基于全波形信息的混联线路单端行波定位方法

Single-Ended Traveling-Wave-Based Fault Location Algorithm for Hybrid Transmission Line Based on the Full-Waveform

架空线-电缆混联线路,由于各段线路行波波速度不一致,初始行波波头和故障点反射波难以辨识,传统的故障定位算法无法适用。提出了基于全波形信息的故障行波时-频域表现形式;基于故障信号的传播特性和折、反射机理,定性分析了区段内故障和相邻区段故障,行波波形时-频域相似性和差异性,揭示了故障行波全波形与故障点位置一一对应的本质;基于故障行波全波形信息,截取一定时间窗行波信号,对其经连续小波变换得到各频带系数进行时间间隔划分,得到面积相等的时频小块,进而建立故障行波时频谱矩阵,利用波形特征匹配技术,实现混联输电线路准确故障定位。该方法具有清晰的物理意义,无需行波模量波速,无需提取初始行波波头以及后续反射波,可通用于多端混联输电线路。理论研究和大量算例分析结果表明,该方法原理简单,具有较高的实用价值。

Abstract In transmission lines composed of multi-sectional overhead lines and underground cables, due to the difference between traveling wave velocities in overhead line and underground cable, the traditional traveling wave-based fault location algorithm for uniform transmission line is not suitable. Based on the transmission characteristics and the refraction and reflection mechanism of traveling wave, the traveling waveform similarity and difference in the time-frequency domain between the faults occur within section and at adjacent sections are qualitatively analyzed. On this basis, the full-waveform representation of the traveling wave in the time-frequency domains is proposed, and then the one-to-one correspondence relationship between the full-waveform and the fault location is revealed. Extracting the full-waveform within a certain time window, all frequency band coefficients can be obtained by CWT, and then they were divided into small time-frequency pieces which had the same frequency bandwidth and time interval. The time-frequency spectrum matrix was built, and the accurate fault position can be calculated by using the waveform matching technology. The proposed method has clearly physical meaning, which can be used both in hybrid and uniform transmission lines. There is no need to use the modal component velocities, the initial traveling wave-front arrival times and its subsequent reflection waveforms. Extensive simulations under different conditions verify the wide applicability and high accuracy of the proposed algorithm.