Losses in power networks are considered the difference between the transmitted electricity from the producer to the accounted consumed electricity by the consumer. Losses occur on power lines, in power transformers, due to eddy currents when consuming devices with a 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 electrical networks, and also consider measures to reduce them.

Distance from the power plant to the supplying organizations

Accounting and payment for 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 on February 22, 2016) “On Approval of the Rules for Non-Discriminatory Access to Electricity Transmission Services and the Provision of These Services ...” paragraph VI. The procedure for determining losses in electrical networks and paying for 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 electricity is transmitted over long distances from the producer to the supplier to the consumer, part of the energy is lost for many reasons, one of which is the voltage consumed by ordinary consumers (it is 220 or 380 V). If such a voltage is transported directly from the generators of power plants, 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, due to the large weight, laying in the ground will also be expensive.

You can learn more about that in our article!

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

By increasing the voltage during the transmission of electricity in electrical networks, you can significantly reduce the current, which will make it possible to get by with wires with a much smaller diameter. The pitfall of this conversion is that there are losses in transformers that someone has to pay for. When transmitting electricity with such a voltage, it is also significantly lost from poor contact of conductors, which increase their resistance over time. Losses increase with increasing air humidity - the leakage current on the insulators and on the corona increases. Losses in cable lines also increase with a decrease in wire insulation parameters.

The supplier transferred energy to the supplying organization. That, in turn, should bring the parameters to the required indicators: convert the resulting products to a voltage of 6-10 kV, separate them with cable lines point by point, and then again convert them to a voltage of 0.4 kV. Again, there are losses for the transformation during the operation of transformers 6-10 kV and 0.4 kV. Electricity is delivered to the household consumer in the required voltage - 380 V or 220 V. Any transformer has its own efficiency and is designed for a certain load. If the power consumption is more or less than the calculated power, the losses in the electrical networks increase regardless of the desire of the supplier.

The next pitfall is the discrepancy between the power of the transformer that converts 6-10 kV to 220V. If consumers take energy more than the nameplate power of the transformer, it either fails or will not be able to provide the necessary parameters at the output. As a result of a decrease in the mains voltage, 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 falls on the end consumer.

It is made up of:

1. Losses in case of exceeding the calculated consumption parameters.
2. Poor contact in switching devices (knife switches, starters, switches, lamp holders, plugs, sockets).
3. Capacitive nature of the load.
4. Inductive nature of the load.
5. Use of outdated lighting systems, refrigerators and other old equipment.

Consider measures to reduce electricity losses in houses and apartments.

P.1 - there is only one fight against this type of loss: 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 correct these parameters and bring them back to normal, one should put up with the fact that energy is lost to heat 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.

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

P.3, P.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. After a while, electromagnetic induction, which prevented the passage of current, helps its passage and adds to the network part of the energy that is harmful to the general networks. There are so-called eddy currents that distort the true readings of electricity meters and make negative changes in the parameters of the supplied electricity. The same happens with a capacitive load. The resulting eddy currents spoil the parameters of the electricity supplied to the consumer. Struggle - the use of special reactive energy compensators, depending on the load parameters.

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

Separately, I would like to note that it is possible to reduce the loss of electrical energy in the house with the help of. In addition, as we have already 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 we referred to!

The above methods of reducing power consumption reduce 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 for residential consumers because not every owner of an apartment or house is aware of possible losses of electricity, and supplying organizations in their state keep workers specially trained on this topic who are able to deal with such problems.

Losses of electricity in electrical networks
Losses of electricity in electrical networks are 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 supply 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 electrical networks, improvement of methods and means of their operation and management, in improving the accuracy of electricity metering, the efficiency of collecting funds for electricity supplied to consumers, etc. .P.
According to international experts, the relative losses of electricity during its transmission and distribution in the electrical 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 maximum allowable from the point of view of the physics of transmission of electricity through networks.
It is becoming more and more obvious that the 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 a sharp reduction in investments in the development and technical re-equipment of electrical networks, in improving the systems for managing their modes, electricity metering, a number of negative trends have arisen that adversely affect the level of losses in networks, such as: outdated equipment, physical and obsolescence means of electricity metering, discrepancy between the installed equipment and the transmitted power.
It follows from the above 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 electrical networks has not only not lost its relevance, but, on the contrary, has moved into one of the tasks of ensuring the financial stability of energy supply organizations .
Some definitions:
Absolute electricity losses--– the difference between electricity supplied to the electrical network and usefully supplied to consumers.
Technical losses of electricity– losses caused by the physical processes of transmission, distribution and transformation of electricity are determined by calculation.
Technical losses are divided into conditionally constant and variable (depending on the load).
Commercial electricity losses are losses defined as the difference between absolute and technical losses.

