Losses in electric networks are considered the difference between the transmitted electric energy from the producer to the recorded consumed electric energy of the consumer. Losses occur on power lines, in power transformersdue to eddy currents during the consumption of devices with reactive load, as well as due to poor insulation of conductors and theft of unaccounted electricity. In this article we will try to talk in detail about what are the losses of electricity in electric networks, as well as consider measures to reduce them.

Distance from power plant to supplying organizations

Accounting and payment of all types of losses is regulated by the legislative act: “Decree of the Government of the Russian Federation of December 27, 2004 N 861 (as amended of February 22, 2016)“ On the approval of the Rules of non-discriminatory access to electric power transmission services and the provision of these services ... ”p. VI. The procedure for determining losses in electric networks and payment of these losses. If you want to deal with who should pay for part of the lost energy, we recommend that you study this act.

When electric power is transmitted over long distances from the producer to the supplier, it is lost part of the energy for many reasons, one of which is the voltage consumed by ordinary consumers (it is 220 or 380 V). If you carry out the transportation of such voltage from the generators of power plants directly, then it is necessary to lay electrical networks with a wire diameter that will provide all the necessary current with the specified parameters. The wires will be very thick. It will not be possible to hang them on power lines, because of the large weight, laying in the ground will also cost a lot.

You can learn more about that in our article!

To eliminate this factor, high-voltage power lines are used in distribution networks. A simple calculation formula is as follows: P \u003d I * U. Power is equal to the product of current and voltage.

By increasing the voltage during electric power transmission in electric networks, it is possible to significantly reduce current, which will make it possible to dispense with wires with a much smaller diameter. The pitfall of this transformation is that there are losses in transformers that someone has to pay. By transmitting electricity with such a voltage, it is significantly lost from poor contact of conductors, which over time increase their resistance. Losses increase with increasing air humidity - the leakage current at insulators and the crown increases. Also, losses in cable lines increase while reducing the insulation parameters of the wires.

Transferred energy supplier to the supplying organization. That, in turn, should bring the parameters into the necessary indicators: convert the resulting product into a voltage of 6-10 kV, dilute it with cable lines by points, and then again convert it to a voltage of 0.4 kV. Again, transformation losses occur during the operation of transformers 6-10 kV and 0.4 kV. Electricity is delivered to the consumer at the right voltage - 380 V or 220V. Any transformer has its own efficiency and is designed for a specific load. If the power consumption is greater or less than the design power, the losses in the electrical networks increase regardless of the desire of the supplier.

The next pitfall is the mismatch in the power of the transformer, which converts 6-10 kV to 220V. If consumers take energy more than the nameplate power of the transformer, it either fails or fails to provide the necessary output parameters. As a result of reducing the voltage of the network, electrical appliances operate in violation of the passport regime and, as a result, increase consumption.

Measures to reduce technical losses of electricity in power supply systems are discussed in detail in the video:

Home conditions

The consumer received his 220/380 V on the meter. Now, the electrical energy lost after the meter rests with the end user.

It consists of:

1. Losses on exceeding calculated consumption parameters.
2. Bad contact in switching devices (circuit breakers, starters, switches, lampholders, plugs, sockets).
3. The capacitive nature of the load.
4. Inductive nature of the load.
5. The use of outdated lighting systems, refrigerators and other old equipment.

Consider measures to reduce electricity losses in homes and apartments.

Clause 1 - the fight against this type of loss is one: the use of conductors corresponding to the load. In existing networks, it is necessary to monitor the compliance of wire parameters and power consumption. If it is impossible to adjust these parameters and bring them back to normal, you should put up with the fact that energy is lost on heating the wires, as a result of which the parameters of their insulation change and the likelihood of a fire in the room increases. About that, we talked about in the corresponding article.

A.2 - poor contact: in circuit breakers - this is the use of modern designs with good non-oxidizing contacts. Any oxide increases resistance. In starters - the same way. Switches - an on-off system must use a metal that can withstand moisture, elevated temperatures. Contact must be ensured by a good pressing of one pole to another.

A.3, A.4 - reactive load. All electrical appliances that do not belong to incandescent lamps, old-style electric stoves have a reactive component of electricity consumption. Any inductance, when a voltage is applied to it, resists the passage of current through it due to the resulting magnetic induction. Over time, electromagnetic induction, which prevented the passage of current, helps its passage and adds to the network part of the energy, which is harmful to common networks. The so-called eddy currents arise, which distort the true readings of electric meters and make negative changes in the parameters of the supplied electricity. The same thing happens with capacitive loading. The arising eddy currents spoil the parameters of the electricity supplied to the consumer. Fight - the use of special reactive energy compensators, depending on the load parameters.

