On the Transient Behaviour of Vertical Grounding Electrodes Buried in Soils with Frequency-Dependent Electrical Parameters

• Main Authors: Manzi de Azevedo, Walter Luiz, Justo de Araujo, Anderson Ricardo, Filho, Jose Pissolato
• Format: Conference Proceeding
• Language: English
• Subjects: electromagnetic transients; frequency-dependent soils; Grounding; grounding modeling; Harmonic analysis; Lightning; lightning performance; Poles and towers; Power transmission lines; Soil; Voltage
• ISSN: 2572-1445
• DOI: 10.1109/INDUSCON58041.2023.10374898

This paper investigates the transient responses generated on a vertical rod buried in soil with electrical parameters that vary with frequency effect and on a transmission line subjected to impulsive currents. The harmonic grounding impedance (HGI) is calculated for a 5-m rod buried in frequency-dependent (FD) and frequency-constant (FC) soils using full-wave electromagnetic software Altair FEKO employing the Method of Moments (MoM) for a range of 100 Hz to 10 MHz. The time-domain responses are calculated for the rod subjected to lightning current of first and subsequent return strokes and Gaussian pulse. Simulation results show that a significant HGI modification beyond a particular frequency is noted when FD soils are assumed. The induced transient GPR waveforms show a notable reduction in their voltage peaks when the FD soil model is compared with those computed using the frequency-constant (FC) soil model. Finally, a backflashover analysis demonstrates that as the soil resistivity increases, the voltage peaks remarkably decrease. This reduction is more pronounced for shorter front-time subsequent stroke and Gaussian pulse.