This document discusses modeling ferroresonance on voltage transformers (VTs) in a 400kV gas insulated substation (GIS) in Iran. Ferroresonance can cause overheating, damage, and failure of VTs. The document analyzes the specific case of a GIS substation in Karoon 4 power plant. Simulation results using EMTP-RV software show ferroresonance occurring on VTs for different system configurations. A damping circuit consisting of a ferroresonance detecting and suppression device (FDSD) and damping reactor (ZD) is designed and shown to successfully eliminate ferroresonance oscillations when added to the model. The study aims to understand and mitigate the risks of ferroresonance in GIS sub
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The high level electric field intensity produced by high voltage (HV) equipments inside 500/220 kV substations is harmful for the human (staff) health. Therefore the minimum health and safety requirements regarding the exposure of workers to the risk arising from electric fields produced inside these substations is still considered as a competitive topic for utility designers, world health organization (WHO) and biomedical field researchers. It is very important to have knowledge about levels distribution of electric field intensity within these high voltage substations as early stage in the process of substation design. This paper presents results of investigation 50Hz electric field intensity distribution inside 500/220 kV power transmission substations in Cairo, Egypt. This paper presents a method for assessment the distribution of 50HZ electric field intensity distribution inside this substation, this method of analysis is based on the charge simulation technique (CSM). This study will serve for planning service works or for inspection of equipment on HV power transmission substations.
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This study depicts the electric field distributions inside a typical 500/220 kV open distribution substation under actual loading conditions and during different working conditions, Hot-Stick position and Bar-Hand position. The electric field is investigated for different workers heights of 1m, 1.5m and 1.8m above ground during normal working condition (Hot-Stick position) inside this substation. This in addition to assessment of the electric field at a height levels of 8m, 11m, 14m and 17m above ground as positions for live line maintenance under 220 kV Busbars, 500 kV Busbars, 220 kV Incoming and Outgoing feeders and 500 kV Incoming and Outgoing feeders respectively. In this study the simulation results of the electric field obtained using three dimensional (3D) computer model for existing typical high voltage transformation substation are compared with field values measured inside this typical substation and presented and discussed not only in the form of contour maps but also in the form 3D surface and wireframe maps. The simulation results are good matched and agreed with measured values. This in addition to the electric field will be tabulated and compared to international guidelines for personnel exposure to electric field. This study will serve for planning service works or for inspection of equipment inside high voltage (HV) power transformation substations.
Analysis and Modeling of Transformerless Photovoltaic Inverter SystemsIJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
Various techniques and principles of MV system neutral groundings summed up together-May be interesting and useful for practicing Electrtical engineers
Assessment of Electric Field Distribution Inside 500/220 kV Open Distribution...IJAPEJOURNAL
The high level electric field intensity produced by high voltage (HV) equipments inside 500/220 kV substations is harmful for the human (staff) health. Therefore the minimum health and safety requirements regarding the exposure of workers to the risk arising from electric fields produced inside these substations is still considered as a competitive topic for utility designers, world health organization (WHO) and biomedical field researchers. It is very important to have knowledge about levels distribution of electric field intensity within these high voltage substations as early stage in the process of substation design. This paper presents results of investigation 50Hz electric field intensity distribution inside 500/220 kV power transmission substations in Cairo, Egypt. This paper presents a method for assessment the distribution of 50HZ electric field intensity distribution inside this substation, this method of analysis is based on the charge simulation technique (CSM). This study will serve for planning service works or for inspection of equipment on HV power transmission substations.
Investigation of Electric Field Distribution Inside 500/220 kV Transformation...IJAPEJOURNAL
This study depicts the electric field distributions inside a typical 500/220 kV open distribution substation under actual loading conditions and during different working conditions, Hot-Stick position and Bar-Hand position. The electric field is investigated for different workers heights of 1m, 1.5m and 1.8m above ground during normal working condition (Hot-Stick position) inside this substation. This in addition to assessment of the electric field at a height levels of 8m, 11m, 14m and 17m above ground as positions for live line maintenance under 220 kV Busbars, 500 kV Busbars, 220 kV Incoming and Outgoing feeders and 500 kV Incoming and Outgoing feeders respectively. In this study the simulation results of the electric field obtained using three dimensional (3D) computer model for existing typical high voltage transformation substation are compared with field values measured inside this typical substation and presented and discussed not only in the form of contour maps but also in the form 3D surface and wireframe maps. The simulation results are good matched and agreed with measured values. This in addition to the electric field will be tabulated and compared to international guidelines for personnel exposure to electric field. This study will serve for planning service works or for inspection of equipment inside high voltage (HV) power transformation substations.
