基于小波变换的电气化铁道牵引负荷谐波分析

Analysis on Harmonics of Electric Locomotive Based on Wavelet Transform

电力机车作为牵引供电系统的主要不平衡负荷、谐波源负荷,其运行过程中产生的高频谐波电流对电力机车的安全、稳定运行造成很大危害。为精确实时地检测牵引供电系统中的谐波,采用时频域内均可局部化的小波变换进行谐波分析。以HXD3型0017电力机车为例,分析牵引负荷谐波电流的特点,采用最小描述长度准则(MDL)确定分析谐波的最佳小波函数,并确定合理的分解层数,在MATLAB环境下运用小波工具箱中的函数进行小波算法编程,实现对机车电流的谐波分析。仿真结果表明:小波变换可快速准确地将信号中的基波和不同频率的谐波信号分解出来,从而达到检测谐波的目的。

The electric locomotive is the main unbalance load and harmonic source load of the traction power system.The high-frequency harmonic currents generated in its running process will do great harm to its safe and stable operation.In order to detect the harmonics in the traction power system accurately and on a real-time basis,wavelet transform with good time-frequency localization is used in harmonic analysis.Type HXD3-0017 Electric Locomotive was taken as an example to analyze the harmonic current characteristics of the electric traction load.The optimal wavelet function was defined by the minimum description length（MDL） principle,the reasonable number of the decomposition levels was determined.The wavelet algorithm codes were programmed by the functions in the MATLAB wavelet toolbox to accomplish harmonic analysis of the locomotive currents.The simulation results show that wavelet transform can decompose signals to the fundamental wave and different-frequency harmonic waves quickly and accurately,so as to attain the purpose of harmonic detection.