Abstract Due to the opening or closing of circuit breakers and disconnect switches in Gas Insulated Substations (GIS), Very Fast Transient Over-voltages (VFTO) are generated. This paper describes the 500 kV and 750 kV GIS of power system. The variations of VFTO magnitudes at different points in 500 kV and 750 kV GIS during different switching operations have been calculated and compared by using Matlab/Simulink. In this paper the effective factors on the level of VFTO is investigated and the beneficial approaches for the industry to finding the optimum approaches for VFT mitigation is presented. These factors are included residual charges, resistance, spark resistance and entrance capacitance of transformer. Index Terms: Gas Insulated Substation, Very Fast Transient Over voltages, Matlab/Simulink.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Modeling and test validation of a 15 kV - 24 MVA superconducting fault curren...Franco Moriconi
High-power short-circuit test results and numerical simulations of a 15kV–24MVA distribution-class High Temperature Superconductor (HTS) Fault Current Limiters (FCL) are presented and compared in this paper. The FCL design was based on the nonlinear inductance model here described, and the device was tested at 13.1kV line-to-line voltage for prospective fault currents up to 23kArms, prior to its installation in the electric grid. Comparison between numerical simulations and fault test measurements show good agreement. Some simulations and field testing results are depicted. The FCL was energized in the Southern California Edison grid on March 9, 2009.
Analysis of the Performance of Active Type SFCL and FCL for Reduction Capabil...IJSRD
The Active Superconducting Current Controller (ASCC) is a new type of Fault Current Limiters which can limit the fault current in different modes and also has the particular abilities of compensating active and reactive power for AC main circuit in the normal state. The use of the ASCC disturbs the operation of Over Current Relays (OCR) used in the distribution system. In consideration that applying superconducting fault current limiter (SFCL) may be a feasible solution, in this paper, the effects of a voltage compensation type active SFCL. The magnetic field in the air core can be controlled by PWM inverter output. Hence, the equivalent impedance can be maintained and overvoltage suppression is possible. The fault current and voltage suppression characteristics are simulated in mat lab. The simulation results show that the active SFCL and FCL can play an obvious role in restraining the fault current and overvoltage, and it can contribute to avoiding damage on the relevant distribution equipment and improve the systems safety and reliability.
A Fault Current Limiter Circuit to Improve Transient Stability in Power SystemIAES-IJPEDS
Short circuit current limitation in distribution system utilities can be an operational approach to improve power quality, since the estimated voltage sag amplitude during faults may be intensely reduced. The application of superconducting fault current limiter (SFCL) is projected here to limit the fault current that occurs in power system. SFCL utilizes superconductors to instantaneously decrease the unanticipated electrical surges that happen on utility distribution and power transmission networks. SFCL considerably decrease the economic burden on the utilities by reducing the wear on circuit breakers and protecting other expensive equipment. The designed SFCL model is used for determining an impedance level of SFCL according to the fault current limitation necessities of different types of the smart grid system. The representation of this paper about to see the optimum resistive value of SFCL for enhancing the transient stability of a power system. The assessment of optimal resistive value of the SFCL connected in series in a transmission line with a conductor throughout a short circuit fault is consistently determined by applying the equal-area criterion supported by power-angle curves. A Simulink based primary model is developed and additionally the simulation results for the projected model are achieved by using MATLAB.
Suppression methods for very fast transient over voltages on equipment of giseSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
POWER SYSTEM PLANNING AND DESIGN. DESIGN OF EHV TRANSMISSION LINES & BUNDLED ...Jobin Abraham
This document discusses the design of extra high voltage transmission lines and bundled conductors in EHV lines. It outlines the advantages of EHV lines such as reduced transmission losses and material requirements. However, it also notes disadvantages like increased corona losses and insulation needs. Key design considerations for EHV lines include the choice of operating voltage, grounding method, conductor selection, and insulator selection. For lines above 400kV, bundled conductors are used and the document discusses formulas for calculating the inductance, capacitance, surge impedance, and surge impedance loading to determine bundling requirements.
