Evaluation of Series and Parallel Hybrid Filters Applied to Hot Strip Mills With Cycloconverters

This article presents two hybrid filter topologies applied to a hot strip mill electrical system with cycloconverters, to evaluate the harmonic compensation and damping of harmonic resonance. In addition, an evaluation of the performance of hybrid filters in reducing the current rating of the passive filter is also presented. The most relevant waveforms of the system and its harmonic spectrum are analyzed, to assess the performance of each filtering structure in improving the power quality. The results obtained through digital simulation show that a series hybrid filter provides harmonic damping and allows enhancing the harmonic compensation characteristics of the passive filtering system, using an active filter of lower rated power compared to a parallel hybrid filter. However, the series hybrid filter does not present good filtering characteristics in the high-frequency range, that can be performed by a parallel hybrid filter with a higher rating.