Faulty-Line Selection Method Based on Pearson Correlation Coefficient in Neutral Non-Effectively Grounded Systems

Abstract

When a single-phase grounded fault occurs in a distribution network, a quick selection of the faulty line is crucial for the safe and reliable operation of the network. To address the low accuracy of selection devices in detecting grounded faulty lines, a line selection method based on the Pearson correlation coefficient is proposed by analyzing the similarity of the zero-sequence current fitting curve and the slope curve of each line in the distribution network when a single-phase grounded fault occurs. The apparent difference between the slope of the zero-sequence current fitting curve of the faulty and healthy lines is used to select the faulty line. Specifically, a local weighted linear fitting and differentiation are performed on the zero-sequence currents of each line to obtain the corresponding slope curves. Subsequently, the similarity of the slope curves of the zero-sequence current waveforms of the adjacent lines is used to determine the faulty line. If the similarity between a line and two adjacent lines is poor or negative (Pearson correlation coefficient close to or less than 0), it is determined as a faulty line. If the similarity between a line and at least one adjacent line is high (Pearson correlation coefficient close to 1), it is determined to be a healthy line. If the similarity of the slope curves of the zero-sequence current waveform of all lines is high (Pearson correlation coefficient close to 1), it is determined to be a bus fault. Matlab/Simulink simulation results showed that the proposed method is effective under various fault conditions and has a high detection sensitivity to high transition resistance faults.