To understand what are the losses of electricity in electrical networks, you will need to deal with the power supply system itself. It consists of a number of structural elements, each of which under certain conditions contributes to unproductive costs. In addition, they may be associated with the need to meet their own needs for auxiliary equipment of substations. It follows from this that it is practically impossible to do without losses in electrical circuits.
Types and structure
Losses in electric networks from the point of view of energy conservation are the difference between the amount of electricity supplied by the supplier and the energy that the consumer actually receives. In order to normalize and calculate their real value, the following classification was adopted:
- technological losses;
- operational (commercial) costs;
- actual unproductive expenses.
Technical losses are caused by the features of laying power lines, as well as energy dissipation at the contacts. This also includes the selection of part of the supplied electrical energy for the needs of auxiliary equipment. The technological component includes costs in the load chains and the climate component.
The second factor - commercial - is usually linked to such unavoidable reasons as the error of instruments measuring the controlled parameters. It also takes into account a number of nuances regarding erroneous readings on consumption and energy theft.
The studies convincingly prove that the maximum level of costs is associated with the transmission of energy by high-voltage power transmission lines (up to 64 percent).
Most of them are expenses on air ionization due to coronary discharge (17%). The actual losses are those that were determined at the very beginning - the difference between the product sold and its consumed volume. With their simplified calculation, sometimes the two described components simply add up. However, in practice, the technique for calculating this indicator is somewhat different. To determine it, a time-tested technique for calculating losses in wires is applied taking into account all other components.
Their actual value according to a special formula is equal to the influx of energy into the network minus the following components:
- volume received by a private consumer;
- flows to other branches of the power system;
- own technological needs.
Then, the result obtained is divided by the amount of electricity entering the network minus consumption in loads, where there are no losses, minus overflows and own needs. At the final stage of the settlement operation, the final figure is multiplied by 100%. If you want to get the result in absolute values, when using this method they are limited to calculations of the numerator alone.
Determination of the load without cost of overhead (overflows)
In the previously considered formula, the concept of lossless load is introduced, which is determined by means of commercial meters installed in substations. Any enterprise or state organization independently pays for losses in the electric network, fixed by a separate meter at the connection point. “Overflows” are also referred to the category of energy losses without losses (it is more convenient to conduct a calculation).They mean that part of it that is redirected from one power system to another. Separate measuring instruments are also used to account for these volumes.
Own needs
Own needs are usually referred to a special category, classified as actual losses. In this indicator, it is customary to fix the costs of maintaining the health of the following objects:
- substations with transformers installed in them;
- administrative buildings, auxiliary buildings, etc.
Each of the articles is included in the total amount in the proportion normalized for this type of consumer.
The most significant contribution is made by the district substations, since they host the main service equipment. It provides normal operating conditions of the units responsible for the conversion of electricity, as well as its delivery to the consumer.
To fix the value of these costs at substations, their own metering devices are installed.
List of consumers traditionally belonging to the category in question:
- ventilation systems guaranteeing full cooling of the set of transformer equipment;
- heating and ventilation systems for technological rooms, as well as lighting networks mounted in them;
- lighting devices located in sectors and territories adjacent to substations;
- equipment for battery charging;
- heating systems for outdoor installations (for controlling air switches, in particular);
- compressors and auxiliary mechanisms.
The same type of equipment includes devices and tools used for repair work, as well as in the restoration of auxiliary equipment.
Commercial component
First of all, this component concerns the characteristics of metering devices belonging to end consumers (their errors, in particular). To reduce this type of loss, a number of specific measures have been successfully applied in practice. Commercial category includes not only errors when billing a specific consumer, but also unaccounted for theft of electricity. In the first case, they most often occur for the following reasons:
- the contract for the supply of electricity provides incomplete or not entirely correct information about the consumer and the balance sheet of the property assigned to him;
- an error in indicating the selected tariff;
- lack of control over the operation of metering devices (this case is typical for garden cooperatives and SNT, in particular);
- Inaccuracies arising from the adjustment of previously issued invoices, etc.
Typical errors caused by the controversial determination of the boundaries of the asset’s balance sheet are resolved in the manner established by the legislation of the Russian Federation.
The problem of theft is hardly solved in all civilized countries. These illegal actions are constantly suppressed by the relevant authorities, cases on them are sent to local courts. The peak of such thefts is traditionally in the winter season and it is in those regions of the country where there are problems with district heating.
