Smooth control of reactive power using three-phase bridge rectifier

Abstract

This project deals mainly with a study of how reactive power can be controlled using a three-phase bridge rectifier. The aim of this project is to design, construct and test the control circuitry needed for a compensator providing smooth control of reactive power which is required for a three-phase variable load. Most of industrial electric loads have a low power factor not exceeding 0.8. This low power factor implies that for a given applied voltage, V, and current, I, the value of the active power (kW) is low. This means that for a given power with a low power factor, the current is much higher than it would be if the power factor was unity. Hence the losses in the generator itself are larger and the switchgear, transformers and cables etc. are all larger and more expensive. Therefore, in such cases it is desirable that some power factor correction scheme will be installed so that the high reactive currents that are required are kept to a minimum. There are different power factor correction methods used with large lagging or leading nonlinear loads. This project proposes a real-time microprocessor-based power factor correction scheme for low power factor variable (linear or non-linear) loads. The software and hardware required to implement the suggested adaptive power factor correction scheme are explained, and its operation is described.