Taylor, Rory (2023) The Effects of Three Phase Asymmetry on Transmission Line Travelling Waves. [USQ Project]
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Abstract
The effect of transmission line asymmetry on travelling wave propagation velocity was investigated, for the potential to improve fault location accuracy. It was an analytical and simulation-based investigation using the SimPowerSystem application in the Simulink/MATLAB software. Three-phase asymmetric and symmetric models were constructed from derived 3x3 inductance and capacitance matrices, with each phase represented as a standard ideal two-wire circuit. A modified Clarke matrix transformation was used to decouple the asymmetric system for modal velocity calculations.
The models produced a slight overestimation error, with the ideal symmetric velocity being 1.1% above the ideal upper limit of light speed. Any differences observed in aerial mode propagation velocities between the symmetric and asymmetric models were within this inherent model error. The difference in ground mode velocity was outside the error margin, however, it was found to be caused by the much larger earth-return distance in the asymmetric model, which is not a factor of symmetry. It was therefore concluded that asymmetry has no effect on travelling wave propagation velocity.
The model error was investigated, which increased massively when conductor separation distances were reduced to near conductor radius distances (i.e., close to touching). The radius distance appeared to be a focal point of error, which led to suspected problematic assumptions of the model derivations. Specifically, the inductance and capacitance equations don’t actually use the same conductor radius, because the inductance equations account for internal fields, but the capacitance ones don’t. Also, the internal inductance equation doesn’t account for frequency, therefore neglecting both skin effect and proximity effect. It is suggested these issues be addressed to improve the model for use in further investigations.
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| Item Type: | USQ Project |
|---|---|
| Item Status: | Live Archive |
| Faculty/School / Institute/Centre: | Current – Faculty of Health, Engineering and Sciences - School of Engineering (1 Jan 2022 -) |
| Supervisors: | Ahfock, Tony |
| Qualification: | Bachelor of Engineering (Honours) (Electrical) |
| Date Deposited: | 02 Oct 2025 01:14 |
| Last Modified: | 02 Oct 2025 01:14 |
| URI: | https://sear.unisq.edu.au/id/eprint/53007 |
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