An experimental analysis of DC excitation of transformers by geomagnetically induced currents

Takasu, N.; Oshi, T.; Miyawaki, F.; Saito, S.; Fujiwara, Y.

doi:10.1109/61.296304

Cited by 125 publications

(34 citation statements)

References 5 publications

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“…Using a DC power source as a proxy of GICs, Takasu et al (1994) performed experiments on DC excitation for scale models with linear dimensions that were one third to one half of those of actual power transformers. Distortion of wave forms of AC currents was observed by the applied DC currents of several tens ampere to the scale models.…”

Section: Estimation Of Gic and Discussionmentioning

confidence: 99%

Estimation of geomagnetically induced currents based on the measurement data of a transformer in a Japanese power network and geoelectric field observations

Watari

2015

Earth Planet Sp

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Geomagnetically induced currents (GICs) have the potential to cause electric power blackouts. Hence, it is important to study the effects of GICs produced by intense geomagnetic storms. The measurements of GICs were conducted at the Memanbetsu substation, Hokkaido, between December 2005 and March 2008. We obtain the complementary cumulative distribution function (CCDF) of the measured GICs and the empirical equation to estimate GICs using the GIC data and geoelectric field observation data. GICs associated with the past intense geomagnetic storms, e.g., the March 13-15 storm and the October 29-30, 2003 storm, are estimated.

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Section: Estimation Of Gic and Discussionmentioning

confidence: 99%

Estimation of geomagnetically induced currents based on the measurement data of a transformer in a Japanese power network and geoelectric field observations

Watari

2015

Earth Planet Sp

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“…Yet although this direct current is usually rather small, it can shift the (B-H) curve outside the linear design operation region resulting in highly distorted output waveform, very high magnetic fluxes and half-cycle saturation (see, e.g., Bossi et al 1983;Takasu et al 1994;Minhas et al 1999;Price 2002). The magnetic flux leakage from the core of the transformer may lead to overheating, gassing, shutdown and even catastrophic failure.…”

Section: Introductory Theory -Motivationmentioning

confidence: 99%

“…Half-wave saturation also increases the magnetising current and distorts the magnetisation current waveform (see, e.g., Takasu et al 1994). The distorted magnetising current has harmonics that correlate well with the GIC.…”

Section: Introductory Theory -Motivationmentioning

confidence: 99%

Solar activity and transformer failures in the Greek national electric grid

Zois

2013

J. Space Weather Space Clim.

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Aims: We study both the short term and long term effects of solar activity on the large transformers (150 kV and 400 kV) of the Greek national electric grid. Methods: We use data analysis and various statistical methods and models. Results: Contrary to common belief in PPC Greece, we see that there are considerable both short term (immediate) and long term effects of solar activity onto large transformers in a mid-latitude country like Greece. Our results can be summarised as follows:1. For the short term effects: During 1989-2010 there were 43 ''stormy days'' (namely days with for example Ap ! 100) and we had 19 failures occurring during a stormy day plus or minus 3 days and 51 failures occurring during a stormy day plus or minus 7 days. All these failures can be directly related to Geomagnetically Induced Currents (GICs). Explicit cases are briefly presented. 2. For the long term effects, again for the same period 1989-2010, we have two main results:(i) The annual number of transformer failures seems to follow the solar activity pattern. Yet the maximum number of transformer failures occurs about half a solar cycle after the maximum of solar activity. (ii) There is statistical correlation between solar activity expressed using various newly defined long term solar activity indices and the annual number of transformer failures. These new long term solar activity indices were defined using both local (from the geomagnetic station in Greece) and global (planetary averages) geomagnetic data. Applying both linear and non-linear statistical regression we compute the regression equations and the corresponding coefficients of determination.Key words. geomagnetically induced currents (GIC) -solar activity -technological system -non-linear phenomena -aeronomy Introductory theory -motivationThe primary cause of space weather are explosions in the Sun powered by its strong magnetic field which affect man-made technological infrastructure in space, disturb communications and GPS signals and couple through Geomagnetically Induced Currents (GICs for short) with the large-scale high voltage power grid. The most well-known case of the impact of large-scale space weather events on the electric grid is the 1989 Hydro-Quebec blackout caused by the 13 and 14 March super storm. Highly acclaimed institutions (like the US National Academy of Sciences 2008, the UK Royal Society of Engineering 2013, etc.) have issued extended reports arguing that space weather super storms may cause trillions of dollars of damage although it is acknowledged that these estimates may not be totally accurate. There is general consensus however that space weather super storms constitute a serious threat. The main cause of GICs is the interaction of the geomagnetic field with the magnetic field carried within CMEs and the surrounding background magnetised solar wind that is modulated by them. There are several space weather phenomena which tend to be associated with a geomagnetic storm or are caused by a geomagnetic storm (see Chapman & Ferraro 1930...

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“…The DC bias result in abnormal vibration, noise, harmonics, reactive power loss and temperature rise [7]. As for the influence of geomagnetic storms, in addition to the blackout [8], there have been a large number accidents where transformers were severely damaged due to the temperature rise [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Comparative Study of Single-phase Shell & Core Type Transformers in GIC Temperature Rise Effect

Zhai¹,

Zhu²,

Gu³

et al. 2018

dteees

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Abstract. Geomagnetically induced currents (GICs) flowing through transformers may cause temperature rise which could result in permanent damage. As the single-phase-set transformers are widely used in the bulk power transmission, this paper investigates the temperature rise effect both in shell type transformers and core type transformers. Based on the designing parameters of the 500kV single-phase shell type and core type transformer, a 3D finite element model including the transformer iron core, tank and supporting parts has been established, so that the temperature rises in the iron cores and supporting parts are all taken into account. Through calculation with different values of GIC excitations, the different temperature rise characteristics between shell transformer and core transformer are investigated. The simulation results of the temperature rise at different positions in the supporting parts can provide references for the designing of Chinese UHV (ultrahigh voltage) transformers to mitigate the temperature rise due to DC bias.

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An experimental analysis of DC excitation of transformers by geomagnetically induced currents

Cited by 125 publications

References 5 publications

Estimation of geomagnetically induced currents based on the measurement data of a transformer in a Japanese power network and geoelectric field observations

Estimation of geomagnetically induced currents based on the measurement data of a transformer in a Japanese power network and geoelectric field observations

Solar activity and transformer failures in the Greek national electric grid

Comparative Study of Single-phase Shell & Core Type Transformers in GIC Temperature Rise Effect

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