IN electrical networks There are large actual losses of electricity.
Of the total losses, losses in power transformers MUP "PES" account for approximately 1.7%. Electricity losses in power transmission lines with a voltage of 6-10 kV are about 4.0%. Electricity losses in 0.4 kV networks are 9-10%.
An analysis of the dynamics of absolute and relative electricity losses in Russian networks, their operating and loading modes shows that there are practically no significant reasons for the increase in technical losses caused by the physical processes of transmission and distribution of electricity. The main reason for losses is the increase in the commercial component.
The main causes of technical losses are:
Deterioration of electrical equipment;
Use of outdated types of electrical equipment;
Inconsistency of the electrical equipment used with the existing loads;
Non-optimal steady-state conditions in distribution networks by level
voltage and reactive power.
The main causes of commercial losses are:
Unacceptable errors in electricity measurements (non-compliance of metering devices with accuracy classes, non-compliance of current transformers with existing loads, violation of verification deadlines and malfunctions of electricity metering devices);
Use of imperfect methods for calculating the amount of electricity supplied in the absence of metering devices;
Imperfection of methods for taking readings from metering devices and issuing receipts directly by subscribers in the household sector;
Non-contractual and unaccounted for electricity consumption (theft);
Distortion of the volume of electricity supplied to consumers.
ACTUAL ELECTRICITY LOSSES
IN MUP "PODILSK ELECTRIC GRID"
STRUCTURE OF ACTUAL ELECTRICITY LOSSES
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Technological losses of electricity (hereinafter referred to as TLE) during its transmission through TSO electrical networks include technical losses in the lines and equipment of electrical networks, due to the physical processes occurring during the transmission of electricity in accordance with the technical characteristics and operating modes of the lines and equipment, taking into account the consumption of electricity for the own needs of substations and losses caused by permissible errors in the electricity metering system. The volume (quantity) of technological losses of electricity in order to determine the standard for technological losses of electricity during its transmission through electric networks is calculated in accordance with the instructions for organization in the Ministry of Energy Russian Federation work on the calculation and justification of standards for technological losses of electricity during its transmission through electrical networks, approved by order No. 000 of 01/01/2001.
Methods for calculating standard losses electrical energy
Basic Concepts
1. Reception of electrical energy into the network
2. Return of electrical energy from the network
4. Actual (reported) electricity losses in absolute units
6. Technical losses of electricity
9. Standard for technological losses of electricity in absolute units
11. Standard absolute electricity losses
Calculation of losses in electrical network equipment
ü Electricity losses in the overhead line
ü Electricity losses in the cable line
ü Electricity losses in transformers (autotransformers)
ü Electricity losses in current-limiting reactors
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Conditionally permanent losses of electricity
Ü losses in steel of power transformers and autotransformers;
Ü losses in steel of shunt reactors;
Ü corona losses in overhead lines 110 kV and above;
Ü losses in capacitor banks (BCB) and static thyristor compensators;
Ü losses in synchronous compensators (SC);
Ü losses in surge suppressors;
Ü electricity losses in direct-connection meters;
Ü losses in current and voltage measuring transformers;
Ü losses in insulation of cable lines;
Ü losses from leakage currents through overhead line insulators;
Ü losses in connecting wires and busbars of substations;
Ü electricity consumption for melting ice;
Ü electricity consumption for the auxiliary needs of substations, taking into account losses in steel and copper of auxiliary transformers if the metering does not coincide with the border balance sheet.
Variable power losses
Ü load losses of electricity in transformers and autotransformers
Ü load losses of electricity in air and cable lines
Ü electricity losses in current-limiting reactors
Methods for calculating variable losses
Method of operational calculations of steady-state conditions using data from operational control systems (OIC)
Method for calculating losses based on the data of the design day (using operational data for characteristic days)
Method for calculating losses based on average loads
Mode loss calculation method maximum loads networks using the number of hours of greatest power loss
Estimated calculation methods
Method of operational calculations
Electricity losses over a time interval in a three-winding transformer
Settlement day method
Electricity losses for the billing period
Graph shape factor
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Average load method
The more electricity losses network companies have, the higher the price of electricity, the constant increase of which places a heavy burden on the consumer.
General information
The structure of actual electricity losses consists of many components. Previously, they were often combined into two large groups: technical and commercial losses. The first included load, conditionally constant losses and electricity consumption for the own needs of substations. All other losses, including instrumental measurement errors, were attributed to the second group of losses. There are certain conventions in this classification. Electricity consumption for own needs is not inherently a “pure” technical loss, and is taken into account by electric meters. Also, metrological errors, unlike other components of commercial losses, have a different origin. Therefore, “commercial losses” were initially interpreted quite broadly; there is even such a definition as “acceptable level of commercial losses” - the value of commercial losses of electricity due to errors in the electricity metering system (electricity meters, current and voltage transformers) when the metering system complies with the requirements of the Electrical Electricity Regulations.
