How to compensate the power factor？

In modern power system, the power factor directly affects the utilization efficiency of electric energy and the operation quality of power grid. Power factor refers to the ratio of actual power (active power) to apparent power, usually expressed as cosφ. The ideal power factor is 1, which means that all electric energy is effectively used; However, low power factor will lead to waste of electric energy, increase of line loss and even affect the normal operation of equipment.

First, the reasons for low power factor

Low power factor mainly occurs in systems with a large number of inductive loads, such as motors, transformers, fluorescent lamp ballasts, etc. These devices will absorb a lot of reactive power in the working process, which will increase the apparent power and reduce the power factor. In addition, nonlinear loads (such as frequency converters, rectifiers, etc.) will also cause harmonic currents, further affecting the power factor.

Second, the significance of power factor compensation

The main purpose of power factor compensation is to improve the power factor of the system and reduce the flow of reactive power, thus achieving the following effects:

1. Improve the efficiency of electric energy utilization: reduce the reactive power loss in the line and improve the utilization rate of power supply equipment;
2. Reduce the line loss: reduce the current in the transmission line and reduce the power loss;
3. Improve voltage quality: stabilize system voltage to prevent voltage drop;
4. Reduce electricity expenses: Many power supply enterprises charge extra fees for users with low power factor, and improving power factor helps to reduce electricity expenses;
5. Extend the service life of equipment: reduce the burden of transformers, cables and other equipment and extend the service life.

Third, the common power factor compensation methods

1. Shunt capacitor compensation
This is the most common and economical way of compensation. By connecting capacitors in parallel in the circuit, capacitive reactive power can be provided to offset the inductive reactive power generated by inductive load, thus improving the power factor. Suitable for the occasion of stable load.

2. Static Var Generator (SVG)
SVG is a kind of power electronic device, which can emit or absorb reactive power dynamically, with fast response speed and high adjustment precision, and is suitable for occasions with large load fluctuation, such as industrial production lines and wind farms.

3. Synchronous camera compensation
Synchronous motor runs in over-excited state without mechanical load, which can provide reactive power to the system and is often used in high voltage transmission systems.

4. Automatic compensation device
Intelligent controller is used to automatically switch capacitor banks according to the change of system power factor to realize fine compensation, which is suitable for scenes with frequent load changes.

Four, the implementation of power factor compensation matters needing attention

1. The compensation capacity should be designed reasonably to avoid over-compensation or under-compensation;
2. Whether there are harmonics in the system should be considered to avoid resonance between capacitors and harmonics;
3. For dynamic loads, priority should be given to dynamic compensation devices;
4. Maintain the compensation equipment regularly to ensure its normal operation.

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With the rising of energy cost and the continuous improvement of environmental protection requirements, power factor compensation has become an important means of optimal operation of power system. Through reasonable selection of compensation methods and scientific management, not only can the utilization rate of electric energy be improved, but also the operating cost of enterprises can be reduced and the overall economic benefits can be improved. Therefore, it is of great practical significance and broad application prospect to popularize and apply power factor compensation technology in the fields of industry, construction and transportation.