Ways to Ensure Electromagnetic Compatibility of Powerful Frequency Converters in Internal Power Supply Systems of Industrial Enterprises in the Presence of Resonance Phenomena

摘要

Modern powerful adjustable electric drives, such as rolling mill drives with asynchronous and synchronous medium voltage motors, contain frequency converters with active rectifiers, which are the source of higher harmonics. In this perspective, the issue of the electromagnetic compatibility of such electric drives with an internal 6–35 kV average voltage network with extensive cable lines is relevant. This paper considers the interaction of the transformer inductance of the main low-voltage substation and the distributed capacity of cable lines, the extremum of the current resonance in the network frequency response which can be located in the field of higher harmonics of high-power frequency converters. As a result, some distortions can appear in the common units of switchboards which can lead to the failure of different electrical equipment. Therefore, the relevant objective is to study the ways of reduction the effect of high-power frequency converters on the supply network. The article considers such methods as the use of a special network frequency characteristic correction filter and the use of the improved pulse-width modulation algorithm for frequency converters.