Interharmonic Analysis for Static Frequency Converter Station Supplying a Swedish Catenary System

Abstract

The paper aims to present a waveform distortion analysis focused on interharmonics in measurements from a 70 kV busbar feeding a traction supply substation with four static frequency converters (SFC). The substation supplies a Swedish catenary system from 50 Hz public grid to 15 kV 16 ⅔ Hz. The paper assesses the interharmonics for different scenarios regarding the point of a connection configuration between the traction substation and the upstream grid, as well as a change in the number of SFCs connected in the substation. The IEC 61000-4-7 grouping method and spectrograms were used to illustrate the issue. The significant presence of interharmonics calls attention to the subject in railway application. The total indexes help to evaluate the broad picture of the phenomena. The work contributes to the waveform distortion and interharmonics in railway systems studies.