Assessment of different formulations for the ground return parameters in modeling overhead lines

• Published in: Electric power systems research Vol. 164; pp. 20 - 30
• Main Authors: Lima, Antonio C.S., Moura, Rodolfo A.R., Schroeder, Marco Aurélio O., Correia de Barros, Maria Teresa
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-11-2018; Elsevier Science Ltd
• Subjects: Cables; Closed form solutions; Conductors; Electric currents; Electric power; Electric power lines; Electric properties; Exact solutions; Formulations; Infinite integrals; Mathematical models; Parameters; Power lines; Time-domain analysis; Transmission line modeling; Transmission line theory frequency domain synthesis; Transmission lines; Underground cables; Transmission line modeling; Transmission line theory frequency domain synthesis; Time-domain analysis
• ISSN: 0378-7796; 1873-2046
• DOI: 10.1016/j.epsr.2018.07.011

•Contribution to the modeling of overhead lines when ground displacement currents are considered.•Presentation of distinct formulation of ground return parameters as a function of the variable used for representing the conductors’ voltage.•Identification of scenarios where a simplified formulation may lead to acceptable results regarding the transient response of an overhead lines.
There is a growing concern regarding a more accurate assessment of the transient behavior of overhead lines and underground cables. Traditionally, displacement currents are neglected in the evaluation of the ground return correction terms, thus only the transmission line impedance being affected. However, if these currents are to be considered, the ground cannot be assumed as an equipotential and there are some ambiguities depending on the definition used to determine the conductors’ voltages. Furthermore, given the numerical challenges associated with the infinite integrals needed to obtain the ground return parameters, it is rather common to use closed-form approximations instead. In this paper, we assess the influence that the different formulations may have in modelling two distinct overhead lines. Both frequency and time-domain results are presented and discussed. The results indicated that there are some mismatches between induced voltages calculated using the voltage formulation with quasi-TEM approximation and those using the potential formulation with closed-form approximations.