Improved Railway Static Power Conditioner Using C-type Filter in Scott Co-phase Traction Power Supply System

Railway static power conditioner (RPC) has been utilized to compensate power quality indices (current unbalance, voltage/current harmonics and grid-side power factor) simultaneously in AC electrified railway. In this paper, a hybrid configuration including C-type filter (CTF) and RPC is proposed in Scott co-phase traction power system. Some part of the load reactive power is compensated by the CTF, while the RPC compensates the remaining part of the reactive power. Furthermore, harmonic mitigation analysis is investigated for high-order harmonics suppression. By implementing the CTF, the VA rating reduction of the RPC is achieved and the dc-link voltage can be also operated at a lower level for a specific traction load. Without imposing any complexity to the control system, modified instantaneous PQ theory is adapted to obtain the reference currents. A theoretical analysis process is given and simulation results verify the validity of the proposed structure.