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Why should reactive power compensation be carried out? What is the principle and form of reactive power compensation?
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- Time of issue:2022-08-02
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(Summary description)1、 Why should reactive power compensation be carried out? Reactive power is by no means useless power. In the AC power supply system, inductance and capacitance are essential loads, such as ferromagnetic loads such as motors and transformers. If there is no excitation of inductive reactive power, the equipment cannot work normally. For example, the line itself that transmits power at a fixed distance is a capacitive load. As long as it is transmitting power, it will be equivalent to the capacitor working. In other words, in the AC power supply system, the existence of reactive power is of great significance to the transmission and exchange of energy, which is indispensable, or the exchange system without reactive power can not work normally.
Why should reactive power compensation be carried out? What is the principle and form of reactive power compensation?
(Summary description)1、 Why should reactive power compensation be carried out?
Reactive power is by no means useless power. In the AC power supply system, inductance and capacitance are essential loads, such as ferromagnetic loads such as motors and transformers. If there is no excitation of inductive reactive power, the equipment cannot work normally. For example, the line itself that transmits power at a fixed distance is a capacitive load. As long as it is transmitting power, it will be equivalent to the capacitor working. In other words, in the AC power supply system, the existence of reactive power is of great significance to the transmission and exchange of energy, which is indispensable, or the exchange system without reactive power can not work normally.
- Categories:Industry News
- Author:
- Origin:
- Time of issue:2022-08-02 10:02
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1、 Why should reactive power compensation be carried out?
Reactive power is by no means useless power. In the AC power supply system, inductance and capacitance are essential loads, such as ferromagnetic loads such as motors and transformers. If there is no excitation of inductive reactive power, the equipment cannot work normally. For example, the line itself that transmits power at a fixed distance is a capacitive load. As long as it is transmitting power, it will be equivalent to the capacitor working. In other words, in the AC power supply system, the existence of reactive power is of great significance to the transmission and exchange of energy, which is indispensable, or the exchange system without reactive power can not work normally.
So, where does a lot of reactive power come from? There are many reactive loads in the system, especially inductive reactive loads. Normally, the reactive power absorbed by these loads is provided by the power plant, that is to say, when the generator is working, it will release active energy to the system and provide corresponding reactive energy to inductive loads. Proper reactive power output must be maintained when the generator is running. If there is no reactive power output, it will have a destructive impact on the power generation system, that is to say, the reactive power balance of the protection system is very important.
When the reactive power demand in the system increases, if the reactive power compensation device is not installed artificially in the system, the power plant should increase the reactive power output by phase modulation. Because the capacity of the generator is limited, it is necessary to reduce the output of active power, that is, to reduce the output capacity of the generator. In order to meet the requirements of electricity consumption, the capacity of the generator, power supply line and transformer needs to be increased, This will not only increase power supply investment and reduce equipment utilization, but also increase line loss.
In order to reduce the reactive power supply pressure of the power plant, we put corresponding capacitors at the points where the inductive load consumes a lot in the power supply system to provide reactive power for the inductive load, which greatly reduces the reactive power supply pressure of the power plant. On the basis of improving the natural power factor of power consumption, users should design and install reactive power compensation devices, and timely input or remove them according to the changes of load and voltage to prevent reactive power reverse transmission. At the same time, the power factor of users should be up to the corresponding standard to avoid the power supply department charging extra electricity. Therefore, whether for power supply departments or power consumption departments, automatic compensation of reactive power to improve the power factor and prevent reactive power reverse transmission is of great significance to save electric energy and improve operation quality.
2、 Basic principle of reactive power compensation
Generally speaking, most of the reactive loads in the system are inductive reactive loads. The devices with capacitive power loads are connected with the inductive power loads in the same circuit. When the inductive reactive load absorbs energy, the capacitive load releases energy, while the inductive load releases energy, the capacitive load absorbs energy, and the energy is exchanged between the capacitive load and the inductive load, In this way, the reactive power absorbed by the capacitive load can be compensated from the reactive power output by the capacitive load device, and the reactive power can be balanced locally, so as to reduce the line loss, improve the load capacity, reduce the voltage loss and alleviate the power supply pressure of the power plant. This is the basic principle of reactive power compensation.
Basic principle of phase analysis reactive power compensation:
The current IL in the inductive load lags behind the voltage by 90 °, while the current IC of the pure capacitor leads the voltage by 90 °. The phase difference between the current in the capacitor and the current in the inductance is 180 °, which can offset each other.
Most of the loads in the power system are inductive loads, so the total current I will lag the voltage by an angle Φ 1. If the shunt capacitor is connected in parallel with the load, then I '= i+ic, the current of the capacitor will offset part of the inductive current, so that the total current is reduced from I to I', and the phase angle is changed from Φ 1 reduced to Φ 2. The power factor can be increased and the reactive power can be balanced locally.
3、 Compensation form of reactive power compensation
1) Individual compensation individual compensation is a method to compensate the reactive power required by a single electric equipment nearby. Connect the capacitor directly to the same electrical circuit of a single electric equipment, control it with the same switch, and put it into operation or disconnect at the same time. This compensation method has the best effect. The capacitor is close to the electrical equipment and balances the reactive current locally, which can avoid over compensation when there is no load and ensure the quality of power supply. This compensation method is often used in high and low voltage motors and other electrical equipment. However, this compensation method can not give full play to its compensation benefits due to the low utilization rate of capacitors when the user equipment operates discontinuously.
2) Decentralized compensation decentralized compensation is to install capacitors in groups on the outgoing lines of each branch of the workshop distribution room or substation. It can input or remove capacitor banks according to the change of system load, and the compensation effect is also better. But the cost is relatively high.
3) Centralized compensation centralized compensation refers to the centralized installation of capacitor banks on the bus at the primary or secondary side of the substation. This compensation method is simple to install and reliable to operate, but the compensation effect is worse than the first two compensation methods, and the cost is relatively high.
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