Currently, when classifying electricity losses, the term “technological losses of electricity” is more often used, the definition of which is established by Order of the Ministry of Energy of the Russian Federation dated December 30, 2008 No. 326 “On the organization in the Ministry of Energy of the Russian Federation of work to approve standards for technological losses of electricity during its transmission through electric networks " The collective expression “commercial losses of electricity” is currently not enshrined in legislation, but is found in industry regulatory and technical documents. In one of them, commercial losses are understood as the difference between reporting and technical losses, while “technical losses of electricity” are considered to be all “technological consumption of electricity for its transport through electrical networks, determined by calculation.”
Also, in the form of federal statistical observation No. 23-N “Information on the production and distribution of electrical energy”, approved by Order of the Federal State Statistics Service dated October 1, 2012 No. 509, the reporting indicator “commercial losses” is used. Its definition within the framework of Form 23-N sounds like “data on the amount of electricity not paid for by subscribers,” without providing a calculation formula. In industry reporting documents of network companies, for example, in forms 2-reg, 46-EE (transmission), only actual losses are indicated, and in the layouts of 7-energo, a detailed structure of technological losses is indicated. Commercial losses, as well as non-technical or non-technological losses, are not reported on these forms.
In the tables for justification and examination of technological losses of electricity for a regulated period, filled out by network organizations, the mathematical difference between actual and technological losses of electricity is called “non-technical losses of electricity”, although it is more logical to call them “non-technological”.
To avoid confusion in the terminology used, in the aggregated structure of actual electricity losses it is more correct to designate two groups:
1. Technological losses.
2. Commercial losses.
Technological losses include technical losses in electrical networks due to physical processes occurring during the transmission of electricity, electricity consumption for the own needs of substations, and losses due to permissible errors in the electricity metering system.
They are not losses of the enterprise in the fullest sense of the word, since the cost of their standard volume is taken into account in the tariff for electricity transmission. Funds to cover financial costs associated with the purchase of electricity to compensate for technological losses within the established standard are received by the network company as part of the collected revenue for the transmission of electricity.
Technical losses of electricity can be calculated according to the laws of electrical engineering, permissible errors of metering devices - based on their metrological characteristics, and consumption for the substations’ own needs can be determined based on the readings of electricity meters.
Commercial losses cannot be measured with instruments and calculated using independent formulas. They are defined mathematically as the difference between actual and technological losses of electricity and are not subject to inclusion in the standard for electricity losses. The costs associated with their payment are not compensated by tariff regulation.
The applied definition of “commercial” (English: “commerce” - “trade”) for this type of loss emphasizes the connection of the loss with the process of turnover of goods, which is electricity. Electricity losses classified as commercial are mostly electricity consumption, which various reasons not documented. Therefore, it is not taken into account as a return from the networks, and is not presented to any consumers for payment.
In accordance with current legislation, network organizations are required to pay for actual losses of electrical energy that occur in their network facilities, and therefore, for commercial losses in their composition. Commercial losses of electricity, unlike technological ones, are a direct financial loss for network companies. Being, on the one hand, the reason for the monetary expenses of the network enterprise, they are at the same time its lost profit from unpaid electricity transmission. Therefore, network organizations, to a greater extent than other participants in the electricity market, are interested in the most accurate accounting of electricity and the correct calculation of its volumes at delivery points at the borders of their balance sheet.
We can talk about the incorrectness of shifting all financial responsibility for commercial losses of electricity to network companies, since the causes of their occurrence, as well as the effectiveness of their identification and elimination, depend not only on the electric network companies. But the fact remains: commercial losses of electricity are a “headache” primarily for network organizations.
At the same time, the imperfection of the legislative and legal framework, the lack of direct contractual relations between network enterprises on energy supply with consumers, insufficient funding and the impossibility of significantly increasing the staff of employees monitoring electricity consumption, limit the ability of network organizations to identify and eliminate the causes of commercial losses of electricity.
Causes of commercial power losses
The amount of commercial electricity losses depends on the values of other structural indicators of the electricity balance. To find out the volume of commercial losses of electricity for a certain period, you must first draw up a balance of electricity for the section of the electrical network in question, determine the actual losses and calculate all the components of technological losses of electricity. Further analysis of electricity losses helps to localize their areas and identify the causes of their occurrence for the subsequent selection of measures to reduce them.
The main causes of commercial electricity losses can be grouped into the following groups:
1. Instrumental, associated with errors in measuring the amount of electricity.
2. Errors in determining the values of electricity supply to the network and useful supply to consumers.
4. Errors in calculating technological losses of electricity.
1. Work measuring systems electricity is accompanied by an instrumental error, the magnitude of which depends on the actual technical characteristics metering devices and actual operating conditions. The requirements for measuring instruments established by legislative and regulatory technical documents ultimately affect the maximum permissible amount of under-accounting for electricity, which is included in the standard process losses. Deviation of actual under-metering of electricity from the calculated one permissible value refers to commercial losses.
The main reasons leading to the emergence of commercial “instrumental” losses:
Overload secondary circuits measuring current transformers (CT) and voltage transformers (VT),
Low power factor (cos φ) of the measured load,
The influence of magnetic and electromagnetic fields of various frequencies on the electricity meter,
Asymmetry and significant voltage drop in secondary measuring circuits,
Deviations from the permissible operating temperature conditions,
Insufficient sensitivity threshold of electricity meters,
Inflated transformation ratio of measuring CTs,
Systematic errors induction electricity meters.
