Original scientific paper
An EMTP Extension for Computing Earthing System Transient Step and Touch Voltages
S. Vujević
; University of Split, Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, Split Croatia
P. Sarajčev
; University of Split, Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, Split Croatia
Abstract
This paper presents a novel technique for computing dangerous voltages due to lightning
transients imposed on earthing system, which is based on the use of the well-known
ATP-EMTP software package. Earth surface transient potential distributions, as well as step
and touch voltages computations, are performed through extending the widely used EMTP
software package with a new post-processor (computer program), developed especially for
that purpose. The earthing grid is approximated by the circular cross-section conductors. In
numerical model, conductors are subdivided into segments (1D finite elements) and Clark's
model with distributed constant parameters is then applied. Leakage conductance of
conductor segments is modeled in EMTP as an additional lumped parameter. Analytical
expressions for distributed and lumped segment parameters are derived using the average
potential method. Due to the limitations of the EMTP, EM coupling between segments is
neglected. The earth model is limited to the homogenous earth. Soil ionization effect is not
accounted for, but could be incorporated, through some modifications of algorithms.
Lightning surge model used is based on the Heidler's model of current source.
Keywords
Average potential method; ATP-EMTP; Earthing grid; Lightning analysis; Step and touch voltages
Hrčak ID:
198137
URI
Publication date:
19.6.2017.
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