What is compensation?
In the electrical system, the process of balancing the inductive reactive power created on the network due to the fact that the devices such as electric motors, coils, etc., which convert electrical energy into electrical energy or a different energy with the effect of magnetization, shift the phase current back (creating inductive power) with this magnetization effect, and pull the current of the phase back to the position it should be. COMPANIZATION It is called
In which two ways is compensation done?
Dynamic phase shifters (synchronous motor)
A synchronous motor is not economical if it is not used for any other purpose in the compensated system.
Static Phase Shifters (Capacitors)
Capacitors are used extensively in reactive power compensation systems because they are economical.
Capacitors are static phase shifters. Capacitors are used in reactive power compensation today due to the fact that they have no maintenance costs and are economical.
Why is compensation necessary?
Electric energy must be transported with minimum losses in its distribution from the power plant to the smallest receiver. Nowadays, with the development of technology and the spread of receivers for different uses, the need for electrical energy is increasing day by day, energy production is getting more and more expensive, and indirectly, this situation makes it more imperative that the electrical energy carried in the network is high quality, cheap and truly working active energy.
As mentioned in the definition of compensation, if a receiver connected to the grid is a motor, a transformer, a fluorescent lamp, they draw inductive reactive power from the grid to supply their magnetic field. Inductive reactive power, which does not do any work and only serves to create a magnetic field in the motor, causes unnecessary losses in transmission lines, transformers, switches and cables.
When these losses can be eliminated, the transformers will undoubtedly have the capacity to feed more motors, and the cables used can be selected in smaller cross-sections.
In addition to energizing the engine with less investment, less electricity will be paid each month in terms of the tariffs applied. As can be seen, at first glance, the transportation of reactive power from the power plant to the receiver appears to be a major economic loss. This energy, which is usually unnecessarily transported in energy distribution networks, has been determined to be between 75% and 100% of the active energy transported.
As a result, by supplying this reactive energy by capacitor plants (static phase shifter) from a region closest to the motor instead of the power plant, all existing facilities from the power plant to the motor will be relieved of the burden of transporting this reactive power.
What happens if compensation is not done?
If reactive powers are not compensated
causes power losses in the network,
- It reduces the capacity of the production and distribution system,
- In distribution lines where the voltage drop limits the power carried, it causes a decrease in the energy carrying capacity.
Therefore, in order to prevent overloads and voltage sags and to make the most efficient use of the grid, reactive loads must be compensated and eliminated at the point where they occur.
For this reason, subscribers who are obliged to install compensation panels are obliged to consume compensated electricity within the limits specified by the decision of the Energy Market Regulatory Authority. Otherwise, subscribers are liable to pay a penalty.
MEASUREMENT and ANALYSIS IN COMPANIZATION
In order to make compensation, the system must first be overhauled and the characteristics of the loads on the system must be known. Not knowing the measurements of the system can cause the compensation to be completely inaccurate.
Nowadays, most small systems consist of single-phase loads and these loads can have different characteristics. For example, an electrician examining the system cannot calculate the reactive power in the system if one phase is 4 amperes, the other is 3 amperes and the other phase is 5 amperes, unless CosÆ value is taken for each phase. This is because a change in the angle Æ causes a change in the values of the reactive and active powers.
Because current is the ratio of apparent power to voltage. For this reason, it is necessary to determine the amount of reactive power drawn in order to provide the correct compensation. If there are ohmic loads in the system, it would be scientifically incorrect to measure only the current and start with the estimated CosÆ value. As it is known, compensation can be provided in two ways
- To ensure active energy consumption at unchanging reactive loads,
- To prevent reactive energy consumption in a certain amount of active energy consumed,
What we need to do is to prevent reactive energy consumption in a certain amount of active energy consumed. Because spending active energy to reduce the reactive rate will be no different from paying a penalty. The important thing is that the required energy should be consumed and the reactive power balance should be maintained.
