Abstract
AbstractSpace weather poses a hazard to grounded electrical infrastructure such as high voltage (HV) transformers, through the induction of geomagnetically induced currents (GICs). Modeling GICs requires knowledge of the source magnetic field and the Earth's electrical conductivity structure, in order to calculate the geoelectric fields generated during magnetic storms, as well as knowledge of the topology of the HV network. Direct measurement of GICs at the ground neutral in substations is possible with a Hall effect probe, but such data are not widely available. To validate our HV network model, we use the differential magnetometer method (DMM) to measure GICs in the 400 kV grid of Great Britain. We present DMM measurements for the 26 August 2018 storm at a site in eastern Scotland with up to 20 A recorded. The line GIC correlates well with Hall probe measurements at a local transformer, though they differ in amplitude by an order of magnitude (a maximum of 2 A). We deployed a long‐period magnetotelluric (MT) instrument to derive the local impedance tensor which can be used to predict the geoelectric field from the recorded magnetic field. Using the MT‐derived electric field estimates, we model GICs within the network, accounting for the difference in magnitude between the DMM‐measured line currents and earth currents at the local substation. We find that the measured line and earth GICs match the expected GICs from our network model, confirming that detailed knowledge of the complex network topology and its resistance parameters is essential for accurately computing GICs.
Highlights
During severe space weather events, geomagnetic storm conditions arise when the Earth's magnetic field becomes strongly disturbed
The development of modern low-resistance ground infrastructure such as the high voltage (HV) power transmission network, gas pipelines, and railways allows the electric field to equalize through the earthing points of these conductors; the additional quasi steady DC currents are known as geomagnetically induced currents (GICs)
We present the design and initial deployment of the first differential magnetometer method (DMM) systems in the United Kingdom
Summary
During severe space weather events, geomagnetic storm conditions arise when the Earth's magnetic field becomes strongly disturbed. The development of modern low-resistance ground infrastructure such as the high voltage (HV) power transmission network, gas pipelines, and railways allows the electric field to equalize through the earthing points of these conductors; the additional quasi steady DC currents are known as geomagnetically induced currents (GICs). This phenomenon is a threat to the optimal performance and operation of HV transformers (Albertson et al, 1981; Boteler, 2006; Pulkkinen et al, 2012). We compare the line GICs and measurements from a local substation Hall probe with GIC values obtained from a network model
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