A.5. Use of outdated lighting systems (incandescent bulbs). Their efficiency has a maximum value of 3-5%, and maybe less. The remaining 95% goes to the heating of the filament and, as a consequence, to the heating of the environment and radiation that is not perceived by the human eye. Therefore, to improve this type of lighting has become impractical. Other types of lighting appeared - fluorescent lamps, which have become widely used recently. The efficiency of fluorescent lamps reaches 7%, and LED up to 20%. Using the latter will save energy right now and during operation due to the long service life - up to 50,000 hours (incandescent lamp - 1,000 hours).

Separately, I would like to note that it is possible to reduce the loss of electric energy in the house with the help. In addition, as we have said, electricity is lost when it is stolen. If you notice that, you must immediately take appropriate measures. Where to call for help, we told in the corresponding article, which referred to!

The above methods of reducing power consumption give a reduction in the load on the wiring in the house and, as a result, reduce losses in the power grid. As you already understood, the methods of struggle are most widely disclosed to household consumers because not every owner of an apartment or house knows about possible losses of electricity, and the supplying organizations in their state keep specially trained workers on this topic who are able to deal with such problems.

Electricity losses in electric networks
Loss of electricity in electric networks is the most important indicator of the efficiency of their work, a clear indicator of the state of the electricity metering system, the efficiency of energy sales activities of energy supplying organizations.
This indicator more and more clearly testifies to the accumulating problems that require urgent solutions in the development, reconstruction and technical re-equipment of electric networks, improvement of methods and means of their operation and management, in improving the accuracy of electricity metering, the efficiency of collecting money for electricity supplied to consumers, etc. .P.
According to international experts, the relative losses of electric energy during its transmission and distribution in the electric networks of most countries can be considered satisfactory if they do not exceed 4-5%. Losses of electricity at the level of 10% can be considered the most admissible from the point of view of physics of transmission of electric energy through networks.
It is becoming increasingly apparent that a sharp aggravation of the problem of reducing electricity losses in electric networks requires an active search for new ways to solve it, new approaches to choosing appropriate measures, and most importantly, to organizing work to reduce losses.
Due to the sharp reduction in investments in the development and technical re-equipment of electric networks, in improving the systems for managing their modes, accounting for electricity, a number of negative trends arose that negatively affect the level of losses in the networks, such as outdated equipment, physical and moral depreciation of electricity metering devices, mismatch of installed equipment of transmitted power.
From the above it follows that against the background of ongoing changes in the economic mechanism in the energy sector, the economic crisis in the country, the problem of reducing electricity losses in electric networks has not only not lost its relevance, but, on the contrary, has been put forward as one of the tasks of ensuring the financial stability of energy supplying organizations .
Some definitions:
Absolute power loss   --– the difference of the electricity supplied to the electric network and useful to the consumers.
Technical energy losses   - losses due to physical processes of transmission, distribution and transformation of electricity are determined by calculation.
Technical losses are divided into conditionally constant and variables (depending on the load).
Commercial electricity losses are losses defined as the difference between absolute and technical losses.

STRUCTURE OF COMMERCIAL ELECTRICITY LOSSES
In the ideal case, commercial losses of electricity in the electric network should be zero. It is obvious, however, that in real conditions, the supply to the network, useful leave and technical losses are determined with errors. The differences of these errors are in fact the structural components of commercial losses. They should be minimized as far as possible through the implementation of appropriate measures. If this is not possible, it is necessary to amend the readings of the electricity meters to compensate for the systematic errors in the measurement of electricity.

Measurement errors of electricity supplied to the network and useful energy supplied to consumers.
The measurement error of electricity in the general case can be divided into
many components. Consider the most significant error components of measuring complexes (IR), which may include: current transformer (CT), voltage transformer (VT), electricity meter (SE), line connecting the SE to the VT.
The main components of the measurement errors of the electricity supplied to the network and useful electricity released include:

