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Electric power characteristics of all-parallel AT traction power supply system

All-parallel autotransformer (AT) traction power supply system is widely applied to China high-speed railways. The traction feeding network of this kind is more complicated than traditional AT networks. It contains more current loops and the current distribution become more complex. This paper proposes a novel and efficient method to analyze its characteristics. On the basis of the analysis of the autotransformer characteristics, the current distribution can be obtained. Then, several typical short-circuit faults are analyzed by loop analysis method. The proposed current distribution results are compared with the simulation using PSCAD/EMTDC as well as the field test recorded wave data. Through analyzing the characteristics of the all-parallel AT traction feeding system, the short circuit behavior of the traction network can be identified. At the same time it can be indicated to provide theory guide for the relay protection and fault location for this power supply mode.