Effects of System Characteristics on Geomagnetically Induced Currents

Kang, Zheng; Boteler, D. H.; Pirjola, Risto; Liu, Lianguang; Becker, Richard A.; Marti, L.; Boutilier, Stephen; Guillon, Sébastien

doi:10.1109/tpwrd.2013.2281191

Cited by 80 publications

(49 citation statements)

References 16 publications

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“…When a transformer has different values of GIC in its windings, an "effective GIC" can be calculated that gives the same degree of transformer saturation as GIC in a single winding (Albertson et al, 1981;Zheng et al, 2014). For both two-winding transformers and autotransformers, the effective GIC is given by…”

Section: Discussionmentioning

confidence: 99%

Comparison of methods for modelling geomagnetically induced currents

Boteler

Pirjola

2014

Ann. Geophys.

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Abstract. Assessing the geomagnetic hazard to power systems requires reliable modelling of the geomagnetically induced currents (GIC) produced in the power network. This paper compares the Nodal Admittance Matrix method with the Lehtinen-Pirjola method and shows them to be mathematically equivalent. GIC calculation using the Nodal Admittance Matrix method involves three steps: (1) using the voltage sources in the lines representing the induced geoelectric field to calculate equivalent current sources and summing these to obtain the nodal current sources, (2) performing the inversion of the admittance matrix and multiplying by the nodal current sources to obtain the nodal voltages, (3) using the nodal voltages to determine the currents in the lines and in the ground connections. In the Lehtinen-Pirjola method, steps 2 and 3 of the Nodal Admittance Matrix calculation are combined into one matrix expression. This involves inversion of a more complicated matrix but yields the currents to ground directly from the nodal current sources. To calculate GIC in multiple voltage levels of a power system, it is necessary to model the connections between voltage levels, not just the transmission lines and ground connections considered in traditional GIC modelling. Where GIC flow to ground through both the high-voltage and low-voltage windings of a transformer, they share a common path through the substation grounding resistance. This has been modelled previously by including non-zero, off-diagonal elements in the earthing impedance matrix of the Lehtinen-Pirjola method. However, this situation is more easily handled in both the Nodal Admittance Matrix method and the Lehtinen-Pirjola method by introducing a node at the neutral point.

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Section: Discussionmentioning

confidence: 99%

Comparison of methods for modelling geomagnetically induced currents

Boteler

Pirjola

2014

Ann. Geophys.

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“…The equivalent ''single phase'' model gives values that are all three times the ''all phases'' values, i.e., the transmission line and transformer winding resistances per phase and three times the substation grounding resistance. The actual resistance values vary from system to system, however, there are some general characteristics as shown by Zheng et al (2014). Higher voltage lines use bundles of conductors for each transmission line resulting in lower resistances.…”

Section: Setting Up the Modelmentioning

confidence: 99%

Methodology for simulation of geomagnetically induced currents in power systems

Boteler¹

2014

J. Space Weather Space Clim.

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To assess the geomagnetic hazard to power systems it is useful to be able to simulate the geomagnetically induced currents (GIC) that are produced during major geomagnetic disturbances. This paper examines the methodology used in power system analysis and shows how it can be applied to modelling GIC. Electric fields in the area of the power network are used to determine the voltage sources or equivalent current sources in the transmission lines. The power network can be described by a mesh impedance matrix which is combined with the voltage sources to calculate the GIC in each loop. Alternatively the power network can be described by a nodal admittance matrix which is combined with the sum of current sources into each node to calculate the nodal voltages which are then used to calculate the GIC in the transmission lines and GIC flowing to ground at each substation. Practical calculations can be made by superposition of results calculated separately for northward and eastward electric fields. This can be done using magnetic data from a single observatory to calculate an electric field that is a uniform approximation of the field over the area of the power system. It is also shown how the superposition of results can be extended to use data from two observatories: approximating the electric field by a linear variation between the two observatory locations. These calculations provide an efficient method for simulating the GIC that would be produced by historically significant geomagnetic storm events.

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“…If a transmission circuit is sufficiently long, the line resistance becomes much larger than the station grounding and winding resistances of the transformers connected to the circuit. Since induced voltage and line resistance are proportional to line length, the circuit can be approximated by a constant, length-independent current source so long as the earth conductivity is laterally uniform [3]. A simplified circuit representation is shown in Fig.…”

Section: Gic Flow In a Networkmentioning

confidence: 99%

“…In an autotransformer, effective GIC takes into consideration that a different GIC flows through the series and common wind- ings. In the case of generator step-up transformers, the effective GIC is the same as the current in the wye-grounded winding [3]. Table II summarizes the effective current in the autotransformer.…”

Section: Gic Flow In a Networkmentioning

confidence: 99%

Effects of Series Compensation Capacitors on Geomagnetically Induced Currents

Marti

2014

IEEE Trans. Power Delivery

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A series compensation capacitor bank presents a high-impedance path to geomagnetically induced currents (GICs), which are induced into the power network during geomagnetic disturbances. The notion that a series capacitor generally blocks GIC is only true for the transmission circuit connected in series with the capacitor. In many cases, the series capacitor simply re-distributes GIC in the network and may actually increase GIC flow at terminal stations. The conditions under which an increase in GIC can take place and illustrative examples with and without piecewise layered earth modeling are discussed.Index Terms-Electric field, geomagnetically induced currents (GICs), geomagnetism, reactive power control.

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Effects of System Characteristics on Geomagnetically Induced Currents

Cited by 80 publications

References 16 publications

Comparison of methods for modelling geomagnetically induced currents

Comparison of methods for modelling geomagnetically induced currents

Methodology for simulation of geomagnetically induced currents in power systems

Effects of Series Compensation Capacitors on Geomagnetically Induced Currents

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