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International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
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The performance of Earthing grid system is very important to ensure the human and protective devices in safe environment. Actual
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greatly influence on actual step and mesh voltage of substation grounding system. Ground potential rise also mainly depends on the length and
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devices the streamlined technology for high-frequency and high-power applications for next-generation
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Mr. Veerabrahmam from PRDC has spoken about the transformers failures and few of the case studies. Few failures and reasons for failures are also discussed.
Performance Analysis of Actual Step and Mesh Voltage of Substation Grounding ...Editor IJCATR
The performance of Earthing grid system is very important to ensure the human and protective devices in safe environment. Actual
Step and Mesh voltage of a substation must keep under the maximum allowable limits under fault condition. Ground potential rise, GPR is
greatly influence on actual step and mesh voltage of substation grounding system. Ground potential rise also mainly depends on the length and
numbers of ground rods and grid spacing. This paper presents performance analysis of actual step and mesh voltages of a substation grounding
system under the variance of length and number of ground rods. The performance result is also carried out by using current injection method and
with the help of MULTISIM simulation software.
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saturation electron drift velocity [1–3]. Such excellent material properties have made AlGaN/GaN
devices the streamlined technology for high-frequency and high-power applications for next-generation
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IOSR Journal of Applied Chemistry (IOSR-JAC) is an open access international journal that provides rapid publication (within a month) of articles in all areas of applied chemistry and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Chemical Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
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Design and Simulation of Permanent Magnet Linear Generator for Wave Energy Po...ijtsrd
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The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Harmonic Mitigation in Distribution System by using Passive Filtersijtsrd
The advent of power electronics and computerized equipment in recent decades has brought enhanced efficiency and improved system but at the same time also created harmonics and waveform distortion to the power system network. Due to the growing use of nonlinear load equipment and new technologies in buildings, harmonic currents and voltages generated in distribution systems pose a new problem for electrical engineers. This is a serious problem when power quality is a prime concern. Harmonics are the main types of power quality problem that are very common to the power system containing electric arc furnace EAF . Electric arc furnace EAFs are widely used in steelmaking and in melting of nonferrous metals. In this paper, EAF is presented guide lines for the accurate evaluation of harmonics generated in No. 3 Steel Mill, Ywama, Yangon. Passive filters have been most commonly used to limit the flow of harmonic currents in distribution systems. Their performance is limited to a few harmonics, and they can introduce resonance in the power system. Nyein Nyein Chan | Hnin Wai Hlaing "Harmonic Mitigation in Distribution System by using Passive Filters" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-1 , December 2018, URL: http://www.ijtsrd.com/papers/ijtsrd19027.pdf
http://www.ijtsrd.com/engineering/electrical-engineering/19027/harmonic-mitigation-in-distribution-system-by-using-passive-filters/nyein-nyein-chan
Voltage Profile Improvement using Switched Capacitors: Case of Single Wire Ea...IJMERJOURNAL
ABSTRACT: Most rural areas in Africa are characterized by scattered villages with a very low demand in electricity. Due to improper planning and lack of knowledge on low cost technologies, the cost of extending the grid to supply these area is very high relative to the returns. Rural electrification by means of extending the main grid and distributing power using a single wire with earth return (SWER) has shown to be the least expensive rural electrification method in remote area where loads are light and scattered.This paper presents a developed model of Single wire earth return distribution network and a voltage profile of the network using backward and forward sweep method load flow algorithm. And finally presents the analysis of the effect of shunt capacitors on the voltage profile of the network using Maximum power saving method for the sizing and placement of the capacitor.
