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Train–Network Interactions and Stability Evaluation in High-Speed Railways–Part I: Phenomena and Modeling

This paper presents an impedance-based model to systematically investigate the interaction performance of multiple trains and traction network interaction system, aiming to evaluate the serious phenomena, including low-frequency oscillation (LFO), harmonic resonance, and harmonic instability. The train–network interaction mechanism is therefore studied, and one presents a detailed coupling model for investigating the three interactive phenomena and their characteristics, influential factors, analysis methods, and possible mitigation schemes. In Part I of the two-part paper, the measured waveforms of such three phenomena are first characterized to indicate their features and principles. A unified framework of the train–traction network system for investigating the three problems is then presented. In order to reveal the interaction mechanism, all-frequency impedance behaviors of the electric trains and traction network are equally modeled. In which, an impedance-based input behavior of the train is fully investigated with considering available controllers and their parameters in DQ-domain. The entire traction network, including traction transformer, catenary, supply lines, is represented in a frequency-domain nodal matrix. Furthermore, the impedance–frequency responses of both electric train and traction network are measured and validated through frequency scan method. Finally, a generalized train–network simulation and experimental system are conducted for verifying the theoretical results of the two-part paper.