Geomagnetically Induced Current Model Validation From New Zealand's South Island

Divett, Tim; Manus, Daniel H. Mac; Richardson, Gemma; Beggan, Ciarán; Rodger, Craig J.; Ingham, M.; Clarke, Ellen; Thomson, Alan; Dalzell, Michael D; Obana, Yuki

doi:10.1029/2020sw002494

Cited by 25 publications

(95 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Observed GICs and even‐THD at 0145 UT on 8 December were associated with rates of change of the horizontal field of 10 nT/min at Dunedin, 5.3 nT/min at EYR, and 3.7 nT/min at Te Wharau. A large rate of change of 30.6 nT/min at Dunedin between 1200 and 1300 UT 8 September saw smaller rates of change at EYR (12.3 nT/min) and Te Wharau (7.9 nT/min), while, in accordance with the result of Divett et al (2020), rates of change during the St. Patrick's Day storm were relatively uniform across all four locations. Additionally, shown in Figure 13 is a comparison of rates of change ( dB x / dt ) of the northward component of the magnetic field at an MT site close to New Plymouth and at the Eyrewell geomagnetic observatory.…”

Section: Validation Of Gic Predictionssupporting

confidence: 84%

Calculation of GIC in the North Island of New Zealand Using MT Data and Thin‐Sheet Modeling

et al. 2020

Self Cite

View full text Add to dashboard Cite

Geomagnetically induced currents (GICs) in the North Island New Zealand power transmission network during two large magnetic storms are calculated from both magnetotelluric (MT) data and a thin-sheet conductance model of New Zealand previously used to study GIC in the South Island. We focus on the 2015 St. Patrick's Day magnetic storm and the storm of 20 November 2003. Lack of MT data in the northwestern part of the Island means that the transmission network in this region is represented by an equivalent circuit. Lack of GIC observations in the North Island means that results cannot be directly compared with measured GIC. However, our calculation of GIC shows that substations and individual transformers in the lower part of the Island with significant currents are generally the same as those where total harmonic distortion has been observed during periods of enhanced geomagnetic activity. MT data in the period range 2-30 min are used to predict GIC associated with the sudden storm commencement and rapid variations in the magnetic field. In contrast, the thin-sheet modeling approach shows that GIC may be expected to occur in conjunction with longer-period variations. Calculations for the 2003 storm suggest that at some locations GIC in excess of 10 A may persist for long periods of time and may produce significant harmonic distortion which could lead to localized transformer heating. It is concluded that despite its relatively low latitude the North Island power network is potentially at risk from significant GIC during extreme storms. Plain Language Summary Variations in the Earth's magnetic field with time during so-called "magnetic storms" can result in currents (geomagnetically induced currents-GICs) entering and leaving power transmission lines through the ground connections on transformers. Large GIC, or even smaller currents occurring repeatedly, can not only damage transformers but, in the worst-case scenario, cause disruption to an entire transmission network. To attempt to assess the potential vulnerability of the transmission network in the North Island of New Zealand to such effects, we present model calculations of GIC resulting from two magnetic storms. The results show that despite the relatively low geomagnetic latitude of New Zealand's North Island, there are some substations and individual transformers where large GIC can be expected and may be problematic.

show abstract

Section: Validation Of Gic Predictionssupporting

confidence: 84%

Calculation of GIC in the North Island of New Zealand Using MT Data and Thin‐Sheet Modeling

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…The comparison of values of ℎ ⁄ also shows that the thin-sheet model results for the South Island can be extended to shorter periods than they can for the North Island. This agrees with the conclusion reached by Divett et al, 2020. A third condition relates to the spacing of the numerical grid, which must be less than /4 which is also satisfied in the conductance grid selected (Divett et al, 2017).…”

Section: Figure 2 14supporting

confidence: 88%

“…The model uses geoelectric field as input to compute transformer level GIC in every transformer of the network. These studies used thin-sheet conductance model to derive the geoelectric fields used for GIC modelling for the South Island power network and results have been compared with measured data (Divett et al, 2020).…”

Section: Gic Studies In New Zealandmentioning

confidence: 99%

“…The thin-sheet (TS) approach has been used by McKay (2003) and Beggan et al (2013) to study GIC in the United Kingdom and by Kelly et al (2017) and Bailey et al (2017Bailey et al ( , 2018 in continental Europe. A thin-sheet conductance model has also been extensively used for GIC modelling in the South Island of New Zealand (Divett et al, 2017(Divett et al, , 2018(Divett et al, , 2020.…”

