Grounding Grid Design For High Voltage Substation : An Assessment Of Effectiveness For Lightning Current

An electrical grounding system is an important element to ascertain a safe environment for both humans and equipment during fault or transient conditions. The performance of grounding systems under lightning current is quite different from the conventional frequency based power. In order to understa...

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Main Author: Hanaffi, Farhan
Format: Thesis
Language:English
Published: UTeM 2016
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Online Access:http://eprints.utem.edu.my/id/eprint/18860/1/Grounding%20Grid%20Design%20For%20High%20Voltage%20Substation%20%20An%20Assessment%20Of%20Effectiveness%20For%20Lightning%20Current%2024%20Pages.pdf
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spelling my.utem.eprints.188602017-07-31T00:58:51Z http://eprints.utem.edu.my/id/eprint/18860/ Grounding Grid Design For High Voltage Substation : An Assessment Of Effectiveness For Lightning Current Hanaffi, Farhan T Technology (General) TK Electrical engineering. Electronics Nuclear engineering An electrical grounding system is an important element to ascertain a safe environment for both humans and equipment during fault or transient conditions. The performance of grounding systems under lightning current is quite different from the conventional frequency based power. In order to understand the grounding grid behaviour under lightning current, researchers typically carry out experiments on actual grounding systems or on laboratory scaled models. Although experiments can provide insights of the actual grounding operation, the shortcoming is that a large area of lab space is required which reflects into high costs. As an alternative, computer simulation has been introduced, and can be categorised into three different approaches, namely circuit approach, transmission line approach or electromagnetic approach. In this work, the simulations are performed based on the electromagnetic approach under three dimensions (3D) mode due to its accurate results. For further understanding, a comparison between circuit and electromagnetic approaches is also carried out, where the resulting outcome shows that the circuit approach underestimates the impulse impedance at injection point compared with simulations by the electromagnetic approach. When the electromagnetic approach is applied, a finite element method is used to solve the partial differential electromagnetic equations in the time domain. Thereafter, the simulations results are validated with the existing published results covering the electromagnetic simulations by using the method of moment (MOM), and as well as actual field experiments. In addition, simulations are performed to understand the effect of different parameters, including lightning current, soil parameters, grounding design, and location of injection point of lightning current. Moreover, a comparison study is carried out for potential rise between power frequency and impulse current at different grid sizes. The study shows the potential generated at injection point for both current and saturation point when the grid size reaches a certain point. It’s important to consider both types of current to get better grounding grid design. Besides that, empirical equations are used out to calculate the effective area under lightning conditions, where the effect of the down-conductor is taken into consideration as part of the grounding model. The effective area is an important parameter for the optimization of the grounding grid design when increasing grounding size does not improve the impulse impedance. Transient ground potential rise (TGPR) above the ground is another interesting parameter to analyse. In this work, a good correlation is shown between the effective area and the impulse impedance at the injection point with rising transient ground potential. It is found that the TGPR is larger when it is closer to the injection point, but only lasts for a few microseconds. Step voltage evaluations are performed for different standing positions of the human above the grid, including the distance of the step voltage location from the injection point, and the effect of grid size to step voltage value. UTeM 2016 Thesis NonPeerReviewed text en http://eprints.utem.edu.my/id/eprint/18860/1/Grounding%20Grid%20Design%20For%20High%20Voltage%20Substation%20%20An%20Assessment%20Of%20Effectiveness%20For%20Lightning%20Current%2024%20Pages.pdf Hanaffi, Farhan (2016) Grounding Grid Design For High Voltage Substation : An Assessment Of Effectiveness For Lightning Current. PhD thesis, Universiti Teknikal Malaysia Melaka. http://library.utem.edu.my:8000/elmu/index.jsp?module=webopac-d&action=fullDisplayRetriever.jsp&szMaterialNo=0000102313 HF5351.M34 2016
institution Universiti Teknikal Malaysia Melaka
building UTEM Library
