An electrical system generates total energy, which is divided into useful, or active and residual, called reactive energy. The article will tell about what it is and how it is kept.
Residual energy: what is it?
All electric machines are represented by reactive and active elements. 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 that create reactive current are indexed at these resistances.
Installations and devices that create alternating current use reactive energy in the electric network, which creates a magnetic field of an electric field.
The effect of inductive resistance on the creation of a magnetic field
All devices 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, the electricity generated in the inductive element in reserve, oscillating movements emanate through the network due to the load from the generator and vice versa. This process is called reactive power, which creates a magnetic field of an electric field.
Why is reactive energy necessary?
We can say that it is aimed at regulating the changes that the electric current causes in the network. This includes:
- magnetic field support during inductance in the circuit;
- in the presence of capacitors and wires support their charge.
Reactive power generation problems
If the network has a large share of reactive power generation, then you have to:
- increase the power of power devices that are designed to convert electrical energy of one voltage value into electrical energy of another voltage value;
- increase cable cross-section;
- combat the increase in power loss in power devices and transmission lines;
- increase the charge for electricity consumption;
- fight 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 to heat the room, prepare food, heat water in the bathroom (who uses individual water heaters) and other useful electrical energy. It is she who is called active.
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 full power. Accordingly, it is unprofitable for consumers to pay for reactive energy in the electric network in addition to active energy, and it is beneficial for suppliers to pay for full power. Is there any way to resolve this issue? Let's look at it.
How is energy consumption measured?
To measure the energy consumed, an 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 needs. Power is supplied by single-phase current.
Three-phase meters are used to record total energy. They are classified based on the power supply scheme into three- and four-wire.
Distinguishing counters by the way they are turned on
By the way they turn on, they are divided into three groups:
- They do not use transformers and directly connected meters are directly connected to the network.
- Using power devices, half-turn-on counters are turned on.
- Indirect inclusion counters. They are connected to the network not only using current power devices, but also using voltage transformers.
Distinguishing counters by payment method
According to the method of charging electricity, it is customary to divide the meters into the following groups:
- Meters based on the use of two tariffs - their effect is that the tariff for energy consumption changes during the day. That is, in the morning and in the afternoon it is less than in the evening.
- Pre-paid meters - their operation is based on the fact that the consumer pays for electricity in advance, as he is in remote places of residence.
- Meters indicating the maximum load - the consumer pays separately for the energy consumed and for the maximum load.
Full power accounting
Accounting for useful energy is aimed at determining:
- Electric energy generated by machines for producing voltage at power plants.
- The amount of energy that is spent on the own needs of the substation and power plant.
- Electricity aimed at spending it by consumers.
- Energy transferred to other power systems.
- Electric energy, which is put on the buses of power plants to consumers.
It is necessary to take into account reactive electric energy when transferring to consumers from a power plant only if these data calculate and control the operation mode of devices that compensate for this energy.
Where do you control the remaining energy?
Reactive energy meter set:
- In the same place as the meters for accounting for useful energy. Install them for consumers who pay for the full power they use.
- At sources of connection of reactive power for consumers. This is done if you have to control the work process.
If the consumer is allowed to let the remaining energy into the network, then they put 2 counters in the elements of the system, where the metering of useful energy is carried out. In other cases, put a separate meter for accounting reactive energy.
How to save on electricity consumption?
The device for saving electricity is very popular in this direction. Its action is based on the suppression of residual electricity.
In the modern market you can find many similar devices, which are based on a transformer that directs electricity to the right direction.
The device for saving electricity directs this energy to a variety of household equipment.
Rational use of electricity
For the rational use of electricity , reactive energy compensation is used. For this, capacitor units, electric motors and compensators are used.
They help reduce the loss of active energy due to reactive power flows. 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% savings in the cost of using electric energy in all corners of the Russian Federation.
The cash investments 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 profitable.
Capacitor Advantages
The use of capacitor units has the following positive aspects:
- A slight loss of active energy.
- In capacitor units there are no rotating parts.
- They are easy to operate 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.
The difference between capacitor units and compensators and synchronous motors is that filter-compensating units synchronously perform power compensation and partially inhibit the harmonics present in the compensated network. From how much power is compensated and the cost of electricity will depend, and, accordingly, from the current tariff.
What types of compensation exist?
In the process of applying capacitor units, the following types of suppressed power are distinguished:
- Individual.
- Group
- Centralized.
Let us consider each of them in more detail.
Individual power
Capacitor units are located directly at the electrical receivers and are switched at the same time as they are.
The disadvantages of this type of compensation is the dependence of the turn-on time of the capacitor unit on the start time of the electrical receivers. In addition, before carrying out work, it is necessary to coordinate the capacity of the installation and the inductance of the electrical receiver. This is necessary to prevent resonant overvoltage.
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 the same switchgear with a common capacitor installation.
In the process of simultaneously switching on the load, the coefficient increases, which leads to a decrease in power. This contributes to a better condenser installation. 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 adjustable. It is used for a wide range of changes in the consumption of residual energy.
A large role in regulating the power of the capacitor unit is played by the function of the reactive load current. In this case, the installation should be equipped with an automatic controller, and its full compensation power is divided into separately commutated steps.
What problems do capacitor plants solve?
Of course, they are primarily aimed at suppressing reactive power, but in production they help to solve the following problems:
- In the process of suppressing reactive power, respectively, the total power decreases, which leads to a decrease in the load of power transformers.
- The power supply of the load is provided via a cable with a smaller cross section, while the insulation does not overheat.
- It is possible to connect additional active power.
- It allows avoiding a deep voltage drop on the power lines of remote consumers.
- The use of the power of autonomous diesel generators is maximized (ship electrical installations, power supply to geological lots, construction sites, exploratory drilling installations, etc.).
- Individual compensation makes it possible to simplify the operation of induction motors.
- In the event of an emergency, the capacitor unit immediately shuts down.
- The heating or ventilation of the unit is automatically switched on.
There are two options for capacitor units. It is modular, used in large enterprises, and monoblock - for small enterprises.
To summarize
Reactive energy in the power grid negatively 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.
In this regard, compensators of this power are actively used. Their benefit consists not only in good money savings, but also in the following:
- The service life of power devices is increasing.
- The quality of electrical energy is improving.
- Saves money on the purchase of small cables.
- Electric energy consumption is reduced.