Total harmonic distortion analysis of uninterruptible power supply (UPS) development

Abstract

This project paper showed that how Uninterruptible Power Supply (UPS) distort utility voltages under charging mode and produce large harmonic distortions under supply mode. The output voltage waveforms of commonly used UPS and inverters have been classified according to their waveform types, e.g., square waveform, modified sine waveform or pure sine waveform inverters. The quality of UPS or inverter can be judged on the basis of harmonic current drawn during charging mode and voltage harmonic distortions produced in the supply mode. The aim of this project is to develop a controller of UPS using smart relay. To analysis the Total Harmonic Distortion (THD) of UPS a smart relay must be connected to a timer and 240Vac relay. The effort has further been made to check the harmonic contents and determine the suitability applications in the electrical system.