chapter  20
52 Pages

Harmonic Mitigation and Filters

WithJ.C. Das

The harmonic mitigation at source, without filters, has attracted the attention of industry and researchers. This covers a wide field, spanning industrial applications to transmission systems and high-voltage dc. For a system of zero harmonic impedance, all the harmonic current will flow into the system and none in the filter. The lower the system impedance, that is, the higher the short-circuit current, the smaller is the voltage distortion, provided the filter impedance is lowered so that it takes most of the harmonic current. With the increase in consumer nonlinear load, the harmonics injected into the power supply system and their consequent effects are becoming of greater concern. Harmonic currents seeking a low impedance path or a resonant condition can travel through the power system and create problems for the consumers who do not have their own source of harmonic generation. The tolerance on filter reactors and capacitors may change due to aging or temperature effects.