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应用在时频空间皆具有良好聚焦特性的小波包 ,以适当频率带宽 ,对故障后暂态电气量进行分解。对于中性点接地方式不同的配电网 ,按照能量的观点 ,选择不同的频带来实现故障选线。基于选出的故障选线时频窗 ,提出了一种新型的选线判据 :以波形识别作主判据 ,以模值比较作副判据 ,经逻辑排序 ,最终给出故障选线序列。理论及大量的 EMTP仿真表明 :该选线方法可以准确、可靠地实现单相故障接地选线 ,适合于接地方式不同的各种配电网 ,而且现场安装简单、无需定值调节。
The wavelet packet with good focusing characteristics in both time and frequency space is applied to decompose the faulty transient electrical quantities with appropriate frequency bandwidth. For neutral point grounding different distribution network, according to the energy point of view, choose a different frequency band to fault line selection. Based on the selected time-frequency window of fault line selection, a new type of line selection criterion is proposed: taking the waveform identification as the main criterion and the modulus comparison as the secondary criterion, the logical alignment results in the final fault line selection sequence . The theory and a large number of EMTP simulations show that this method can accurately and reliably implement single-phase faulty grounding line selection and is suitable for various distribution networks with different grounding modes. Moreover, it is easy to install in the field and needs no setting regulation.