What is the power factor, the meaning of the power factor, the common method of improving the power factor?

First of all, to explain, usually we write "power factor", which is a number, is a coefficient, a coefficient not greater than 1. That is, the work that can be done, but it can't be done so much, and it does some useless work, so multiply a factor.
Look at the interpretation of the encyclopedia and basically answer your question.
In an AC circuit, the cosine of the phase difference (Φ) between voltage and current is called the power factor and is represented by the symbol cosΦ. In terms of value, the power factor is the ratio of active power to apparent power, ie cosΦ=P/S
The power factor is related to the load nature of the circuit. For example, the power factor of a resistive load such as an incandescent bulb or an electric resistance furnace is 1. The power factor of a circuit with an inductive or capacitive load is generally less than one. Power factor is an important technical data for power systems. Power factor is a factor that measures the efficiency of electrical equipment. The low power factor indicates that the reactive power of the circuit for alternating magnetic field conversion is large, thereby reducing the utilization rate of the device and increasing the power loss of the line. Therefore, the Power Supply department has certain standard requirements for the power factor of the power unit.
(1) The most basic analysis: take the equipment as an example. For example, the power of the device is 100 units, that is, 100 units of power is delivered to the device. However, due to the inherent reactive losses of most electrical systems, only 70 units of power can be used. Unfortunately, although only 70 units are used, there is a fee of 100 units. In this example, the power factor is 0.7 (if most devices have a power factor less than 0.9, they will be fined). This reactive loss is mainly found in electrical equipment (such as blowers, pumps, compressors, etc.). Inductive load. Power factor is a measure of motor performance.
(2) Basic analysis: Each motor system consumes two large powers, which are real useful work (called kilowatts) and reactive useless work. The power factor is the ratio of useful work to total power. The higher the power factor, the higher the ratio of useful work to total power, and the more efficient the system is.
(3) Advanced analysis: In an inductive load circuit, the peak value of the current waveform occurs after the peak of the voltage waveform. The separation of the two waveform peaks can be expressed in terms of power factor. The lower the power factor, the larger the separation of the two waveform peaks. Paulkin can bring the two peaks back together, which increases the efficiency of the system.
For power factor improvement, power loads in power grids such as motors, transformers, fluorescent lamps and electric arc furnaces are mostly inductive loads. These inductive devices not only need to absorb active power into the power system but also absorb reactive power during operation. . Therefore, after installing the parallel capacitor reactive power compensation device in the power grid, it can provide the reactive power consumed by the inductive load, and reduce the reactive power supply of the power supply side and the reactive power delivered by the line. Since the flow of reactive power in the power grid is reduced, the power loss caused by the transmission of reactive power in the Transformer and the busbar in the transmission and distribution line can be reduced, which is the benefit of reactive power compensation.

The main purpose of reactive power compensation is to increase the power factor of the compensation system. Because the electricity sent by the power supply bureau is calculated by KVA or MVA, but the charge is charged by KW, which is the actual work done. There is a difference between the two, which is generally the difference between the two. Reactive power in KVAR. Most of the invalid work is inductive, that is, the so-called motor, transformer, fluorescent lamp... Generally, almost all invalid work is inductive, and capacitive is very rare. It is because of this inductive existence that a KVAR value in the system is a trigonometric relationship between the three:

Square of KVA = square of KW + squared text of KVAR

Simply put, in the above formula, if the value of today's KVAR is zero, KVA will be equal to KW, then the power of 1KVA sent by the power supply bureau is equal to the consumption of 1KW of the user, and the cost-effectiveness is the highest, so The power factor is a factor that the power supply bureau is very concerned about. If the user does not reach the ideal power factor, it is relatively consuming the resources of the power supply bureau, so this is also why the power factor is a regulatory limit. At present, the power factor regulation in China must be between 0.9 and 1 inductive, and below 0.9, or above 1.0, penalties are required. This is why we have to control the power factor to a very precise range, too much or too little.

In order to improve their cost-effectiveness, the power supply bureau requires users to increase the power factor. What is the benefit of improving the power factor for our users?

1 By reducing the power factor, the total current in the line and the electrical components in the power supply system, such as transformers, electrical equipment, wires, etc., are reduced, which not only reduces the investment cost, but also reduces the loss of its own power.

