Calculation techniques and results of effects of GIC currents as applied to two large power transformers

Girgis, R.S.; Ko, Chang-Sung

doi:10.1109/tdc.1991.169558

Cited by 15 publications

(7 citation statements)

References 2 publications

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Section: A Ahfock and A J Hewittmentioning

confidence: 99%

“…In addition, a systematic procedure has been developed to evaluate the primary current distortion in both single and three phase The question of DC injection into the AC network has received significant attention over recent years [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The DC current could be geomagnetically induced [1,2] or could be due to power electronic equipment operating under normal conditions [3,9] or under abnormal conditions [10][11][12]. Depending on the level and duration of DC injection, possible adverse effects that may result from it are transformer half cycle saturation, AC current distortion, transformer overheating [1,2], increased reactive power demand [13], corrosion of grounding equipment [5], metering errors and malfunctioning of protective equipment [1].…”

Section: A Ahfock and A J Hewittmentioning

confidence: 99%

“…The DC current could be geomagnetically induced [1,2] or could be due to power electronic equipment operating under normal conditions [3,9] or under abnormal conditions [10][11][12]. Depending on the level and duration of DC injection, possible adverse effects that may result from it are transformer half cycle saturation, AC current distortion, transformer overheating [1,2], increased reactive power demand [13], corrosion of grounding equipment [5], metering errors and malfunctioning of protective equipment [1]. This paper focuses on the prediction of magnetising current distortion resulting from DC offset currents on the load side of single phase and three phase three limb core type transformers.…”

Section: A Ahfock and A J Hewittmentioning

confidence: 99%

“…Price [1] uses a time-stepping approach to analyse the effects of balanced DC injection on several types of transformers. Girgis and Ko [2] also confine their study to balanced DC injection and investigate only shell type transformers. Fuchs, You and Roesler [14] propose a model to evaluate the effects of DC bias currents on three-limb core type transformers.…”

Section: A Ahfock and A J Hewittmentioning

confidence: 99%

See 3 more Smart Citations

DC magnetisation of transformers

Ahfock

Hewitt

2006

IEE Proc., Electr. Power Appl.

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-A high enough DC component in the current on the secondary side of a transformer causes distortion of the primary side current. Prediction of such distortion relies on the availability of magnetization curves that extend deep enough into saturation.A simple test, carried out at rated voltage, is proposed which allows the magnetization curve to be deduced from measured data. In addition, a systematic procedure has been developed to evaluate the primary current distortion in both single and three phase

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Section: A Ahfock and A J Hewittmentioning

confidence: 99%

Section: A Ahfock and A J Hewittmentioning

confidence: 99%

Section: A Ahfock and A J Hewittmentioning

confidence: 99%

Section: A Ahfock and A J Hewittmentioning

confidence: 99%

See 2 more Smart Citations

DC magnetisation of transformers

Ahfock

Hewitt

2006

IEE Proc., Electr. Power Appl.

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“…It is essential to know the effect of transformer load current on the leakage flux of a transformer with GIC in order to reduce or mitigate the effect of GIC on transformer. Some tests and simulations have been performed to investigate the effect of GIC on transformer with no-load [10][11][12][13]. But there are few papers or studies on the effect of GIC on transformer with different load current.…”

Section: Introductionmentioning

confidence: 99%

Effect of load current on leakage flux of transformer with geomagnetically induced current

Zhang

Liu

et al. 2010

Euro. Trans. Electr. Power

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Geomagnetic storms caused by solar activity can induce geomagnetic-induced current (GIC) in the power grids. The flow of GIC in the power transformer winding can cause half-cycle saturation of transformer. This saturation can cause distorted exciting current, transformer overheat, and some additional power system problems. There will also be more leakage flux leaving the core and entering into the tank due to GIC. This will cause large tank loss and overheat the transformer. Besides GIC, the leakage flux is also related to the transformer load current. This paper presents a 2D finite-element transformer model. Based on the finite element model, the transformer leakage flux and the tank loss caused by GIC with different transformer load current are studied. As a consequence of GIC, the transformer power factor and the magnitude of transformers load current have an important effect on the leakage flux of transformer.

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Long‐Term Geomagnetically Induced Current Observations From New Zealand: Peak Current Estimates for Extreme Geomagnetic Storms

et al. 2017

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Geomagnetically induced current (GIC) observations made in New Zealand over 14 years show induction effects associated with a rapidly varying horizontal magnetic field (dBH/dt) during geomagnetic storms. This study analyzes the GIC observations in order to estimate the impact of extreme storms as a hazard to the power system in New Zealand. Analysis is undertaken of GIC in transformer number six in Islington, Christchurch (ISL M6), which had the highest observed currents during the 6 November 2001 storm. Using previously published values of 3,000 nT/min as a representation of an extreme storm with 100 year return period, induced currents of ~455 A were estimated for Islington (with the 95% confidence interval range being ~155–605 A). For 200 year return periods using 5,000 nT/min, current estimates reach ~755 A (confidence interval range 155–910 A). GIC measurements from the much shorter data set collected at transformer number 4 in Halfway Bush, Dunedin, (HWB T4), found induced currents to be consistently a factor of 3 higher than at Islington, suggesting equivalent extreme storm effects of ~460–1,815 A (100 year return) and ~460–2,720 A (200 year return). An estimate was undertaken of likely failure levels for single‐phase transformers, such as HWB T4 when it failed during the 6 November 2001 geomagnetic storm, identifying that induced currents of ~100 A can put such transformer types at risk of damage. Detailed modeling of the New Zealand power system is therefore required to put this regional analysis into a global context.

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Calculation techniques and results of effects of GIC currents as applied to two large power transformers

Cited by 15 publications

References 2 publications

DC magnetisation of transformers

DC magnetisation of transformers

Effect of load current on leakage flux of transformer with geomagnetically induced current

Long‐Term Geomagnetically Induced Current Observations From New Zealand: Peak Current Estimates for Extreme Geomagnetic Storms

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