Modified PWM Technique For Reduction of Voltage Harmonic Distortion Uisng AC-AC Converter

摘要

The proliferation of nonlinear loads, such as static power converters and arc furnaces, has resutled in a variety of undesirable phenomena in the operation of power systems. Often, the most important among these are harmonic distortion, increased reactive power demand and power system voltage oscillations. This paper addresses the problem of line voltage distortion at a point of common coupling (PCC) by installing an AC -AC voltage converter between the PCC and the sensitive equipment. The AC -AC buck converter is considered. Sinusoidal PWM of the duty ratio of the AC -AC buck converter isolates the sensitive equipment from the harmonic components of the line voltage at the PCC. The influence of varying the switching frequency on the efficiency of the buck converter as a harmonic solator is also studied. The validity of applicability of the AC -AC voltage converters for isolating the harmonic componetns of the line voltage at the PCC from the sensitive equipment has been established through MATLAB simulation. Two differnet compositions of the line voltage at the PCC in addition to the fundamental component are considered.