Title
Poboljšani metodi za merenje sigurnosnih karakteristika sistema uzemljenja u visokonaponskim postrojenjima
Creator
Kostić, Vojin I. 1977-
Copyright date
2016
Object Links
Select license
Autorstvo-Nekomercijalno-Bez prerade 3.0 Srbija (CC BY-NC-ND 3.0)
License description
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Language
Serbian
Cobiss-ID
Theses Type
Doktorska disertacija
description
Datum odbrane: 02.12.2016.
Other responsibilities
mentor
Raičević, Nebojša B. 1965-
član komisije
Aleksić, Slavoljub R.
član komisije
Cvetković, Nenad N. 1970-
član komisije
Janjić, Aleksandar D. 1966-
član komisije
Kovačević, Dragan S.
Academic Expertise
Tehničko-tehnološke nauke
University
Univerzitet u Nišu
Faculty
Elektronski fakultet
Group
Katedra za energetiku
Alternative title
Improved methods for measuring safety performance metrics of the grounding system in high-voltage facilities
Publisher
[V. I. Kostić]
Format
XXII, 154 listova
description
Grounding systems
Abstract (en)
The grounding system has an important role to maintain safe and reliable operation of highvoltage
(HV) power facility (usually substation). The main task of a grounding system is to
discharge maximum ground fault current expected into the soil, without exceeding safety
limits for touch and step voltages within the substation and the surrounding area.
It is desirable that the substation grounding provides a near zero resistance to remote earth.
The prevailing practice is to install a grounding grid of horizontal ground electrodes (buried
bare copper conductors) supplemented by a number of vertical ground rods connected to the
grid, and by a number of equipment grounding mats and interconnecting cables. The
grounding grid provides a common ground for the electrical equipment and for all metallic
structures at the substation. It also limits the surface potential gradient. Grounding is
traditionally modeled as a pure resistance. This is a good approximation at low frequencies,
but as the frequency gets higher, inductance starts to play an important role.
National and international standards give detailed guidelines for grounding system design, as
well as for testing, under power frequency conditions, but only limited recommendations for
high frequency and transient conditions are available.
The main performance metrics of the grounding system are: grounding grid integrity,
grounding system impedance, and touch and step voltage.
The performance metrics should be periodically tested. The goal is to perform the test when
the substation is in-service (to avoid interruption of service and costly downtime). Due to
conductive interference in the grounding system (usually several amperes, up to about 15 A),
caused by power frequency, its harmonics and background noise, the active HV substation is
an extremely challenging environment for the measurement on grounding system. This is
further compounded by the impact of very low impedance of the grounding system (typically
less than 0.5 Ω).
Essential data to calculate safety risks in advance is often not available. Measurements are
therefore an essential supplement to the theory. Unlike the theoretical approaches, empirical
approaches are not widely available in the literature due to the arduous work involved, the
difficulty to obtain permissions, and safety restrictions.
There is a continual interest in scientific community and standardization bodies to improve
the measurement of performance metrics of the grounding system. The drawbacks of actual
measurement methods are related to less or more subjectivity and requirements for high level
of test current (up to 100 A AC and up to 300 A DC). In this thesis, in order to avoid
mentioning drawbacks, we elaborated and experimentally verified the efficient methods.
The overall contribution of this thesis is the substantial enhancement of the grounding system
measurement by eliminating the current restrictions found in the IEEE standards 80 and 81,
respectively.
The original works, that constitute the core of this thesis, have been published in referring
publications.
This thesis is divided into three parts. Part I includes Chapters 2 and 3. Part II includes
Chapters 4 to 7. Part III contains Chapter 8.
Part I gives an extensive review of published literature related to the analytical and simulation
investigations of earth electrode systems. Part I also analyzes the existing methods for
measurement performance metrics of the grounding system. Critical review of the constraints
inherent in existing methods was given.
Part II includes original contributions of the thesis: new method for measurement of
grounding grid integrity (Ch.4); an effective method (so called FSM) for eliminating the
effect of conductive interference at power frequency (Ch. 5); new method for grounding
system impedance measurement (so called FOP-FSM) (Ch.6); new method for measurement
of touch and step voltage (so called FEM-FSM) (Ch.7). Our experiment-driven verification
approach of the proposed measurement methods is based on totally 49 power facilities
(voltage range: 110 kV, 220 kV and 400 kV) in Serbia.
