:

where U 1N - Nominal primary voltage.

This is a transformer characteristic, indicated in the passport.

5.3 Load mode

The load mode of the transformer is the transformer mode in the presence of currents of at least two main windings, each of which is closed on the outer chain, while the currents flowing in two or more windings in idle mode are not taken into account:

If a voltage is connected to the primary winding of the transformer U 1.and secondary winding to connect with the load, currents will appear in the windings I 1. and I 2.. These currents will create magnetic streams Φ 1. and Φ 2.to meet each other. The total magnetic flux in the magnetic circuit decreases. As a result of this, induced by the total flow of EDC ε 1. and ε 2. decrease. Active voltage value U 1. It remains unchanged. Reduction ε 1. Causes an increase in current I 1.:

With increasing current I 1. flow Φ 1. Increases exactly enough to compensate for the fluxing effect Φ 2.. The equilibrium is restored again with a practically the same value of the total flow.

IV. Electricity transmission

Transmission of electricity from the power plant to consumers is one of the most important energy tasks.
Electricity is transmitted mainly by alternating current air lines (LEP), although there is a tendency to more widely use cable lines and DC lines.

The need to transmit electricity to the distance is due to the fact that electricity is produced by large power plants with powerful aggregates, and consumed relatively low-power electric drivers distributed in a significant area. The trend towards the concentration of generating facilities is due to the fact that relative costs for the construction of power plants decrease with their growth and the cost of the generated electricity is reduced.
The accommodation of powerful power plants is carried out taking into account a number of factors such as, for example, the presence of energy resources, their appearance, stocks and possibilities of transportation, natural conditions, the possibility of working in the composition of the unified power system, etc. Often, such power plants are significantly removed from the main centers of electricity consumption. The operation of single electric power systems, covering extensive areas depends on the efficiency of electricity transmission.
Transmit electricity from its production places to consumers is necessary with minimal losses. The main reason for these losses is to transform the part of the electricity into the internal energy of the wires, their heating.

According to the law of Jowle-Lenza, the amount of heat Q.allocated for t in the conductor resistance R. When passing current I. Equally:

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

Therefore, to maintain the power transmitted to long distances, it is necessary to increase the voltage in the same time, which time the current is reduced in the wires:

From the formula it follows that with constant values \u200b\u200bof the transmitted power of the current and resistance of wires, the losses for heating in the wires are inversely proportional to the square voltage in the network. Therefore, for transmission of electricity at a distance of several hundred kilometers, high-voltage power lines (LEP) are used, the voltage between the wires of which is tens, and sometimes hundreds of thousands of volts.
With the help of LEP, adjacent power plants are combined into a single network called the power system. The Unified Energy System of Russia includes a huge number of power plants managed from a single center and ensures uninterrupted power supply to consumers.

V. GOELRO.

1. History

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

Over 200 figures of science and technology were involved in the work of the Commission. He headed the commission GM. Krzhizhanovsky. The Central Committee of the Communist Party and Personally V.I. Lenin sent the work of the Goelro Commission, determined the basic principal provisions of the country's electrification plan.

By the end of the 1920, the Commission made a huge work and prepared the "Electrification Plan of the RSFSR" - the volume of 650 pages of text with cards and regimens of electrification areas.
The plan of the Goello, designed for 10-15 years, implemented Leninist ideas of electrification of the entire country and creating a large industry.
In the field of electricity economy, the plan consisted of a program designed for the restoration and reconstruction of pre-war electric power industry, the construction of 30 district electric stations, the construction of powerful regional thermal power plants. The power plants were planned to equip the boilers and turbines.
One of the main ideas of the plan was the widespread use of huge hydrophorenergores of the country. The root reconstruction on the basis of electrification of all sectors of the country's national economy and mainly the increase in heavy industry, the rational placement of industry throughout the country is envisaged.
The implementation of the GOALRO plan began in difficult conditions of the Civil War and the economic destroyer.

Since 1947, the USSR held the 1st place in Europe and the 2nd in the world for the production of electricity.

Plan Goello played a huge role in our country: without him, it would not be possible to bring the USSR in such a short time among the most developed countries in the industrial environment. The implementation of this plan has formed the entire domestic economy and still determines it to a large extent.

The preparation and implementation of the GOELRO plan became possible and exclusively due to the 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, focusing in the hands of all economic and political power, its strength and will, as well as Traditional Cathedral Community Mentality of the People and its obedient relationship to the Supreme Governors.
The Goello plan and its implementation have proven the high efficiency of the state planning system in the conditions of severely centralized power and predetermined the development of this system for long decades.

2. Results

By the end of 1935, the electrical construction program was overfulfilled several times.

