地铁直流牵引供电系统振荡机理分析

地铁直流牵引供电系统低频振荡电流是导致DDL保护误动的主要原因。从系统分析的角度，建立了计及电动车辆影响的直流牵引供电系统电磁暂态模型及系统振荡时的非线性二阶动态模型。在唯一平衡点邻域内，利用李亚普诺夫间接法将非线性动态系统转换为线性系统后，确定出系统振荡的结构条件。实例计算和仿真表明，牵引变流器和牵引电机的等效负电阻是系统不稳定的主要电气参量，系统振荡频率主要取决于车载滤波电容与滤波电感，且系统仿真波形在众多特征上与实际记录的电流波形基本一致。

An Analysis of the Oscillation Mechanism for Metro DC Traction Power Supply System

The malfunction of DDL protection system is mainly caused by the low‐frequency oscillation current of metro DC traction power supply system .Based on the system analysis method ,the electromagnetic transient model of the DC traction power supply system is built with the consideration of the influence of electric vehicles . T he nonlinear second‐order dynamic equations are acquired in the case of low‐frequency oscillation . Using the linear processing method in the neighborhood of unique equilibrium point by the indirect method of Lyapunov ,the structural conditions causing low‐frequency oscillation were ascertained .The case calculation and simulation result show that the main reason for the system instability is the equivalent negative resistance of traction converter and traction motor . The system oscillation frequency mainly depends on filter inductor and filter capacitor of the vehicle .In addition ,the simulation current waveforms are generally consistent with the recorded current waveforms in several features .