传统行波故障定位方法有行波波头难以识别,无法实现自动化的固有缺点,为此,基于直流线路发生故障时,线路两侧的直流滤波器和平波电抗器组成的物理边界会对电压行波中的高频信号产生全反射,而且高频电压行波在故障点折射强于反射的特点,采用线路的分布参数模型,提出了一种高压直流输电线路单端行波自动故障定位方法。该方法用线路高频电压分量和高频电流分量计算沿线电压分布,识别出前行波和反行波的最强叠加点即可实现故障定位。此方法避免了传统行波测距中需要人工识别行波波头的缺点,所需数据窗短,测距特征明显易于实现自动化,仿真验证表明该方法定位精度高,1000km线路最大测距误差仅为800m,且不受过渡电阻的影响。
Traditional traveling wave methods for locating faults on transmission lines have the deficiency of being hard to catch the second wave head and unable to automatically achieve. A novel automatic method to the single-ended travel- ing wave fault location for CSC-HVDC transmission lines is presented. When a fault occurs on a DC line, the DC filter and the smoothing reactor which are located in the end of the DC line constitute a physic boundary for the voltage travel- ing wave, and the boundary will cause total reflection to high-frequency traveling voltage waves. Since the refraction of the traveling wave at the fault point is much stronger than the reflection, based on the distributed parameter model, the voltage distribution of the DC line can be calculated by using the high-frequency voltage and current measured in the lo- cal terminal. Therefore, the fault can be located by seeking the strongest superposition point that is constituted by the forward and back voltage waves. Different from traditional traveling wave methods, the proposed method does not need to catch the second wave head and it is automatic. Simulation results show that this method has satisfying accuracy that the error of 1000 km is only 800 meter, and its results are free from the influence of transition resistance.