Hybrid Railway Traction Power Quality Compensator for power rating reduction of converters

AC electrified railway traction loads create a lot of problems related to power quality due to their non-linear nature and being single-phase, such as significant amount of Negative Sequence Current (NSC), low power factor, harmonic injection, reactive power consumption, etc. In order to solve above problems, a Hybrid Railway Traction Power Quality Compensator (HRTPQC) based on a Railway Power Conditioner (RPC) and two Static VAR Compensators (SVCs) is proposed in this paper. The HRTPQC will significantly reduce the initial investment cost of compensation system and converters rating of the RPC. The RPC is only used to balance active powers of two adjacent feeder sections and suppress harmonic currents. The SVCs are applied to compensate reactive power and suppress the third and fifth harmonic currents. In this paper firstly, the principle of power quality compensation is analyzed step by step. Then, the control strategies for SVC and RPC are presented. Finally, a simulation carried out using Matlab/Simulink software to demonstrate the effectiveness and correctness of the HRTPQC and compensation strategy and also show that the HRTPQC could compensate all power quality problems.