The Research of The Disturbance of Lightning Strike on Rogowski Coil Current Transformer According to Wavelet Analysis

Abstract

Although there are many Rogowski coil current transformers being widely used, its stability and accuracy of measurement is not very good due to the effects of various factors. In practice, there are still some new interfering factors. In this paper, the principle of a new interference factors is analyzed, and the appropriate solution is put forward. The new interference is that when the power system is struck by lightning strike or over-voltage, the induced electromotive force of secondary side of the Rogowski current transformer is significantly interfered because of the fluctuation of capacitive coupling. So it will raise the measured current greatly and cause the measurement error. At last, the protective relaying will trip incorrectly. In this paper, the wavelet transform method is used to analyze the current of the transformer in normal conditions. Then the article analyzes the increased measured current caused by lightning strike and grid faults. And according to the results, the differences will be found which can be used to judge whether the increased current is caused by lightning strike or the grid faults. Keywords-electronic current transformer, Rogowski coil, Wavelet Analysis, lightning strike