Influence of Pulse Interval on Soil Dispersion Characteristics under Continuous Impulse

Abstract

Under continuous lightning strikes, the impulse dispersion characteristics of grounding devices more effectively indicate the effectiveness of tower grounding for lightning protection. These characteristics exhibit distinct behaviors under different lightning current pulse intervals. To investigate these characteristics, the present study employed ATP-EMTP simulation software to develop a dual-pulse model that accounted for the time-varying properties of soil and spark effects. The combined simulation and experimental approach was used to examine, the continuous impulse characteristics of grounding devices. The results reveal that the impulse characteristics under continuous strikes are significantly different from those under single strikes, primarily due to variations in the soil environment surrounding the grounding devices. The spark and recovery effects exert different impacts on soil impulse dispersion performance. Shorter pulse intervals lead to a superposition of first and second impulse currents, which increases current amplitude and spark effect, temporarily reducing soil resistivity and making the recovery effect of soil less pronounced. This results in lower impulse grounding resistance compared to longer intervals. Furthermore, with the increase in soil resistivity, the ratio of the second to the first impulse grounding resistance decreases, indicating that soil resistivity also influences the intensity of the spark effect on soil.

Keywords

• continuous impulse current
• impulse grounding resistance
• lightning protection
• pulse interval
• vertical grounding electrodes.