The measurement result is also influenced the following factors, the presence of which is largely determined by the existing network organization level of monitoring the condition and correct operation of the used fleet of metering devices:
Excessive service life of measuring systems,
Malfunction of metering devices,
Errors during the installation of metering devices, including incorrect connection diagrams, installation of measuring CTs with different transformation ratios in different phases one connection, etc.
There are still outdated induction electricity meters of accuracy class 2.5 that have exhausted their service life. Moreover, such metering devices are found not only among consumers - citizens, but also among consumers - legal entities.
According to the law in force until 2007. GOST 6570-96 “Inductive active and reactive energy meters”, the service life of electricity meters with accuracy class 2.5 was limited by the first calibration interval, and from 07/01/97 the production of meters of class 2.5 was discontinued.
Induction meters of accuracy class 2.5 are excluded from the State Register of Measuring Instruments; they are not produced and are not accepted for verification. The verification period for a single-phase induction meter is 16 years, and for a three-phase one – 4 years. Therefore, according to the timing of the verification interval, three-phase induction electricity meters of accuracy class 2.5 should not be used for commercial electricity metering for several years.
The currently valid GOST R 52321-2005 (IEC 62053-11:2003) applies to electromechanical (induction) watt-hour meters of accuracy classes 0.5; 1 and 2. For induction electric meters of class 2.5 there are currently no existing regulatory documents, establishing metrological requirements.
It can be concluded that the current use of single-phase induction electricity meters with accuracy class 2.5 as measuring instruments does not comply with the provisions Federal Law dated June 26, 2008 No. 102-FZ "On ensuring the uniformity of measurements."
2. Errors in determining the values of electricity supply to the network and useful supply to consumers are due to the following factors:
Distortion of data on actual readings of electricity meters at any stage of the operational process. This includes errors in visual meter readings, inaccurate data transfer, incorrect entry of information into electronic databases, etc.
Inconsistency of information about the metering devices used, calculated coefficients, and their actual data. Errors can occur already at the stage of concluding a contract, as well as when information is entered inaccurately into electronic databases, their untimely updating, etc. This should also include cases of replacing metering devices without simultaneously drawing up reports and recording the readings taken and installed meter, transformation ratios of instrument transformers.
Unsettled contractual terms in the field of electricity supply and the provision of electricity transmission services in relation to the composition of delivery points, metering devices and the applied algorithms for calculating losses in electrical equipment when they are installed not at the border of the balance sheet. Such situations can lead not only to errors in calculations, especially when the owner of a facility changes, the restructuring of organizations that consume electricity, etc., but also to the actual “non-contractual” power supply of facilities in the absence of official inclusion of specific delivery points in energy supply or service contracts for electricity transmission.
Lack of simultaneity in taking readings from electricity meters, both at consumers and at points of electricity supply to the network (return from the network).
Inconsistency between the calendar periods for identifying and including unaccounted for electricity in the volume of its transmission.
Installation of metering devices not on the balance sheet boundary of the networks, inaccuracies and errors in the applied algorithms for calculating electrical energy losses in network elements from the balance sheet border to the measurement point, or the absence of such algorithms for “additional calculation” of electricity losses.
Determination of the amount of transmitted electricity by calculation methods in the absence of metering devices or its malfunction.
- “Unmetered” power supply, with determination of the amount of electricity consumed by installed capacity electrical receivers, as well as using other regulatory and calculation methods. Such cases violate the provisions of Federal Law No. 261 - Federal Law "On energy saving and increasing energy efficiency and on introducing amendments to certain legislative acts of the Russian Federation" dated November 23, 2009, regarding the installation of electrical energy metering devices and their commissioning.
Insufficient equipment of electrical energy metering devices at the boundaries of the balance sheet of electrical networks, incl. with multi-apartment residential buildings.
The presence of ownerless networks, the lack of work to identify their balance holders.
Application of replacement (calculated) information during the period of under-metering of electricity in the event of a malfunction of the meter.
3. Unauthorized power consumption.
This category includes the so-called “theft” of electricity, which includes unauthorized connection to electrical networks, connection of electrical receivers in addition to the electric meter, as well as any interference with the operation of metering devices and other actions with the aim of understating the electricity meter readings. This should also include untimely notification to the energy supply organization about malfunctions of metering devices.
Unauthorized electricity consumption often accounts for the bulk of commercial losses, especially in the 0.4 kV network. Most household consumers, especially in the private residential sector, engage in all kinds of electricity theft, but there are cases of electricity theft by industrial and trading enterprises, mostly small.
The volume of electricity theft increases during periods of low air temperature, which indicates that the bulk of unaccounted electricity during this period is spent on heating.
4. Errors in calculations of technological losses of electricity:
Since commercial losses are a calculated value obtained mathematically, errors in determining technological energy consumption have a direct impact on the value of commercial losses. Errors in calculations of technological losses are determined by the calculation methodology used, completeness and reliability of information. The accuracy of calculations of load losses of electricity carried out by methods of operational calculations or calculation days is undoubtedly higher than when calculating using the method of average loads or generalized network parameters. In addition, the actual technical parameters of the electrical network elements often have deviations from the reference and passport values used in the calculations, which is associated with the duration of their operation and the actual technical condition electrical equipment. Parameter information electrical modes network operation, electricity consumption for own needs, also does not have ideal reliability, but contains a certain amount of error. All this determines the total error in calculations of technological losses. The higher their accuracy, the more accurate the calculation of commercial electricity losses will be.
