基于阻抗测量信息的电气化铁路“多车共网”系统稳定性分析

Stability Analysis of Electrified Railway Multiple Train-Network System Based on Impedance Measurement Information

阻抗测量技术能够准确地获取“牵引供电网-列车”(简称“车-网”)系统的宽频阻抗特性,但在阻抗测量信息的利用方面目前多是针对单车系统的稳定性分析,缺少对“多车共网”系统宽频稳定性问题的分析。因此,该文提出一种基于牵引供电网与列车阻抗测量信息的“多车共网”系统稳定性分析方法。首先,利用阻抗测量的方式获取牵引供电网节点阻抗矩阵与列车阻抗信息;然后,建立“多车共网”系统模型,采用基于阻抗回差矩阵行列式的稳定性分析方法,分别从低频到高频分析了电气化铁路中低频振荡、谐波谐振和谐波不稳定三类典型振荡问题,并给出相关的振荡信息,实现多类稳定性问题的统一分析;最后,利用Matlab/Simulink仿真验证了所提稳定性分析方法的有效性。

With the increasing investment of electric trains in electrified railways,the wide-band oscillation phenomenon frequently occurs in the electric train-traction power supply network(train-network)system.The use of impedance measurement technology to accurately obtain the wide-band impedance characteristics of the traction power supply network and electric train has become an important way to reveal the wide-band oscillation problem of the electrified railway train-network system.However,the utilization of impedance measurement information is mainly focused on the stability analysis of single train system,lacking the wide-band stability analysis of multiple train system that consider the impedance of traction lines between difference trains.Moreover,existing analyses often focus on a single stability issue,only analyzing impedance measurement information in a specific frequency band,and have not fully applied the entire wide-band impedance information of train and network.Therefore,this paper presents a stability analysis method for the multiple train-network system based on impedance measurement information,which can conduct a unified analysis of typical wide-band oscillation problems in train-network system.Firstly,an active measurement method for the dq-frame impedance matrix of traction power supply network nodes and train is provided,which is used to obtain the impedance information of train and network required for stability analysis.Secondly,considering the impedance of traction lines between different trains,a multiple train-network system model based on multi-nodes is established and its impedance transfer function matrix is derived,which can be equivalent to a multi-input multi-output(MIMO)negative feedback system.The stability of multi-train system is evaluated by the determinant of impedance return-difference matrix of the train and network system,and the oscillation frequency of system can be obtained by identifying its right half plane(RHP)zero,extremely simplifying the analysis process of the multiple train-network system.The proposed method is used to analyze three typical oscillation problems:low-frequency oscillation,harmonic resonance and harmonic instability in electrified railway,and compared with the cascaded system analysis method based on a single node.The results indicate that ignoring the impedance of the traction line may lead to incorrect analysis results.Finally,the analysis method is simulated and verified based on Matlab/Simulink.The simulation results of the multiple train-network system under different conditions are basically consistent with the stability analysis results,which proves the effectiveness of the proposed method.The following conclusions can be drawn from the simulation analysis:(1)The three types of stability problems of electrified railways can be unified in the frequency domain by utilizing the measured train and network wide-band impedance information,which compensates for the shortcomings of only analyzing single oscillation problems.(2)The stability analysis process is simple,and the oscillation frequency of system can be directly identified by finding the RHP zero point of the determinant of impedance return-difference matrix,avoiding the tedious process of verifying the Nyquist curve for each eigenvalue.(3)Compared to stability analysis methods based on theoretical modeling,the proposed method only requires impedance measurement data and can predict the stability of multiple train-network system,without the need to master detailed parameters of the network and train.