Implementation of Continously Controlled Static VAR Compensator for Power Factor Correction System Using Pspice

Abstract

In an electric power system, a load with a low power factor draws more current than a load with a high power factor for the same amount of useful power transferred. The higher currents increase the energy lost in the distribution system, and require larger wires and other equipment. Because of the costs of larger equipment and wasted energy, electrical utilities will usually charge a higher cost to industrial customers where there is a low power factor. The inductive loads constitute major portion of the power consumed in industrial complexes. Reactive power required by inductive loads increases the amount of apparent power in the distribution system. This increase in reactive and apparent power results in a larger angle and hence results in low power factor. There are many advantages of maintaining high power factor which include elimination of penalty billing, increased system capacity, increased voltage level etc. The proposed methodology employs a thyristor switched-capacitor bank to generate a controllable static VAR for single phase AC system. The capacitor bank is constructed of five binary weighted thyristorswitched  capacitors. This arrangement leads to a capacitor bank capable of generating stepping reactive power having thirty one equidistant non-zero levels. Each capacitor is controlled by a single thyristor shunted by a reverse diode. The system is capable of correcting lagging power factor up to unity or adjusting it according to user desire. Each capacitor is connected to a series reactor for protecting the solid state combination from inrush current occurring at the first instant of compensator plug in to power system network.