A preliminary risk assessment of the Australian region power network to space weather

Abstract

It is well documented that power networks at high latitudes are vulnerable to the effects of space weather. In recent years the eastern Australia state power networks have been connected across state boundaries in order to improve robustness under increasing load demands and deliver power at competitive prices. However, this interconnectivity is likely to increase susceptibility of the network to space weather. Geomagnetically induced currents (GICs) flow in power transmission lines as the result of “geoelectric” fields and their associated geomagnetic field variations according to Faraday's Law. In this paper previously documented occurrences of GIC activity from regions around the world are investigated and categorized by their effects on nearby power networks. A frequency domain filter that produces an index representing GIC activity is applied to geomagnetic field data recorded at locations near the documented GIC activity to determine risk level “GIC index” thresholds. Geomagnetic field data from the Australian region are processed using the “GIC filter” to provide a preliminary risk assessment of space weather related GIC activity to the Australian power network. The analysis suggests lower limit threshold GICy indices of 50, 100, 250, and 600 corresponding to the risk levels of “low,” “moderate,” “high,” and “extreme,” respectively. Analysis of GICy indices derived from Australian magnetometer data shows that only southern Australian regions reached the “moderate” risk levels defined in this study with mainland southern Australia stations reaching this risk level twice over the previous two solar cycles. Southern Australian regions such as Tasmania reached moderate levels approximately 20 times during the previous solar cycle. Furthermore, elevated risk levels are typically only observed in Australia during solar maximum and its decline phase.

Geomagnetically induced currents in Europe

“…Examples are available from Australia (Marshall et al 2011), New Zealand (Marshall et al 2012), South Africa (Ngwira et al 2008) and Brazil (Trivedi et al 2007). …”

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).…”