Dual-Harmonic Linearization Modeling and Analysis of Power Electronic Transformer- Based Train Traction System

An accurate model of the power electronic transformer-based train traction system (PET-TTS) is essential for stability analysis. However, in most of the existing impedance modeling of PET-TTS, the complex frequency coupling effects (FCEs) are barely focused, which reduces the accuracy of modeling and the stability analysis suffers from degraded correctness. To tackle this, firstly, this paper constructs a frequency-shift paths analysis to reveal the generation mechanism of the mirror-frequency coupling and high-frequency coupling in the PET-TTS. Then, the dual-harmonic linearization (DHL) modeling method is proposed to make a trade-off between the model accuracy and the model complexity. Afterwards, a complete single-input single-output impedance model of the PET-TTS with FCEs is derived in the stationary frame. With this model, the impedance characteristic and FCEs features are analyzed, and the stability of PET-TTS with and without considering the FCEs is analyzed and compared. Eventually, the suggested model and relevant analysis are validated by the simulations and experimental tests.