Structure, types of power losses ...
The loss of electricity in electric networks is the most important indicator of the economy of their operation, a clear indicator of the state of the electricity metering system, and the efficiency of the energy supply activities of energy supply organizations. This indicator is increasingly indicative of the accumulating problems that require urgent decisions in the development, reconstruction and technical re-equipment of electric grids, and means of their operation and management, in increasing the accuracy of electricity metering, efficiency 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%. The loss of electricity at the level of 10% can be considered the maximum permissible from the point of view of the physics of transmission of electricity through networks. It is becoming increasingly evident that the sharp aggravation of the problem of reducing the losses of electric power in electric networks requires an active search for new ways of solving it, new approaches to the selection of appropriate measures, and, most importantly, to organizing work to reduce losses. In connection with a sharp reduction in investments in the development and technical re-equipment of electric grids, in improving the management systems of their regimes, electricity metering, a number of negative trends have emerged that adversely affect the level of losses in networks, such as obsolete equipment, physical and moral wear and tear of electricity meters , inconsistency of installed equipment of transmitted power. From the above, it follows that, against the backdrop of 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 grids has not only lost its relevance, but rather has become one of the tasks of ensuring the financial stability of energy supplying organizations.
Absolute losses of electricity - the difference of electricity released into the electrical network and useful to consumers.
Technical losses of electricity - losses caused by physical processes of transmission, distribution and transformation of electricity are determined by calculation. The technical losses are divided into conditionally-constant and variable (depending on the load).
Commercial losses of electricity - losses, defined as the difference between absolute and technical losses.
STRUCTURE OF COMMERCIAL LOSSES OF ELECTRICITY
In an ideal case, the commercial losses of electric power in the electrical network must be zero. Obviously, however, that in real conditions, vacation in the network, productive leave and technical losses are determined with inaccuracies. The differences in these errors are in fact the structural components of commercial losses. They should be minimized to the extent possible through the implementation of appropriate activities. If this is not possible, corrections must be made to the meter readings, which compensate for the systematic errors in the measurement of electricity.
Measurement errors sent to the grid and usefully released electricity to consumers.
The error in the measurement of electricity in the general case can be broken down into many components. We will consider the most significant components of the errors of measuring complexes (IR), which may include: current transformer (CT), voltage transformer (VT), electricity meter (SE) to TN. The main components of measurement errors released into the network and usefully released electricity are:
- the errors in the measurement of electricity under normal operating conditions of the IR, determined by the accuracy classes of TT, TN and SE;
- additional errors in the measurement of electricity in the real operating conditions of the IR, due to;
- underestimated against the normative coefficient of load power (additional angular error);
- the effect on the solar cells of magnetic and electromagnetic fields of different frequencies;
- underload and overload of TT, VT and SE;
- asymmetry and the level of the 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 over-normative service life of infrared radiation;
- inaccuracies associated with incorrect circuits for connecting electricity meters, CTs and VTs, in particular, by phasing in the connection of meters;
- inaccuracies caused by faulty electricity metering devices;
- the errors in reading the electricity meters because of;
- errors or deliberate misrepresentation of records of evidence;
- non-simultaneous or non-fulfillment of the established deadlines for the meter reading, violation of the counter work schedules;
- errors in the determination of the coefficients for converting the readings of meters into electricity.
It should be noted that with the same signs of the components of the errors in the measurement of supply to the grid and productive supply, commercial losses will decrease, and for different - increase. This means that from the point of view of reducing commercial power losses it is necessary to carry out a coordinated technical policy to improve the accuracy of measurements of supply to the grid and productive leave. 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, incidentally, takes place in practice.
Commercial losses caused by understatement of productive vacations due to shortcomings in energy sales activity.
These losses include two components: loss on invoicing and losses from theft of electricity.
Losses on invoicing
This commercial component is due to:
- inaccuracy of data on electricity consumers, including insufficient or erroneous information on concluded contracts for the use of electricity;
- errors in billing, including unbilled accounts to consumers due to the lack of accurate information on them and constant monitoring of the update of this information;
- lack of control and errors in billing customers using special tariffs; .
