中文摘要：

为提高高压直流线路故障检测的准确性,提出一种利用直流线路两端暂态测量阻抗特征的故障判别方法。基于长线路传输方程,分析直流区内、外故障暂态过程中线路两端的暂态测量阻抗特征（定义为暂态电压分量与暂态电流分量之比）。由于直流线路与边界在不同频带下呈现的阻抗特征存在差异,区内、外故障时,线路两端暂态测量阻抗将不同,据此可形成故障判据。利用暂态测量阻抗进行故障判别,克服传统暂态谐波保护中谐波幅值低、易受线路衰减及过渡电阻的影响等缺陷。结合双极线路低频段暂态分量耦合系数小的特点,提出利用低频段暂态电流比值进行故障极判别。仿真分析与现场录波数据测试表明,该方法能准确、可靠地实现直流线路的故障判别,具有较强的抗过渡电阻能力,且对于系统参数的变化具有一定的适应性。

英文摘要：

In order to improve the accuracy of fault detection for HVDC transmission lines, a fault identification method was proposed. Based on the transmission equation of long line, the transient measured-impedance, which is defined as the ratio of transient voltage component and transient current component, was analyzed in detail. The transient measured- impedances at the both sides of DC line are quite different during the internal and external faults due to the different impedance paths provided by the DC line boundary to the transient component with different frequency. This difference is used for fault identification. By employing this method, the shortcomings of traditional protection principles using transient harmonics, such as low amplitude, sensitive to fault resistance and line attenuation, are overcome. The coupling coefficient between the bipolar lines for low-frequency transient component is small. Therefore, the faulted pole selection can be achieved by using the ratio of low-frequency transient component of the bipolar lines. The results of simulation and the test with field data show that the proposed fault identification method is able to identify internal faults with high fault resistance from external faults reliably. In addition, the proposed method is suitable for the situations when the system parameters vary with large range.