基于电容器投切法的牵引供电系统谐波阻抗测试分析

针对牵引供电系统供电拓扑结构复杂、系统等效阻抗难以精确计算等特点,提出基于电容器投切法的谐波阻抗测试方法。并联电容器开关闭合的过程可以等效为一个谐波源向系统注入谐波电流,基于此建立了阻抗测试系统用于处理拓扑结构特殊的牵引供电系统,该阻抗测试系统由27.5 kV/380 V的变压器、电容器、开关和负载阻抗组成。考虑到现场测量中存在背景谐波、噪声等干扰,利用波动量法和小波分层算法对采集信号进行处理。基于Simulink仿真平台搭建牵引供电系统阻抗测量模型,仿真及误差分析结果验证了所提方法能有效地测量牵引供电系统的谐波阻抗。

Harmonic impedance measurement analysis of traction power supply system based on capacitor switching technology

Due to the complex topology of traction power supply system and numerical accurate calculation difficulty of system equivalent impedance, a harmonic impedance measurement method based on capacitor switching technology is proposed. The switching process of the shunt capacitor can be equivalent to a harmonic source injecting harmonic currents into the system, based on which a harmonic impedance measurement system is established to deal with the special topology of the traction power supply system. The harmonic impedance measurement system is composed of a 27.5 kV/380 V transformer, a shunt capacitor, a switch and a load impedance. Fluctuation quantity method and wavelet decomposition algorithm are applied to deal with the collected signals in field measurement with background harmonics and noises. The impedance measurement model of traction power supply system is built on Simulink simulation platform, and simulative results and error analysis results verify that the proposed method can measure the harmonic impedance of the traction power supply system effectively.