STRUCTURE OF COMMERCIAL POWER LOSSES
In the ideal case, commercial losses of electricity in the electrical network should be equal to zero. It is obvious, however, that in real conditions, supply to the network, useful supply and technical losses are determined with errors. The differences between 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 make adjustments to the readings of electric meters to compensate for systematic errors in electricity measurements.

Errors in measurements of electricity supplied to the network and usefully supplied to consumers.
The measurement error of electricity in the general case can be divided into
many components. Let's consider the most significant components of the errors of measuring complexes (MC), which may include: current transformer (CT), voltage transformer (VT), electricity meter (SE), line connecting the ESS to the VT.
The main components of the measurement errors of the electricity supplied to the network and usefully supplied electricity include:

measurement errors of electricity in normal conditions
IC work, determined by accuracy classes ТТ, ТН and СЭ;
additional errors in electricity measurements in real operating conditions of the IC, due to:
understated against the normative power factor
load (additional angular error); .
the effect on the SE of magnetic and electromagnetic fields of various frequencies;
underload and overload of CT, TN and SE;
asymmetry and the level of voltage supplied to the IR;
operation of solar cells in unheated rooms with unacceptably low
what temperature, etc.;
insufficient sensitivity of solar cells at their low loads,
especially at night;
systematic errors due to excess service life of the IC.
errors associated with incorrect connection diagrams of electric meters, CT and VT, in particular, violations of the phasing of the connection of meters;
errors due to faulty electricity metering devices;
errors in taking readings of electric meters due to:
errors or deliberate distortions of records of indications;
non-simultaneity or failure to meet deadlines
taking meter readings, violation of schedules bypassing the account-
chiki;
errors in determining the coefficients of conversion of indications
electricity meters.
It should be noted that with the same signs of the components of the measurement errors of supply to the network and useful supply, commercial losses will decrease, and with different signs they will increase. This means that from the point of view of reducing commercial losses of electricity, it is necessary to pursue an agreed technical policy to improve the accuracy of measurements of supply to the network and productive supply. In particular, if we, for example, unilaterally reduce the systematic negative measurement error (modernize the accounting system), without changing the measurement error, commercial losses will increase, which, by the way, takes place in practice.

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

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

where T on - the time of switching on or the time of operation 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 = 8760 h.

The total value of electricity losses in the network is

W=W"+W". (8.2)

Consider ways to determine variable losses in an electrical network. Let for an element of an electrical network, for example, an overhead line with active resistance R, the annual load schedule is known. This graph is presented as a step graph for 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 will be expressed as

W= . (8.3)

This energy is the area of ​​the figure bounded by the load curve.

On the same graph, we will construct a rectangle with a height equal to the maximum load R max , and an area equal to the area of ​​the actual load curve. The base of this rectangle will be the time T max. This time is called duration of use of the maximum load. During this time, during the operation of the network element with the greatest load, the same electric power will be transmitted through it as during 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 i-th time interval will be

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

where cos is the load power factor.

On fig. 8.1, b a stepped graph of power losses, built according to expression (8.4), is shown. The area of ​​this graph is equal to the annual variable losses of electricity in the considered network element

a) b)

Rice. 8.1. Load-by-duration graphs for timing

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 ​​the actual electricity loss graph. The base of this rectangle will be the time max . This time is called time of greatest power loss. During this time, when the network element with the highest load is operating, the power losses in it will be the same as when operating according to the actual annual load schedule.

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

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

In the long-term design of electrical networks, the load schedule of consumers, as a rule, is not known. With a certain degree of certainty, only the highest design load is known R max.

For typical consumers in the reference literature, values ​​are given T max. In this case, the variable annual losses of electricity in the electrical network element are determined by the expression

W"=P max max , (8.7)

where max is calculated from expression (8.6).

Security questions for section 8

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

2. Name the components of permanent losses.

3. What is the number of hours of use of the heaviest load?

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

5. How variable energy losses are calculated in design

electrical networks?

Energy Losses
- Causes and remedies.

Topic "

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

As you must 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 a substance). The most optimal option for transmitting electricity over a distance is copper and aluminum (from which conductive conductors, wires and cables are drawn). But in addition to the substance itself, other factors also affect 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 electrical power network is a functional (devices, systems, devices, circuits, etc.) parts that are interconnected by wires and cables. Different parts of the power grid have their own power losses. Let's first look at the losses that are 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 wire section corresponds to its own rated current, which can flow with minimal losses. To reduce this type of loss, it is necessary, in the calculations, to correctly select the cross section of the power cable (guided by special tabular data).

