Structure, types of electricity losses ...
Electricity losses in electric 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 supply activities of energy supplying organizations. This indicator more and more clearly indicates 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 increasing the accuracy of electricity metering, Nost cash collection for electricity supplied to consumers, etc. According to international experts, the relative losses of electricity during 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 maximum allowable from the point of view of physics of electricity transmission through networks. It is becoming increasingly apparent that a sharp aggravation of the problem of reducing energy losses in electric networks requires an active search for new ways to solve it, new approaches to the selection of appropriate measures, and most importantly, the organization of work to reduce losses. In connection with a sharp reduction in investments in the development and technical re-equipment of electric networks, in improving the systems for controlling their modes, electricity metering, a number of negative trends arose that negatively affect the level of losses in the networks, such as outdated equipment, physical and moral deterioration of electricity metering devices , mismatch of the installed equipment of the transmitted power. From the foregoing, it follows that amid the 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 advanced to one of the tasks of ensuring the financial stability of energy supplying organizations.
Absolute loss of electricity is the difference between the electricity supplied to the electrical network and the useful energy supplied to consumers.
Technical losses of electricity - losses caused by physical processes of transmission, distribution and transformation of electricity are determined by calculation. Technical losses are divided into conditionally constant and variable (depending on 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, productive supply and technical losses are determined with errors. The differences of these errors are actually the structural components of commercial losses. They should be minimized to the extent possible by 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 error in measuring electricity in the general case can be divided into many components. Let us consider the most significant error components of measuring complexes (IR), which may include: current transformer (CT), voltage transformer (VT), electricity meter (SE), connection line for solar cells to TN. The main components of the measurement errors of the electricity supplied to the network and useful electricity released include:
- errors of electric power measurements under normal conditions of IR operation, determined by accuracy classes of CT, VT and SE;
- additional errors in the measurement of electricity in real operating conditions of the infrared due to;
- underestimated against the normative load power factor (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 temperatures, etc .;
- insufficient sensitivity of solar cells at their low loads, especially at night;
- systematic errors due to excess IR life;
- 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;
- non-simultaneity or non-fulfillment of the established deadlines for taking readings of meters, violation of schedules for bypassing meters;
- errors in determining conversion factors for meter readings into electricity.
It should be noted that with the same signs of the component errors of the measurements of 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 supply to the network and useful supply. 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, by the way, takes place in practice.
Commercial losses due to underestimation of productive leave due to shortcomings in energy sales activities.
These losses include two components: billing losses and losses from theft of electricity.
This commercial component is due to:
- inaccuracy of data on consumers of electricity, including insufficient or erroneous information on concluded contracts for the use of electricity;
- errors in invoicing, including unbilled invoices to consumers due to the lack of accurate information on them and constant monitoring of the updating of this information;
- lack of control and billing errors for customers using special rates; .
- lack of control and accounting for adjusted accounts, etc.
Losses from theft of electricity
This is one of the most significant components of commercial losses, which is a matter of concern for power engineers in most countries of the world. The experience of combating theft of electricity in various countries is summarized by a special Expert Group to study issues related to the theft of electricity and unpaid bills (non-payments). The group is organized as part of the research committee on economics and tariffs of the international organization UNIPEDE. According to a report prepared by this group in December 1998, the term "theft of electricity" is used only in cases where electricity is not taken into account or is not fully recorded due to the fault of the consumer, or when the consumer opens the meter or violates the power supply system in order to reduce the meter power consumption. The generalization of international and domestic experience in the fight against theft of electricity showed that mainly these consumers are engaged in theft. Theft of electricity is carried out by industrial and commercial enterprises, but the volume of these thefts cannot be considered decisive. Electricity theft has a fairly clear upward trend, especially in regions with poor heat supply to consumers during the cold periods of the year. And also in almost all regions in the autumn-spring periods, when the air temperature has already dropped significantly, and heating has not yet been turned on. There are three main groups of methods of theft of electricity: mechanical, electrical, magnetic.
