基于小波包分析的配电网故障选线新方法

提出了基于小波包分析的配电网故障选线新方法用于解决低频采样零序电流信号因发生不同程度的能量衰减而导致的选线错误问题。当发生单相接地故障时,分别对零序电流信号进行低频采样和高频采样,计算高频采样零序电流信号的首波头极性和最大值以及低频采样零序电流信号的最大值,以此为依据对低频采样的零序电流信号做增强处理,然后利用小波包分析方法对增强的信号进行小波包分解,根据能量最大的原则实现故障选线。基于上述原理研制了配电网接地选线装置,给出了装置的硬件结构及软件流程。分别针对零序电流信号能量衰减严重和极性检测错误的情况进行仿真试验。结果表明,该方法有效地提高了小电流接地选线的准确性。

Faulty line detection based on wavelet packet analysis for distribution network

A novel faulty line detection method based on wavelet packet analysis for distribution network is proposed to avoid improper detection caused by energy decay of zero sequence current signals at low sampling rate.When a single-phase-to-earth fault takes place,the zero sequence current signals are sampled with both higher and lower sampling rate.The maximum amplitude and polarity of faster sampled zero sequence current signals and the maximum amplitude of lower sampled zero sequence current signals are calculated,based on which the lower sampled zero sequence current signals are enhanced.Then the enhanced signals are decomposed by wavelet package transform and the faulty line can thus be detected according to maximum energy principle.A device to detect grounding feeder is developed based on the method mentioned above.Its hardware structure and software flowchart are given.Simulation tests are carried out for the severe energy decay and false polarity detection of sampled zero sequence current signals.Results indicate that the method effectively raises the accuracy of faulty line detection for power system with small grounding current.