Geomagnetically induced current model for the Namibian High Voltage Network

New geomagnetically induced current (GIC) computations for mainland Portugal include the entire power network, with network parameters and topology provided by the transmission grid operator for all the high voltage lines (150, 220, and 400 kV). The first 3D conductivity model for the west region of the Iberian Peninsula, based on 31 broadband magnetotelluric soundings, is used in calculations, revealing the effect of different crustal domains in GIC distribution. Geomagnetic field variations are taken from Coimbra or San Fernando magnetic observatories, according to the Nearest Neighbor method, and used together with surface impedance values predicted from the new conductivity model to calculate the induced electric field on a regular grid. The global distribution of GICs over the power network is characterized based on results derived for the eight most significant storms registered in the Iberia during solar cycle 24. Substations susceptible to the highest GICs are found near the transition between the granitic geotectonic unit of Central Iberian Zone and the Lusitanian Basin. A prototype of a Hall effect sensor has been installed at a substation and is active since the end of August 2021. In order to validate our GIC model, recent measurements are compared with simulations. GIC computation is prone to uncertainties from various sources, possibly contributing with different weights to the final error in computed values. Here, we evaluate the contribution of substation earthing resistance and nonuniqueness of the conductivity model to the final GIC uncertainties.

Geomagnetic disturbances (GMDs) are known to disturb power system equipment performance. The danger is associated with geomagnetically induced currents (GICs) occurring at the Earth's surface during GMD. GICs do not endanger power system operation conditions by themselves. The main challenge posed by GICs to power system states is the change in power system equipment operation conditions provoked by GIC flow. The primary avenue of blackout caused by GMDs is through power transformers. This, in turn, can impair the operation of other power system equipment such as synchronous machines. Modern powerful synchronous machines are not designed and engineered to cope with the negative impacts of GMDs. Moreover, the actual legal norms are inadequate in this case. Enhancing the grid's resiliency to such an event is highly interesting to the industry. The physical processes in synchronous machine windings triggered by GICs and limitations brought to power grid operations are described. First, the idea of the impact of GMDs on the power grid operation is described. The analysis of the impact of GMDs on synchronous machines is performed in the second section. In the end, the power system response under GMDs is studied.

Averages of geomagnetically induced currents (GIC) in the Finnish 400 kV electric power transmission system and the effect of neutral point reactors on GIC

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.

Geomagnetically Induced Currents (GICs) flowing along electrically conductive infrastructure, such as power transmission lines, are produced by a naturally induced geoelectric field during geomagnetic disturbances, such as magnetic storms. GICs can cause widespread blackouts across power grids, resulting in the loss of electric power. Although GIC intensity is greater in high latitudes, recent studies highlight the importance of considering GIC risks for countries located in the low and middle latitudes, including the Mediterranean region. GIC index is a proxy of the geoelectric field calculated entirely from geomagnetic field variations. Following a recent study where we investigated the GIC index levels for the Mediterranean (i.e., Greece, Italy, France, Spain, Algeria, and Turkey) for the most intense magnetic storms of solar cycle 24 (2008–2019), here we expand the analysis to encompass solar cycle 25. From the beginning of solar cycle 25 six major magnetic storms occurred with Dst index ≤ -100 nT. The three most intense magnetic storms (-163 nT < Dst < -212 nT) occurred in March, April and November 2023. We focus on those to compare with previous results showing that GIC index increases are well correlated with Storm Sudden Commencements (SSCs) and shed more light upon the expected GIC activity levels in the Mediterranean region during extreme events.

Geomagnetic disturbances trigger quasi-dc currents that flow through grounding circuits into power systems, mostly through power transformers. Geomagnetically-induced currents (GICs) can cause severe harmonic distortions, disruption in reactive power flow, and/or thermal damage to power transformers. These adverse effects of GIC events on power transformers depend on the GIC magnitude, transformer core design, grounding circuit, and winding configuration. This paper analyzes the effects of grounding circuit designs on the adverse impacts of GIC flows in power transformers. These effects are analyzed through experimental tests carried out using laboratory 3ϕ, multicore power transformers. Experimental tests are performed for several grounding circuit designs for the test power transformers. Normal, magnetizing inrush, line-to-line, and line-to-neutral fault conditions are conducted for each tested grounding circuit design. Results of experimental tests show that grounding circuits with low impedance have minor effects on the GIC flows, while grounding circuits with high impedance tend to reduce the magnitude of the GIC. In addition, test results demonstrate that grounding circuits have little influence on the harmonic distortion (mainly the 2nd harmonic component) created by a GIC flow.