Instead 30, 40 district power plants were built, at which, together with other large industrial stations, 6914 thousand kW of capacity was introduced (from them district, 4540 thousand kW - almost three times more than according to the Helro plan).
In 1935, among district power plants there were 13 electric centers of 100 thousand kW.

Before the revolution, the capacity of the largest power station of Russia (1st Moscow) was only 75 thousand kW; There was not a single large hydroelectric station. By the beginning of 1935, the total installed capacity of hydroelectric power plants reached almost 700 thousand kW.
The largest Dneprovskaya HPP, Svirkaya 3rd, Volkhovskaya, and others, the Svirkaya 3rd, Volkhovskaya and others were built in the highest point of their development.

Electricity was almost unknown in the villages before the revolution. Large landowners installed small power plants, but there were few of them.

Electricity has become applied in agriculture: in mills, feed cutters, grain-cleaning machines, on sawmills; In industry, and later - in everyday life.

List of used literature

Venikov V. A., long-range electricity, M.- L., 1960;
Sovalov S. A., power transmission modes 400-500 square meters. UES, M., 1967;
Bessonov, L.A. Theoretical foundations of electrical engineering. Electrical chains: Tutorial / L.A. Bessonov. - 10th ed. - M.: Gardarians, 2002.
Electrical engineering: educational and methodical complex. /AND. M. Kogol, G. P. Dubovitsky, V.N. Borodyanko, V. S. Gong, N. V. Klinachev, V. V. Krymsky, A. Ya. Ergard, V. A. Yakovlev; Edited by N. V. Klinachev. - Chelyabinsk, 2006-2008.
Electrical systems, t. 3 - energy transmission by variable and direct current of high voltage, M., 1972.

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ELECTRODYNAMICS

Electromagnetic induction phenomenonlies in the occurrence of electric current in a closed circuit with any change of magnetic flux Through the surface limited to this circuit.

Alternating current-this is an electric current whose strength in any way changes with time.

Transformer-this is a device for increasing or lowering alternating voltage.

1. Production:

Thermal power plant (TPP), a power plant generating electrical energy as a result of the transformation of thermal energy released during organic fuel combustion.

On thermal power plants, the chemical energy of fuel is converted first into mechanical, and then into electrical. Fuel for such a power station can serve as coal, peat, gas, combustible shale, fuel oil.

2. Transmission:

Transformer-Development, which allows you to raise and lower the voltage. AC conversion is carried out using transformers. The transformer consists of a closed iron core, on which two (sometimes more) coils with wire windings are attached. One of the windings, called the primary, connects to the source of alternating voltage. The second winding to which the "load" is attached, i.e., devices and devices that consume electricity are called secondary. The transformer effect is based on the phenomenon of electromagnetic induction. When the AC passed on the primary winding in the iron core, an alternating magnetic flux appears, which excites induction EMF in each winding.

3. Consumption:

Electronization and automation of production are the most important consequences of the "second industrial" or "microelectronic" revolution in the economy of developed countries. The development of comprehensive 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 embedded in various devices for managing their work. Science in the field of communications and communications is very violently developed. Satellite communications is already used not only as a means of international communication, but also in everyday life - satellite antennas are not uncommon and in the city.

Electros saving problems. Russia has enormous energy saving prospects and at the same time is one of the most wasteful countries in the world. Energy saving directly depends on the rational use of existing energy resources. Huge energy losses are characterized by housing and communal services. According to expert counts, about 70% heat loss occurs due to the negligence relationship of consumers. Often in apartments have batteries without power adjustment, as a result of which they work for the whole and tenants have to open windows to reduce the temperature in the room. To implement the potential of energy saving in the housing and public utilities, it is planned to introduce the widespread introduction of accounting devices, proceed to the required standards of energy efficiency for new and reconstructed buildings, modernize the heat supply systems of buildings and structures, introduce energy-saving lighting systems, the introduction of energy-saving instruments and technologies on boiler houses, sewage facilities, Vodokanal enterprises, Providing budget organizations of the rights of the order by means of the funds saved as a result of the implementation of energy saving projects for up to 5 years and the other.

Electrical Current Safety.Dangerous for a person is considered a current from 25 V. In this situation, it is necessary to clearly distinguish the voltage and current strength. Kills exactly the last one. For example: Blue sparks of static discharges have a voltage of 7000 V, but insignificant force, whereas the voltage of the socket is 220 V, but with a current of 10-16 a may cause death. Moreover, the passage of current with a force of 30-50 mA through the heart muscle can already cause fibrillation (fluttering) of the heart muscle and the reflex stop of the heart. How it will end, quite understandable. If the current does not hit the heart (and the path of electricity in the human body is very bunciful), then its impact may cause paralysis of the respiratory muscles, which is also nothing good.

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

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

Speed \u200b\u200bof electromagnetic waves.The wavelength is the private from the fission division.