measurement errors of electricity in normal conditions
iR operations defined by accuracy classes TT, VT and SE;
additional errors in the measurement of electricity in real operating conditions of the infrared due to:
underestimated against standard power factor
load (additional angular error); .
the effect on magnetic fields of electromagnetic and electromagnetic fields of various frequencies;
underloading and overloading of CT, VT and SE;
asymmetry and level of voltage supplied to the IR;
operation of solar cells in unheated rooms with unacceptably low
temperature, etc .;
insufficient sensitivity of solar cells at their low loads,
especially at night;
systematic errors due to excess operating life of the IC.
errors associated with incorrect connection schemes of electric meters, current transformers and current transformers, in particular, violations of phasing of connection of meters;
errors due to faulty electricity meters;
errors in taking readings of electric meters due to:
errors or intentional misrepresentations of the records;
inconsistencies or failure to meet deadlines
meter reading, violation of the bypass counting schedules -
chikov;
errors in determining conversion rates
electricity meters.
It should be noted that with the same values \u200b\u200bof the components of the errors in measuring the supply to the network and productive supply, commercial losses will decrease, and for different ones, they will increase. This means that from the point of view of reducing commercial losses of electricity, it is necessary to pursue a coordinated technical policy to improve the accuracy of measurements of net supply and net output. In particular, if, for example, we unilaterally reduce the systematic negative measurement error (modernize the accounting system) without changing the measurement error, the commercial losses will increase, which, incidentally, takes place in practice.

The value of permanent losses of electricity in the elements of the electric network is

W"=(R   to + R   y + R   xx) T   on \u003d R"T   on, (8.1)

where T   on - the on time or the operating time of the elements of the electrical network during the year. For overhead and cable lines and transformers, when performing design calculations, it is accepted T   on \u003d 8760 hours

The total amount of electricity loss in the network is

W=W"+W". (8.2)

Consider methods for determining variable losses in the electrical network. Let for an element of an electric network, for example an overhead line having active resistance R, the annual load schedule is known. This graph is presented as a step graph of duration D t   i of each load R   i. (Fig. 8.1, a).

The energy transmitted during the year through the considered element of the network is expressed as

W= . (8.3)

This energy is the area of \u200b\u200bthe figure bounded by the load curve.

On the same graph, construct a rectangle with a height equal to the largest load R   max, and an area equal to the area of \u200b\u200bthe actual load curve. The base of this rectangle will be time   T   max This time is called maximum load duration. During this time, during the operation of the network element with the highest load, the same electricity will be transmitted through it as during the operation according to the actual annual load schedule. Averages T   max for various industries are given in.

Power losses in the considered network element for each itime interval will be

R   i \u003d ( S   i / U   nom) 2 R=(P   i / U   nom cos) 2 R, (8.4)

where cos is the load power factor.

In fig. 8.1 b a step-by-step graph of power losses, constructed according to expression (8.4), is given. The area of \u200b\u200bthis graph is equal to the annual variable electricity losses in the considered network element

  a) b)

Fig. 8.1. Duration load graphs for time

T   max ( a) and time max ( b)

W"= . (8.5)

By analogy with fig. 8.1 a   construct a rectangle with a height equal to the largest loss R   max, and an area equal to the area of \u200b\u200bthe actual schedule of electricity losses. The base of this rectangle will be the time max. This time is called time of greatest power loss. During this time, during the operation of the network element with the highest load, the energy losses in it will be the same as during the operation according to the actual annual load schedule.

Connection between T   max and max are approximately established by empirical dependence

max \u003d (0.124+ T   max 10 -4) 2 8760. (8.6)

With the prospective design of electrical networks, the load schedule of consumers is usually not known. With a certain degree of certainty, only the largest design load is known. R   max

For typical consumers, reference values \u200b\u200bprovide values T   max In this case, the variable annual energy losses in the element of the electric network are determined by the expression

W"=P   max max, (8.7)

where max is calculated by the expression (8.6).

Security Questions for Section 8

1. Explain the terms “permanent losses” and “variable losses” of electricity.

2. What are the components of permanent losses.

3. What is the number of hours of heavy use?

4. What is the number of hours of greatest power loss?

5. How variable energy losses are calculated during design

electrical networks?

Electricity Losses
  - causes and remedies.

Topic "

To begin with, it is necessary to clarify with the concept of electric energy losses for a better understanding of the problem. As in any other field (mechanics, electronics, heat engineering, etc.), during the operation of a particular system, there are natural energy losses. In mechanics they are caused by friction, in heat engineering - by heat transfer and imperfect thermal insulation. Electricity also has factors that can reduce the efficiency of electric power transmission over a distance, and this is primarily electrical resistance.

As you should remember from school physics, electrical resistance directly depends on the conductivity of the material (through which electric current is passed - the ordered movement of electrically charged particles). The conductivity of various materials depends on the internal structure of the crystal lattice (molecular or atomic structure of the substance). The best option for transmitting electricity over a distance is copper and aluminum (from which conductive wires, wires and cables are pulled). But in addition to the substance itself, other factors also influence the electrical resistance of conductors - this is the length of the conductor, its cross-section, the quality of contact between the individual parts of the power line, the physical processes that occur during the operation of the electrical system, etc.

