ABSTRACT

The penetration of sensitive and non linear loads like Personal computers (PC's) increases distortion levels and can cause severe problems to power systems. Personal computers are non linear devices that draw non-sinusoidal current with harmonics. Production of harmonics in personal computers has special interest to power quality (PQ) due to fact that personal computers are usually concentrated in large groups.
As the number of harmonics producing loads have increased over the years, it has become increasingly necessary to address their influence with good level of accuracy when making any additions or changes to an installation.
The Switch Mode Power Supply (SMPS) is vital part of PC's cause significant sources of harmonics. Harmonic emission from SMPS based loads depend upon on operating conditions and the changes in their circuit's parameters. The adverse effects of harmonic increased magnitudes of neutral currents in three-phase systems, overheating in transformers and induction motors, overloading, as well as the degradation of system voltage waveforms. There is a great need of an experimental investigation to understand the effects of different conditions and factors on harmonic generation in personal computers. it is important to know when and how to address this issue.
The purpose of work is to ensure that the line current and voltage harmonic content of group of PC s connected to the AC supply mains is limited to meet regulatory standards. For this purpose, an experimental investigation is conducted to develop mathematical model related to harmonics and concentration of personal computers. The current waveforms, voltage waveforms, Individual harmonics spectrum, ThDí and THDv magnitudes with respect to quantities of personal computers are studied and investigated in detail. In this work curve fitting and Sim power system toolbox in MATLAB are used to formulate mathematical function. Measured results have been compared with international standard. The performance with accuracy, simplicity are the main advantages of this project which is investigated and verified with its results.
as satisfactory.
Keywords: Personal computers (PC's), Power Quality (PQ), Total Harmonic Distortion (THD), Point of Common Coupling (PCC), Harmonic Emission (HE), Curve fitting.