基于压缩感知理论的小电流接地故障选线法

Line Selection of HHT Detection for Small Current Grounding Fault Based on Compressed Sensing

将一种全新的信号处理方法——压缩感知理论应用于小电流接地故障的选线中,采用压缩采样方法对故障前1/4周期到故障后1/4周期各线路零序电流进行低频压缩采样,然后通过恢复算法对所采信号进行精确重构。对重构信号采用小波去噪后进行经验模态分解(empirical mode decomposition,EMD),选出各线路零序电流最高频IMF分量作差分运算,依据故障线路零序电流最高频IMF分量在故障发生时刻的一阶差分极性和健全线路相反的原则实现故障选线。Matlab仿真试验表明该方法不受采样频率限制,选线结果具有较高的准确度。

A new signal processing method- the compressed sensing theory is applied in the line selection of small current grounding fault. Each line＇ s zero sequence current within 1/4 cycle before and after the fault is sampled at lower frequency with the method of compressive sampling, and then the original fault current is accurately reconstructed for the sampled signal. After denoised by wavelet, the reconstructed signal is decomposed by the empirical mode decomposition method （EMD） to get the highest IMF component. Based on the principle that the polarity of the highest IMF component＇ s first order difference of fault line＇ s zero＇ s sequence current is opposite to that of the normal ones at the moment fault occurs, the faulty one is selected. Matlab simulation shows that this method is not restricted by sampling frequency and the results have high accuracy.