Section: Calculation Of Geoelectric Field Using a Thin-sheet Conductance Modelmentioning

confidence: 99%

See 1 more Smart Citation

Geomagnetically induced currents in the New Zealand power system

Mukhtar¹

View full text Add to dashboard Cite

This thesis focuses on the use of magnetotelluric (MT) data from both the North Island and South Island of New Zealand to model Geomagnetically Induced Currents (GIC) in the New Zealand power network. The model results have been compared with those from a previously used thin-sheet (TS) conductance model and with measured GIC. Initially, a single station modelling approach using a uniform conductivity Earth model is used to model the measured GIC in a transformer at Islington (ISL). This model is further improved by separately modelling low and high frequency components of GIC and then combining these to give full GIC. The model reproduces most of the GIC variations and the correlation coefficient is >70% for major magnetic storms from 2002-2015. As the model reproduces an average response of the network towards geoelectric fields it underestimates the most of extreme GIC. The analysis of GIC from other substations suggests that measured GIC depend on local geoelectric fields and the substation configuration within the network which cannot be captured using a single station approach. These limitations of single station model are addressed using more realistic geoelectric fields based on magnetotelluric data and consideration of the full network. To compute geoelectric fields in the whole network the gaps between MT sites are filled using a Nearest Neighbor interpolation technique. As the northern part of the North Island has no MT data an equivalent circuit approach is followed to model GIC for only the lower part of the network. The MT model GIC are in the period range of 2-30 minutes, based on the available MT data period range. Both the MT and TS techniques are used to compute geoelectric fields and to model GIC for the St. Patrick’s Day storm of 2015 and a 20 November 2003 magnetic storm. Both the MT and TS methods show the same transformers as experiencing large GIC during both storms. The primary difference between the models is that amplitudes of high frequency components of the TS model are significantly smaller than for the MT model. In particular they do not produce large GIC during the sudden storm commencement (SSC) of the St. Patrick’s Day magnetic storm. For the 20 November 2003 storm the TS model effectively reproduces the low frequency components and extreme GIC. The model results show that the North Island power network could be at risk during adverse space weather conditions. Although the South Island has sparser MT data the same technique is used to model SI GIC during both the St. Patrick’s Day and 2003 magnetic storms. Results are compared with measured data from ISL, South Dunedin (SDN) and Halfway Bush (HWB) transformers. The MT model effectively reproduces the measured GIC variations particularly during SSC during the St. Patrick’s Day storm. The TS model gives a very small GIC magnitude during the SSC. During the 20 November 2003 storm both the MT and TS models reproduce strong amplitudes of low frequency components seen in the ISL measured data. Both the MT and TS models show a substantial scale difference between measured and model GIC both for ISL and HWB transformers that needs to be further explored either in terms of better geoelectric interpolation or power network parameters. Overall, the MT model appears much more promising for future GIC modelling, particularly during a sudden storm commencement and for abrupt GIC variations.

show abstract

“…Many previous studies in connection with GIC operated with simplified models either of conducting Earth (one-dimensional (1-D) or thin sheet conductivity models) or the source (vertically propagating laterally uniform electromagnetic (EM) field; plane wave), or both (e.g., Bailey et al, 2017Bailey et al, , 2018Beggan, 2015;Beggan et al, 2013;Divett et al, 2017Divett et al, , 2020Honkonen et al, 2018;Kelly et al, 2017;Püthe & Kuvshinov, 2013;Püthe et al, 2014;Viljanen et al, 2012Viljanen et al, , 2013Viljanen et al, , 2014.…”

Section: Introductionmentioning

confidence: 99%

Comparing three approaches to the inducing source setting for the ground electromagnetic field modeling due to space weather events

Marshalko

Kruglyakov

Kuvshinov

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

Geomagnetically Induced Current Model Validation From New Zealand's South Island

Cited by 25 publications

References 35 publications

Calculation of GIC in the North Island of New Zealand Using MT Data and Thin‐Sheet Modeling

Calculation of GIC in the North Island of New Zealand Using MT Data and Thin‐Sheet Modeling

Geomagnetically induced currents in the New Zealand power system

Comparing three approaches to the inducing source setting for the ground electromagnetic field modeling due to space weather events

Contact Info

Product

Resources

About