Mechanical methods of theft of electricity
Mechanical intervention in the work (mechanical opening) of the meter, which can take various forms, including:
- drilling holes in the bottom of the case, cover or glass of the meter; insertion (into the hole) of various objects such as a film 35 mm wide, needles, etc. in order to stop the rotation of the disk or reset the counter;
- moving the counter from a normal vertical to a half-horizontal position in order to reduce the speed of rotation of the disk;
- unauthorized failure of seals, violation of the alignment of the axes of mechanisms (gears) to prevent complete recording of energy consumption;
- the glass rolls when inserting a film that stops disk rotation.
Typically, mechanical intervention leaves a mark on the meter, but it is difficult to detect if the meter is not completely cleaned of dust and dirt and examined by an experienced specialist. The mechanical method of theft of electricity can be attributed to the intentionally widespread intentional damage to solar cells by household consumers or theft of meters installed on the stairwells of residential buildings. As the analysis showed, the dynamics of deliberate destruction and theft of meters almost coincides with the onset of cold weather with insufficient heating of the apartments. In this case, the destruction and theft of meters should be seen as a peculiar form of protest by the population against the inability of local administrations to ensure normal living conditions. The aggravation of the situation with heat supply to the population inevitably leads to an increase in commercial losses of electricity, which is already confirmed by the sad experience of the Far Eastern and some Siberian energy systems.
Electric methods of theft of electricity
The most common electrical method of theft of electricity in Russia is the so-called “surge” on an overhead line made with bare wire. Widely used are also such methods as:
- inverting the phase of the load current;
- the use of various types of “winders” for partial or full compensation of the load current with a change in its phase;
- shunting of the current circuit of the meter - installation of the so-called "short circuits";
- grounding of the load neutral wire;
- violation of the alternation of phase and neutral wires in a network with a grounded neutral of the supply transformer.
If the meters are switched on via measuring transformers, the following can also be used:
- disconnection of CT current circuits;
- replacement of normal VT fuses with blown ones, etc.
Magnetic methods of theft of electricity
Using magnets on the outside of the meter may affect its performance. In particular, it is possible, when using induction counters of old types, to slow down the rotation of the disk with a magnet. Currently, new types of meters manufacturers are trying to protect from the influence of magnetic fields. Therefore, this method of power theft is becoming more and more limited.
Other methods of theft of electricity
There are a number of methods for the theft of electricity of purely Russian origin, for example, theft due to the frequent change of ownership of a company with the permanent renewal of contracts for the supply of electricity. In this case, the energy supply is not able to keep track of the change of owners and receive payment for electricity from them.
Commercial electricity losses due to unowned consumers
Crisis phenomena in the country, the emergence of new joint-stock companies have led to the fact that in most energy systems in recent years there have appeared and for quite some time there are residential houses, shelters, whole residential villages that are not on the balance sheet of any organizations. Electricity and heat supplied to these houses are not paid to tenants. Attempts by power systems to turn off non-payers do not give results, as residents again unauthorizedly connect to networks. The electrical installations of these houses are not serviced by anyone, their technical condition threatens with accidents and does not ensure the safety of life and property of citizens.
Commercial losses due to the non-simultaneous payment of electricity for household consumers - the so-called “seasonal component”.
This very significant component of commercial losses of electricity takes place due to the fact that household consumers are objectively unable to simultaneously take readings of meters and pay for electricity. As a rule, payments lag behind real electricity consumption, which, of course, introduces an error in determining the actual net supply by the household consumer and in calculating the actual unbalance of electricity, since the lag can be from one to three months or more. As a rule, in the autumn-winter and winter-spring periods of the year there are underpayments for electricity, and in the spring-summer and summer-autumn periods, these underpayments are compensated to a certain extent. In the pre-crisis period, this compensation was almost complete, and energy losses for the year rarely had a commercial component. Currently, autumn-winter and winter-spring seasonal underpayments for electricity far exceed in most cases the total payment in other periods of the year. Therefore, commercial losses occur in months, quarters and for the year as a whole.
Errors of calculation of technical losses of electricity in electric networks
Since commercial electricity losses cannot be measured. They can be calculated with one error or another. The value of this error depends not only on the measurement errors of the volume of theft of electricity, the presence of “ownerless consumers”, other factors considered above, but also on the error in calculating the technical losses of electricity. The more accurate the calculations of technical losses of electricity will be, the obviously more accurate will be the estimates of the commercial component, the more objectively it is possible to determine their structure and outline measures to reduce them.