Frequency Considerations in GIC Applications. Issue 8 (25th August 2021)

• Record Type: Journal Article
• Authors: Trichtchenko, L.
• Is Part Of: Space weather. Volume 19:Issue 8(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-08-25
• Subjects: geomagnetically induced currents -- geoelectric fields -- geomagnetic storms -- harmonics; Space environment -- Periodicals; 551.509992
• DOI: 10.1029/2020SW002694
• Languages: English
• ISSNs: 1542-7390

Abstract

Abstract: Geomagnetically induced currents (GIC) are a phenomenon well known for its negative effects on the operations of power systems. To efficiently mitigate them requires different types of power system modeling, from GIC to alternating current harmonic generation, to three‐dimensional finite element models of transformers. GIC are initiated by variations of the geomagnetic field in the presence of the conductive Earth, that is, the geophysical variables characterized by continuous frequency spectra, making GIC also exhibit continuous spectra. In order to adequately estimate their variations and peak values for mitigation purposes, an analysis is required of how sampling rate and spectral frequency content impact the measured characteristics of GIC and harmonics. The study is based on the geomagnetic measurements and the power network data (i.e., GIC and harmonics) with high sampling rates recorded during two geomagnetic storms, March 31, 2001 and July 26–27, 2004. Availability of data covering both the source and the result of geomagnetic storm impacts on power grid allows (a) analysis of the influence of spectral content on adequate representation of both geomagnetic and geoelectric variations during the intervals with significant increases in GIC and harmonics and (b) identifying the sampling rate sufficient to usefully represent the network response presented as GIC and harmonics variations. In summary, the adequate sampling rate is suggested and the deficiencies associated with undersampling of the geoelectric and GIC variations are identified and discussed. Plain Language Summary: One of the most detrimental impacts of space weather on critical infrastructure is the effect of the geomagnetic storms on the operations of electrical power systems. Depending on the severity of the geomagnetic storms, significant geomagnetically induced currents (GIC) can be produced, followed by multiple negative effects, from voltage fluctuations to power blackouts and damage to transformers. To efficiently mitigate them requires different types of the power system modeling, from GIC to alternating current harmonic generation, to three‐dimensional finite element models of transformers. In order to adequately estimate their variations and peak values for mitigation purposes, the analysis of the impact of sampling rate and the spectral frequency content of the geophysical parameters on GIC and harmonics characteristics is presented. Key Points: Study of spectral content and sampling rate of geophysical and power network data is presented Analysis is based on geomagnetic and power network data recorded during the geomagnetic storms of March 31, 2001 and July 26–27, 2004 Recommendations on sampling rate, and other results related to the GIC applications, are provided