collection Institutional Repository
continent Asia
country Malaysia
content_provider Universiti Teknikal Malaysia Melaka
content_source UTEM Institutional Repository
url_provider http://eprints.utem.edu.my/
language English
topic T Technology (General)
TK Electrical engineering. Electronics Nuclear engineering
spellingShingle T Technology (General)
TK Electrical engineering. Electronics Nuclear engineering
Hanaffi, Farhan
Grounding Grid Design For High Voltage Substation : An Assessment Of Effectiveness For Lightning Current
description An electrical grounding system is an important element to ascertain a safe environment for both humans and equipment during fault or transient conditions. The performance of grounding systems under lightning current is quite different from the conventional frequency based power. In order to understand the grounding grid behaviour under lightning current, researchers typically carry out experiments on actual grounding systems or on laboratory scaled models. Although experiments can provide insights of the actual grounding operation, the shortcoming is that a large area of lab space is required which reflects into high costs. As an alternative, computer simulation has been introduced, and can be categorised into three different approaches, namely circuit approach, transmission line approach or electromagnetic approach. In this work, the simulations are performed based on the electromagnetic approach under three dimensions (3D) mode due to its accurate results. For further understanding, a comparison between circuit and electromagnetic approaches is also carried out, where the resulting outcome shows that the circuit approach underestimates the impulse impedance at injection point compared with simulations by the electromagnetic approach. When the electromagnetic approach is applied, a finite element method is used to solve the partial differential electromagnetic equations in the time domain. Thereafter, the simulations results are validated with the existing published results covering the electromagnetic simulations by using the method of moment (MOM), and as well as actual field experiments. In addition, simulations are performed to understand the effect of different parameters, including lightning current, soil parameters, grounding design, and location of injection point of lightning current. Moreover, a comparison study is carried out for potential rise between power frequency and impulse current at different grid sizes. The study shows the potential generated at injection point for both current and saturation point when the grid size reaches a certain point. It’s important to consider both types of current to get better grounding grid design. Besides that, empirical equations are used out to calculate the effective area under lightning conditions, where the effect of the down-conductor is taken into consideration as part of the grounding model. The effective area is an important parameter for the optimization of the grounding grid design when increasing grounding size does not improve the impulse impedance. Transient ground potential rise (TGPR) above the ground is another interesting parameter to analyse. In this work, a good correlation is shown between the effective area and the impulse impedance at the injection point with rising transient ground potential. It is found that the TGPR is larger when it is closer to the injection point, but only lasts for a few microseconds. Step voltage evaluations are performed for different standing positions of the human above the grid, including the distance of the step voltage location from the injection point, and the effect of grid size to step voltage value.
format Thesis
author Hanaffi, Farhan
author_facet Hanaffi, Farhan
author_sort Hanaffi, Farhan
title Grounding Grid Design For High Voltage Substation : An Assessment Of Effectiveness For Lightning Current
title_short Grounding Grid Design For High Voltage Substation : An Assessment Of Effectiveness For Lightning Current
title_full Grounding Grid Design For High Voltage Substation : An Assessment Of Effectiveness For Lightning Current
title_fullStr Grounding Grid Design For High Voltage Substation : An Assessment Of Effectiveness For Lightning Current
title_full_unstemmed Grounding Grid Design For High Voltage Substation : An Assessment Of Effectiveness For Lightning Current
title_sort grounding grid design for high voltage substation : an assessment of effectiveness for lightning current
publisher UTeM
publishDate 2016
url http://eprints.utem.edu.my/id/eprint/18860/1/Grounding%20Grid%20Design%20For%20High%20Voltage%20Substation%20%20An%20Assessment%20Of%20Effectiveness%20For%20Lightning%20Current%2024%20Pages.pdf
http://eprints.utem.edu.my/id/eprint/18860/
http://library.utem.edu.my:8000/elmu/index.jsp?module=webopac-d&action=fullDisplayRetriever.jsp&szMaterialNo=0000102313
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