Wind parks are made up of a large number of
saturable inductances (power transformers, inductive voltage
transformers (IVTs)), as well as capacitors (cables, wind turbine
harmonic filters, capacitor voltage transformers (CVTs), voltage
grading capacitors in circuit-breakers). Therefore, they may
present scenarios in which ferroresonance occurs. This paper
presents the scenarios that can lead to ferroresonant circuits in
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Transients Caused by Switching of 420 kV Three-Phase Variable Shunt ReactorBérengère VIGNAUX
This paper describes transients caused by uncontrolled and controlled switching of three-phase 420 kV variable shunt reactor (VSR).
Inrush currents due to VSR energization and overvoltages due to de-energization were determined at tap positions corresponding to lowest 80 MVAr and highest 150 MVAr reactive power. Based on the calculation results, mitigation measures and operating switching strategy of VSR were proposed.
A Study of Thermal Behaviour of HTS Devices at Alternating Current IJECEIAES
The paper presents a study on thermal behavior of a coil made of a hightemperature supercon-ducting tape representing operation of a superconducting device (for example, a transformer). Based on the results of a physical experiment, a mathematical model of superconducting coil operation under short circuit conditions at the load side was developed. Regimes of overheating by variable short circuit currents were investigated. In this case, short circuit current amplitudes ex-ceeded a critical current of a superconductor, and coil parameters (e.g. an average nonlinearity parameter of a current-voltage characteristic, a superconductor length, and others) were varied. Permissible overheating for a coil with the possibility of its return into the superconducting state after emergency conditions in a dead-time period of automatic reclosing was considered. A crite-rion for return of a superconducting device into the superconducting state within a dead-time period of automatic reclosing has been obtained.
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The transformers are an integral part of the power system. In transformers, the main consequence of harmonic
currents is an increase in losses, mainly in windings, because of the deformation of the leakage fields. Higher losses mean that
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Modeling of Ferro-resonance on the VT of GIS substation
1. IOSR Journal of Electrical and Electronics Engineering (IOSR-JEEE)
e-ISSN: 2278-1676,p-ISSN: 2320-3331, Volume 6, Issue 5 (Jul. - Aug. 2013), PP 68-73
www.iosrjournals.org
www.iosrjournals.org 68 | Page
Modeling of Ferro-resonance on the VT of GIS substation
S.M.Hassan.Hosseini1
, Y. Toghani Holari2
, S.M.Hosseini.Bafghi3
1, 2, 3
(Department of Electrical Engineering, Islamic Azad University South Tehran Branch, Tehran, IRAN)
Abstract : The main subject of the essay is study of ferroresonance in the voltage transformers at 400kV GIS
substation. Ferroresonance has destructive effects such as, undulations of high voltages, warming of
transformers, increasing of heat, temperature increasing and damaging voltage transformers, high noise due to
evolution due to magnet and bad working of protective instruments. So we have to apply limitations on system
parameters to avoid such an undesirable phenomenon like this. In this paper ferroresonance phenomenon on
VTs of real GIS substation (karon 4 power plant had been studied. With regarding high risk of ferroresonance
due to studied substation conditions, damping circuit (FDSD, ZD) had been designed with help of EMTP-RV
and the results are presented in two conditions of being without damping and by using of damping in the circuit.
The results show damping circuit is successful in obviation of these dangerous oscillations.
