希尔伯特变换在配电网故障选线中的应用

为克服目前小电流接地系统单相故障发生在相电压过零点附近选线方法灵敏度低的缺点,提出了一种基于希尔伯特变换的综合选线判据。将零序电流进行小波包分解的同时,运用希尔伯特变换对分解结果进行瞬时频率分析,计算频带能比因子。将频带能比因子作为启动选线方法的条件,当高频分量多时比较小波高频能量,当低频分量多时比较直流分量能量,将两种方法进行有机综合可以构成完善的故障选线方案。仿真结果表明该方法有效、准确、且适用性强,不受系统结构和运行方式等的影响。

Application of Hilbert transform in faulty line selection of distribution network

In order to overcome the disadvantage of low sensitivity of line selection method in neutral ineffectively grounded system when fault occurs near the zero-crossing point of phase voltage, a faulty line selection based on Hilbert transform is proposed, which carries out the wavelet packet decomposition of transient zero-sequence current for each line into low and high frequency subbands, whose instantaneous frequency are calculated by Hilbert transform at the same time, calculates the frequency band energy factors according to the wavelet coefficients. The frequency band energy factor is used as a condition of starting line selection method, when the high-frequency component is the main ingredient, we select the faulty line according to the maximum value of high-frequency wavelet energy; when the low-frequency component is the main ingredient, we select the faulty line according to the maximum value of DC component energy. A perfect scheme will be worked out combining with the two methods. Results of simulation show that, the proposed method, which is immune to the system structures and the mode of operations, has the characteristics of reliability, accurately and practicality.