MICROPROCESSOR CONTROLLER FOR HARMONIC REDUCTION IN NON LINEAR THYRISTOR FED LOADS

Abstract

The flow of current harmonics in the AC power system is a matter, which causes interference with the communication circuits and other equipment. System incorporating this type of equipment is characterized by poor power factor, which is defined as the product of displacement factor by the distortion factor. A conventional method of alleviating these problems is to employ banks of capacitors and filters. In applications where a wide ' range of reactive power supply is required. The stepwise control provided by the above approach may be unacceptable because a great number of parallel branches may be required. In this thesis the switched capacitors (SC) technique is employed as a reactive power compensator (RPC) or a filter. An experimental work is done. In this technique the capacitors with variable impedance circuit are switched at frequency higher than the supply frequency. These capacitors are switched through very fast MOSFET switches. The switching pattern of the MOSFET is implemented using a microprocessor (M6800). This compensatory action reduces the most significant cunent harmonics produced by non-linear loads. The principal methods of control analysis and of the switched capacitor circuits are presented. Theoretical and experimental results obtained from the prototype filter are presented, and useful conclusions are drawn.