Ways to reduce commercial losses
Measures aimed at reducing commercial electricity losses are determined by the reasons for their occurrence. Many measures to reduce commercial electricity losses are covered in sufficient detail in the scientific and technical literature. The main list of measures aimed at improving electricity metering devices is given in the industry instructions.
Measures to reduce commercial electricity losses can be divided into two groups:
1. Organizational, increasing the accuracy of calculations of electricity balance indicators, incl. useful holiday to consumers.
2. Technical, mainly related to the maintenance and improvement of electricity metering systems.
To the main organizational events the following should be included:
- Checking the availability of acts of delineation of balance sheet ownership by points of supply of external and internal sections of electricity metering, timely recording of all points of supply of electricity, checking for compliance with contractual terms.
- Formation and timely updating of databases on electricity consumers and metering groups, linking them to specific elements of the electrical network diagram.
- Reconciliation of actual technical characteristics of metering devices and those used in calculations.
- Checking the presence and correctness of algorithms for “additional calculation” of losses when installing metering devices not on the balance sheet boundary.
- Timely reconciliation of meter readings, maximum automation of operational activities for calculating electricity volumes to eliminate the influence of " human factor».
- Elimination of the practice of “unmetered” electricity supply.
- Carrying out calculations of technological losses of electricity, increasing the accuracy of their calculations.
- Monitoring actual imbalances of electricity at substations, timely taking measures to eliminate excess deviations.
- Calculations of “feeder” balances of electricity in the network, balances for 10(6)/0.4 kV transformer substations, in 0.4 kV lines, to identify “hot spots” of commercial electricity losses.
- Detection of electricity theft.
- Providing personnel to check metering devices and identify electricity thefts, necessary tool and inventory. Training in methods of detecting electricity theft, increasing motivation with additional material rewards taking into account work efficiency.
To the main technical activities, aimed at reducing commercial electricity losses, include the following:
- Inventory of electric power measuring systems, marking them with visual control signs, sealing of electric meters, measuring transformers, installation and sealing of protective covers of terminal clamps of measuring circuits.
- Timely instrumental testing of metering devices, their verification and calibration.
- Replacement of electricity meters and instrument transformers with metering devices with increased accuracy classes.
- Elimination of underload and overload of current and voltage transformers, unacceptable level of voltage losses in VT measuring circuits.
- Installation of metering devices at the boundaries of the balance sheet, incl. electricity metering points at the boundary of the balance sheet section passing along power lines.
- Improvement of calculation and technical accounting of electricity, replacement of outdated ones measuring instruments, as well as metering devices with technical parameters, which do not comply with legislative and regulatory-technical requirements.
- Installation of metering devices outside private property.
- Replacement of “bare” aluminum wires of overhead lines - 0.4 kV with SIP, replacement of inputs into buildings made with bare wire with coaxial cables.
- Introduction of automated information and measurement systems for commercial electricity metering (AIIS KUE), both for industrial and household consumers.
The last of the listed measures is the most effective in reducing commercial electricity losses, since it is a comprehensive solution to the main key tasks, providing reliable and remote receipt of information from each measurement point, constantly monitoring the serviceability of metering devices. In addition, the implementation of unauthorized power consumption is made as difficult as possible, and the identification of “hot spots” of losses in as soon as possible with minimal labor costs. The limiting factor for widespread automation of electricity metering is the high cost of AIMS KUE systems. The implementation of this activity can be carried out in stages, identifying priority nodes of the electrical network for automation of accounting based on a preliminary energy survey with an assessment economic efficiency implementation of the project.
To address issues of reducing commercial electricity losses, it is also necessary to improve the regulatory framework in the field of energy supply and electricity metering. In particular, the application of consumption standards utilities on electricity supply should encourage subscribers to install metering devices as quickly as possible (eliminate their malfunctions), and not to calculate the benefits of their absence. The procedure for admitting representatives of network companies to check the condition of metering devices and take their readings from consumers, primarily from individuals, should be as simple as possible, and liability for unauthorized electricity consumption should be strengthened.
Conclusion
Commercial losses of electricity are a serious financial loss for network enterprises and divert their funds from solving other pressing problems in the field of electricity supply.
Reducing commercial electricity losses is a complex task, which in its solution requires the development of specific measures based on a preliminary energy survey and determination of the actual structure of electricity losses and their causes.
ANO "Energy Saving Agency UR" carries out all work related to energy inspection of enterprises, monitoring of electricity consumption, calculation and standardization of technological losses of electricity, determination of the structure of electricity losses and development of measures to reduce them.
