A railway power quality conditioner based on chain circuit

To improve the power quality of electrified railway system, a new railway power conditioner (RPC) is proposed. The RPC consists of three single-phase voltage source converters based on the chain circuit inverters. It connects the railway traction power system directly without isolation transformer. Power rating of the conditioner can be increased simply by adding chain links in series. The proposed topology is suitable for traction power system with impedance-matching balance transformer. Regarding the traction substation as a control object, the power quality of the traction substation with RPC can be improved integrally. The RPC always makes the traction substation become a nearly balanced three-phase power system in the public grid whether the loads of two feeders are balanced or not. According to simulation results, the proposed RPC is feasible, and it can compensate reactive power, harmonic, and negative-sequence currents in two feeders together.