Keywords: Gas Insulated Substation (GIS), Voltage Transformers (VT), Ferroresonance, FDSD, ZD
I. INTRODUCTION
Regarding to the advantages of GIS substations in comparison with AIS (Air Insulated Substation) and
purposing that instruments such as current and voltage transformer , bypass disconnector switch, high voltage
conductor , grounding switchgear, breaker and etc. that are kept in boxes under pressure of SF6 gas , and
increasing usage of these substations toward the past and regarding to this point that urban and industries areas
with increasing load and insufficient area and needing high voltages are regarded , in last year's the use of GIS
substation have increased.[1]. In this paper we study the Karoon 4 power plant GIS substation that is a 400kV
substation with double bus bar and disconnector switch, this substation is fed by 4 single phase 100MW
transformers. The outputs of these transformers are connected to the 400kV network with 4 air lines. Despite the
advantages of this gas insulated substations, it has fundamental problems. One of the main ingredients of
destruction of the instruments in GIS substations is ferroresonance that influenced the insulation of network at
different point. Ferroresonance is one of the rare and destructive phenomena in power network that figured as a
nonlinear resonance that happen between the capacitor of the network and the nonlinear inductance of voltage
transformer at the saturation instant. The word of ferroresonance, that arrived to the books and papers from the
end of the second decade of 20th century , use for all the oscillation phenomena in electrical circuits that consist
of at least nonlinear self , capacitor , voltage source (generally sinusoidal). The effective elements in causing
resonance and ferroresonance in power systems are, harmonic, core saturating, changing inductance of wiring,
cutting of 1 or 2 phases of system, unsymmetrical load, inappropriate use of circuit breakers and fuses, using
cables with high capacitance. Ferroresonance has other destructive effects such as oscillation of high voltages,
intricacy in wave forms of voltage and current , warming of transformers , damaging voltage transformers (VT),
for example in Karoon 4 power plant 400kV GIS substation , loud noise due of evolution due to magnet ,
malfunction protective instruments. Numerous cases of ferroresonance in power system have been reported in
years. In last year's the number of ferroresonance because of the intricacy of system and operating modern
instrument has increased. [2], [3] outbreak of ferroresonanc has some signs like permanent over voltage with
vast amplitude as phase to phase or phase to ground, permanent over current with vast amplitude, shifting
voltage zero point, increasing temperature of voltage transformer, continual increasing of the noise altitude of
transformers and reactors, damaging electrical equipment's such as capacitor banks and CVT because of
increasing the thermal effect or breakage of dampers of the protective equipment's. Therefore some limitations
should be applied to parameters of systems to avoid occurrence of undesirable phenomena like these. [4], [5].
All of the studies have been simulated by EMTP-RV software.
II. Parallel Capacitor In H.V Circuit Breaker
Power capacitors have different usage in structure and mechanism of power circuit breaker especially
at high voltage levels. Like grading capacitors that have two breaking boxes in series. Voltage usually doesn’t
distribute equally on breaking boxes. To avoid making stress of high voltage and smoothing voltage on them,
capacitors parallel with contacts of circuit breaker that usually have capacity between 900 to 1600 pF for each
breaking box are used. Although by the development of technology usage of these capacitors have been reduced
but they are used in high voltages yet.[3],[6]. Some defects of these capacitors are increasing the risk of
2. Modeling of Ferro-resonance on the VT of GIS substation
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ferroresonance with nearby voltage transformers, increasing the weight, complexity of installation operation and
increasing leakage current.
III. Karoon 4 Case Study
The purpose of this paper is to study the ferroresonance on voltage transformers (VT) in Karoon 4
power plant GIS 400kv substation as an example of GIS substation with bus bar and long line that have been
effected by this phenomenon by increasing the voltage and damaging isolation and heating, destruction and
damaging of VT . These simulations are done by EMTP-RV Software and finally propose the practical method
to resist it. There conductive wires of A & C phase of damping reactor have been burnt by the high current at
secondary circuit because of the single phase with VT ferroresonance. One of the reasons of this phenomenon is
that the VT Company adequately doesn’t consider the capacity of the damping reactor to absorb the resonance
energy in VT in some cases of GIS switching conditions during first energizing at site. [7] Special
recommendation presented in this paper offer to avoiding over heating Beside VT of BUS 1 and 2 and damping
reactor until additional FDSD (Ferroresonance Detecting and Suppression Device) at site became adjusted. The
related circuit breaker (CB) for each 400kV GIS bay should be closed about 5 minutes after closing of both DS's
(disconnecting switches) during energization. Reversely, during power Outage one of both DS's should be
opened within 5 minutes after opening of the circuit breaker [3], [8]. On 19 & 24 November in 2010, VT of #1
bus was exposed to ferro-resonance 2 times during energizing (10min.) & de-energizing (2min.) by switching of
CB & DS of C03 bay that is shown is shown in Figure 1.
Fig1. Karoon4 400kV substation single line diagram state of energizing from first circuit output line of Karon3
and bus 1 and corresponding VT
On 20 & 21 November in 2010, VT of #2 bus were exposed to ferroresonance 2 times during
energizing (5min.) and de-energizing (2min.) by switching of CB & DS of C04 bay through #2 bus bar.
