Abstract

Abstract. Geomagnetically induced currents in power systems are due to space weather events which create geomagnetic disturbances accompanied by electric fields at the surface of the Earth. The purpose of this paper is to evaluate the use of the finite element method (FEM) to calculate the magnetic and electric fields to which long transmission lines of power systems on the Earth are exposed. The well-known technique of FEM is used for the first time to simulate magnetic and electric fields applicable to power systems. Several test cases are modelled and compared with known solutions. It is shown that FEM is an effective modelling technique that can be applied to determine the electric fields which affect power systems. FEM enables an increased capability beyond the traditional methods for modelling electric and magnetic fields with layered earth conductivity structures, as spatially more complex structures can be considered using FEM. As an example results are presented for induction, due to a line current source, in adjacent regions with different layered conductivity structures. The results show the electric field away from the interface is the same as calculated for a single region; however near the interface the electric field is influenced by both regions.

Highlights

  • During geomagnetic disturbances, the changing magnetic field produces an electric field that drives large electric currents in power transmission networks

  • The changing magnetic field produces an electric field that drives large electric currents in power transmission networks. These geomagnetically induced currents (GIC) can cause a variety of problems for operation of power transmission systems (Boteler et al, 1998; Molinski, 2002; Pirjola et al, 2004). This has been considered a problem for highlatitude power systems, in recent years, GIC have been found in power systems of some mid- or low-latitude countries such as Japan (Kappenman, 2003), Brazil (Pinto et al, 2004; Trivedi et al, 2007), South Africa (Koen and Gaunt, 2003; Gaunt and Coetzee, 2007) and China (Liu et al, 2009)

  • The well-known technique of finite element method (FEM) was used for the first time to calculate magnetic fields and associated electric fields that could drive GIC in power systems

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Summary

Introduction

The changing magnetic field produces an electric field that drives large electric currents in power transmission networks. The Fast Hankel Transform (FHT) method can be used to calculate the integrals that give exact expressions for the electric and magnetic fields at the surface of an uniform or layered earth due to an overhead line current (Johansen and Sorensen, 1979; Pirjola, 1985). Cases of laterally nonuniform layered earth models are considered to show the new results associated with the surface impedance that can be obtained with the FEM technique These cases show how the source and the earth structure influence the surface impedance calculations related to the electric fields that drive GIC in power systems

The finite element method
Free space case
Layered Earth
Conclusions
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