2 By ensuring the good power factor, the voltage loss in the power supply system can be reduced, the load voltage can be made more stable, and the quality of the power can be improved.

3 can increase the margin of the system and tap the potential of the power supply equipment. If the power factor of the system is low, then after the capacitor is installed, the power factor can be increased and the capacity of the load can be increased.

For example, increase the power factor of a 1000KVA transformer from 0.8 to 0.98:

Before compensation: 1000×0.8=800KW
After compensation: 1000×0.98=980KW
The same 1000KVA transformer, after the power factor is changed, it can bear a load of 180KW.

4 Reduced user's electricity bills; through the reduction of the above-mentioned components and the increase in power factor.

In addition, some power electronic equipment such as rectifiers, inverters, switching power supplies, etc.; saturable equipment such as transformers, motors, generators, etc.; arc equipment and electric light source equipment such as electric arc furnaces, fluorescent lamps, etc., these are the main harmonic sources At runtime, a large amount of harmonics will be generated. Harmonics affects all electrical equipment connected to the grid, such as engines, transformers, motors, capacitors, etc., which are mainly caused by harmonic additional losses, overloading and overheating of equipment, and insulation aging of harmonic overvoltage accelerating equipment. .

Capacitors that are connected in parallel to the line for reactive compensation will amplify the harmonics, making the distortion of the system voltage and current more serious. In addition, the harmonic current is superimposed on the fundamental current of the capacitor, which increases the effective value of the current of the capacitor, causes the temperature to rise, and reduces the service life of the capacitor.

Harmonic currents increase the copper loss of the transformer, causing local overheating, vibration, increased noise, and additional heating of the windings.

Harmonic pollution also increases the loss of transmission lines such as cables. Moreover, harmonic pollution has an impact on communication quality. When the current harmonic component is high, it may cause overvoltage protection of relay protection and malfunction of overcurrent protection.
Therefore, if the system measures the harmonic content is too high, in addition to the capacitor terminal needs to be connected in series with the appropriate tuning (detuned) reactance, and need to add harmonic improvement device for the load characteristics project.
Active load: A load that produces machine or thermal energy in a power system. However, the pure resistive load in the load only consumes active power. For example, electric power, electric furnace, lighting and other electrical loads are completely active loads. In the load of the asynchronous motor and the synchronous motor, both the active power and the reactive power are consumed, and the work generates a part of the active load of the machine energy. The active load is supplied by the generator's active power.
Reactive power is relatively abstract, it is used to exchange electric and magnetic fields in the circuit, and is used to establish and maintain the electrical power of the magnetic field in electrical equipment. It does not work externally, but instead transforms it into other forms of energy. For electrical equipment with electromagnetic coils, reactive power must be consumed to establish a magnetic field. For example, a 40-watt fluorescent lamp requires more than 40 watts of active power (the ballast also consumes a part of the active power) to emit light. It also needs about 80 consuming reactive power for the ballast coil to establish an alternating magnetic field. Because it does not work externally, it is called "reactive." The sign of reactive power is represented by Q, and the unit is either Var or kVar.
The force rate is the power factor!
Advance is to say that your capacitor compensation is too much, local power equipment can not be used, the rest will be fed back into the power supply system, the lag is that your local reactive load is too large but there is no capacitor compensation, so the power supply system will give You compensate, but the reactive power supply bureau does not charge you the equivalent of your reactive power to occupy a part of the grid, the power factor should be controlled within 0.9, or the power supply bureau must punish the power of the generator. The factor is called the force rate. Power generation usually has both active and reactive power. This operating state is called the power rate phase, or hysteresis. At this time, the generator sends a certain inductive reactive power. From the dial, active and reactive. The power meter indications are all positive, that is, the current lag voltage. In addition, often send the active, absorb reactive, this operating state is called the force rate phase, also known as the lead, that is, the current lead voltage. At this time, the generator sends a certain capacitive reactive power. From the dial, the active power meter indicates positive, while the reactive power meter indicates negative.
Generally, electric appliances consume a certain amount of electric energy to convert into other forms of energy when the current passes, and the electric energy consumed includes two parts, one part is actually used by the electric appliance (active), and some is used in the process of using the electric appliance. Other aspects are consumed (reactive). The power factor is the percentage of active power (active + reactive). The power factor is not equal to 1 for a typical conductor. The greater the power factor, the higher the effective utilization of electrical power.