Geomagnetically induced currents: present knowledge and future research

Boteler, D. H.

doi:10.1109/61.277679

Cited by 82 publications

(48 citation statements)

References 13 publications

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“…Thus, the generated GICs will be variable but in proportion to the amplitudes shown in Figures 7 and 8. What is unchanged is the realization, as indicated by Boteler (1994) and Pirjola (2008b), that the GICs are maximized when the incident electric field is in the direction of the bisector of the angle formed by two transmission lines arriving at a substation and minimized in the perpendicular direction. Thus, the transformers at intermediate stations along a long line are not particularly vulnerable to GICs, and therefore, in principle, they are not interesting sites to undertake measurements.…”

Section: Data and Resultsmentioning

confidence: 99%

Assessing the hazard from geomagnetically induced currents to the entire high-voltage power network in Spain

2014

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After the good results obtained from an assessment of geomagnetically induced currents (GICs) in a relatively small subset of the Spanish power transmission network, we now present the first attempt to assess vulnerability across the entire Spanish system. At this stage, we have only included the power grid at the voltage level of 400 kV, which contains 173 substations along with their corresponding single or multiple transformers and almost 300 transmission lines; this type of analysis could be extended to include the 220-kV grid, and even the 110-kV lines, if more detailed information becomes available. The geoelectric field that drives the GICs can be derived with the assumption of plane wave geomagnetic variations and a homogeneous or layered conductivity structure. To assess the maximum expected GICs in each transformer as a consequence of extreme geomagnetic storms, a post-event analysis of data from the Ebre Geomagnetic Observatory (EBR) during the 2003 Halloween storm was performed, although other episodes coincident with very abrupt storm onsets, which have proven to be more hazardous at these mid-latitudes, were analyzed as well. Preferred geomagnetic/geoelectric field directions in which the maximum GICs occur are automatically given from the grid model. In addition, EBR digital geomagnetic data were used to infer statistical occurrence probability values and derive the GIC risk at 100-year or 200-year return period scenarios. Comparisons with GIC measurements at one of the transformers allowed us to evaluate the model uncertainties.

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Section: Data and Resultsmentioning

confidence: 99%

Assessing the hazard from geomagnetically induced currents to the entire high-voltage power network in Spain

2014

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“…Z in a particular area depends on local conditions, such as conductivity and magnetic permeability of the ground. The depth at which the magnetic fields can penetrate the ground is also important as the average conductivity along this depth will affect the electric field (Boteler, 1994). Therefore the geology of the UK and the magnetic field variations will both have an effect on the induced electric fields in the surface.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of variations in the ground magnetic field during substorms at mid latitudes

et al. 2009

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Abstract. Substorms are known to cause geomagnetically induced currents (GIC) in power transmission lines through variations in the ground magnetic field. An improved knowledge and understanding of how the different phases of substorms affect the ground magnetic field will ultimately help to better understand how GIC arise. Although usually associated with high latitude power transmission networks, GIC potentially pose a risk to mid latitude networks such as the UK's National Grid. Using a list of substorm expansion phase onsets derived from auroral observations by the IMAGE-FUV satellite, this study examines 553 individual onsets. In order to cover mid latitudes, ground magnetometer data from the UK Sub-Auroral Magnetometer Network (SAMNET) are exploited. These high time resolution (5 s) data are used to study the ground magnetic field for an hour after onset, in particular the time derivative of the horizontal magnetic field, H. The data covers the period from 2000 to 2003 (just after solar maximum). Results are compared with a previous study of magnetic field variations at higher latitudes, using data with a much lower (1 min) cadence during substorms identified from geomagnetic indices during a period just after solar minimum.

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“…E f to obtain ( ) E t This is the so-called "frequency-domain method" [10,11]. Utilising the convolution theorem, which states that multiplication in the frequency domain corresponds to convolution in the time domain, equation (1) leads to the time-domain relation between ( ) E t and ( ) B t as follows…”

Section: Calculation Of the Geoelectric Fieldmentioning

confidence: 99%

Truncation of the Earth Impulse Responses Relating Geoelectric Fields and Geomagnetic Field Variations

Pirjola¹,

Boteler²

2017

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Abstract. To assess the geomagnetic hazard to power systems, it is necessary to model the Geomagnetically Induced Currents (GIC) produced during space weather storms. This requires knowledge of the geoelectric fields that drive GIC. In the time domain, the geoelectric fields can be calculated using a convolution integral including the geomagnetic field or its time derivative and an impulse response function for the Earth. In principle, the integral extends to infinity but for practical calculations the impulse responses must be truncated at a finite length. In this paper, we investigate the effects of the truncation on the calculation of the geoelectric fields. We consider how long the impulse responses need to be to obtain sufficiently accurate geoelectric field values. It is found that the high-pass impulse response used with geomagnetic data can be truncated very early, e.g. at 1 h, while the low-pass impulse response used with geomagnetic time derivative data must be extended much longer, e.g. until 24 h.

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Geomagnetically induced currents: present knowledge and future research

Cited by 82 publications

References 13 publications

Assessing the hazard from geomagnetically induced currents to the entire high-voltage power network in Spain

Assessing the hazard from geomagnetically induced currents to the entire high-voltage power network in Spain

Characteristics of variations in the ground magnetic field during substorms at mid latitudes

Truncation of the Earth Impulse Responses Relating Geoelectric Fields and Geomagnetic Field Variations

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