Editing Geomagnetic storm (section)

==== Electrical grid ====

When [[magnetic field]]s move about in the vicinity of a conductor such as a wire, a [[geomagnetically induced current]] is produced in the conductor. This happens on a grand scale during geomagnetic storms (the same mechanism also influenced telephone and telegraph lines before fiber optics, see above) on all long transmission lines. Long transmission lines (many kilometers in length) are thus subject to damage by this effect. Notably, this chiefly includes operators in China, North America, and Australia, especially in modern high-voltage, low-resistance lines. The European grid consists mainly of shorter transmission circuits, which are less vulnerable to damage.<ref name="kappenman">{{cite news | url=https://spectrum.ieee.org/energy/the-smarter-grid/a-perfect-storm-of-planetary-proportions/0 | archive-url=https://web.archive.org/web/20120127072117/http://spectrum.ieee.org/energy/the-smarter-grid/a-perfect-storm-of-planetary-proportions/0 | url-status=dead | archive-date=27 January 2012 | title=A Perfect Storm of Planetary Proportions | work=[[IEEE Spectrum]] |date=February 2012 | access-date=2012-02-13 }}</ref><ref>Natuurwetenschap & Techniek Magazine, June 2009</ref>

The (nearly direct) currents induced in these lines from geomagnetic storms are harmful to electrical transmission equipment, especially [[transformer]]s—inducing core [[saturation (magnetic)|saturation]], constraining their performance (as well as tripping various safety devices), and causing coils and cores to heat up. In extreme cases, this heat can disable or destroy them, even inducing a chain reaction that can overload transformers.<ref>{{cite web |url=http://192.211.16.13/curricular/ENERGY/0708/articles/solar/SolarForecast07SkyTel.pdf|title=Solar Forecast: Storm AHEAD |archive-url=https://web.archive.org/web/20080911192808/http://192.211.16.13/curricular/ENERGY/0708/articles/solar/SolarForecast07SkyTel.pdf |archive-date=2008-09-11 |url-status=dead}}</ref><ref>{{Cite web|url=http://science.nasa.gov/headlines/y2009/21jan_severespaceweather.htm|title=NASA - Severe Space Weather--Social and Economic Impacts|date=24 January 2009|archive-url=https://web.archive.org/web/20090124153337/http://science.nasa.gov/headlines/y2009/21jan_severespaceweather.htm |accessdate=27 June 2023|archive-date=24 January 2009 |url-status=dead}}</ref> Most generators are connected to the grid via transformers, isolating them from the induced currents on the grid, making them much less susceptible to damage due to [[geomagnetically induced current]]. However, a transformer that is subjected to this will act as an unbalanced load to the generator, causing negative sequence current in the stator and consequently rotor heating.

A 2008 study by Metatech corporation concluded that a storm with a strength comparable to that of 1921 would destroy more than 300 transformers and leave over 130 million people without power in the United States, costing several trillion dollars.<ref>{{cite book |title=Severe Space Weather Events: Understanding Societal and Economic Impacts : a Workshop Report |location=Washington, D.C. |publisher=National Academies, 2008 |url=http://www.nap.edu/openbook.php?record_id=12507&page=1 |date=15 November 2011 |pages=78,105,106|doi=10.17226/12507 |isbn=978-0-309-12769-1 }}</ref> The extent of the disruption is debated, with some congressional testimony indicating a potentially indefinite outage until transformers can be replaced or repaired.<ref>{{cite web |title=Testimony of the Foundation For Resilient Societies before the Federal Energy Regulatory Commission | url=https://www.resilientsocieties.org/uploads/5/4/0/0/54008795/resilient_societies_testimony_rm15-11-00_march_1_2016_tech_conference_final_feb_23_2016.pdf}}</ref> These predictions are contradicted by a [[North American Electric Reliability Corporation]] report that concludes that a geomagnetic storm would cause temporary grid instability but no widespread destruction of high-voltage transformers. The report points out that the widely quoted Quebec grid collapse was not caused by overheating transformers but by the near-simultaneous tripping of seven relays.<ref>{{cite web |url=https://www.frcc.com/Public%20Awareness/Lists/Announcements/Attachments/105/GMD%20Interim%20Report.pdf |title=2012 Special Reliability Assessment Interim Report: Effects of Geomagnetic Disturbances on the Bulk Power System |publisher=North American Electric Reliability Corporation |date=February 2012 |access-date=2013-01-19 |url-status=dead |archive-url=https://web.archive.org/web/20150908075507/https://www.frcc.com/Public%20Awareness/Lists/Announcements/Attachments/105/GMD%20Interim%20Report.pdf |archive-date=2015-09-08 }}</ref> In 2016, the United States [[Federal Energy Regulatory Commission]] adopted NEARC rules for  equipment testing for electric utilities. Implementation of any upgrades needed to protect against the effects of geomagnetic storms was required within four years, and the regulations also directed further research.<ref>{{cite web |url=https://www.federalregister.gov/documents/2016/09/30/2016-23441/reliability-standard-for-transmission-system-planned-performance-for-geomagnetic-disturbance-events |title=Rule Reliability Standard for Transmission System Planned Performance for Geomagnetic Disturbance Events |date=September 30, 2016 |author=Federal Energy Regulatory Commission}}</ref>

Besides the transformers being vulnerable to the effects of a geomagnetic storm, electricity companies can also be affected indirectly by the geomagnetic storm. For instance, Internet service providers may go down during geomagnetic storms (and/or remain non-operational long after). Electricity companies may have equipment requiring a working Internet connection to function, so during the period the Internet service provider is down, the electricity too may not be distributed.<ref>Kijk magazine 6/2017, mentioned by Marcel Spit of Adviescentrum Bescherming Vitale Infrastructuur]</ref>

By receiving geomagnetic storm alerts and warnings (e.g. by the [[Space Weather Prediction Center]]; via Space Weather satellites as SOHO or ACE), power companies can minimize damage to power transmission equipment, by momentarily disconnecting transformers or by inducing temporary blackouts. Preventive measures also exist, including preventing the inflow of GICs into the grid through the neutral-to-ground connection.<ref name="kappenman"/>