Power quality is an umbrella concept for multitude of individual types of power system disturbances. Quality of Supply
may be categorized. However, in practice, power systems, especially distribution systems, have numerous nonlinear loads, which
significantly affect the quality of the power supply. As a result of these nonlinear loads, the purity of the supply waveform is lost
in many places. This ends up producing many power quality problems. An important percentage of all power quality problems
are of the voltage -quality type where what matters is the deviation of the voltage waveform from its ideal form. The best known
disturbances of the voltage waveform are voltage sags and swells, harmonics, inter harmonics and voltage imbalances.
