基于行波时频特征的单端故障测距方法

A Single Terminal Fault Location Method Based on Time-Frequency Characteristic of Traveling Wave

行波波速度的确定及故障行波波头到达时刻的标定是影响行波测距精度的主要因素。在考虑线路参数频变特性对行波传播特性的影响的基础上,提出基于行波时频特征的单端测距方法:利用行波信号的利普希茨(Lipschitz)指数将行波信号的时频特性联系起来,运用最小二乘法拟合检测到的第2个行波波头的Lipschitz指数,并据此确定故障行波的频率成分及其到达时刻,计算故障距离。EMTDC仿真实验结果表明:所提方法测距精度较传统的行波测距方法有较明显的提高,且不受故障距离、故障电阻、故障初相角和故障类型的影响,能很好地适应完全换位和非完全换位线路。

accuracy of determination There are two main factors influencing the traveling wave fault location, namely the of traveling wave velocity and the demarcation of the time when the wavefront of fault traveling wave arrives. On the basis of considering the impact of frequency-varying feature of parameters of transmission line on propagation characteristic of traveling wave, a single-terminal fault location method based on the time-frequency characteristics of traveling wave is proposed： firstly, the time characteristic of traveling wave＇s wavefront is linked with its frequency characteristic by Lipschits exponent of traveling wave signal; then by use of least squares method the Lipschits exponent of the detected second wavefront of traveling wave is fitted; finally, according to fitting result, the frequency components of fault traveling wave and the time when it arrives are determined, thus the fault distance can be calculated. Simulation results of EMTDC show that using the proposed fault location method, the accuracy of fault location is evidently higher than that by traditional traveling wave fault location methods, a^d the locatio~ accuracy is not affected by fault distance, fault resistance, fault inception angle and fault type, besides, the proposed method can well adapt to both transposed and untransposed lines.