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Reactive energy in the electrical network. Accounting for reactive energy

The electrical system produces a fullenergy, which is divided into useful, or active and residual, called reactive energy. The article will tell about what it is and how it is recorded.

Residual energy: what is it?

All electrical machines are reactiveand active elements. It is they who consume electrical energy. These include reactive cable connections, capacitor and transformer windings.

In the course of AC current, reactive electromotive forces are indexed on these resistances, which create a reactive current.

In installations and devices that create alternating current, the reactive energy in the electrical network is used, which creates a magnetic field of the electric field.

The influence of inductive resistance on the creation of a magnetic field

All appliances that are powered from the mains,have inductive resistance. It is thanks to him that the signs of current and voltage are opposite. For example, the voltage has a negative sign, and the current is positive, or vice versa.

At this time, electricity generated inan inductive element in reserve, oscillates along the network due to the load from the generator and back. This process is called reactive power, which creates a magnetic field of the electric field.

What is the use of reactive energy?

We can say that it is aimed at adjusting the changes that cause an electric current in the network. This includes:

support of the magnetic field during the inductance in the circuit;
if there are capacitors and wires support their charge.

Problems in generating reactive power

If the network has a large share of generating reactive power, then it is necessary:

increase the power of power devices that are designed to convert the electrical energy of a single voltage value into electrical energy of another voltage value;
increase the cross-section of cables;
to combat the growth of power loss in power devices and transmission lines;
increase the charge for electricity consumption;
to fight with the loss of voltage in the network.

What is the difference between active and reactive energy?

People are used to paying for that electricity,which they consume. They pay for the energy used to heat the room, prepare food, heat the water in the bathroom (who uses individual water heaters) and other useful electrical energy. It is called active.

Active and reactive energies are different in thatThe second is the remainder of the energy that is not used in useful work. In other words, they both form the total power. Accordingly, it is not profitable for consumers to pay for reactive energy in the power grid in addition to active energy, and it is advantageous for suppliers to pay for their full capacity. Is there any way to settle this issue? Let's look at this.

What is the measure of energy consumption?

To measure the consumed energy, the active and reactive energy meter is used. All of them are divided into counters with one phase and three phases. What is their difference?

Single-phase meters are used to account for electrical energy from consumers who use it for domestic use. Power is supplied by single-phase current.

Three-phase meters are used to account for the total energy. They are classified on the basis of a three-and four-wire power supply scheme.

Distinguishing counters by the method of switching on

By the way they are included, they are divided into three groups:

Do not use transformers and directly included in the network of direct counters.
With the use of power devices, semi-indirect inclusion counters are turned on.
Indirect inclusion counters. They are connected to the network not only with the use of power devices of current, but also with the use of voltage transformers.

Distinguishing counters by the way of payment

By the method of calculating electricity fees, it is customary to divide the counters into the following groups:

Counters based on the application of two tariffs - their effect is that the tariff for consumed energy varies within a day. That is, in the morning and afternoon it is less than in the evening.
Meters with prepayment - their action is based on the fact that the consumer pays for electricity in advance, as is in remote places of residence.
Counters indicating the maximum load - the consumer pays separately for the energy consumed and for the maximum load.

Full power accounting

The calculation of the useful energy is aimed at determining:

The electrical energy produced by machines for the production of voltage at a power plant.
The amount of energy that is spent on the own needs of the substation and power plants.
Electricity aimed at its consumption by consumers.
Energy transferred to other power systems.
The electric energy that is pumped through the power station tires to consumers.

Consider reactive electrical energy whentransfer to consumers from the power plant is necessary only if this data counts and controls the operation of devices that compensate for this energy.

Where do they control the remaining energy?

Reactive energy meter install:

In the same place where the counters for the accounting of useful energy. Install them for consumers who pay for the full power they use.
At the sources of connection of reactive power for consumers. This is done if you have to control the process of work.

If the consumer is allowed to let the remainingenergy into the network, then put 2 counters in the elements of the system, where the accounting of useful energy. In other cases, put a separate meter to account for reactive energy.

How to save on electricity consumption?

The device for economy of electricity uses the big popularity in this direction. Its action is based on the suppression of residual electricity.

In today's market, you can find many similar devices, which are based on a transformer that directs electricity in the right direction.

The device to save electricity directs this energy to a variety of household equipment.

Rational use of electricity

For the rational use of electricity, reactive energy compensation is applied. For this purpose, capacitor units, electric motors and compensators are used.

They help reduce the loss of active energy,which are caused by the flow of reactive power. This significantly affects the level of transport technological losses of distribution electric networks.

What is the advantage of power compensation?

The use of facilities for power compensation can bring great benefits in economic terms.

According to statistics, their use brings up to 50% of the cost savings for the use of electric energy in all corners of the Russian Federation.

Cash investments that are spent on their installation, pay off in the first year of their use.

In addition, where these installations are designed, the cable is purchased with a smaller cross section, which is also very profitable.

Advantages of condenser installations

The use of condenser installations has the following advantages:

Slight loss of active energy.
In condenser installations there are no rotating parts.
They are easy to work and operate.
Investment costs are not high.
Work silently.
They can be installed anywhere in the electrical network.
You can pick up any required power.

Difference of condenser installations from compensatorsand synchronous motors consist in the fact that the filter-compensating installations synchronously perform the power compensation and partially constrain the harmonics present in the compensated network. On how much power is compensated and the cost of electricity will depend, and, respectively, on the current tariff.

What types of compensation exist?

In the process of using condenser installations, the following types of suppressed power are distinguished:

Individual.
Group.
Centralized.

Let us consider in more detail each of them.

Individual power

Condenser installations are located directly at the electrical receivers and are switched at the same time as they.

The disadvantages of this type of compensation is consideredthe dependence of the on-time of the capacitor installation from the time of the beginning of the operation of power consumers. In addition, before carrying out work it is necessary to coordinate the installation capacity and inductance of the electrical receiver. This is necessary to prevent resonant overvoltages.

Group power

The name speaks for itself.This power is used to compensate for the power of several inductive loads, which are simultaneously connected to a single switchgear with a common capacitor installation.

В процессе одновременного включения нагрузки coefficient increases, which leads to a decrease in power. This contributes to the better performance of the condenser system. Residual energy is suppressed more efficiently than with individual power.

The negative side of this process is the partial unloading of reactive energy in the power grid.

Centralized power

Unlike individual and group power, this power is regulated. It is used for a wide range of changes in the consumption of residual energy.

Large role in power controlThe condenser unit plays the function of reactive load current. In this case, the installation should be equipped with an automatic regulator, and its full compensation power is divided into separately switched stages.

What problems solve condenser installations

Of course, first of all they are aimed at suppressing reactive power, but in production they help to solve the following tasks:

In the process of suppressing reactive power, respectively, the total power decreases, which leads to a decrease in the load on the power transformers.
The load is powered by a cable with a smaller cross-section, and the insulation does not overheat.
Possible to connect additional active power.
Allows to avoid deep voltage drops on power lines of remote consumers.
The use of autonomous diesel-generator power goes to the maximum (ship electrical installations, power supply of geological batches, construction sites, exploration drilling installations, etc.).
Individual compensation allows you to simplify the operation of asynchronous motors.
In the event of an emergency, the condensing unit shuts off immediately.
The heating or ventilation of the installation is automatically switched on.

There are two options for condenser installations. These are modular, used in large enterprises, and single-block - for small enterprises.

Let's sum up

Reactive energy in the electrical network adversely affects the operation of the entire electrical system. This leads to consequences such as loss of voltage in the network and an increase in fuel costs.