Calculation of geomagnetically induced currents (GIC) in a high-voltage electric power transmission system and estimation of effects of overhead shield wires on GIC modelling

During geomagnetic storms the electrical power grid is vulnerable to geomagnetically induced currents (GICs) caused by sharp changes in magnetic and geoelectric fields. In the UK the measurement of GIC in the power grid is extremely limited with most GIC estimates coming from a model of the high voltage grid. The US has collected geomagnetic disturbance (GMD) data for 18 geomagnetic storms. Network theory is routinely used to estimate the resilience of the physical power grid, and its robustness to the removal of nodes, when faced with threats ranging from natural hazards to cyber-attacks but is currently not applied to GIC. By applying network theory to both the modelled UK dataset and measured US dataset, we can utilize known parameters to test for vulnerabilities to space weather in the power grid across varying spatial and temporal scales. The network is formed using methods of association between the GIC data at each transformer. The monitors are the nodes of the network and the links are defined as when the wavelet cross-correlation of the GIC is sufficiently high (1). The wavelet transform is used to localise the GIC response to the storm across time scales. Whilst previous network science studies have focused on the physical topology of the power grid, our method focuses on the dynamical response of the grid to GIC. Despite the difference in latitude and local time we see many similarities between the modelled UK and measured US GIC data, particularly during the sudden commencement. Initial results show the same nodes repeatedly appearing as the most highly connected to the network across multiple events. These nodes could be key to providing resilience and/or prediction of forthcoming disturbance of the power grid in the event of a large geomagnetic storm.(1) Orr, L., Chapman, S. C., Beggan, C. D. (2021). Space Weather, 19, e2021SW002772.

Arising from solar storms, the emerging disturbances imposed on Earth’s magnetic field, can drive the flow of quasi-DC geomagnetically induced currents (GICs) in power transmission systems. The ground connections of power transformers provide a closed path through which GICs flow and push their cores into half-cycle saturation. In addition, series capacitor units are often utilized to compensate HV transmission systems. The half-cycle saturation of power transformers due to GICs, on the one hand, and the proximity of such saturated transformers to capacitor compensation units on the other can lead to the inception of ferroresonance in series compensated power systems. To prevent catastrophic equipment failures due to ferroresonance during GICs, it is crucial to determine ferroresonance solutions of networks. This paper’s principal contribution is to develop an approach to analyze ferroresonance in series capacitor compensated networks during GICs. This is attained by employing a simplified equivalent single-phase model on which to mount the analysis. The authenticity of this method is verified through an EMTP-RV simulation of a benchmark example power system.

As a result of space weather events, geomagnetically induced currents (GIC) emerge in the power system. These low-frequency currents in the power supply can be thought of as quasi-DC currents. A half-cycle periodic saturation of the core occurs when a DC enters a power transformer. Heating, harmonics, and reactive power losses arise from periodic core saturation. A detailed understanding of power transformer design and performance to determine the exact effect of GIC on power transformers. The paper also provides a succinct explanation of the causes of transformer failure/overheating that have been linked to GIC currents in the published literature. The research shows that, due to the nature of GIC currents, even large levels of GIC would not cause much overheating or damage to the vast majority of power transformers. If subjected to high levels of GIC, only a few specific transformers may experience winding damage due to high winding circulation currents. The report also discusses the underlying problem with GIC, which is the narrow pulse of magnetizing current that occurs when transformer cores are subjected to part-cycle, semi-saturation. We designed or provided such filter to reduce this produced Dc voltages and give Deficient output which is introduced by studying various reviews on GIC in power system transformer by adding GIC effect on the transformer which will add mutually induced DC voltages which does not give proper output as introduces input so we designed or provided such filter to reduce this produced Dc voltages and give Deficient output which is introduced by adding GIC effect on transformer by adding GIC effect on the transformer which will add mutually induced DC voltages which does not give proper output It produces high-quality output and increases the reliability of the system.

Strong solar storms causing geomagnetic disturbances (GMD) are capable of disrupting power grid operation through undesired electromagnetic interaction. Specifically, GMDs can generate quasi-DC geomagnetic induced currents (GIC) in transformer neutral windings which saturate the iron cores and lead to increased excitation current and reactive power demand: if this phenomenon is sufficiently strong and widespread it will cause a generalized decrease in bus voltages, a diminishment of the voltage stability margin and, in the worst case, a system blackout. This paper gives a brief overview of the GMD physical process and its influence on power systems and performs an explicit numerical assessment of potential GIC values and of their impact on the grid for the Swiss Transmission Network.

