Reactive energy in the electrical network. Accounting for reactive energy

The electrical system generates total energy, which is divided into useful, or active and residual, called reactive energy. About the fact that this is and how it is recorded, the article will tell.

Residual energy: what is it?

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

During the flow of alternating 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.

Effect of inductive resistance on the creation of a magnetic field

All appliances that are powered by 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, the electric power generated in the inductive element in reserve, with oscillatory motions, flows through 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;
• When 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 one 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 the electricity they consume. They pay for the energy used for heating the room, cooking food, heating the water in the bathroom (who uses individual water heaters) and other useful electrical energy. It is called active.

The active and reactive energies are different in that the second is the rest of the energy that is not used in useful work. In other words, they both form the full 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 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 electricity 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:

1. Do not use transformers and directly included in the network of direct counters.
2. With the use of power devices counters are switched on semi-indirect switching.
3. 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:

1. 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.
2. 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.
3. Counters indicating the maximum load - the consumer pays separately for the energy consumed and for the maximum load.

Full power accounting

The calculation of useful energy is aimed at determining:

1. Electric energy produced by machines for producing voltage at a power plant.
2. The amount of energy that is expended on the own needs of the substation and power plant.
3. Electricity, aimed at consuming it by consumers.
4. Energy transferred to other power systems.
5. Electric energy, which is sent on the buses of power plants to consumers.

To take into account reactive electrical energy when transmitting to consumers from a power plant is necessary only if these data count and control the operating mode of devices that compensate for this energy.

Where do you monitor the remaining energy?

The reactive energy counter is set:

1. In the same place, where and counters on the account of useful energy. They are installed for consumers who pay for the full power they use.
2. On the sources of connection of reactive power for consumers. This is done if you have to monitor the work process.

If the consumer is allowed to let the remaining energy into the network, then two counters are placed in the elements of the system, where the useful energy is accounted for. In other cases, a separate meter is placed to account for reactive energy.

How to save on electricity consumption?

The device for saving electricity is very popular in this direction. Its operation is based on the suppression of residual electricity.

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

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

Rational use of electricity

Compensation of reactive energy is used for the rational use of electricity. To do this, use condenser units, motors and compensators.

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

What is the advantage of power compensation?

The use of installations for power compensation can bring great economic benefits.

According to statistical data, their use brings up to 50% savings in spending for the use of electrical energy in all parts of the Russian Federation.

Monetary investments that are spent on their installation pay off within 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 beneficial.

Advantages of capacitor installations

The use of condenser plants has the following positive aspects:

1. Slight loss of active energy.
2. In the condenser units there are no rotating parts.
3. They are easy to operate and operate.
4. Investment costs are not high.
5. They work silently.
6. They can be installed anywhere on the grid.
7. You can choose any required power.

The difference between capacitor installations from expansion joints and synchronous motors is that the filter compensating plants synchronously perform power compensation and partially restrain harmonics present in the compensated network. On how much the capacity is compensated and the cost for electricity will depend, well, accordingly, on the current tariff.

What types of compensation exist?

During the application of capacitor installations, the following types of suppressed power are distinguished:

1. Individual.
2. Group.
3. Centralized.

Let us consider each of them in detail.

Individual power

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

Disadvantages of this type of compensation is the dependence of the time of switching on the capacitor installation on the time of the beginning of the operation of the electric receivers. In addition, before carrying out the work, it is necessary to coordinate the capacity of the installation and the inductance of the electrical receiver. This is necessary to prevent resonance overvoltages.

Group capacity

The name speaks for itself. This power is used when power is compensated for several inductive loads, which are simultaneously connected to one switchgear with a common capacitor unit.

During the simultaneous activation of the load, the coefficient increases, which leads to a decrease in power. This helps to improve the performance of the condenser unit. The residual energy is suppressed more efficiently than with an 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.

The function of the reactive load current plays a large role in regulating the power of the capacitor unit. In this case, the installation must be equipped with an automatic regulator, and its total compensation power is divided into separately switched stages.

What problems are solved by capacitor installations

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

1. In the process of reactive power suppression, respectively, the total power decreases, which leads to a decrease in the load of power transformers.
2. The load is supplied by a cable with a smaller cross-section, and there is no overheating of the insulation.
3. It is possible to connect additional active power.
4. It allows to avoid a deep drawdown on the power lines of remote consumers.
5. The use of the power of autonomous diesel generators goes on as much as possible (ship electrical installations, power supply of geological lots, construction sites, exploratory drilling rigs, etc.).
6. Individual compensation makes it possible to simplify the operation of induction motors.
7. In the event of emergency, the capacitor installation is immediately disconnected.
8. The heating or ventilation of the unit is automatically turned on.

There are two variants of capacitor installations. It is modular, used in large enterprises, and monoblock - for small businesses.

Let's sum up

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

In connection with this, compensators of this power are actively used. Their benefit consists not only in good money saving, but also in the following:

1. The service life of power devices is increasing.
2. Improves the quality of electrical energy.
3. Money is saved for the purchase of small cables.
4. The consumption of electric energy is reduced.