Reactive energy
What is reactive energy?
Reactive energy, from the point of view of physics, is that part of the total delivered electrical energy that is spent on establishing and maintaining the magnetic field in electrical machines.
Got its name due to the fact that its consumption does not contribute to active or useful power, but without the consumption of reactive energy, the electric machine would not even be able to work.
Currently, the tariff system introduced by Elektroprivreda Srbija is in force, and any consumption of reactive energy below the limits of the technical optimum, i.e. describes a power factor of 0.95 as excessive reactive energy.With the help of reactive power compensation equipment, the average industrial consumer can increase the power factor, i.e. reduce reactive power bills.
Who are the consumers of
reactive energy?
- Asynchronous motors
- Transformers
- Electric arc furnaces
- Induction furnaces
- Electric traction substations
Lighting (fluorescent)
Who are the producers-consumers
of reactive energy?
- Synchronous generators
- Synchronous compensators
- Overhead lines and cables
- Capacitor batteries
- Chokes
Reactive energy compensation
Compensation reactive energy means the installation of equipment that generates reactive energy at the installation site and thus compensates the consumption of reactive energy in the plant.
This drastically reduces the amount of reactive energy taken from the network, and thus the bills for spent reactive energy.
Costs typically account for about 15% of the total electricity bill.
By reactive power compensation this whole item should be almost completely eliminated.
Compensation equipment prices are such that this investment pays for itself within 6 months to 2 years.
The power line from the source to the receiver is loaded with active and reactive current.
If we want to relieve the power supply line and the sources at the beginning of the lines (transformers and generators), it is necessary to install compensators in the immediate vicinity of the receiver, i.e. sources of reactive current, which is necessary for the receivers (electric motors, transformers, ballasts,…)
Why is it necessary to perform reactive energy compensation?
PROFIT FOR THE CONSUMER:
Consumers who have an item for reactive energy in their account have a direct financial gain (after reactive energy compensation is performed, the item related to reactive energy is eliminated from the account or significantly reduced). The invested money for the compensation of reactive energy is returned in the period of exploitation multiple (from 10-15) times.
PROFIT FOR EES:
By compensating reactive energy, the total current in the network is reduced by the value of the reactive current, the load on the transformer is reduced, the stability of the electric power system (EES) increases, the security of supply to consumers and finally the reduction of technical losses of active energy in the entire EES.
Compensation using
capacitor batteries
Compensation is most often done using capacitor batteries called static compensators
Protection of capacitor batteries
When capacitors and batteries are turned off under load, short-term current overloads occur, such as short-circuit currents.
Therefore, for the protection of personnel and the installation, it is necessary to use contactors intended for this purpose for compensation.
The use of standard contactors puts personnel and the entire installation at risk
Capacitor contactors
Capacitor contactors turn on and off capacitor batteries that have low inductances and low losses.
The damping resistors are switched on just before switching on the capacitor banks, in order to reduce the switching currents below 70·In.
Capacitor bank fuses are 1.6·In….2.5·In
EXAMPLE:
The calculation of energy at the ED company is reduced to:
- consumption of active energy (kWh)
- consumption of reactive energy (kVAr)
If the consumption of reactive energy exceeds the free amount of 50% of active energy, then the excess of consumed reactive energy must be paid.
Typical consumption value :
- consumption of active energy: 9200 kWh/monthly
- consumption of reactive energy: 11200 kVArh/monthly
- free amount of reactive energy: 4800 kVArh/monthly
- reactive energy for charging: 6600 kVArh/monthly
Effects of reactive energy compensation
- Reduction of costs
- Reduction of voltage drop
- Unloading of transformers and cables
- Improvement of voltage quality
Elins doo
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- elinsdoo@gmail.com
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