AC railway electrification systems — An EMC perspective

Railways are electrified in many different ways. In this article, the main options for electrifying a high speed AC railway are reviewed from an electromagnetic compatibility (EMC) perspective. Firstly, the trend of increasing the usage of electrified trains to replace conventional diesel locomotives is pointed out. On this basis, the significance of considering EMC in the railway environment is explained, with a view to preventing the malfunction of the railway system. Secondly, different electrification options are introduced, namely the rail-return, booster-transformer and auto-transformer systems. The benefits and drawbacks of each electrification option are considered based on the interference level to the trackside railway signaling and telecommunication systems. The discussion of each electrification system is verified using electromagnetic simulations. By comparing the different electrification schemes, it is shown that the auto-transformer system has better EMC performance and delivers higher power to the train.