An Electric Railway Power Conditioning System Based on Asymmetrical Connection Balance Transformer

Considering the emerging power quality problems of electrified railway, an electric railway power conditioning (RPC) system based on asymmetrical connection balance transformer is proposed, which has good comprehensive performance on eliminating the negative sequence current (NSC), compensating reactive power, and compensating harmonic. Instead of the step-down transformer, the inductive filtering transformer is utilized, which can filter selected harmonic at a low voltage level to reduce the influence of harmonic on RPC. Meanwhile, to improve the cost-efficiency and stability of the compensation system, a cost optimization algorithm has been presented, which allocates the compensation capacity of reactive power for RPC effectively and the fully tuned (FT) branches of inductive filtering transformer has been presented, which creates the condition for large scale industrial application. The case study is used to validate the presented compensation system, and shows that this system can improve the power quality significantly, and will be suitable for electrified railway system.