Analysis and Design of CMOS Source Followers and Super Source FollowerIDES Editor
The source follower circuit is used as a voltage
buffer and level shifter. It is more flexible level shifter as the
dc value of voltage level can be adjusted by changing aspect
ratio of MOSFETs. It is desired to have low output resistance
for such applications. Source follower can give minimum
output resistance 1/(gm+gmb) with load resistance and channel
resistance tending to infinity. The super source follower is a
circuit formed using negative feedback through another
MOSFET. This offers even reduced output resistance but with
reduced voltage gain as that of source follower.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Modeling and test validation of a 15 kV - 24 MVA superconducting fault curren...Franco Moriconi
High-power short-circuit test results and numerical simulations of a 15kV–24MVA distribution-class High Temperature Superconductor (HTS) Fault Current Limiters (FCL) are presented and compared in this paper. The FCL design was based on the nonlinear inductance model here described, and the device was tested at 13.1kV line-to-line voltage for prospective fault currents up to 23kArms, prior to its installation in the electric grid. Comparison between numerical simulations and fault test measurements show good agreement. Some simulations and field testing results are depicted. The FCL was energized in the Southern California Edison grid on March 9, 2009.
Analysis of the Performance of Active Type SFCL and FCL for Reduction Capabil...IJSRD
The Active Superconducting Current Controller (ASCC) is a new type of Fault Current Limiters which can limit the fault current in different modes and also has the particular abilities of compensating active and reactive power for AC main circuit in the normal state. The use of the ASCC disturbs the operation of Over Current Relays (OCR) used in the distribution system. In consideration that applying superconducting fault current limiter (SFCL) may be a feasible solution, in this paper, the effects of a voltage compensation type active SFCL. The magnetic field in the air core can be controlled by PWM inverter output. Hence, the equivalent impedance can be maintained and overvoltage suppression is possible. The fault current and voltage suppression characteristics are simulated in mat lab. The simulation results show that the active SFCL and FCL can play an obvious role in restraining the fault current and overvoltage, and it can contribute to avoiding damage on the relevant distribution equipment and improve the systems safety and reliability.
A Fault Current Limiter Circuit to Improve Transient Stability in Power SystemIAES-IJPEDS
Short circuit current limitation in distribution system utilities can be an operational approach to improve power quality, since the estimated voltage sag amplitude during faults may be intensely reduced. The application of superconducting fault current limiter (SFCL) is projected here to limit the fault current that occurs in power system. SFCL utilizes superconductors to instantaneously decrease the unanticipated electrical surges that happen on utility distribution and power transmission networks. SFCL considerably decrease the economic burden on the utilities by reducing the wear on circuit breakers and protecting other expensive equipment. The designed SFCL model is used for determining an impedance level of SFCL according to the fault current limitation necessities of different types of the smart grid system. The representation of this paper about to see the optimum resistive value of SFCL for enhancing the transient stability of a power system. The assessment of optimal resistive value of the SFCL connected in series in a transmission line with a conductor throughout a short circuit fault is consistently determined by applying the equal-area criterion supported by power-angle curves. A Simulink based primary model is developed and additionally the simulation results for the projected model are achieved by using MATLAB.
Suppression methods for very fast transient over voltages on equipment of giseSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
POWER SYSTEM PLANNING AND DESIGN. DESIGN OF EHV TRANSMISSION LINES & BUNDLED ...Jobin Abraham
This document discusses the design of extra high voltage transmission lines and bundled conductors in EHV lines. It outlines the advantages of EHV lines such as reduced transmission losses and material requirements. However, it also notes disadvantages like increased corona losses and insulation needs. Key design considerations for EHV lines include the choice of operating voltage, grounding method, conductor selection, and insulator selection. For lines above 400kV, bundled conductors are used and the document discusses formulas for calculating the inductance, capacitance, surge impedance, and surge impedance loading to determine bundling requirements.
