Improving the power factor means taking the necessary steps to increase the power factor in a defined section of the installation by locally delivering the necessary reactive power so that the value of the current and consequently of the power flowing through the upstream network can be reduced, at the same required output power. In this way, the lines, the generators and the transformers can be sized for a lower apparent power.
Improving the power factor is a solution which allows technical and economic advantages; in fact, managing an installation with a low cos φ implies an increase of costs for the power supply authority, who consequently applies a tariff structure which penalizes the withdrawal of energy with low power factors.
The legislative measures in force in the different countries allow the national power supply authorities to create a more or less detailed tariff system. Such system is structured so that the absorbed reactive energy exceeding that corresponding to a cos φ equal to 0.9 must be paid according to defined amounts depending on the voltage level of the supply (low, medium or high) and on the power factor. According to the tariff system applied, the consumer can determine the amount of his own additional charge and therefore can evaluate the savings on the penalties to be paid in comparison with the cost of an installation for power factor correction.
According to the location modalities of the capacitors, the main methods of power factor correction are:
- distributed power factor correction;
- grouped power factor correction;
- centralized power factor correction;
- combined power factor correction;
- automatic power factor correction.