Electronic meters include the electricity counting process, the meter integration and the microprocessor that receives and processes the measured values from the meter integration and stores them in its memory. The microprocessor software in the electronic meter processes the measured values from each phase independently into active, inductive, and capacitive counters. In other words, if one phase is inductive and the other is capacitive at the same time, it does not take the difference of the reactive power of these two phases. These two phases are processed independently to the meters. When the phases are evaluated independently, in the compensation of unbalanced load systems by taking a triple capacitor between RST, even if compensation is achieved in terms of compound, the electronic meter can write from both inductive and capacitive sides. For this reason, selecting a reactive power control relay becomes much more important.
In analyzing the system with electronic meters, it will not be enough to look only at the reactive power imbalance between the phases! First of all, three-phase and single-phase loads must be commissioned and measured on their own. Three-phase loads can be compensated with three-phase capacitors. Single-phase loads can also be compensated with three-phase three-group capacitors if they are evenly distributed over three phases and operate simultaneously. The real problem starts when we try to compensate with triple group capacitors in single-phase load-dominated systems with unbalanced reactive power between phases. Please read carefully to learn how to do this. The important thing here is to connect the capacitors that will meet the needs of the phases to the relevant phases.
The relay we will use for this, whichever phase is needed, takes the required amount of capacitor in the relevant phase into the system.
It must be remembered that solutions that are not appropriate for the system will never get you results. The best results come from the best analyzed system.
IMPORTANCE OF CHOOSING A REACTIVE RELAY
As a result of incorrect reactive relay selection, compensation cannot be fully provided in many enterprises, naturally, enterprises cannot consume the energy they spend efficiently and therefore they face penalty bills.
Of course, it is in your hands to prevent such undesirable situations from occurring. Using the right reactive power control relay for the right system prevents your business from loss and contributes to the national economy.
When selecting a reactive power control relay, the features that the relay should have.
- It should be able to detect the capacitor with a value suitable for the amount of power drawn from the system and activate and deactivate it by itself.
- Automatically correct faulty current and voltage connections
- Ability to use single-phase and three-phase capacitors together
- Ability to compensate each phase separately
- Capacitor power can be determined automatically
- To be able to detect defective and empty capacitor stages
- Ability to activate and deactivate the capacitors required by the system at one time
- Revise the target cos according to the measured energy value
- It should have manually adjustable capacitor pick-up and discharge time feature.
FILTER APPLICATION
Where capacitors are used, there may be harmonics originating from the network.
Harmonics cause capacitors to draw more current and wear out.
Capacitors can withstand these currents under certain conditions. However, in cases where harmonics are unacceptable, the use of a filter becomes mandatory.
Which type of capacitor should be selected for filter application?
Capacitors produced with ALL Film technology, defined as AS Vartor, are more resistant to overcurrents. Due to its fused structure, the capacity loss steps are higher and the possibility of falling into razonance is less than metalized film capacitors. Since the capacitance change in metallized film type capacitors is scanned at infinite intervals, the tune point of the filter will change. The rated voltage of the capacitors used in the filters should be selected by considering the voltage rise at the ends of the capacitors when they are activated together with the reactor.
What is the Importance of a Capacitor Contactor?
As soon as the capacitor is switched on, high current flows through the circuit. The intensity of this current
depends on whether there are other working groups other than the activated capacitor. Circulating currents pass through the capacitors during their gradual activation. If the capacitor is not selected appropriately, its life is short.
REMEMBER:
The use of contactors specially developed for compensation will extend the life of the capacitor and switchgear in the panels.
What is rapid discharge? What does it do?
The discharge resistors inside the capacitors reduce the voltage remaining on the capacitor after it is disconnected from the circuit to below 50 volts within 60 seconds. This applies to the safety of the person in contact with the terminals. Fast discharge ensures that the voltage remaining on the capacitor group after it is removed from the circuit is sufficiently low during re-commissioning. At the moment of re-commissioning, an overvoltage is applied to the capacitor that encounters reverse alternans and causes damage. Resistors for fast discharge are connected to the capacitor via the auxiliary contacts of the contactor. When the contactor is withdrawn (capacitors in the circuit) the resistors are not connected to the capacitor. When the contactor is released (capacitors are deactivated), resistors are connected in parallel to the ends of the capacitor and fast discharge occurs. The ideal fast discharge time is 12s. Remember: the resistance inside the capacitor is for life safety, the fast discharge resistance is for property safety. In fast discharge compensation panels, the life of the capacitor and switchgear will be extended.