Output-transformerless traction substation based on three-phase to single-phase cascaded converter

As an ideal power supply, the advanced traction power supply system (ATPSS) is approved to totally remove the neutral sections and promote the power quality, which is a new direction development for traction power supply system. The existing ATPSS based on three-phase to single-phase converter needs to match the step-up transformer. The output current of this system is so heavy that it requires parallel structure to share current, which makes high requirements for manufacturing facilities. What´s more, circulation suppression in the parallel system must be taken into consideration. In this paper, a new ATPSS based on a three-phase to single-phase cascaded converter without output transformer is been studied. The structure of three-phase to single-phase converter and its control system are deeply analyzed. Then the cascade structure implementation of the converter is studied. Finally, a simulation model for this system is built. The simulation results show that the new system built in this paper can remove the output transformer, not only meets the voltage of the traction network and capacity requirements, but also improves power quality. The results verify the correctness and feasibility of main circuit structure and control strategy.