中文摘要：

根据云广特高压直流输电系统实际参数,建立特高压直流输电线路以及由平波电抗器、直流滤波器和PLC滤波器所构成的特高压直流输电线路边界的频域模型,分析特高压直流输电线路和线路边界的频率特性.对特高压直流输电线路及其边界对故障暂态信号高频量的衰减作用,以及故障位置对保护安装点所检测到的故障暂态信号高频量的影响进行了研究.研究结果表明,边界和线路对暂态信号高频量的衰减作用大小和故障与保护安装点的距离有关,当故障发生点与保护安装点的距离大于-ln ｜G（jω）｜/α时,线路对频率为ω/（2π）高频量的衰减作用将大于边界的衰减作用.建立云广特高压直流输电系统实际参数仿真模型,对特高压直流输电线路及其边界对故障暂态信号高频量的衰减作用进行仿真验证,仿真结果证明了上述结论的正确性.

英文摘要：

According to the actual parameters of Yunnan-Guangdong UHVDC transmission system,the frequency-domain model of UHVDC transmission line and its boundary consisting of smoothing reactor,DC filter and PLC filter is built and the frequency characteristics of UHVDC transmission line and its boundary are analyzed.The influence of UHVDC transmission line and its boundary on the high-frequency component attenuation of fault transient signal and the influence of fault position on the high-frequency components of fault transient signal detected by relay protection are studied,which leads to following conclusion：the fault transient signal attenuation degree is relative to the distance between fault position and relay protection.When the distance is longer than-ln ｜G（jω） ｜/α,the influence of transmission line on the ω/（2π）-frequency component attenuation is greater than that of boundary.The simulation model with actual parameters is built and the simulative results show the validity of above conclusion.