Geomagnetically induced currents in Norway: the northernmost high-voltage power grid in the world

Myllys, Minna; Viljanen, A.; Rui, Øyvind August; Ohnstad, T.

doi:10.1051/swsc/2014007

Cited by 48 publications

(50 citation statements)

References 18 publications

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“…Then the smaller conductivities in the north produce further enhancement of the electric field compared to the case of the single 1-D layered model applied everywhere. These findings are basically the same as mentioned by Myllys et al (2014) concerning a model study of the Norwegian power grid.…”

Section: Block 24supporting

confidence: 89%

“…A common approach is to use long geomagnetic data sets to extrapolate indices (Siscoe, 1976;Love et al, 2015;Riley, 2012), or to extrapolate the amplitude of the variation field or its time derivative (Danskin & Lotz, 2015;Love et al, 2016;Thomson et al, 2011). A related possibility is to extrapolate the geoelectric field modelled from magnetic field data (Myllys et al, 2014;Nikitina et al, 2016;Pulkkinen et al, 2012;2015;Wintoft et al, 2016). In a few cases, there are long enough time series of the recorded electric field allowing for deriving statistics (Langlois et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

“…Another way is to apply simulations of the solar windmagnetosphere-ionosphere interaction (Ngwira et al, 2013;. In principle, this approach is ideal, since it produces time series of ground magnetic and electric fields.…”

Section: Introductionmentioning

confidence: 99%

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Influence of spatial variations of the geoelectric field on geomagnetically induced currents

Viljanen

Pirjola

2017

J. Space Weather Space Clim.

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-The geoelectric field driving geomagnetically induced currents (GIC) has complex spatial variations. It follows that different patterns of the field vectors in a given area having the same regional mean can produce very different GIC. In this study, we consider a few power grid models and calculate GIC due to a modelled geoelectric field with a regional mean magnitude of 1 V/km. Altogether 8035 snapshots of the electric field are included. We also assume two different ground conductivity models, of which the simpler one consists of two layers across the whole region, and another model has four different two-layer blocks. As a measure of GIC, we use the sum of currents at all substations of the power grid. We also consider the distribution of GIC at a single site. For a given grid, differences between the two ground conductivity models are small. When comparing different power grid models, the sum of GIC varies relatively more for a grid with a small number of substations and transmission lines. When the area and the number of substations increase, the relative difference between the smallest and largest GIC sum decreases. In all cases, assuming a spatially uniform electric field leads to a reasonable estimation of the GIC magnitudes, but it does not produce the largest GIC sum. For a single substation, there is a large variety of GIC values due to different electric field configurations.

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Section: Block 24supporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

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Influence of spatial variations of the geoelectric field on geomagnetically induced currents

Viljanen

Pirjola

2017

J. Space Weather Space Clim.

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“…The relevance of E or dB/dt to GIC has led to several studies related to their extreme behaviour (Wik et al, 2009;Myllys et al, 2014;Pulkkinen et al, 2015). In Thomson et al (2011) extreme event analysis (EVA) was performed on dB/dt from stations covering similar latitudes as in this study, and 100-and 200-year return levels were estimated.…”

Section: P Wintoft Et Al: Extreme Value Analysis Of Magnetic and Elmentioning

confidence: 99%

Extreme value analysis of the time derivative of the horizontal magnetic field and computed electric field

Wintoft¹,

Viljanen²,

Wik³

2016

Ann. Geophys.

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Abstract. High-frequency ( ≈ minutes) variability of ground magnetic fields is caused by ionospheric and magnetospheric processes driven by the changing solar wind. The varying magnetic fields induce electrical fields that cause currents to flow in man-made conductors like power grids and pipelines. Under extreme conditions the geomagnetically induced currents (GIC) may be harmful to the power grids. Increasing our understanding of the extreme events is thus important for solar-terrestrial science and space weather. In this work 1-min resolution of the time derivative of measured local magnetic fields (|dB h /dt|) and computed electrical fields (E h ), for locations in Europe, have been analysed with extreme value analysis (EVA). The EVA results in an estimate of the generalized extreme value probability distribution that is described by three parameters: location, width, and shape. The shape parameter controls the extreme behaviour. The stations cover geomagnetic latitudes from 40 to 70 • N. All stations included in the study have contiguous coverage of 18 years or more with 1-min resolution data. As expected, the EVA shows that the higher latitude stations have higher probability of large |dB h /dt| and |E h | compared to stations further south. However, the EVA also shows that the shape of the distribution changes with magnetic latitude. The high latitudes have distributions that fall off faster to zero than the low latitudes, and upward bounded distributions can not be ruled out. The transition occurs around 59-61 • N magnetic latitudes. Thus, the EVA shows that the observed series north of ≈ 60 • N have already measured values that are close to the expected maxima values, while stations south of ≈ • N will measure larger values in the future.

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“…Highlatitude countries (in particular those in the auroral zone band of 55-70 • geographic latitude, where the auroral electrojet dominates) and regions of high ground resistivity are most susceptible to GICs , and there have been several studies conducted in these areas (Viljanen and Pirjola, 1994;Beamish et al, 2002;Wik et al, 2008;Myllys et al, 2014). Research into GICs in lowlatitude and equatorial countries such as the Czech Republic (Hejda and Bochníček, 2005), Brazil (da Silva Barbosa et al, 2015), Spain (Torta et al, 2012), Greece (Zois, 2013), Japan (Watari et al, 2009), South Africa (Bernhardi et al, 2008;Matandirotya et al, 2015), Australia (Marshall et al, 2011), and New Zealand (Beland and Small, 2005), which were previously considered to be at low risk from all but the most extreme geomagnetic storms, show that considerable GICs (in the range of tens of amperes) do also appear at lower latitudes.…”

Section: Introductionmentioning

confidence: 99%

Modelling geomagnetically induced currents in midlatitude Central Europe using a thin-sheet approach

et al. 2017

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Abstract. Geomagnetically induced currents (GICs) in power systems, which can lead to transformer damage over the short and the long term, are a result of space weather events and geomagnetic variations. For a long time, only high-latitude areas were considered to be at risk from these currents, but recent studies show that considerable GICs also appear in midlatitude and equatorial countries. In this paper, we present initial results from a GIC model using a thinsheet approach with detailed surface and subsurface conductivity models to compute the induced geoelectric field. The results are compared to measurements of direct currents in a transformer neutral and show very good agreement for shortperiod variations such as geomagnetic storms. Long-period signals such as quiet-day diurnal variations are not represented accurately, and we examine the cause of this misfit. The modelling of GICs from regionally varying geoelectric fields is discussed and shown to be an important factor contributing to overall model accuracy. We demonstrate that the Austrian power grid is susceptible to large GICs in the range of tens of amperes, particularly from strong geomagnetic variations in the east-west direction.

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Geomagnetically induced currents in Norway: the northernmost high-voltage power grid in the world

Abstract: We have derived comprehensive statistics of geomagnetic activity for assessing the occurrence of geomagnetically induced currents

Cited by 48 publications

References 18 publications

Influence of spatial variations of the geoelectric field on geomagnetically induced currents

Influence of spatial variations of the geoelectric field on geomagnetically induced currents

Extreme value analysis of the time derivative of the horizontal magnetic field and computed electric field

Modelling geomagnetically induced currents in midlatitude Central Europe using a thin-sheet approach

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