A Novel Power Quality Compensator for Negative-Sequence and Harmonic Currents in High-Speed Electric Railway

In order to solve the power quality problem of negative-sequence and harmonic currents in high-speed railway traction systems, a novel power quality compensator is proposed, which is constituted by railway static power conditioner (RPC), two thyristor-controlled reactors and two thyristor-controlled 3rd filters. The RPC contains two converters which are connected back-to-back by sharing the DC link and is only used to transfer active power and suppress harmonics. The thyristor-controlled 3rd filters are used to suppress 3rd harmonic current and change the phase angle of power supply current. The thyristor-controlled reactors are as the same used to change the phase angle of power supply current. The proposed power quality compensator has small capacity and low cost. Furthermore, based on the working principle of the proposed power quality compensator, its equivalent electrical models are established in fundamental and harmonic domain respectively. Simulation results are provided to demonstrate that the negative-sequence currents is zero and the THD of power arm current is reduced from 14% to 3%, after the proposed power quality compensator is run.