基于HHT一化迭代的输电线路故障测距研究

Study on fault location of transmission line based on HHT iteration

针对目前行波测距法中波速测定精度差的不足和波头检测算法存在的缺陷,通过分析行波波速随频率的变化规律,推导出波速稳定时的频率区间范围,从而消除波速对测距结果的影响;在研究高压直流输电线路故障行波到达时刻与行波特定瞬时振幅关系的基础上,分析瞬时振幅影响行波测距的机理,提出一种基于瞬时振幅的输电线路故障测距方法,利用希尔伯特黄变换(HHT)一化迭代的方法形成高频电流故障信号的一化时幅图,依据一化时幅图确定波头时刻与该时刻特定的瞬时振幅,形成高压直流输电线路故障测距算法。MATLAB/Simulink仿真结果表明,该方法的相对误差在0.3%以内,且该方法与HHT变换的定位方法相比,具有更高定位精度,基本不受故障距离、过渡电阻的影响。

Aiming at the deficiency of the measurement accuracy of the wave velocity in the current traveling wave ranging method and the defect of the detection algorithm of the wave head, by analyzing the changing law of traveling wave speed with frequency, the frequency range when the wave speed is stable is derived, so as to eliminate the influence of the wave velocity on the ranging result. On the basis of studying the relationship between the arrival time of the traveling wave of the high-voltage direct current(HVDC) transmission line fault and the specific instantaneous amplitude of the traveling wave, the mechanism of the instantaneous amplitude affecting the traveling wave location is analyzed, and a fault location method of the transmission line based on the instantaneous amplitude is proposed. The iterative method forms a time-amplitude diagram of the high-frequency current fault signal. According to the time-amplitude diagram, the wave head time and the specific instantaneous amplitude at that time are determined to form a HVDC transmission line fault location algorithm. MATLAB/Simulink simulation results show that the relative error of this method is within 0.3%, and compared with the positioning method of Hilbert Huang transform, this method has higher positioning accuracy and is basically not affected by fault distance and transition resistance.