Analysis of Harmonic Resonance for Locomotive and Traction Network Interacted System Considering the Frequency-Domain Passivity Properties of the Digitally Controlled Converter

Jing Li,Qiujiang Liu,Yating Zhai,Marta Molinas,Mingli Wu

doi:10.3389/fenrg.2020.523333

Abstract

Harmonic resonance is a kind of oscillatory instability phenomenon occurring in the electric railway. To investigate this problem, the frequency-domain model of the single-phase voltage source converter (VSC) for locomotives is derived based on the transfer function of the current control loop. The equivalent circuit of the traction network is also included in this frequency-domain model. Particularly, the time delay and zero-order-holder effect of the digital pulse width modulation (DPWM) are taken into consideration in order to obtain more accurate a model of the digital controller. After that, the harmonic resonance of the locomotive-network (L-N) system is assessed through the passivity properties of the interacted frequency-domain impedance model. Finally, the effectiveness of the theoretical analysis is demonstrated by simulations and experiments. As a result, the harmonic resonance can be predicted before a new electric railway is put into use so that some mitigation measures can be taken in advance.

Highlights

Lots of power electronic converters are applied to high-power locomotives and electric multiple units (hereafter, all referred to locomotives) with an AC-DC-AC traction drive system
In electric railways, lots of power electronic converters are applied to high-power locomotives and electric multiple units with an AC-DC-AC traction drive system
The frequency-domain impedance of the L-N system is derived by taking the control delay and the ZOH effect of the digital pulse width modulation (DPWM) into consideration

Summary

Introduction

Lots of power electronic converters are applied to high-power locomotives and electric multiple units (hereafter, all referred to locomotives) with an AC-DC-AC traction drive system. The traction network is modeled as a harmonic resonance circuit (Kolar et al, 2010). The frequency-domain modeling of the VSC and the traction network is widely investigated to probe into their influence on the stability of the interacted system. The frequency-domain model of the VSC including the parameters of the traction network is beneficial to the comprehensive analysis of the L-N system.

Results

Conclusion