LITERATURE:
1. RD 34.09.254 “Instructions for reducing the technological consumption of electrical energy for transmission through electrical networks of power systems and energy associations. And 34-70-028-86”, M., SPO Soyuztekhenergo, 1987
2. RD 153-34.0-09.166-00 “Standard program for conducting energy surveys of electrical network divisions of JSC-Energo”, SPO ORGRES, 2000
3. Order of the Ministry of Energy of the Russian Federation dated December 30, 2008 No. 326 “On the organization in the Ministry of Energy of the Russian Federation of work to approve standards for technological losses of electricity during its transmission through electrical networks”
4. Rules for non-discriminatory access to services for the transmission of electrical energy and the provision of these services (approved by Decree of the Government of the Russian Federation of December 27, 2004 No. 861)
5. Vorotnitsky V.E., Kalinkina M.A. Calculation, regulation and reduction of electricity losses in electrical networks ( Educational and methodological manual) – M.: IUE GUU, VIPKenergo, IPKgossluzhby, 2003
6. Vorotnitsky V.E., Zaslonov S.V., Kalinkina M.A., Parinov I.A., Turkina O.V. Methods and tools for calculating, analyzing and reducing losses of electrical energy during its transmission through electrical networks M.: DialogueElectro, 2006
Methodology for calculating technological losses of electricity
in the power line VL-04kV of the gardening partnership
Until a certain time, the need to calculate technological losses in power lines, owned by SNT as a legal entity, or by gardeners who have garden plots within the boundaries of any SNT, was not needed. The board didn't even think about it. However, meticulous gardeners, or rather doubters, forced us to once again throw all our efforts into ways to calculate electricity losses in Power lines. The easiest way, of course, is to stupidly contact a competent company, that is, an electricity supply company or a small firm, which will be able to calculate the technological losses in their network for gardeners. Scanning the Internet made it possible to find several methods for calculating energy losses in an internal power line in relation to any SNT. Their analysis and analysis of the necessary values for calculating the final result made it possible to discard those of them that involved measuring special parameters in the network using special equipment.
The methodology offered to you for use in a gardening partnership is based on knowledge of the basics of transmission electricity via the wires of the base school course physics. When creating it, the standards of the order of the Ministry of Industry and Energy of the Russian Federation No. 21 of 02/03/2005 “Methodology for calculating standard electricity losses in electrical networks” were used, as well as the book by Yu.S. Zhelezko, A.V. Artemyev, O.V. Savchenko “Calculation, analysis and regulation of electricity losses in electrical networks”, Moscow, JSC “Publishing House NTsENAS”, 2008.
The basis for the calculation of technological losses in the network discussed below is taken from here. Methodology for calculating losses Town Hall A. You can use it, outlined below. The difference between them is that here on the site we will together analyze a simplified technique, which, using the simple, very real TSN “Prostor”, will help you understand the very principle of using formulas and the procedure for substituting values in them. Next, you will be able to independently calculate losses for your existing electrical network in TSN with any configuration and complexity. Those. The page is adapted to TSN.
Initial conditions for calculations.
IN power lines used wire SIP-50, SIP-25, SIP-16 and a little A-35 (aluminum, cross-section 35mm², open without insulation);
To simplify the calculation, let’s take the average value, wire A-35.
In our gardening association, the wires are of different sections, which is what happens most often. Anyone who wants to, having understood the principles of calculations, will be able to calculate losses for all lines with different sections, because the technique itself involves production calculation of electricity losses for one wire, not 3 phases at once, but just one (one phase).
Losses in the transformer (transformers) are not taken into account, because total consumption meter electricity installed after the transformer;
= Transformer and connection losses high voltage line The energy supply organization "Saratovenergo" calculated for us, namely the distribution network of the Saratov region, in the village "Teplichny". They averaged (4.97%) 203 kWh per month.
The calculation is made to determine the maximum amount of electricity losses;
The calculations made for maximum consumption will help cover those technological losses, which are not taken into account in the methodology, but, nevertheless, are always present. These losses are quite difficult to calculate. But, since they are, after all, not so significant, they can be neglected.
The total connected power in SNT is sufficient to provide maximum power consumption;
We proceed from the fact that, provided that all gardeners turn on their allocated power to each, there is no reduction in voltage and allocated electricity in the network. supplying organization electrical power enough so that the fuses do not burn out or the circuit breakers are not knocked out. The allocated electrical power must be specified in the Electricity Supply Agreement.
The annual consumption value corresponds to the actual annual consumption electricity in SNT- 49000 kW/h;
The fact is that if the total of gardeners and SNT electrical installations exceeds the amount of electricity allocated to everyone, then accordingly calculation of technological losses must be specified for a different amount of kW/h consumed. The more electricity the SNT consumes, the greater the losses will be. Adjustment of calculations in this case is necessary to clarify the amount of payment for technological losses in the internal network, and its subsequent approval at the general meeting.
33 sites (houses) are connected to the electrical network through 3 feeders with identical parameters (length, wire grade (A-35), electrical load).
Those. To switchboard SNT, where the common three-phase meter is located, 3 wires (3 phases) and one neutral wire. Accordingly, 11 gardeners’ houses are evenly connected to each phase, for a total of 33 houses.
The length of the power line in SNT is 800 m.
- Calculation of electricity losses by the total length of the line.