Analysis and Design of CMOS Source Followers and Super Source FollowerIDES Editor
The source follower circuit is used as a voltage
buffer and level shifter. It is more flexible level shifter as the
dc value of voltage level can be adjusted by changing aspect
ratio of MOSFETs. It is desired to have low output resistance
for such applications. Source follower can give minimum
output resistance 1/(gm+gmb) with load resistance and channel
resistance tending to infinity. The super source follower is a
circuit formed using negative feedback through another
MOSFET. This offers even reduced output resistance but with
reduced voltage gain as that of source follower.
This paper addresses the approach to improve the efficiency of the quasi Z-source inverter. In order to increase the efficiency the reduction of conduction losses is one way to approach. Sequentially to decrease the conduction losses in the quasi z-source inverter the replacement of diode is replacing with switches is proposed which is also called as synchronous rectification. The paper represents basics of the approach, analysis and comparison of the power losses of the traditional and proposed designs of the grid connected PV-system with quasi z-source inverter system. The proposed approach validated on the computer simulations in the MATLAB environment.
Iaetsd placement of super conducting fault current limiters to mitigateIaetsd Iaetsd
This document discusses the use of superconducting fault current limiters (SFCLs) to mitigate fault currents in smart grids with different types of distributed generation sources like wind farms, solar panels, and diesel generators. The author models an SFCL and a smart grid system in MATLAB/Simulink. Simulation results show that locating an SFCL at the point where distributed generation connects to the grid (Location 3) provides the best performance, reducing fault currents from all distributed generation sources by 68-84% while also limiting fault current from the main grid. In contrast, placing SFCLs upstream in the distribution system can unexpectedly increase fault currents from some distributed generators.
Impact of Thyristor Controlled Series Capacitor Insertion on Short-circuit Ca...IJAPEJOURNAL
This research paper presents a study on phase to earth fault short-circuit calculation with fault resistance on a single transmission line 400 kV in eastern Algerian transmission networks at Algerian Company of Electricity and Gas (Sonelgaz Group) compensated by series Flexible AC Transmission System (FACTS) i.e. Thyristor Controlled Series Capacitor (TCSC) installed in midline. The facts are used for controlling transmission voltage, power flow, reactive power, and damping of power system oscillations at high power transfer levels. The direct impacts of TCSC insertion on the total impedance, active power and reactive power a electrical transmission line and also parameters of short-circuit : symmetrical currents, line currents, symmetrical voltages and line voltages are carried out. More the effects of injected voltage by TCSC for three case studies are presented.
This document discusses sheath voltage limiters (SVLs), which are surge arresters used to protect the outer jacket of underground high voltage cables. SVLs limit the voltage stress across the cable jacket during transient overvoltage events like faults, switching surges and lightning strikes to prevent puncture and moisture ingress. The document provides guidelines for selecting the proper rating for SVLs, including calculating the voltage that could appear on the cable sheath during faults based on cable characteristics, and ensuring the SVL's voltage rating is above this level so it does not conduct during faults. It also discusses using simulations and margins of protection to determine if the SVL can adequately protect the cable jacket from other transient overvoltages.
Concept of energy transmission & distribution ZunAib Ali
Downlaod is NOW Allowed (08/06/2016)
for more help: email me at zunaib_91@yahoo.com
Purpose of Electrical Transmission System
Main Parts of Power System
One-Line Diagram of Generating Station
Main Parts of Generating Station
Components of a Transmission Line
Grounding or earthing offers two principal advantages. First, it provides protection to the power system. Secondly, earthing of electrical equipment ensures the safety of the persons handling the equipment.
In today circumstance, rapid development of power system network cause the fault current of the system increased greatly .
The levels of fault current in many places have often exceeded the withstand capacity of existing power system equipment.
As implication to this matter ; security , stability and reliability of power system will be negatively affected .
Thus , limiting the fault current of the power system to a safe level can greatly reduce the risk of failure to the power system equipment due to high fault current flowing through the system. Because of that, there is no surprise to fault current limiter (FCL) become a most favourite research since this technology can limit the fault current .
