Modeling Geomagnetically Induced Currents in the Alberta Power Network: Comparison and Validation Using Hall Probe Measurements During a Magnetic Storm

Abstract

During space weather events, geomagnetic disturbances (GMDs) induce geoelectric fields which drive geomagnetically induced currents (GICs) through electrically‐grounded power transmission lines. Alberta, Canada—located near the auroral zone and thus prone to large GMDs—has a dense network of magnetometer stations and surface impedance measurements to better characterize the GMD and ground conductivity, respectively. GIC monitoring devices were recently installed at five substation transformer neutrals, providing a unique opportunity to compare data to modeled GICs. GICs are modeled across the >240 kV provincial power transmission network during a moderate GMD event on 24 April 2023. GIC monitoring devices measured larger neutral‐to‐ground currents than expected up to 117 Amps during peak storm time, providing unequivocal evidence linking network GICs with GMDs. The model performs reasonably well (correlation coefficients >0.5; performance parameter >0.15) at four of five substations, but generally underestimates peak GIC values (sometimes by a factor >2), suggesting that the present model underrepresents overall network risk. The model performs poorly at one of the five substations (correlation = 0.46; performance parameter = 0.10), the reasons for which may be due to simplifications and/or unknowns in network parameters. Despite these underestimates, during this GMD, the model predicts the largest GIC at substations located in the northeastern part of the province (240 kV) or around Edmonton (500 kV)—regions which have significant electrical and industrial infrastructure. Further refinement of the network model with transformer resistances, more line and earthing resistances, and/or including lower voltage levels is necessary to improve data fit.

Modeling GIC in the Southern South Island of Aotearoa New Zealand Using Magnetotelluric Data

“…However, the lack of actual GIC measurements in the North Island during that period meant that calculated GIC could not be compared to actual observations. Although previous studies (e.g., Blake et al, 2016;Marshall et al, 2019;Torta et al, 2017) have used MT data in deriving conductivity models from which GIC have been calculated from model impedances, in this work the GIC are calculated directly from measured MT impedances and are compared to measured GIC (Butala et al, 2017;Cordell et al, 2024;Gannon et al, 2020;Kelbert, 2020;Shetve et al, 2018). We also compare our results with how well GIC calculated using thin-sheet technique can reproduce measured GIC.…”

Using a Differential Magnetometer Technique to Measure Geomagnetically Induced Currents: An Augmented Approach

“…Comparison to an HV network model of the Alberta power network is needed to understand the GIC flowing to ground at Ellerslie substation (cf. for example the recent paper by Cordell et al, 2024). Missing information about the resistance parameters of the power network limits further comparison (cf.…”

“…This would be a similar approach to Hübert et al (2020) and Matandirotya et al (2016), but would maintain the benefits of providing two independent GIC estimates as demonstrated here. Lastly, we plan to utilize a recently developed HV network model (Cordell et al, 2024) to make appropriate comparisons between the GIC in the power line and the GIC flowing to ground in the substation and to inform future DMM deployment locations.…”