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Measurement and modelling of geomagnetically induced currents (GIC) in power lines
Author(s)
Matandirotya, Electdom
Date Issued
2016
Type
Thesis
Publisher
Cape Peninsula University of Technology
Abstract
Geomagnetically induced currents (GIC) are currents induced in ground-based conductor
networks in the Earth's surface. The GIC are driven by an electric eld induced by geomagnetic
variations which are a result of time-varying magnetospheric-ionospheric currents during adverse
space weather events. Several studies have shown that there is a likelihood of technological
damage (the power grid) in the mid- and low-latitude regions that could be linked to GIC during
some geomagnetic storms over the past solar cycles. The effects of GIC in the power system can
range from temporary damage (e.g. protective relay tripping) to permanent damage (thermal
transformer damage). Measurements of GIC in most substations are done on the
neutral-to-ground connections of transformers using Hall-effect transducers. However, there is a
need to understand the characteristics of GIC in the power lines connected to these transformers.
Direct measurements of GIC in the power lines are not feasible due to the low frequencies of these
currents which make current measurements using current transformers (CT) impractical. This thesis discusses two techniques that can be employed to enhance understanding GIC
characteristics in mid-latitude regions. The techniques involve the measurement of GIC in a power
line using differential magnetometer measurements and modelling GIC using the finite element
method. Low frequency magnetometers are used to measure magnetic felds in the vicinity of the
power lines and the GIC is inferred using the Biot-Savart law. A finite element model, using
COMSOL-Multiphysics, is used to calculate GIC with the measured magnetic field and a realistic
Earth conductivity profile as inputs. The finite element model is used for the computation of
electric field associated with GIC modelling.
networks in the Earth's surface. The GIC are driven by an electric eld induced by geomagnetic
variations which are a result of time-varying magnetospheric-ionospheric currents during adverse
space weather events. Several studies have shown that there is a likelihood of technological
damage (the power grid) in the mid- and low-latitude regions that could be linked to GIC during
some geomagnetic storms over the past solar cycles. The effects of GIC in the power system can
range from temporary damage (e.g. protective relay tripping) to permanent damage (thermal
transformer damage). Measurements of GIC in most substations are done on the
neutral-to-ground connections of transformers using Hall-effect transducers. However, there is a
need to understand the characteristics of GIC in the power lines connected to these transformers.
Direct measurements of GIC in the power lines are not feasible due to the low frequencies of these
currents which make current measurements using current transformers (CT) impractical. This thesis discusses two techniques that can be employed to enhance understanding GIC
characteristics in mid-latitude regions. The techniques involve the measurement of GIC in a power
line using differential magnetometer measurements and modelling GIC using the finite element
method. Low frequency magnetometers are used to measure magnetic felds in the vicinity of the
power lines and the GIC is inferred using the Biot-Savart law. A finite element model, using
COMSOL-Multiphysics, is used to calculate GIC with the measured magnetic field and a realistic
Earth conductivity profile as inputs. The finite element model is used for the computation of
electric field associated with GIC modelling.
Additional information
Thesis (DTech (Electrical Engineering))--Cape Peninsula University of Technology, 2016.
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210233729-Matandirotya-Electdom-Dtech-Electrical-Engineering-Eng-2017.pdf
Description
Thesis
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