Microcontroller based power factor improvement
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Date
2010
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Publisher
UMT Lahore
Abstract
Power factor correction (PFC) is a technique of counteracting the undesirable effects of electric loads that create a power factor (p.f.) less than 1. Power factor correction may be applied either by an electrical transmission utility to improve the stability and efficiency of the transmission network, or correction may be installed by individual electrical customers to reduce the costs charged to them by their electricity supplier. The most practical and economical power factor correction device is the capacitor. Incorporation of a microcontroller into a static capacitor device facilitates a form of automatic control action whereby the power factor is always kept at a fixed value, irrespective of the load power factor conditions. It improves the power factor because the effects of capacitance are exactly opposite to those of inductance. The microcontroller determines the power factor of the system at any instant of time and calculates the reactive power to be supplied and the value of capacitance to be switched in to make the power factor unity. The capacitor is switched in parallel to the load through a relay controlled by the processor. The circuit is capable of correcting the power factor for any inductive load within the rating of the system.