A key space weather hazard is the generation of Geomagnetically Induced Currents (GICs) in grounded, conducting infrastructure (e.g., power networks).  These GICs are driven by the changing magnetic field at the surface of the Earth and in extreme cases can cause disruption or even damage to power systems.  Due to a sparsity of GIC measurements around the globe, the rate of change of the magnetic field (e.g., H’) is often used as a proxy, under the assumption that larger rates of change of the geomagnetic field will be related to larger GICs.  While a range of magnetospheric processes can result in large GICs, in this work we focus on one: Sudden Commencements (SCs).  SCs are rapid, coherent changes in the geomagnetic field caused by the impact of a large increase in solar wind dynamic pressure (e.g., an interplanetary shock).  Globally, in one-minute cadence ground magnetic field data SCs appear relatively homogenous, lasting only a few data points.  However, it has previously been found that in New Zealand SCs on the dayside have been linked to 30% larger measured GICs for a given H’.  We investigate a deceptively simple question: why?In this work we examine the sub-minute structure of SCs in New Zealand and their impact on the resulting GICs.  We introduce an analytical model that describes the key features of the magnetic field signature, allowing us to fully describe the key features of an SC.  The use of parameters (e.g., maximum H’) from the fitted analytical model strengthens the correlation between maximum H’ and GIC during SCs, but leaves remnant dependencies which are yet to be explained.  We conduct synthetic experiments with our analytical SC model and a high resolution magnetotelluric-derived map of the southern part of New Zealand to examine which properties of an SC make it more-likely to cause disproportionately large GIC.

This review, offered for the first time in the Russian scientific literature, is devoted to various aspects of the problem of the space weather impact on ground-based technological systems. Particular attention is paid to hazards to operation of power transmission lines, railway automation, and pipelines caused by geomagnetically induced currents (GIC) during geomagnetic disturbances. The review provides information on the main characteristics of geomagnetic field variability, on rapid field variations during various space weather mani-festations. The fundamentals of modeling geoelectric field disturbances based on magnetotelluric sounding algorithms are presented. The approaches to the assessment of possible extreme values of GIC are considered. Information about economic effects of space weather and GIC is collected. The current state and prospects of space weather forecasting, risk assessment for technological systems from GIC impact are discussed. While in space geophysics various models for predicting the intensity of magnetic storms and their related geomagnetic disturbances from observations of the interplanetary medium are being actively developed, these models cannot be directly used to predict the intensity and position of GIC since the description of the geomagnetic field variability requires the development of additional models. Revealing the fine structure of fast geomagnetic variations during storms and substorms and their induced GIC bursts appeared to be important not only from a practical point of view, but also for the development of fundamentals of near-Earth space dynamics. Unlike highly specialized papers on geophysical aspects of geomagnetic variations and engineering aspects of the GIC impact on operation of industrial transformers, the review is designed for a wider scientific and technical audience without sacrificing the scientific level of presentation. In other words, the geophysical part of the review is written for engineers, and the engineering part is written for geophysicists. Despite the evident applied orientation of the studies under consideration, they are not limited to purely engineering application of space geophysics results to the calculation of possible risks for technological systems, but also pose a number of fundamental scientific problems.

This contribution addresses the first assessment of the impact of geomagnetically induced currents (GIC) on the 400‐kV power grid of Mexico. As an initial approach, we modeled GIC using a uniform conductivity for the entire Mexican territory and spatially uniform geomagnetic disturbance. Power grid data were provided by the electric operator of Mexico; the geophysical data were inferred from the main features of Mexican geology. We calculate the power grid response during four geomagnetic storms from Solar Cycles 23 and 24 (i.e., 15 July 2000, 20 October 2003, 17 March 2015, and 7 September 2017), as well as during an extreme scenario (a Carrington‐like event). The results show that the Mexican power grid can be affected by three‐phase GIC ranging from 20 to 75 A during geomagnetic disturbances. According to the model, sites located in coastal areas or close to the edges of the network can experience large GIC during time intervals between 3 and 10 hr, depending on the intensity of the geomagnetic disturbance. It is an interesting result that these sites are of the major economic and strategic significance for the country. In the case of a Carrington‐like event, the power grid could be affected by GIC ranging between 25 and 150 A under a uniform 1 V/km EW geoelectric field. Such an event might produce significant distortions in the grid hardware (i.e., transformers and static VAR compensators), potentially leading to widespread damage.

Prior research on the impact of geomagnetic disturbances (GMD) on the electric grid has mainly focused on improving GMD modeling for off-line analyses. Given the recent industry emphasis on monitoring the earth’s magnetic field and geomagnetically induced currents (GIC), this paper describes a real-time GMD monitoring system. The real-time magnetic field measurements come from a network of six magnetometers installed in the US State of Texas. The paper focuses on the real-time GIC monitoring application implemented in a simulation environment, which could be extended to the real grid. The magnetic field measurements are coupled with ground conductivity models to calculate real-time electric fields, which are passed to a grid model to estimate and visualize GICs in real-time. Results are demonstrated on a synthetic but realistic and publicly available model of the Texas grid. The simulation environment is interactive with communication capabilities, making operational control and GMD mitigation possible in the near future.