This only confirms the interconnectedness of the commercial cost components for each of the categories of energy resources.
The main causes of power leaks
A competent approach to calculating electricity losses involves taking into account the reasons why they arise. In the study of the problem, the sources of unproductive expenses should be divided in accordance with the already familiar classification. You should start with the technical component, which is usually linked to such elements:
- transformers;
- high voltage cable or overhead line;
- equipment serving the line.
Any power transformer has several windings, the frame of which is mounted on a ferromagnetic core. In it, most of the energy transformed into heat is lost (it then simply dissipates into space).
The mode of its operation also influences the amount of losses in various elements of the power supply network: idling or “under load”. In the first case, they are assessed as constant, independent of internal and external factors. When a consumer is connected, the level of losses depends on the magnitude of the load current in the circuit, which changes every day. Therefore, to evaluate it, static observations are carried out for a certain period (for a month, for example).
Losses in explosive power lines are formed during the transportation of energy due to leaks associated with corona discharge, as well as due to the heating of conductors. The category of service equipment includes installations and devices involved in the generation, transportation, as well as in the metering and consumption of supplied energy. The values of excess losses in this category generally do not change with time or are taken into account by means of electric meters.
The concept of a normative indicator
This term refers to the confirmed in practice and economically viable amount of losses for a certain period of time. When approving the standard, all previously considered components are taken into account, for each of which a separate analysis is carried out. Based on their results, the actual (absolute) value is calculated and possible options for reducing this indicator are considered.
The normalized value does not remain constant all the time - it is continuously adjusted.
In this case, absolute indicators are understood as the difference between the power transferred to the consumer and technological (variable) losses. The normative values for the last parameter are calculated by the corresponding formulas.
Who pays for electricity losses
To determine who should pay for unproductive electricity costs in the network, one should take into account the specific situation, as well as a number of additional criteria. When it comes to the costs of replenishing technological losses, their payment falls on the shoulders of consumers - private or legal entities.
It is not directly accounted for, but laid down in existing tariffs.
Each consumer, when paying electricity bills, pays with the network organization for all kinds of losses in transmission lines and transformers. In the case of the commercial component, for any excess of the indicator over the normalized value, it is necessary to pay the company that releases energy to the client.
Ways to reduce losses
It is possible to reduce unproductive expenses by reducing the commercial and technological components of the total losses. In the second case, this can be done by taking the following special measures:
- optimization of circuit decisions and operating modes of the power supply network;
- study of statistical data and identification of nodes of maximum loads;
- a decrease in the total capacity pumped through the network due to an increase in the reactive component;
- optimization of transformer load lines;
- updating equipment and applying different approaches to load balancing.
These measures can significantly reduce the total consumption and losses and ensure high quality voltage in the network (it will not "sag").
Methodology and calculation example
The following methods are known for the approximate calculation of losses in power lines:
- operational calculations;
- daily calculations;
- determination of maximum losses for a certain period of time;
- use of generalized data.
Full information on officially approved methods for determining this parameter can be found in the relevant regulatory documentation.
As an example, consider the calculation of losses in the feeder of a high-voltage line with a transformer TP 6-20 / 04kV.
When implementing the method of on-line cost calculation, depending on the linear voltage drop, the phase potentials are first measured on the buses of the transformer substation at the most remote point at maximum load. According to the results of the measurements, the absolute and relative decrease in DU in percent is recognized: it is taken in relation to its average phase value on 0.4 kV TP 6-20 buses.
The energy loss W in a 0.4 kV line (as a percentage of electricity shipment to the network) can be found by the following formula:
W = 0.7 KN x DU x t / T, Where
- Kn - coefficient taking into account the phase imbalance or uneven distribution among consumers;
- U - voltage loss in the load (at the most distant point of the line, that is, the calculated maximum);
- T is the observation time (in hours);
- t is the value of the time dimension, characterizing the completion of the schedule for checking the transfer of useful power to the consumer.
Choosing the values of the parameters for a particular feeder according to one of the tables laid out on the Internet (TP-4) and substituting them into the formula, using the calculator we get the value of 11.4 percent.
For feeders of other brands, the required value of technological losses can be calculated using the same tables with the data given in them.
The Internet has a wide variety of online payment methods that anyone can use if necessary.
