Active Suppression of Low-frequency Interference Currents by Implementation of the High-performance Control System for the Grid-interfaced Converters

Operation of traction drive and auxiliary power supply converters installed onboard modern vehicles causes increased content of line harmonics and interharmonic components in the line current. Passive techniques for filtration of low frequency interference line currents appeared to be insufficient, but are combined with active mitigation techniques. The paper describes and suggests active suppression methods based on proper design of the grid interface of the power converter and its corresponding control system. Interference currents, including those induced by the operation of onboard power converters can significantly influence the correct operation of telecommunication, train control systems and other railway signaling infrastructure along the tracks, having direct impact to the safety of the railway transport. Therefore, suppression of low-frequency interference line currents requires careful implementation of active/passive methods. For purpose of quality evaluation of performances of the grid interface of the traction drive converters and its corresponding control system in particular, a series of tests for assessment of the line current frequency spectrum, resulting from the operation of the converter in typical exploitation conditions, were performed. Tests were performed in laboratory conditions and on the vehicle, with satisfactory results.