Geomagnetically induced currents in an electric power transmission system at low latitudes in Brazil: A case study

Abstract

Geomagnetically induced currents (GICs) are a ground end manifestation of space weather processes. During large geomagnetic storms, GICs flow between the grounding points of power transformers and along electric power transmission lines connecting the transformers. In high‐latitude regions, damages to power transformers are reported where storm time geomagnetic variations are very rapid and large (>1000 nT), and hence the GICs as large as or even greater than 100 A end up flowing through the windings of power transformers. At low latitudes, geomagnetic variations are less severe, and hence much smaller GIC values are generally reported there. However, the flow of GICs and their effects on power transformers are complex processes, and careful evaluation is needed even in such low‐latitude regions as, for example, Brazil. We report here a study on GIC measurements in Brazil conducted under a cooperative project between FURNAS (the Brazilian electric power company) and the National Institute for Space Research. During a large geomagnetic storm, which took place on 7–10 November 2004, the GIC amplitudes, measured on the basis of geomagnetic variations in 500 kV power transmission lines in the S–E region of Brazil, were found to be around 15 A.

Geomagnetically induced currents in a power grid of northeastern Spain

“…Kappenman [2005] argued that the source of sustained GICs at low and middle latitudes are linked with high rates of variation associated with impulsive increases in the solar wind dynamic pressure or ring current intensifications. These facts have encouraged several research groups and agencies to initiate vulnerability assessment studies on power grids or pipelines located at regions previously considered to have low GIC-risk other than South Africa, such as China [Liu et al, 2009], Japan [Watari et al, 2009], Czech Republic [Hejda and Bochníček, 2005], Kazakhstan [Vodyannikov et al, 2006], Australia [Marshall et al, 2011] or Brasil [Trivedi et al, 2007]. We were similarly motivated to perform such an analysis in a power grid of northeastern Spain, where we are settled.…”

Continental scale modelling of geomagnetically induced currents

“…In 2000s, and especially motivated by the October 2003 event, GIC has reached attention also at lower geomagnetic latitudes: see Bernhardi et al (2008) (South Africa), Trivedi et al (2007) (Brazil), Liu et al (2009) (China), Watari et al (2009) (Japan) and Marshall et al (2011) (Australia).…”

Space Weather: Physics, Effects and Predictability

“…The GICs can saturate the transformer core reducing their efficiency dramatically, perhaps damaging the transformer due to increased heating or triggering safety systems that remove the transformer from the circuit, and possibly creating knockon effects in the rest of the grid (Clark 2001;Crosby et al 2006). It is not only the geoelectric field that dictates the GIC magnitude in power systems but also their geometrical and structural details have a significant influence (Molinski 2002;Trivedi et al 2007). Usually GICs vary greatly from site to site in a power system, and model calculations may reveal those sites that are probably prone to the largest GIC magnitudes (Viljanen and Pirjola 1994;Wik et al 2008).…”