So, as you know, any electric power network is a functional (devices, systems, devices, circuits, etc.) parts that are interconnected by wires and cables. In various parts of the power grid, electricity losses occur. Let us first consider the losses characteristic of the transmitting part of the network (power wires and cables). As mentioned above, cable and wire products have their own electrical resistance. A certain section of the wire corresponds to its own nominal current strength, which can flow with minimal losses. To reduce this type of loss, it is necessary, when calculating, to correctly select the cross section of the power cable (guided by special tabular data).

When choosing the material of a power electric wire or cable, it is usually worth choosing between price and quality. Aluminum is cheaper in terms of cost, but it has a number of significant drawbacks, one of which is the worse electrical conductivity (therefore, large losses of electricity during its transmission). Copper wires and cables are preferable in terms of reducing energy losses, although they are more expensive (comparing with aluminum).

The next important factor on which the loss of electricity in electric networks depends is the quantity and quality of switching electrical connections of wires and power cables. That is, any electrical network or system contains many contact connections (electrical connections of wires and cables, contact connections between switching elements, such as relays, conductive brushes of traction lines and electric motors, etc.). Even the best electrical contact (made by welding and soldering) can not be compared with a homogeneous conductor. Moreover, it should be noted that over time, any electrical contact is subject to aging and loss of its original connection quality. To reduce energy losses in this case, you should initially make and use high-quality electrical connections and devices, as well as periodically carry out preventive maintenance of these places.

Although not the main, but an important factor affecting the loss of electricity in networks, devices and systems is the presence of reactive electric power. To combat it, special compensating elements should be used in power networks. Compensation of reactive energy is done using specially selected capacitors (electric capacitors) and inductors (coils).

Separation of losses into components can be carried out according to different criteria: the nature of losses (constant, variable), voltage classes, groups of elements, production units, etc. For the purposes of analysis and rationing of losses, it is advisable to use an enlarged structure of electricity losses, in which losses are divided into components based on their physical nature and specificity of methods for determining their quantitative values.

Based on this approach, actual losses can be divided into four components:

1) technical losses of electricity caused by physical processes that occur during the transmission of electricity through electric networks and expressed in the conversion of part of the electricity into heat in the elements of the networks. Theoretically, technical losses can be measured by installing appropriate devices that record the supply and release of electricity at the facility in question. In practice, it is impossible to evaluate their actual value with acceptable accuracy using measuring instruments. For an individual element, this is due to the relatively small value of losses, comparable with the error of metering devices. For example, the measurement of losses in a line, the actual energy loss of which is 2%, using instruments with an error of ± 0.5%, can lead to a result of 1.5 to 2.5%. For facilities that have a large number of points of supply and supply of electricity (electric network), the installation of special devices at all points and the simultaneous taking of their readings is practically unrealistic (especially for determining power losses). Electricity meters are installed at all these points, but we cannot say that the difference in their readings is the actual value of technical losses. This is due to the territorial dispersion of numerous devices and the inability to ensure complete control of the accuracy of their testimony and the absence of cases of exposure to other persons. The difference in readings of these devices represents the actual loss, from which the desired component should be distinguished. Therefore, it can be argued that it is impossible to measure technical losses on a real network object. Their value can only be obtained by calculation based on the known laws of electrical engineering;

2) the power consumption for substations SN, necessary to ensure the operation of the technological equipment of the substations and the life of the staff. This flow rate is recorded by meters installed on transformers CH substations;

3) losses of electricity due to errors in its measurement (underestimation of electricity, metrological losses). These losses are obtained by calculation on the basis of data on metrological characteristics and operating modes of devices used to measure energy (current transformers, current transformers and electric meters themselves). The calculation of metrological losses includes all metering devices for the supply of electricity from the network, including metering devices for the consumption of electricity at MV substations;

4) commercial losses caused by the theft of electricity, inconsistency of meter readings with electricity payments by household consumers, and other reasons in the field of organization of control over energy consumption. Commercial losses do not have an independent mathematical description and, as a result, cannot be calculated autonomously. Their value is defined as the difference between actual losses and the sum of the first three components.

The first three components of the enlarged loss structure are determined by the technological needs of the process of electric power transmission through networks and instrumental accounting of its receipt and supply. The sum of these components is well described by the term technological losses. The fourth component - commercial losses - represents the impact of the “human factor” and includes all the manifestations of such an impact: deliberate theft of electricity by some subscribers by changing meter readings, energy consumption in addition to meters, non-payment or incomplete payment of meter readings, determining the receipt and release of electricity at some accounting points by calculation (if the boundaries of the balance sheet of the networks and the places of installation of metering devices do not coincide), etc.