Radiocommunication principles. The principles of radio communications are as follows. The alternating electric current of high frequency created in the transmitting antenna causes a rapid electromagnetic field in the surrounding space, which is distributed as an electromagnetic wave. Reaching the receiving antenna, the electromagnetic wave causes an alternating current of the same frequency in which the transmitter works.

in physics

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

students 11 class A

MOU school number 85

Catherine.

Essay plan.

Introduction

1. Electricity production.

1. Types of power plants.

2. Alternative energy sources.

2. Electricity transmission.

transformers.

3. Use of electricity.

Introduction

The birth of energy occurred several million years ago when people learned how to use fire. The fire gave them warmth and light, was a source of inspiration and optimism, weapons against enemies and wild animals, therapeutic agent, an assistant in agriculture, preservative of products, technological means, etc.

The beautiful myth of Prometheus, who gave people to people, appeared in ancient Greece much later, as in many parts of the world, methods of pretty sophisticated handling of fire, its production and extinguishing, conservation of fire and rational use of fuel were mastered.

Over the years, fire has been maintained by burning plant energy (wood, shrubs, reeds, grass, dry algae, etc.), and then the opportunity was found to use fossil substances to maintain fire: stone coal, oil, slate, peat.

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

Power generation.

Types of power plants.

Thermal power plant (TPP), power plant generating electrical energy as a result of the transformation of thermal energy released during organic fuel combustion. The first TPPs appeared at the end of the 19th century and received predominant distribution. In the mid-70s, the 20th century TPP is the main type of electrical stations.

Thermal electric stations are divided into condensation (CAC) designed to develop only electrical energy and heat and power center (CHP), excluding electrical thermal energy in the form of hot water and steam. Large COPs of the district value were called state district power plants (GRES).

The simplest concept of the COP, operating on the corner, is presented in the figure. Coal is fed to the fuel bunker 1, and from it - to the crushing unit 2, where turns into dust. Coal dust enters the steam generator firebox (steam boiler) 3 having a system of tubes in which the chemical purified water is circulated, called the nutrient. In the boiler, water heats up, evaporates, and the resulting saturated steam is brought to a temperature of 400-650 ° C and under pressure 3-24 MPa enters steam pipelines into a steam turbine 4. Steam parameters depend on the power of the aggregates.

Thermal condensation power plants have a low efficiency (30-40%), since most of the energy is lost with exhausting filling gases and condenser cooling water. Constructing KES is beneficial in the immediate vicinity of fuel mining. At the same time, electricity consumers can be at a considerable distance from the station.

Heat electrofentral It differs from the condensation station installed on it a special heat process turbine with steam selection. On the CHP, one part of the steam is fully used in a turbine for generating electricity in the generator 5 and then enters the capacitor 6, and the other having a greater temperature and pressure is selected from the intermediate stage of the turbine and is used for heat supply. Condensate pump 7 through deaerator 8 and then the nutritional pump 9 is fed to the steam generator. The number of pair selected depends on the need of enterprises in thermal energy.

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

So much smaller distribution received heat stations with gas turbines (GTES), pARKAZY (PGES) and diesel installations.

In the combustion chamber, GTES burn gas or liquid fuel; The combustion products with a temperature of 750-900 ºС enroll into the gas turbine rotating the electric generator. The efficiency of such TPPs is usually 26-28%, power - up to several hundred MW . GTES is usually used to cover electrical load peaks. CPD PGES can reach 42 - 43%.

The most economical are large thermal steam turbine power plants (abbreviated TPP). Most TPPs of our country are used as a fuel coal dust. For the production of 1 kWh electricity, several hundred grams of coal is spent. In a steam boiler, over 90% of the energies secreted by the fuel are transmitted. In the turbine, the kinetic energy of the jet steam is transmitted by Rotor. The turbine shaft is rigidly connected to the generator shaft.

Modern steam turbines for TPP are very perfect, high-speed, high-economical machines with a large resource of work. Their capacity in general reaches 1 million 200 thousand kW, and this is not the limit. Such machines are always multistage, i.e., there are usually several dozen discs with working blades and the same amount, before each disk, groups of nozzles, through which steam jet flows. Pressure and temperature steam gradually decrease.

From the course of physics, it is known that the efficiency of thermal motors increases with an increase in the initial temperature of the working fluid. Therefore, the steam entering the turbine is adjusted to high parameters: temperatures - almost up to 550 ° C and pressure - up to 25 MPa. The efficiency coefficient of TPP reaches 40%. Most of the energy is lost along with a hot waste steam.

Hydroelectric station (HPP), a complex of structures and equipment, by which the energy of water flow is converted into electrical energy. HPP consists of a serial chain hydraulic structures, providing the necessary concentration of water flow and the creation of pressure and energy equipment that converts the energy moving under pressure into the mechanical energy of rotation, which, in turn, is converted into electrical energy.

