Improving the Power Quality of Traction Power Systems with a Single-Feeding Wire

A topology for traction power systems with a single feeding wire, which consists of a three-phase V/V transformer and a three-phase converter, is proposed at first and then a control strategy based on the repetitive control is developed to deal with the power quality issues in the system. Because of the repetitive controller, all the harmonic and negative-sequence currents generated by locomotives, which are single-phase nonlinear loads, are compensated and only the active power is drawn from the grid. Different from the commonly used hysteresis controllers in traction power systems, the repetitive controller has a fixed switching frequency, which reduces the stress on the power semiconductor devices. Simulation results are provided to illustrate the performance of the system.