Harmonics in power systems and analysis of harmonics

Different kinds of loads appear in electrical systems due to significant developments in the technology in recent years. For reliability of the system, it is preferred that the loads be linear. However, due to developments in the semiconductor technology in last 35 years the number of nonlinear loads in the system has increased rapidly. Nonlinear loads affect the system by generating harmonic currents and voltages. Power electronic components, transformers, uninterruptible power supplies (UPS), converters and high-power induction motors are some power system elements that cause harmonics. Harmonics in the current and voltage waveform cause extra power lose, heating in the system elements and damage in the insulation of system equipment. For these reasons, elimination of harmonics in electrical system has gained more importance. One of the suitable methods for removing harmonics is to use passive filters. In this thesis, the theory about harmonics is given and some investigation about how and why harmonics are produced is carried out. The techniques that can be used for filtering the harmonics are introduced. A test system is studied using MATLABSimulink Power Systems Blockset and the obtained results are discussed.