Passive Filters

Passive filters use passive components, such as inductors, capacitors, and resistors. These cannot increase the signal energy; the frequency range for harmonic filters is limited to approximately 3000 Hz. The single-tuned (ST) filters are efficient filters and will bypass a certain harmonic to which these are tuned. These are most widely used filters in all applications of harmonic mitigation. Bandpass filter is a new breed of filters for harmonics. The filtering performance of type C filters lies between that of second-order and third-order filters. Zigzag transformers and delta-wye transformers act as zero sequence traps when connected in the neutral circuit of a three-phase four-wire system. Transfer function approach using Laplace transform is one method of passive filter designs. The application of computer optimization techniques in power systems is a powerful analytical tool, reaching new dimensions with new algorithm for reliability, speed, and applicability.