Part III gives an extensive review of thesis results. Part III also proposes and elaborates
directions for further automation of the proposed measurement methods.
Authors Key words
uzemljenje, sistem uzemljenja, sistemska smetnja, merenje na sistemu
uzemljenja, kontinuitet sistema uzemljenja, impedansa sistema uzemljenja, napon dodira, napon koraka
Authors Key words
grounding, grounding system, power frequency interference, grounding system
measurement, grounding grid integrity, grounding system impedance, touch voltage, step
voltage
Classification
621.316.99:621.37(043.3)
Subject
T 190
Type
Elektronska teza
Abstract (en)
The grounding system has an important role to maintain safe and reliable operation of highvoltage
(HV) power facility (usually substation). The main task of a grounding system is to
discharge maximum ground fault current expected into the soil, without exceeding safety
limits for touch and step voltages within the substation and the surrounding area.
It is desirable that the substation grounding provides a near zero resistance to remote earth.
The prevailing practice is to install a grounding grid of horizontal ground electrodes (buried
bare copper conductors) supplemented by a number of vertical ground rods connected to the
grid, and by a number of equipment grounding mats and interconnecting cables. The
grounding grid provides a common ground for the electrical equipment and for all metallic
structures at the substation. It also limits the surface potential gradient. Grounding is
traditionally modeled as a pure resistance. This is a good approximation at low frequencies,
but as the frequency gets higher, inductance starts to play an important role.
National and international standards give detailed guidelines for grounding system design, as
well as for testing, under power frequency conditions, but only limited recommendations for
high frequency and transient conditions are available.
The main performance metrics of the grounding system are: grounding grid integrity,
grounding system impedance, and touch and step voltage.
The performance metrics should be periodically tested. The goal is to perform the test when
the substation is in-service (to avoid interruption of service and costly downtime). Due to
conductive interference in the grounding system (usually several amperes, up to about 15 A),
caused by power frequency, its harmonics and background noise, the active HV substation is
an extremely challenging environment for the measurement on grounding system. This is
further compounded by the impact of very low impedance of the grounding system (typically
less than 0.5 Ω).
Essential data to calculate safety risks in advance is often not available. Measurements are
therefore an essential supplement to the theory. Unlike the theoretical approaches, empirical
approaches are not widely available in the literature due to the arduous work involved, the
difficulty to obtain permissions, and safety restrictions.
There is a continual interest in scientific community and standardization bodies to improve
the measurement of performance metrics of the grounding system. The drawbacks of actual
measurement methods are related to less or more subjectivity and requirements for high level
of test current (up to 100 A AC and up to 300 A DC). In this thesis, in order to avoid
mentioning drawbacks, we elaborated and experimentally verified the efficient methods.
The overall contribution of this thesis is the substantial enhancement of the grounding system
measurement by eliminating the current restrictions found in the IEEE standards 80 and 81,
respectively.
The original works, that constitute the core of this thesis, have been published in referring
publications.
This thesis is divided into three parts. Part I includes Chapters 2 and 3. Part II includes
Chapters 4 to 7. Part III contains Chapter 8.
Part I gives an extensive review of published literature related to the analytical and simulation
investigations of earth electrode systems. Part I also analyzes the existing methods for
measurement performance metrics of the grounding system. Critical review of the constraints
inherent in existing methods was given.
Part II includes original contributions of the thesis: new method for measurement of
grounding grid integrity (Ch.4); an effective method (so called FSM) for eliminating the
effect of conductive interference at power frequency (Ch. 5); new method for grounding
system impedance measurement (so called FOP-FSM) (Ch.6); new method for measurement
of touch and step voltage (so called FEM-FSM) (Ch.7). Our experiment-driven verification
approach of the proposed measurement methods is based on totally 49 power facilities
(voltage range: 110 kV, 220 kV and 400 kV) in Serbia.
Part III gives an extensive review of thesis results. Part III also proposes and elaborates
directions for further automation of the proposed measurement methods.
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