Abstract
Abstract. Power transmission lines above the ground, cables and pipelines in the ground and under the sea, and in general all man-made long grounded conductors are exposed to the variations of the natural electromagnetic field. The resulting currents in the networks (commonly named geomagnetically induced currents, GIC), are produced by the conductive and/or inductive coupling and can compromise or even disrupt system operations and, in extreme cases, cause power blackouts, railway signalling mis-operation, or interfere with pipeline corrosion protection systems. To properly model the GIC in order to mitigate their impacts it is necessary to know the frequency dependence of the response of these systems to the geomagnetic variations which naturally span a wide frequency range. For that, the general equations of the electromagnetic induction in a multi-layered infinitely long cylinder (representing cable, power line wire, rail or pipeline) embedded in uniform media have been solved utilising methods widely used in geophysics. The derived electromagnetic fields and currents include the effects of the electromagnetic properties of each layer and of the different types of the surrounding media. This exact solution then has been used to examine the electromagnetic response of particular samples of long conducting structures to the external electromagnetic wave for a wide range of frequencies. Because the exact solution has a rather complicated structure, simple approximate analytical formulas have been proposed, analysed and compared with the results from the exact model. These approximate formulas show good coincidence in the frequency range spanning from geomagnetic storms (less than mHz) to pulsations (mHz to Hz) to atmospherics (kHz) and above, and can be recommended for use in space weather applications.
Highlights
Large-scale technological systems using long conductors are exposed to different types of natural electromagnetic variations, from geomagnetic disturbances resulting from solar sources through their impacts on the magnetosphere and ionosphere, to atmospheric sources, overall covering the frequencies from 0.1 mHz to 1 Hz up to 1 kHz respectively (Campbell, 1997)
These natural electromagnetic variations produce electric currents which interfere with ground networks, such as phone cables, power lines and pipelines (Lanzerotti and Gregori, 1986)
The following samples of the conducting structures were used: typical rail insulated from the ground, insulated solid copper wire used in many applications, bare aluminium conductor steel reinforced (ACSR) used in overhead transmission lines, and coated steel pipeline with gas inside
Summary
Large-scale technological systems using long conductors are exposed to different types of natural electromagnetic variations, from geomagnetic disturbances resulting from solar sources through their impacts on the magnetosphere and ionosphere, to atmospheric sources (lightning), overall covering the frequencies from 0.1 mHz to 1 Hz (periods from days to seconds) up to 1 kHz respectively (Campbell, 1997). These natural electromagnetic variations produce electric currents which interfere with ground networks, such as phone cables, power lines and pipelines (Lanzerotti and Gregori, 1986). Evaluations of the approximate formulas for effective impedance (composed of both a real part, i.e. Ohmic resistance, and an imaginary part), which can be used to obtain the electric current inside the different conductors from the ambient geoelectric field are presented and discussed in Sect. 6, which is followed by Conclusions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