Fig2. Karoon4 400kV substation single line diagram state of energizing from second circuit output line of
Karoon3 and bus 2 and corresponding VT
3. Modeling of Ferro-resonance on the VT of GIS substation
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Fig3.Burnt Damping Reactor (ZD) of A-phase for #2 Bus VT
IV. Ferroresonance Detection Supervision Devise (Fdsd)
By regarding presented figures of this part such as fig 4 , a VT with conversion rate of 400/ to
110/ connected to a ferroresonace detector circuit is shown .[2].
Fig4. Information for adjusting FDSD
In continue internal circuit of detecting unit is connected to burden with value of 0.33 that is equivalent
of parallel branches. and also in figures 5 and 6, appearance of a FDSD and different part of operating lamp
A,B , Power Lamp , sensitivity Change , Test Switch , Optional Output Control in three phase and single phase
detector unit is shown.
Fig5 .picture of seeming figure of FDSD
4. Modeling of Ferro-resonance on the VT of GIS substation
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Fig6. Diagram of three phase FDSD connection
V. Ferroresonance Analysis With Fdsd+Zd
The conditions of standard analysis that can be used in done simulation are as below:
1. CB Capacitance=4,000pF/phase,
2. Unit Earth Capacitance for GIS=52.4pF/m
3. Internal Earth Capacitance of M.Tr: 13,366pF/phase
4. Internal Earth Capacitance of in Shunt Reactor: 3,382pf/phase
In above analysis, karoon 4 power plant GIS substation, that is a 400kV substation with double bus bar with
bypass disconnector switch, is studied and equivalent circuit of GIS substation, that consist of main parameters
like, source and resistance series with it, and CB that capacitor C1 is parallel with it, and as explained at section
3 above GIS circuit breaker had two 2000pF capacitor parallel with contacts of circuit breaker and equivalent
capacitance is 4000pf. The simulation is done on the basis of these values. Above simulated circuit consist of
equivalent capacitor of GIS substation in different studied conditions that are as a result of summation of
existing parameters which is studied in bellow waveforms. Also in this circuit, one VT with prime voltage of
400kV and secondary voltage of 105V is used for simulation and at last ZD and FDSD equivalent circuit for
damping probability of ferroresonance due to 4000pf capacitor parallel with CB are put .[7],[9].
Fig7-a- EMTP model for survey ferroresonance with FDSD+ZD
if C1=4000 pF and C2=3820pF (for VT of bus 1)
Which capacitor (C2= (53.2+5.6+5.6+2+6.5)*52.4=3820).
0 0.5 1 1.5 2 2.5
-300
-200
-100
0
100
200
300
t (ms)
voltagev1(v)
Fig7-b- voltage waveform of VT secondary voltage in damping ferroresonance (V1)
5. Modeling of Ferro-resonance on the VT of GIS substation
www.iosrjournals.org 72 | Page
0 0.5 1 1.5 2 2.5
-4
-2
0
2
4
x 10
5
t (ms)
voltage(v)
Fig7-c- voltage waveform of VT primary
0 0.5 1 1.5 2 2.5
-100
-50
0
50
100
t (ms)
current(i)
Fig7-d- current waveform of VT primary
if C1=4000 pf and C2= 7669pf ( for VT bus )
Which capacitor (C2= (53.2+5.6+7.05+7.2*9+2+7.2+6.5)*52.4 =7669)
0 0.5 1 1.5 2 2.5
-800
-600
-400
-200
0
200
400
600
800
t (ms)
voltagev1(v)
Fig8-a- VT secondary voltage waveform in presence of ferroresonance (V1)
0 0.5 1 1.5 2 2.5
-500
-400
-300
-200
-100
0
100
200
300
400
500
t (ms)
voltagev2(v)
Fig8-b- VT secondary voltage waveform in presence of ferroresonance (V2)
0 0.5 1 1.5 2 2.5
-4
-2
0
2
4
x 10
5
t (ms)
voltage(v)
Fig8-c- used voltage source waveform in simulated diagram with EMTP