Experimental Studies of Power Quality in the 34.5 kV Network of MMK Metalurji During Operation of Electric Drives with Active Rectifiers

Medium voltage distribution networks of 6 - 35 kV are used in in-plant power supply systems in steel mills. As a mutual influence result of the capacitances of long cable lines and the inductances of step-down transformers, resonance phenomena can occur in the medium frequency range. If the high-frequency harmonics generated by frequency converters with active rectifiers fall into the resonant range, this can lead to disturbances in the plant’s internal distribution network. Such phenomena can cause long downtime of technological equipment and product defects. This entails significant economic losses, especially in the production of high value-added products. This paper reflects the experimental research results of voltage quality in 34.5 kV distribution networks of metallurgical plant “MMK Metalurji”. Measures for electromagnetic compatibility improvement of frequency converters with active rectifiers of electric drives in hot strip mill 1750 with supply mains are proposed.