To calculate losses, the following formula is used:
ΔW = 9.3. W². (1 + tan²φ)·K f ²·K L .L
ΔW- electricity losses in kW/h;
W- electricity supplied to power line for D (days), kW/h (in our example 49000 kW/h or 49x10 6 W/h);
K f- load curve shape factor;
To L- coefficient taking into account the load distribution along the line ( 0,37 - for a line with a distributed load, i.e. 11 gardeners’ houses are connected for each phase of three);
L- line length in kilometers (in our example 0,8 km);
tgφ- reactive power factor ( 0,6 );
F- wire cross-section in mm²;
D- period in days (in the formula we use the period 365 days);
K f²- chart fill factor, calculated by the formula:
K f ² = (1 + 2K z)
3K z
Where K z- graph filling factor. In the absence of data on the shape of the load curve, the value is usually taken - 0,3 ; Then: Kf² = 1.78.
Calculation of losses using the formula is performed for one feeder line. There are 3 of them, 0.8 kilometers each.
We assume that the total load is evenly distributed along the lines inside the feeder. Those. annual consumption on one feeder line is equal to 1/3 of total consumption.
Then: W sum.= 3 * ΔW in line.
The electricity supplied to gardeners per year is 49,000 kW/h, then for each feeder line: 49000 / 3 = 16300 kW/h or 16.3 10 6 W/h- it is in this form that the value is present in the formula.
ΔW line =9.3. 16.3²·10 6. (1+0.6²) 1.78 0.37. 0,8 =
365 35
ΔW line = 140.8 kW/h
Then for a year along three feeder lines: ΔW sum.= 3 x 140.8 = 422.4 kW/h.
- Accounting for house entry losses.
Provided that all energy consumption metering devices are placed on power transmission line supports, then the length of the wire from the point of connection of the line belonging to the gardener to his individual device accounting will amount to only 6 meters (total length supports 9 meters).
Wire resistance SIP-16 (self-supporting insulated wire, cross-section 16 mm²) per 6 meters of length is only R = 0.02ohm.
P input = 4 kW(let’s take it as the calculated permitted electrical power for one house).
We calculate the current strength for a power of 4 kW: I input= P input /220 = 4000W / 220V = 18 (A).
Then: input dP= I² x R input= 18² x 0.02 = 6.48W- losses per 1 hour under load.
Then the total losses for the year in the line of one connected gardener: dW input= dP inputx D (hours per year) x Usage max. loads= 6.48 x 8760 x 0.3 = 17029 Wh (17.029 kWh).
Then the total losses in the lines of 33 connected gardeners for the year will be:
dW input= 33 x 17.029 kW/h = 561.96 kW/h
- Accounting for total losses in power lines for the year:
ΔW sum. result= 561.96 + 422.4 = 984.36 kW/h
ΔW sum. %= ΔW sum/ W sumx 100%= 984.36/49000 x 100%= 2%
Total: In an internal overhead power line SNT with a length of 0.8 kilometers (3 phases and zero), a wire with a cross-section of 35 mm², connected by 33 houses, with a total consumption of 49,000 kW/h of electricity per year, losses will be 2%
Introduction
Literature Review
1.2 Load power losses
1.3 Losses idle speed
1.4 Climate-related electricity losses
2. Methods for calculating electricity losses
2.1 Methods for calculating electricity losses for various networks
2.2 Methods for calculating electricity losses in 0.38-6-10 kV distribution networks
3. Programs for calculating electricity losses in electrical distribution networks
3.1 The need to calculate technical losses of electricity
3.2 Application of software for calculating electricity losses in distribution networks 0.38 - 6 - 10 kV
4. Rationing of electricity losses
4.1 Concept of loss standard. Methods for setting standards in practice
4.2 Standard characteristics of losses
4.3 The procedure for calculating standards for electricity losses in distribution networks 0.38 - 6 - 10 kV
5. An example of calculating electricity losses in 10 kV distribution networks
Conclusion
References
Introduction
Electrical energy is the only type of product that does not use other resources to move it from places of production to places of consumption. For this, part of the transmitted electricity is consumed, so its losses are inevitable; the task is to determine their economically justified level. Reducing electricity losses in electrical networks to this level is one of the important areas of energy saving.
Throughout the entire period from 1991 to 2003, total losses in Russian power systems grew both in absolute value and as a percentage of electricity supplied to the network.
The growth of energy losses in electrical networks is determined by the action of completely objective laws in the development of the entire energy industry as a whole. The main ones are: the tendency to concentrate electricity production at large power plants; continuous growth in electrical network loads associated with a natural increase in consumer loads and lagging growth rates bandwidth networks on the growth rate of electricity consumption and generating capacity.
In connection with the development of market relations in the country, the importance of the problem of electricity losses has increased significantly. The development of methods for calculating, analyzing electricity losses and selecting economically feasible measures to reduce them has been carried out at VNIIE for more than 30 years. To calculate all components of electricity losses in networks of all voltage classes of JSC-Energo and in the equipment of networks and substations and their regulatory characteristics, a software package has been developed that has a certificate of conformity approved by the Central Dispatch Office of the UES of Russia, Glavgosenergonadzor of Russia and the Department of Electric Networks of RAO UES of Russia.
Due to the complexity of calculating losses and the presence of significant errors, lately Particular attention is paid to the development of methods for normalizing electricity losses.
