ABSTRACT
This chapter discusses the undesirable effects of harmonics occurring in the power system and examines shunt filters used to reduce these harmonic levels to the limits recommended in the relevant standards. It summarizes the typical representations of common network components for the calculation of the ac network impedance. Inclusion of the frequency-dependent effects requires the calculation of unit-length line constants for each harmonic frequency. This requires much input data for harmonic analysis programs. Harmonics above the 50th harmonic are usually so small that they do not cause problems in power systems. For most transformers, the effect of stray capacitance becomes noticeable only for frequencies higher than 4 kHz; hence, they can be neglected. In view of the higher speed of the rotating magnetic field of the harmonics compared with that of the rotor in synchronous and induction machines, the harmonic impedance approaches the negative-sequence impedance.
