AusLAMP shines a light on space weather hazards in the Australian high-voltage power grid

Abstract

AbstractA geomagnetic storm, also known as a geomagnetic disturbance (GMD), is a major disturbance of the Earth’s magnetic field caused by solar activity. A geomagnetic storm induces electric currents in the Earth that feed into power lines through substation neutral earthing, causing instabilities and even blackouts in electricity transmission systems. The intensity of geomagnetically induced currents (GICs) is closely associated with the electrical conductivity of the surrounding geology. In this paper, we analyse one of the most well-known geomagnetic storms, the 1989 “Québec storm” and 688 magnetotelluric (MT) survey sites from the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) to gain insight into the space weather hazard posed for Australia's modern-day power grids. Transmission lines may exhibit local maxima at differing times depending on their spatial orientation and length with respect to the time-varying magnetic field. Localised peak voltages over 100 V can be observed on some individual lines. This assessment identifies the distribution of GICs in south-eastern Australia for the 1989 Québec storm and transmission lines that are more vulnerable to GICs. It is relevant to national strategies and risk assessment procedures to mitigate space weather hazards in the Australian high-voltage power grid and the design of a more resilient power transmission system. We also analyse the 2015 “St Patrick’s Day storm” to study under-estimation of the space weather hazard associated with the band-limited geomagnetic data and MT data sets.Key points The subsurface geology has a great influence on the intensity of geomagnetically induced electric fields, potentially causing up to three orders of magnitude difference between conductive basins and resistive cratonic regions in south-eastern Australia.Analysis using the 1989 “Québec geomagnetic storm” and AusLAMP magnetotelluric data shows the intensity of the geoelectric fields in south-eastern Australia could reach up to 5 [V/km].Geomagnetically induced voltages in the Australian high-voltage power grid could be in excess of 100 V in some transmission lines for a geomagnetic storm with intensity comparable with the 1989 Québec geomagnetic storm.KEYWORDS: Space weather hazardgeomagnetically induced currentshigh-voltage power gridgeomagnetic storms AcknowledgementsThe authors thank Geoscience Australia, the Geological Surveys of Victoria, South Australia, and New South Wales, the University of Adelaide and AuScope for making their MT datasets available for investigation.The geomagnetic field data can be downloaded from the Geoscience Australia Geomagnetism Program (http://www.ga.gov.au).The SECS-MT Python code of Campanyà et al. (Citation2019) has been used for computation of geoelectric field time series. The software of Wessel and Smith (Citation1998) has been used to produce some figures in this paper.We thank Dr Kate Brand, an anonymous reviewer, and editor Dr Mark Lackie for their helpful comments in improving the manuscript during the review process. We are also grateful to Dr Wenping Jiang and Dr Josef Holzschuh of Geoscience Australia for reviewing a draft manuscript.This paper is dedicated to the memory of Dr F.E.M. (Ted) Lilley who was our inspiration to pursue electromagnetic induction research from Earth conductivity to space weather hazards.This research is published with permission of the CEO, Geoscience AustraliaDisclosure statementNo potential conflict of interest was reported by the author(s).