The methodology for determining loss standards has not yet been established. Even the principles of rationing have not been defined. Opinions about the approach to standardization lie in a wide range - from the desire to have an established firm standard in the form of a percentage of losses to control of “normal” losses through constantly carried out calculations on network diagrams using appropriate software.
Electricity tariffs are set based on the obtained energy loss rates. Tariff regulation is entrusted to the state regulatory bodies FEC and REC (federal and regional energy commissions). Energy supply organizations must justify the level of electricity losses that they consider appropriate to include in the tariff, and energy commissions must analyze these justifications and accept or adjust them.
This paper examines the problem of calculating, analyzing and rationing electricity losses from a modern perspective; The theoretical provisions of the calculations are presented, a description of the software that implements these provisions is given, and the experience of practical calculations is outlined.
Literature Review
The problem of calculating electricity losses has been worrying power engineers for a very long time. In this regard, very few books on this topic are currently published, since little has changed in fundamental structure networks. But at the same time enough is produced large number articles where old data is clarified and new solutions to problems related to the calculation, regulation and reduction of electricity losses are proposed.
One of latest books published on this topic is the book by Zhelezko Yu.S. "Calculation, analysis and regulation of electricity losses in electrical networks". It most fully presents the structure of electricity losses, methods for analyzing losses and the selection of measures to reduce them. Methods for normalizing losses are substantiated. Described in detail software, which implements methods for calculating losses.
Previously, the same author published the book “Selection of measures to reduce electricity losses in electrical networks: A guide for practical calculations.” Here, the greatest attention was paid to methods for calculating electricity losses in various networks and the use of one or another method was justified depending on the type of network, as well as measures to reduce electricity losses.
In the book Budzko I.A. and Levin M.S. “Power supply to agricultural enterprises and populated areas,” the authors examined in detail the problems of power supply in general, focusing on distribution networks that supply agricultural enterprises and settlements. The book also provides recommendations for organizing control over electricity consumption and improving accounting systems.
Authors Vorotnitsky V.E., Zhelezko Yu.S. and Kazantsev V.N. in the book “Electricity Losses in Electrical Networks of Power Systems” they examined in detail general issues related to reducing electricity losses in networks: methods for calculating and forecasting losses in networks, analyzing the structure of losses and calculating their technical and economic efficiency, planning losses and measures to reduce them.
In the article by Vorotnitsky V.E., Zaslonov S.V. and Kalinkini M.A. "Program for calculating technical losses of power and electricity in distribution networks 6 - 10 kV" describes in detail the program for calculating technical losses of electricity RTP 3.1 Its main advantage is ease of use and easy-to-analyze output of the final results, which significantly reduces personnel labor costs for the calculation.
Article by Zhelezko Yu.S. "Principles of normalization of electricity losses in electrical networks and calculation software" is dedicated to current problem rationing of electricity losses. The author focuses on the targeted reduction of losses to an economically feasible level, which is not ensured by the existing rationing practice. The article also makes a proposal to use standard loss characteristics developed on the basis of detailed circuit calculations of networks of all voltage classes. In this case, the calculation can be made using software.
The purpose of another article by the same author entitled “Estimation of electricity losses caused by instrumental measurement errors” is not to clarify the methodology for determining the errors of specific measuring instruments based on checking their parameters. The author of the article assessed the resulting errors in the system for accounting for the receipt and supply of electricity from the network of an energy supply organization, which includes hundreds and thousands of devices. Particular attention is paid to systematic error, which currently turns out to be a significant component of the loss structure.
In the article by Galanov V.P., Galanov V.V. “The influence of power quality on the level of power losses in networks” pays attention to the current problem of power quality, which has a significant impact on power losses in networks.
Article by Vorotnitsky V.E., Zagorsky Ya.T. and Apryatkina V.N. "Calculation, regulation and reduction of electricity losses in urban electrical networks" is devoted to clarifying existing methods calculation of electricity losses, normalization of losses in modern conditions, as well as new methods of reducing losses.
In the article by Ovchinnikov A. “Electricity losses in distribution networks 0.38 - 6 (10) kV,” the emphasis is on obtaining reliable information about the operating parameters of network elements, and above all about the loading of power transformers. This information, according to the author, will help to significantly reduce electricity losses in networks of 0.38 - 6 - 10 kV.
1. Structure of electricity losses in electrical networks. Technical losses of electricity
1.1 Structure of electricity losses in electrical networks
When transmitting electrical energy, losses occur in each element of the electrical network. To study the components of losses in various elements networks and assessing the need for a particular measure aimed at reducing losses, an analysis of the structure of electricity losses is carried out.
Actual (reported) electricity losses Δ W Otch is defined as the difference between the electricity supplied to the network and the electricity supplied from the network to consumers. These losses include components of various natures: losses in network elements that are purely physical in nature, electricity consumption for the operation of equipment installed at substations and ensuring the transmission of electricity, errors in recording electricity by metering devices and, finally, theft of electricity, non-payment or incomplete payment meter readings, etc.
Losses can be divided into components according to different criteria: the nature of losses (constant, variable), voltage classes, groups of elements, production departments, etc. For the purposes of analysis and standardization 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 the specifics of determination methods their quantitative values.
