Observation and Analysis of Surge Impact Characteristics of Low-voltage Overhead Lines Caused by Natural Lightning

Abstract In this paper, the residual voltage of a surge impacting surge protective device (SPD) generated by the coupling of a 710 m low-voltage overhead line is observed and analyzed. Based on the observation results of 65 natural lightning returns, it is found that, with a duration of 97.3 µs, the peak value of the SPD’s residual voltage was 767.6 V. In addition, the peak current flowing through the SPD was 6.4 A, and the energy absorbed by the SPD was only 0.2 J. According to the different return stroke process and its superimposed M component, the surge impacting SPD was divided into three categories. The currents flowing through SPD of type A and type B were basically the same, but the residual voltage waveform differed, The surge impact was mainly in the return stroke process. Type C was quite different from the other two types: The surge impact was expanded in the form of superposition of M component in the return stroke process, the residual voltage duration and peak current flowing through SPD were about twice those of the other two types, and the energy absorbed by SPD was about 5.8 times. There was a certain correlation between the current peak value of the subsequent return stroke flowing through SPD and the ratio of lightning current peak value and distance, with the determination coefficient R2 reaching 0.71, while the correlation of the first return stroke was weak, the R2 being only 0.48.