Power System Harmonics Sources, Effects and Elimination

Abstract

The use of non linear loads is increasing day by day. This increasing use of non linear loads has created more distortions in current and voltage waveforms. This increased power quality disturbances has lead to various optimizations techniques and filter designs. Harmonic distortions are the major cause for power quality problems. The harmonics in distribution systems come from transformers or satiable reactors, are furnace, welding machines, florescent lamps, rotating machines and power electronics devices. In general, the non linear loads in which the relationship between the voltage and current is not constant. It is considered that there is no risk of harmful perturbation from 5 to 10% above 10%, problems will certainly occur. Equipments can be affected by the harmonics like transformers with increase of losses , risk of overheating , noise and even insulation stress problems .cables that can heat too much due to as Kelvin effect above 400HZ. Induction relays and meters that are permutated by harmonic torques incorrect tripping and readings. The solutions that can be used to improve the power factor and to protect the capacitors are either de-rate the capacitors or using detuning reactors, and also by using harmonic filters. This thesis presents the definitions of harmonic, generation, causes, effects on electrical power system and elimination.