Based on this approach, actual losses can be divided into four components:
1) technical losses of electricity caused by physical processes occurring during the transmission of electricity through electrical networks and expressed in the conversion of part of the electricity into heat in network elements. Theoretically, technical losses can be measured by installing appropriate instruments that record the supply and release of electricity at the facility in question. In practice, it is impossible to estimate their actual value with acceptable accuracy using measuring instruments. For individual element this is explained by the relatively small value of losses, comparable to the error of metering devices. For example, measuring the loss of a line whose actual energy loss is 2% using instruments that have an accuracy of ±0.5% may result in a result of 1.5 to 2.5%. For facilities with a large number of points of supply and release of electricity (electrical network), installation special devices at all points and ensuring synchronous reading of them is practically unrealistic (especially for determining power losses). Electricity meters are already 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 impossibility of ensuring complete control over the correctness of their readings and the absence of cases of influence on them by other persons. The difference in the readings of these devices represents the actual losses, from which the required component should be isolated. Therefore, it can be argued that it is impossible to measure technical losses at a real network facility. Their value can only be obtained by calculation based on the known laws of electrical engineering;
2) electricity consumption at MV substations necessary to ensure operation technological equipment substations and the life of maintenance personnel. This consumption is recorded by meters installed on the MV transformers of the substations;
3) losses of electricity due to errors in its measurement (under-metering of electricity, metrological losses). These losses are obtained by calculation based on data on the metrological characteristics and operating modes of instruments used to measure energy (CTs, VTs and the electricity meters themselves). The calculation of metrological losses includes all devices for metering electricity supply from the network, including meters for metering electricity consumption at MV substations;
4) commercial losses caused by theft of electricity, discrepancies between meter readings and electricity payments by household consumers and other reasons in the area 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 determined as the difference between actual losses and the sum of the first three components.
The first three components of the enlarged structure of losses are determined by the technological needs of the process of transmitting electricity 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 manifestations of such 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, determination of receipt and supply of electricity at some metering points by calculation (if the boundaries of the balance sheet of the networks and the installation locations of metering devices do not coincide), etc.
The structure of losses, in which the enlarged 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 losses:
- in transmission line wires;
- power transformers and autotransformers;
- current-limiting reactors;
- high frequency communication barriers;
- current transformers;
- connecting wires and buses of switchgears (RU) of substations.
The last two components, due to the lack of practice in 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 the composition of conditionally constant losses.
No-load losses include constant (load-independent) losses:
- in power transformers (autotransformers); compensating devices (synchronous and thyristor compensators, capacitor banks and shunt reactors);
- electricity metering system equipment (CT, VT, meters and connecting wires);
- valve arresters and surge suppressors;
- 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 (OL) 110 kV and above;
- losses from leakage currents along overhead line insulators;
- energy consumption for melting ice.
Electricity consumption at MV substations is determined by the operating modes of various (up to 23) types of electric power supply. This expense can be broken down into six components:
- for space heating;
- ventilation and lighting of premises;
- substation control systems and auxiliary devices of synchronous compensators;
- cooling and heating of equipment;
- operation of compressors of air switches and pneumatic drives of oil switches;
- current repair of equipment, load voltage regulation devices (OLVs), distillers, indoor ventilation switchgear(closed switchgear), heating and lighting of the entrance (other consumption).
Errors in electricity metering include components caused by errors in measuring transformers, transformers 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 a portion of electricity as losses can be of a physical or economic nature. Some experts believe that electricity consumption at MV substations should be attributed to the supply of electricity, and the remaining components to losses. The consumption of MV 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 useful supply, which is understood as electricity supplied to consumers. Electricity consumption at MV substations is the internal consumption of the network facility. In addition, this approach unreasonably assumes that the consumption of part of the energy in network elements to deliver another part of it to consumers (technical losses), in contrast to the consumption of MV substations, is not useful.
Metering devices do not change power flows through the network, they just do not accurately record them. Therefore, some experts believe that it is theoretically incorrect to classify under-accounting of electricity due to instrument errors as losses (after all, the volume of electricity does not change depending on how the instruments record it!).
One can agree with the theoretical correctness of such reasoning, 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), and economics. Therefore, economic criteria should be applied to analyze reported losses. 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. The useful supply of electricity is understood not only as the electricity for which the money was actually received in the current account of the energy supply organization, but also that for which invoices are 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 residential energy consumption are usually unknown. The useful supply of electricity to household subscribers is determined by the payment received for the month, so all unpaid energy automatically falls into losses.
Electricity consumption at MV substations is not a product paid for by the end consumer, and from an economic point of view is no different from electricity consumption in network elements for transmitting the rest of it to consumers.
Underestimation of the volumes of useful electricity supplied by metering devices (under-metering) has the same economic nature as the two components described above. The same can be said about electricity theft. Therefore, all four components of losses described above are the same from an economic point of view.
Actual losses are a strictly determined value, strictly related to in cash received for sold energy. 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 money received (and not received).
A lost ruble remains lost no matter for what reason or where it was lost. But in order to accept 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 areas of losses and assess the possibilities of reducing them to economically justifiable values. One of the methods for such diagnostics of losses is the analysis of electricity imbalances at facilities (substations, network enterprises) and in network organizations.