New Methodology for Calculation of the Special Passive Filter Parameters with the Aim of Voltage Quality Improving in Networks with Active Rectifie

The article is devoted to the improvement of electromagnetic compatibility (EMC) of FC-AR as a part of electric drives of rolling mill stands with the in-plant power supply system of metallurgical plants in the presence of resonance phenomena through the use of specialised passive filters (SPF). Often the use of traditional filters to eliminate strong voltage distortions on 6-35 kV sections lacks a proper effect. Installation of traditional filters is accompanied by additional parasitic current resonances, which worsen the power quality at the point of common connection of drives with FC-AR. Also harmonics amplify and strongly distort the voltage waveform when the frequency response of the distribution network overlaps with the region of high-frequency harmonics generated by modern FC-ARs. This situation often occurs in the in-plant power supply systems of metallurgical plants with one main step-down substation and long medium-voltage distribution cable networks. This problem can be solved by installing SPFs in the in-plant distribution network. The power scheme of SPFs is similar to the Single-tuned filter, but the tuning and selection of inductance L and capacitance C parameters is carried out according to the specialised methodology, providing a shift of current pair resonance into the safe region of frequency response of the supply network. In this article the calculation methodology for parameters and selection of necessary SPFs for elimination of high-frequency harmonics and shifting of network resonance to the region where there are no harmonics generated by modern FC-ARs for EMC improvement is considered in detail.