Wide-band modelling and transient analysis of the multi-conductor transmission lines system considering the frequency-dependent parameters based on the fractional calculus theory

This paper presents a probabilistic evaluation, based on Monte-Carlo method, for the estimation of insulation risk of failure of overhead transmission lines (TLs). The proposed method takes into account the wide-band model of tower-footing grounding system. The wide-band model of grounding system in frequency domain is obtained by the method of moment solution to the governing electrical field integral equations. The electrical parameters of soil are considered to be either constant or frequency dependent. The time-domain representation of the grounding system is inferred through pole-zero characterization of its associated frequency response. The case of a typical 400-kV transmission line is modelled in EMTP_RV with the tower-footing grounding system integrated with the transmission line (TL) system. The results of the paper show that the failure risk of transmission lines is affected by the grounding system model. This effect is more pronounced when the soil electrical parameters are assumed to be frequency dependent.

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Transient Analysis of Multiphase Transmission Lines Located above Frequency-Dependent Soils

Energies ◽

10.3390/en14175252 ◽

2021 ◽

Vol 14 (17) ◽

pp. 5252

Author(s):

Tainá Fernanda Garbelim Pascoalato ◽

Anderson Ricardo Justo de Araújo ◽

Pablo Torrez Caballero ◽

Jaimis Sajid Leon Colqui ◽

Sérgio Kurokawa

Keyword(s):

Power Systems ◽

Frequency Dependence ◽

Transmission Lines ◽

Transient Analysis ◽

Transient Responses ◽

Frequency Dependent ◽

Lightning Strikes ◽

Significant Difference ◽

Soil Conductivity ◽

The Impact

This paper evaluates the influence of frequency-dependent soil conductivity and permittivity in the transient responses of single- and double-circuit transmission lines including the ground wires subjected to lightning strikes. We use Nakagawa’s approach to compute the ground-return impedance and admittance matrices where the frequency-dependent soil is modeled using Alípio and Visacro’s model. We compare some elements of these matrices with those calculated by Carson’s approach which assumes the frequency constant. Results show that a significant difference can be obtained in high resistive soils for these elements in impedance and admittance matrices. Then, we compute the transient responses for single- and double-circuit lines with ground wires located above soils of 500, 1000, 5000, and 10,000 Ω·m considering the frequency constant and frequency-dependent parameters generated for two lightning strikes (subsequent stroke and Gaussian pulse). We demonstrate that the inclusion of frequency dependence of soil results in an expressive reduction of approximately 26.15% and 42.75% in the generated voltage peaks in single- and double-circuit lines located above a high-resistive soil. These results show the impact of the frequency-dependent soils that must be considered for a precise transient analysis in power systems.

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