Lightning return stroke electromagnetics - time domain evaluation and application
Date
2016
Authors
McAfee, Carson William Ian
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Abstract
The work presented extends and contributes to the research of modelling lightning return
stroke (RS) electromagnetic (EM) fields in the time domain. Although previous work in
this area has focused on individual lightning electromagnetic pulse (LEMP) modelling
techniques, there has not been an investigation into the strengths and weaknesses of
different methods, as well as the implementation considerations of the models. This
work critically compares three unique techniques (Finite Antenna, FDTD, and Single
Cell FDTD) under the same ideal simulation parameters. The research presented will
evaluate the EM fields in the range of 50m to 500m from the lightning channel. This
range, often referred to as the near field distance, has a significant effect on lightning
induced overvoltages on distribution lines, which are primarily created by the horizontal
EM fields of the RS channel. These close distances have a significant effect on the
model implementations, especially with the FDTD method. Each of these modelling
methods is explained and tested through examples. The models are implemented in
C++ and have been included in the Appendix to aid in future implementation. From
the model simulations it is clear that the FDTD method is the most comprehensive
model available. It allows for non-ideal ground planes, as well as complex simulation
environments. However, FDTD has a number of numerical related errors that the Finite
Antenna method does not suffer from. The Single Cell FDTD method is simple to
implement and does not suffer from the same numerical errors as a full FDTD implementation,
but is limited to simple simulation environments. This work contributes to
the research field by comparing and evaluating three techniques and giving consideration
to the implementation and the applicability to lightning EM simulations.
Description
A dissertation submitted to the Faculty of Engineering and the Built
Environment, University of the Witwatersrand, Johannesburg, in fulfilment of
the requirements for the degree of Master of Science in Engineering, 2016
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Citation
McAfee, Carson William Ian (2016) Lightning return stroke electromagnetics - time domain evaluation and application, University of the Witwatersrand, <http://hdl.handle.net/10539/22677>