基于暂态零序电流时频特征量的配网故障选线方法

Faulty line selection based on time-frequency characteristics of transient zero-sequence current

中性点经消弧线圈接地的配电网系统不同故障条件下发生单相接地故障时,健全馈线和故障馈线的暂态零序电流在短窗时域和频域分布特性不同。利用各馈线故障后1/4工频周期时窗的故障暂态零序电流数据,经小波包分解并将其重构至不同频段,进而求得的时频特征量能在一时频窗内充分反映信号的时频特性,利用相关系数表征暂态零序电流的时频分布特性及其变化规律,并结合综合相关系数形成选线判据,实现配电网单相接地故障选线。大量电磁暂态仿真表明,该方法准确、可靠。

When single-phase grounding fault occurs in the power distribution system with its neutral point grounded through arc suppression coil,the distribution characteristics of transient zero-sequence current in short-window time-domain and frequency-domain are different between sound feeder and faulty feeder. The fault transient zero-sequence current data of different feeders are extracted for the last quarter of power cycle,which are then decomposed by the wavelet packet and reconstructed into different frequency bands. The time-frequency characteristics obtained for a short window can fully reflect the time-frequency characteristics of the signal. The correlation coefficients are then used to characterize the time-frequency distribution and variation law of transient zero-sequence current,which are combined with the complex correlation coefficient to form the criterion for faulty line selection. Electromagnetic transient simulations show the proposed method of faulty line selection is accurate and reliable.