Research on Converter Topology and Control of Co-phase Traction Power Supply System Based on MMC Topology

Abstract

With the rapid development of railways, high-quality power supply and safe operation of trains have received extensive attention. Aiming at the problems of electrified railway power quality and electric phase separation device, combined with the status quo of engineering transformation, converter reliability, economy and redundant backup of the power supply system. Summarized and compared the advantages of MMC topology in the traction power supply system. Proposed a co-phase power supply system based on modular multi-level converter (MMC) and traction transformer. When the converter works normally, the power is obtained from the three-phase power grid, the three-phase power is converted into two-phase power through the traction transformer, the two-phase power is respectively connected to two single-phase MMC to become direct current, the direct current is converted into single-phase alternating current for the locomotive through the single-phase MMC; when the converter fails, due to the traditional traction transformer structure is retained, the conventional power supply mode can be operated to achieve the redundancy backup purpose of the system. Then, analyzed the DC capacitance voltage control, circulation suppression, control strategy and modulation strategy suitable for MMC topology during normal operation. Finally, obtained some research conclusions of the co-phase power supply system based on MMC topology and traction transformer.