ABSTRACT
One of the most common methods for control of harmonic distortion in industry is the use of passive filtering techniques that make use of single-tuned or band-pass filters. The more sophisticated active filtering concepts operate in a wide frequency range, adjusting their operation to the resultant harmonic spectrum. Probably the most common harmonic filter in industrial applications, the passive filter, presents very low impedance at the tuning frequency, through which all current of that particular frequency will be diverted. The design of a passive filter requires a precise knowledge of the harmonic-producing load and of the power system. All harmonic currents whose frequency coincides with that of the tuned filter will find a low-impedance path through the filter. Filter designs usually offer a robust mechanism that provides some minor filtering action for a fraction of other harmonic currents whose order is close to the tuning frequency, provided that no filters tuned at those frequencies exist.