The loss structure, in which the aggregated loss components are grouped according to various criteria, is shown in Fig. 1.1.

Each loss component has its own more detailed structure.

Load losses include losses:

• in wires of transmission lines;
• power transformers and autotransformers;
• current limiting reactors;
• high frequency communication traps;
• current transformers;
• connecting wires and buses of substation switchgear (RU).

The last two components, due to the lack of practice of their element-by-element calculations and insignificant values, are usually determined on the basis of specific losses calculated for average conditions and are included in the composition of conditionally constant losses.

Losses idle move   include permanent (load-independent) losses:

• in power transformers (autotransformers); compensating devices (synchronous and thyristor compensators, capacitor banks and shunt reactors);
• equipment of the electric power metering system (TT, VT, meters and connecting wires);
• valve arresters and surge arresters;
• devices for connecting high-frequency communications (RF communications); cable insulation.

Losses due to weather conditions (climate loss) include three components:

• crown losses in overhead power lines (VL) 110 kV and above;
• losses from leakage currents at VL insulators;
• power consumption for smelting ice.

Electricity consumption at SN substations is determined by the operating modes of various (up to 23) types of electric power supply. This consumption can be divided into six components:

• for space heating;
• ventilation and lighting;
• substation control systems and auxiliary devices of synchronous compensators;
• equipment cooling and heating;
• operation of air circuit breaker compressors and pneumatic oil circuit breaker drives;
• maintenance of equipment, voltage regulation devices under load (on-load tap-changer), distillers, ventilation of a closed switchgear (switchgear), heating and passage lighting (other consumption).

Errors in electricity metering include components due to errors in measuring CTs, VTs and electric meters. Commercial losses can also be divided into numerous components that differ in the causes of their occurrence.

All of these components are discussed in detail in subsequent chapters.

The criteria for classifying a part of electricity as loss may be physical and economic in nature. Some experts believe that the energy consumption at the substations SN should be attributed to the supply of electricity, and the remaining components - to losses. The consumption of CH substations by the nature of the use of electricity is really no different from its use by consumers. However, this is no reason to consider it a useful vacation, which is understood as the electricity supplied to consumers. The consumption of electricity at SN substations is the internal consumption of the network facility. In addition, with this approach it is unreasonably assumed that the consumption of part of the energy in the network elements for the delivery of its other part to consumers (technical losses), in contrast to the consumption at substations, is not useful.

Metering devices do not change power flows through the network, they just do not quite accurately register them. Therefore, some experts consider it theoretically incorrect to attribute the underestimation of electricity due to instrument errors to losses (because the amount of electricity does not change on how the devices register it!).

One can agree with the theoretical correctness of such reasoning as, and at the same time, with their practical futility. It is not science that forces us to determine the loss structure (for scientific research, all approaches make sense), but economics. Therefore, to analyze reported losses, economic criteria should be applied. From an economic point of view, losses are that part of the electricity for which its registered useful supply to consumers turned out to be less than the electricity received by the network from electricity producers. A useful supply of electricity is understood not only as the electricity for which the funds actually came into the account of the energy supplying organization, but also the one to which the bills were issued, that is, the energy consumption is fixed. Billing is a practice that applies to legal entities whose energy consumption is recorded monthly. In contrast, the monthly readings of meters that record energy consumption by household customers are usually unknown. The useful supply of electricity to household subscribers is determined by the payment received per month, so all unpaid energy automatically falls into losses.

The energy consumption at SN substations is not a product paid by the final consumer, and from an economic point of view is no different from the energy consumption in network elements for the transmission of the rest of it to consumers.

The underestimation of the volumes of useful electricity supplied by metering devices (underestimation) is of the same economic nature as the two components described above. The same can be said about the theft of electricity. Therefore, all four of the loss components described above are the same from an economic point of view.

Actual losses are a strictly determinate value, strictly related to money received for energy sold. The task of “correcting” reported losses based on accounting for meter errors is meaningless, since it cannot lead to a change in the amount of received (and under-received) funds.

A lost ruble remains lost no matter what the reason and where it is lost. But in order to take the most effective measures to reduce losses, you need to know where and for what reasons they occur. In this regard, the main task of calculating and analyzing losses is to determine their detailed structure, identify specific foci of losses and assess the possibilities of their reduction to economically justified values. One of the methods of such a loss diagnosis is the analysis of electric power imbalances at facilities (substations, network enterprises) and in network organizations.