基于车网耦合下的机车牵引变流器输出电流频谱移动现象研究

Research on the Phenomenon of the Locomotive Converter Output Current Spectrum Move Based on the Coupling of the Train Net System

传统研究认为,牵引网谐振是由于机车或动车组所产生的特征次频谱与牵引网谐振频率点相等或接近造成的,但实际线路运行表明,在机车非特征次频谱范围内也多次发生牵引网谐振现象。该文基于机车瞬态电流控制算法下的机车电流谐波特性,给出在谐波环境下体现车网时变循环作用的数学表达式,分析牵引网由于高次谐波发生谐振时畸变的网压作用于机车整流器脉宽调制过程和机车输出电流,机车输出电流又反作用于网压的交互作用过程,使机车输出电流主要频谱分布趋势会随着牵引网谐振频率的变化向谐振点附近移动。基于仿真和实测数据,通过车网耦合下机车输出电流主要频谱从机车特征次频谱向牵引网谐振点附近移动的现象验证理论分析的正确性。

As the traditional research show,the resonance of the traction network happens when the characteristic spectrums of the AC drive electric locomotive or the EMUs match or are close to the resonant frequency.However,the resonance caused by the non-characteristic spectrum is measured many times in the actual operation.Based on the characteristic of the locomotive current under the transient current control strategy,the mathematical expression of the time varying cyclic effect of the train net coupling in the harmonic environment was given.This paper analyzed such a interaction process that the severely distorted net voltage caused by the resonance of the high-order harmonics acts on the PWM modulation of the rectifier of the locomotive and the locomotive output current,in turn,the locomotive output current acts on the net voltage.As a result,the main spectrum distribution of the locomotive current will move with the variation of the different resonance points of the traction net.Based on the simulation and measured data,the theoretical analysis was verified by the phenomenon of the main order of the locomotive current spectrum moves to the resonant frequency of the traction network.