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JEET, Vol. 13, No. 5, September 2018
Investigation of Large-scale Transmission Tower Grounding Grid with High Amplitude and Uniform Flowing Impulse Current
Shuai Yang
Area C - Electrophysics and Applications
Abstract Impulse characteristic of transmission tower grounding grid is needed for lightning protection of transmission line. This paper describes an outdoor experimental test facility established for large-scale grounding grid of transmission tower, made up of four impulse current generators and a circle current return electrode. The amplitude of impulse current is up to 100 kA. The results of the CDEGS simulation and GPR measurement reveal the uniform current distribution in the test arrangement. An impulse test for a square electrode with extended conductors is carried out in condition of three current waveforms with different amplitude. Based on the electrical network model and iterative algorithm method, a calculation model is proposed to simulate the impulse characteristic of large-scale grounding grid considering soil ionization. The curve of impulse resistance against the current amplitude shows the soil ionization both from the simulation and test. Deviation between the simulation and test result is less than 15%.
Keyword Grounding grid,Impulse performance,Soil ionization,Iterative algorithm.
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