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中文摘要：
高压直流（highvoltagedirectcurrent，HVDC）输电线路两端的平波电抗器和直流滤波器构成现实的边界元件，对暂态电压高频分量呈带阻传变特性，来自直流线路区外的高频电压信号通过平波电抗器和直流滤波器后被衰减，其能量显著减小，不同频带的高频电压信号小波能量可应用小波变换求得。利用区内、外故障时于保护安装处获得的暂态电压小波能量的显著差异来构造直流输电线路区内、外故障判据；利用故障暂态电压小波变换模极大值，构造启动判据；利用正极和负极暂态电压分别与＋800和-800kV的相关系数，构造雷击干扰识别判据；利用两极线极波，构造故障选极判据。给出了特高压直流（ultrahighvoltagedirectcurrent，UHVDC）输电线路单端电气量暂态保护方案。对该保护进行了大量仿真分析，计及了雷击干扰、边界上避雷器动作、不同过渡电阻、换相失败故障等因素的影响。仿真结果表明，该保护具有绝对选择性，能可靠有效地保护直流线路全长。
英文摘要：
The physical boundary of a high voltage direct current （HVDC） transmission line consists of smoothing reactor and DC filter. It has the stop-band characteristic to the highfrequency transient voltage components. The high-frequency voltage signal from the external of DC transmission lines will be weakened when it travels through the smoothing reactor and DC filter. Its power will also be much smaller. The wavelet energy of the high-frequency transient voltage can be gotten through wavelet transformation. The identification criterion of internal and external faults is based on the conspicuous difference of the wavelet energy of high-frequency transient voltage at the point of relay installation. The wavelet transformation modulus maximum of the fault transient voltage was used as the criterion of starting. The correlation coefficients between the bipolar transient voltage and ＋800 kV lines and the correlation coefficients between the bipolar transient voltage and -800 kV lines were calculated to identify the lighting interference. The fault line was selected based on the polarity wave of the two lines. The scheme of single-ended electrical transient protection of the ultra high voltage direct current （UHVDC） transmission lines was presented. The simulation was performed considering the impact of lightning interference, the action of ZnO arrester on the boundary, commutation failure, and the fault distance to the single-ended electrical transient protection. The simulation results show that the protection has absolute selectivity, which can steadily and effectively protect the whole lines.
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