The pressure of the HPP is created by the concentration of the river falling on the bodied area, or derivation or dam and derivation together. The main energy equipment of the HPP is located in the HPP building: in the machine room of the power plant - hydraulic units, Auxiliary equipment, automatic control and control devices; In the central administration of the control - the operator-dispatcher or auto operator hydroelectric power station. Rising transformer substation It is placed both inside the building of the HPP and in individual buildings or on open areas. Distribution devices Often are located in the open area. The HPP building can be divided into sections with one or more units and auxiliary equipment separated from adjacent parts of the building. With the HPP building or inside it, a mounting platform is created for the assembly and repair of various equipment and for auxiliary maintenance operations of the HPP.

Installed power (in MW) distinguish HPP powerful (St. 250), middle (up to 25) and small (up to 5). Power HPP depends on the pressure (difference of levels of the upper and lower beef ), Water consumption used in hydro 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, the impermanence of the load of the power system, the repair of hydraulic units or hydraulic structures, etc.) The pressure and water consumption are continuously changing, and, in addition, consumption changes when adjusting the power of the hydropower plant. There are one-time, weekly and daily operating cycles of the HPP operation.

According to the maximum intake, the HPP is divided into high-pressure (more than 60 m) average (from 25 to 60 m) and low-profrans (from 3 to 25 m). On the plain rivers, the pressure rarely exceed 100 m, Under the mountain conditions, you can create pressure to 300 through the dam m. And more, and with the help of derivation - up to 1500 m. The hydropower station for the pressure used is approximate, conditional.

According to the scheme of use of water resources and the concentrations of heads, the HPP is usually divided into rUSLOSY , veidine , derivational with pressure and non-pressure derivation, mixed, hydroaccumulating and tidal .

In the robust and reginted hydroelectric water pressure, the water pressure is created by a dam, a permitting river and raising the water level in the upper beef. At the same time, some flooding of the river valley is inevitable. The channels and the high-speed hydroelectric power plants also build on plain multi-water rivers and on mountain rivers, in narrow compressed valleys. For channels, hydroelectric power plants are characterized by pressure up to 30-40 m.

At higher pressure, it is inappropriate to transmit hydrostatic water pressure on the building of hydrostatic water. In this case, type applies dam HPP, in which the pressure front is overlapped with a dam, and the HPP building is located beyond the dam, adjacent to the lower befe.

Another type of layout veidine HPP corresponds to mountain conditions at relatively small river expenditures.

Electricity transmission is a process that consists in the supply of electricity to consumers. Electricity is performed on remote sources of production (power plants) with huge generators using coal, natural gas, water, atomic decay or wind.

The current is transmitted through transformers that increase its voltage. It is high voltage is economically beneficial when transmitting energy over long distances. High-voltage power lines extend throughout the country. On them, electric current reaches substations from large cities, where it is lowered by its tension and send it to small (distribution) power lines. Electric current travels through distribution lines in each area of \u200b\u200bthe city and enters into transformer booths. Transformers reduce the voltage to a certain standard value that is safe and necessary for the operation of household devices. The current falls into the house on the wires and passes through the counter showing the amount of energy consumed.

The transformer is a static device that converts an alternating electric current of one voltage into an alternating current of another voltage without changing its frequency. It can only work on alternating current.

The main structural parts of the transformer

The device consists of three main parts:

Primary transformer winding. The number of turns N 1.
Core closed form made of magnetic material (for example, steel).
Secondary winding. The number of turns N 2.

In the diagrams, the transformer is depicted in this way:

Principle of operation

The operation of the power transformer is based on the law of electromagnetic induction of Faraday.

Between two separate windings (primary and secondary), which are associated with a common magnetic flux, mutual induction is manifested. Mutual induction is a process with which the primary winding induces the voltage in the secondary winding located in close proximity to it.

A variable current comes to the primary winding that produces a magnetic stream when connected to a power source. The magnetic stream passes through the core and since it changes over time, it excites in the secondary winding of EMF induction. The current voltage on the second winding may be lower than on the first, then the transformer is called downwards. At the raising transformer on the secondary winding voltage is higher. The frequency of the current remains unchanged. Effective decrease or increase in voltage cannot increase electrical power, so at the output of the transformer, the current strength is accordingly in proportion to or decreases.

For amplitude voltage values \u200b\u200bon windings, you can record the following expression:

k is the transformation coefficient.

For an increase in transformer k\u003e 1, and for lowering - k<1.

During the operation of the real device, there is always loss of energy:

the windings are heated;
the work on the magnetization of the core is spent;
in the core there are currents of Fouco (they have a thermal effect on a massive core).

To reduce losses in heating, transformer cores are made not from a solid piece of metal, but from thin plates, between which the dielectric is located.