PLC based intelligent power factor correctors for industrial power systems-A case study

In recent years, the quality of power supplied to the consumer devices by an ac system has become an issue of great concern due to the rapidly increasing inductive loads, electronic equipments, power electronic devices and high system voltage. Power factor correction (PFC) is a technique of minimizing the undesirable effects of electric loads that create poor power factor conditions. Correction of power factor may be effected either by transmission utility which improves the stability and efficiency of the transmission network or by individuals customers. This paper aims at the correction method using an intelligent power factor corrector based on PLC (Programmable Logic Controller) as a control system especially for the correction of the industrial power factor, which is not only required for the smooth operation of the electrical equipments used in the industries but also to minimize the cost of penalty that has to be paid to power supply utilities for having low power factor. This involves measuring the power factor value from the supply line using Power Meter and development of a PLC program to determine and trigger capacitor banks of required rating in order to compensate deficient reactive power, thus bringing power factor near to unity. The results of this paper is based on the case study on application of the proposed method in a real industrial facility.