When choosing the material of a power electrical wire or cable, it is usually worth making a choice between price and quality. Aluminum is cheaper in terms of cost, but it has a number of significant drawbacks, one of which is the worst electrical conductivity (hence, large losses of electricity during its transmission). Wires and cables made of copper are more preferable in terms of reducing energy losses, although they are more expensive (compared to aluminum).

The next important factor on which the losses of electricity in electrical networks depend 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 wires and cables, contact connections between switching elements, such as relays, current-carrying brushes of traction lines and electric motors, etc.). Even the best electrical contact (made by welding and soldering) cannot be compared to a homogeneous conductor. Moreover, it should be taken into account that over time, any electrical contact is subject to aging and loss of its original connection quality. To reduce power 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 electrical power. To combat it, special compensating elements should be used in power supply networks. Reactive energy compensation is done using specially selected capacitances (electric capacitors) and inductances (coils).

Separation of losses into components can be carried out according to different criteria: the nature of losses (permanent, variable), voltage classes, groups of elements, production units, etc. For the purposes of analysis and normalization 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 specifics of methods for determining their quantitative values.

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

1) technical losses of electricity due to physical processes occurring 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 output of electricity at the facility in question. In practice, it is impossible to estimate their real value with acceptable accuracy using measuring instruments. For an individual element, this is due to a relatively small value of losses, comparable to the error of metering devices. For example, measuring losses in a line with an actual power loss of 2% using instruments with an error of ±0.5% can lead to a result of 1.5 to 2.5%. For objects that have a large number of points of receipt and release of electricity (electrical network), the installation of special devices at all points and the provision of synchronous reading of their readings is practically unrealistic (especially for determining power losses). At all these points, electricity meters are already installed, 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 impossibility of ensuring full control over the correctness of their testimony and the absence of cases of impact on them by other persons. The difference in the readings of these devices is 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 on the basis of the known laws of electrical engineering;

2) electricity consumption at the substation mains, necessary to ensure the operation of the substation technological equipment and the life of the maintenance personnel. This consumption is recorded by meters installed on the MV transformers of the substations;

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

4) commercial losses caused by theft of electricity, inconsistency of meter readings with payment for electricity by household consumers and other reasons in the field of organizing 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 the actual losses and the sum of the first three components.

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

The structure of losses, in which the aggregated components of losses are grouped according to various criteria, is shown in fig. 1.1.

Each loss component has its own more detailed structure.

Load losses include:

• in wires of transmission lines;
• power transformers and autotransformers;
• current-limiting reactors;
• barriers of high-frequency communication;
• current transformers;
• connecting wires and buses of distribution devices (RU) of substations.

The last two components, due to the lack of practice of their element-by-element calculations and their insignificant value, are usually determined on the basis of specific losses calculated for average conditions and are included in 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 electricity metering system (TT, TN, meters and connecting wires);
• valve arresters and surge arresters;
• devices for connecting high-frequency communications (HF communications); cable insulation.

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

• corona losses in overhead power lines (VL) 110 kV and above;
• losses from leakage currents through insulators VL;
• electricity consumption for ice melting.

Electricity consumption at SN substations is determined by the operating modes of various (up to 23) types of ED. This cost can be broken down into six components:

• for space heating;
• ventilation and lighting of premises;
• substation control systems and auxiliary devices of synchronous compensators;
• equipment cooling and heating;
• operation of compressors of air circuit breakers and pneumatic actuators of oil circuit breakers;
• maintenance of equipment, on-load voltage regulation devices (OLTC), distillers, indoor switchgear ventilation (ZRU), heating and lighting of the checkpoint (other consumption).

Electricity metering errors include components due to errors in measuring CTs, VTs and electric meters. Commercial losses can also be divided into numerous components, differing in the reasons for their occurrence.

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

The criteria for classifying part of the electricity as losses can be of a physical and economic nature. Some experts believe that the consumption of electricity at SN substations should be attributed to the supply of electricity, and the rest of the components - to losses. The consumption of SN substations in terms of the nature of the use of electricity is really no different from its use by consumers. However, this is not a reason to consider it as a useful supply, which is understood as 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 of SN substations, is not useful.

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

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

Electricity consumption for MV substations is not a product paid by the end consumer, and from an economic point of view, it does not differ in any way from the electricity consumption in network elements for the transmission of the rest of it to consumers.

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

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

The lost ruble remains lost, no matter for what reason and where it is lost. But in order to take the most effective measures to reduce losses, it is necessary 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 loss centers and assess the possibilities of reducing them to economically justified values. One of the methods for such diagnostics of losses is the analysis of electricity imbalances at facilities (substations, grid enterprises) and in grid organizations.