A study of grounding arrangements composed by vertical electrodes for two-layered stratified soil models

• Published in: Electric power systems research Vol. 180; p. 106129
• Main Authors: Batista, R., Caetano, C.E.F., Paulino, J.O.S., Boaventura, W.C., Lopes, I.J.S., Cardoso, E.N.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.03.2020; Elsevier Science Ltd
• Subjects: Conductors; Electric currents; Electric power lines; Electricity distribution; Electrodes; Electromagnetic model; Grounding; Impedance; Lightning; Soil layers; Soils; Time-domain response; Towers; Transmission line approach; Transmission lines; Two-layer soil; Vertical rod; Transmission line approach; Two-layer soil; Time-domain response; Grounding; Vertical rod; Electromagnetic model
• ISSN: 0378-7796; 1873-2046
• DOI: 10.1016/j.epsr.2019.106129

•Grounding arrangement for transmission line (TL) towers using vertical electrodes.•Grounding arrangement for conditions of high resistivity soil and where the resistivity of the first-layer is higher than the second.•Estimation of harmonic grounding impedance using techniques based on TL-theory and comparison with rigorous electromagnetic (EM) method solution.•The results show that both the grounding resistance and impulse impedance decrease significantly with the use of vertical electrodes.•Significant economy of the conductor material applied to the grounding. This paper presents a study of a grounding arrangement proposed for transmission line (TL) towers, particularly for conditions of a stratified soil where the electric resistivity of the first layer is higher than the second medium. Techniques based on TL-theory are presented to estimate the harmonic grounding impedance of such configurations and are compared to the solution obtained with a rigorous electromagnetic (EM) method. The results show that the grounding resistance, important to low frequency frequency phenomena, and the impulse impedance, to fast transients, decrease significantly with the use of vertical electrodes. For a 230 kV TL, the critical towers can be improved by the proposed arrangement, which includes a significant economy of the conductor material applied to the grounding.