HVDC lines are very susceptible to faults once they are long and can operate under severe weather conditions. The main approaches for fault location in HVDC lines are based on the concept of traveling waves. Their performances depend on the times that the wavefronts reach the monitored terminals as well as the wave velocity. Despite the wave velocity depends on the line parameters and fault location, in the conventional approaches it is assumed constant regardless of the fault location impacting the obtained results. This paper presents a single-terminal fault location approach where the required wave velocity is estimated from line parameters and wavefronts traveling times. The wave velocity is represented by a mathematical function which is fitted to simulated and/or actual fault data, resulting in a more accurate wave velocity estimation for every fault location. Case studies were performed for different fault locations, fault resistances and ground resistivity, considering a 500 km bipolar HVDC transmission line modeled as a Frequency-Dependent (Phase) Model. The proposed approach is compared to the conventional approach in several scenarios. The results indicate that the proposed way to handle the wave velocity improves the accuracy of the fault location.

高压直流输电线路很长，很容易发生故障，并且可以在恶劣的天气条件下运行。高压直流输电线路故障定位的主要方法是基于行波的概念。它们的性能取决于波前到达被监视终端的时间以及波速。尽管波速取决于线路参数和故障位置，但在常规方法中，无论故障位置如何影响所获得的结果，都假定其为常数。本文提出了一种单端故障定位方法，其中根据线路参数和波前传播时间估算所需的波速。波速由适合模拟和/或实际故障数据的数学函数表示，从而使每个故障位置的波速估计更加准确。考虑到将500 km双极高压直流输电线路建模为频率相关（相位）模型，对不同的故障位置，故障电阻和接地电阻率进行了案例研究。在几种情况下，将建议的方法与常规方法进行了比较。结果表明，所提出的处理波速的方法提高了故障定位的准确性。