- lack of control and accounting of 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 within the framework of the research committee on economics and tariffs of the international organization UNIPEDE. According to the report prepared by this group in December 1998, the term "power theft" is only applied in cases where the electricity is not accounted for or fully recorded through the fault of the consumer, or when the consumer opens the meter or breaks the power supply system in order to reduce the count consumption of electricity. The generalization of international and domestic experience in combating theft of electricity showed that mainly these thefts are engaged in household consumers. There are thefts of electricity, carried out by industrial and commercial enterprises, but the volume of these thefts can not be considered determinative. The theft of electricity has a fairly clear tendency to grow, 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 greatly decreased, and the heating has not yet been included. There are three main groups of methods of power theft: mechanical, electrical, magnetic.
Mechanical methods of power theft
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 counter; insert (in the hole) of various objects such as a film with a width of 35 mm, needles, etc. in order to stop the rotation of the disk or reset the counter;
- Moving the counter from the normal vertical to the semi-horizontal position in order to reduce the rotational speed of the disk;
- unauthorized breakdown of seals, a violation in the centering of the axes of the gears (gears) to prevent complete recording of electric power consumption;
- rolling glass when inserting a film that will stop the disk rotation.
Usually mechanical intervention leaves a mark on the meter, but it is difficult to detect if the meter is not completely cleared of dust and dirt and inspected by an experienced technician. To the mechanical method of power theft can be attributed fairly widespread in Russia deliberate damage to household consumers or the theft of meters installed on staircases of residential buildings. As the analysis has shown, the dynamics of deliberate destruction and theft of meters practically coincides with the onset of cold weather with insufficient heating of apartments. In this case, the destruction and theft of meters should be considered as a kind of protest of the population against the inability of local administrations to provide normal housing conditions. The aggravation of the situation with the heat supply of the population inevitably leads to an increase in commercial losses of electric power, which is already confirmed by the sad experience of the Far Eastern and some Siberian power systems.
Electrical methods of power theft
The most common in Russia electric way of power theft is the so-called "draft" on the bare-wire line. Sufficiently widely used are also such methods as:
- inverting the phase of the load current;
- application 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 - the installation of so-called "short circuits";
- grounding of the zero wire of the load;
- violation of alternation of phase and zero 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 fuses for blown fuses and the like.
Magnetic methods of power theft
The use of magnets on the outside of the meter can affect its performance. In particular, it is possible to slow the rotation of the disk by using induction counters of old types with a magnet. At present, manufacturers try to protect new types of meters from the influence of magnetic fields. Therefore, this method of stealing electricity is becoming increasingly limited.
Other ways to steal electricity
There are a number of ways to steal electricity of purely Russian origin, for example, theft due to the frequent change of owners of a particular company with the permanent re-registration of contracts for the supply of electricity. In this case, the power supply is not able to keep track of the change in ownership and to receive payment for electricity from them.
Commercial losses of electricity caused by the presence of orphan consumers
Crisis phenomena in the country, the emergence of new joint-stock companies led to the fact that in most energy systems in recent years there have been and for quite a long time there are residential houses, dwellings, whole residential settlements that do not stand on the balance of any organizations. Electricity and heat supplied to these houses, residents do not pay to anyone. Attempts by power systems to disconnect non-payers do not yield results, as residents again unauthorizedly connect to networks. Electric installations of these houses are not serviced by anyone, their technical condition is threatened by accidents and does not ensure the safety of life and property of citizens.
Commercial losses caused by non-simultaneous payment for electricity by household consumers - the so-called "seasonal component".
This very significant component of the commercial losses of electric power takes place due to the fact that household consumers objectively can not simultaneously take meter readings and pay for electricity. As a rule, payments are lagging behind the actual electric power supply, which certainly introduces an error in determining the actual productive leave by the household consumer and in calculating the actual unbalance of electricity, since the backlog 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 electricity 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 by months, quarters and for the year as a whole.
Errors in calculating technical losses of electric power in electric networks
Since commercial losses of electricity can not be measured. They can be calculated with some margin of error. The significance of this error depends not only on the errors in measuring the volume of theft of electricity, the presence of "ownerless consumers", other factors considered above, but also from the error in calculating the technical losses of electricity. The more accurate are the calculations of the technical losses of electric power, the more obviously the estimates of the commercial component will be more accurate, the more objectively one can determine their structure and outline measures to reduce them.