直流输电线路行波采集二次回路阻抗匹配问题研究

Research on impedance matching of secondary circuit of HVDC transmission lines for travelling wave acquisition

行波信号的准确采集是输电线路行波故障测距的基础,直流输电线路二次回路阻抗不匹配对行波采集存在负面影响。针对此问题,本文研究二次回路波阻抗不匹配的原因,分析由此导致的行波折反射问题及其对单端行波故障测距的不利影响。为解决二次回路阻抗不匹配问题,提出在二次回路传输电缆首端并联电阻的方法,并对常用的传输电缆进行实测和电磁暂态仿真,分析传输电缆的波阻抗变化范围,验证匹配电阻的行波折反射抑制效果。结果表明,本文提出的阻抗匹配方法可有效消除二次回路行波折反射现象,有助于提高单端行波故障测距的可靠性,具有良好的工程适应性。

Accurate acquisition of traveling wave signals is the foundation of traveling wave fault location(TWFL)for transmission lines,and the impedance mismatch of the secondary circuit of high voltage direct current(HVDC)lines has negative impact on traveling wave acquisition.For this issue,this article investigates the reasons of the impedance mismatch in the secondary circuit,and analyzes the resulted phenomenon of traveling wave refraction and reflection(TWRR),as well as its negative impact on single-ended TWFL.To solve the problem,a method of impedance matching is proposed,which adds a parallel resistor at the head end of the transmission cable.The commonly used transmission cable is measured and simulated to analyze the range of wave impedance change of the transmission cable,and to verify the suppression effect of TWRR by matching resistors.The results show that the proposed impedance matching method can effectively eliminate the phenomenon of TWRR on secondary circuit,thus improve the reliability of single-ended TWFL,and has good engineering adaptability.