EHV (extra high voltage) AC transmission refers to equipment designed for voltages greater than 345 kV. Higher transmission voltages increase efficiency by reducing transmission losses and current, decrease infrastructure costs, and increase transmission capacity. However, they also present safety and interference risks. New technologies like FACTS (flexible AC transmission systems) help maximize the benefits of EHV transmission by enabling voltage control and power flow management. There is growing support for expanding national EHV transmission grids to facilitate large-scale renewable energy integration and inter-regional power sharing.
A High-Speed and Power-Efficient Voltage Level Shifter for Dual-Supply Applic...JAYAPRAKASH JPINFOTECH
This document presents a fast and power-efficient voltage level shifter circuit that can convert low input voltages into high output voltages. The proposed circuit improves efficiency by reducing the strength of the pull-up device when the pull-down device is active, and by increasing the strength of the pull-down device using an auxiliary circuit. Post layout simulation results using a 0.18-μm technology show the circuit has a total energy per transition of 157 fJ, static power dissipation of 0.3 nW, and propagation delay of 30 ns when operating with supply voltages of 0.4V and 1.8V at an input frequency of 1 MHz. The paper analyzes logic size, area, and power consumption using the
This document discusses the use of vacuum circuit breakers (VCBs) in flexible AC transmission systems (FACTS). It explains that FACTS devices use power electronics to control parameters like voltage, impedance, and phase angle to enhance power grid stability and transfer capacity. VCBs are replacing power semiconductors in some FACTS applications due to lower cost. Specifically, VCBs can be used in mechanically switched series reactors to help damp power oscillations along with thyristor-controlled series compensators. VCBs can also stabilize voltages by connecting capacitors and reactors to load nodes in mechanically switched devices. This allows VCBs to support FACTS technologies in improving power system performance.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
A Study of Superconducting Transformer with Short-Circuit Current Limitation IJECEIAES
The paper presents physico-mathematical models for analyzing transient processes in electrical networks having transformers with a high temperature superconducting winding. One of the main purposes of the study is the investigation of the short circuit current limitation process with the use of a transformer with a high temperature superconducting winding, that allows the combination of two series-connected elements, transformer and reactor, in one device. The efficiency of this method for short circuit current limitation is provided by the fact that the critical value of superconducting winding temperature is exceeded under short circuit current flowing, then it passes into the normal state with a high impedance winding, thus limiting a short circuit current. It is important to know the moment when superconducting material passes into the normal state with the loss of superconductivity. For this purpose, the program for calculating the quantity of heat under short circuit current flowing before its interruption was developed. If a 40 MVA transformer with a high temperature superconducting winding is considered, short circuit should be cleared after 100 ms without transformer disconnection. It is proposed to use a hybrid winding in addition to the main winding for short circuit current limitation. Conducted investigations showed that the return of a winding into the superconducting state depends primarily on the ratio between a short circuit current and a rated load current. This represents the criterion for returning or not returning into the superconducting state for transformer windings.
Distribution System Voltage Drop and Power Loss CalculationAmeen San
Distribution System Voltage Drop and Power Loss
Calculation
Comparison of Overhead Versus Underground System
Power Loss Calculation,Voltage Drop Calculation
A Resonant Converter with LLC for DC-to-DC Converter Based ApplicationsIJMTST Journal
This document discusses a current mode control scheme for LLC series resonant DC-to-DC converters used for electric vehicle battery chargers. The proposed current mode control employs feedback from the resonant tank current to nullify effects of changes in power stage dynamics, improving performance over conventional voltage mode control. The LLC converter has multiple resonant modes depending on operating frequency and load. Experimental results show the current mode control achieves 97.96% peak efficiency for a 6.6 kW, 390V to 250-450V converter. Future work will focus on design optimization and a simpler design procedure.
IRJET- FPGA Controlled Three Level Diode Clamped Multilevel Inverter for Sola...IRJET Journal
This document discusses a three-level diode clamped multilevel inverter controlled by an FPGA for a solar PV system. It begins with an abstract that outlines the working principle and simulation of the FPGA-controlled three-level inverter fed by a solar PV DC bus. It then discusses the principles of two-level and multilevel inverters, focusing on the diode clamped topology. The document introduces the proposed three-level diode clamped inverter with FPGA control and discusses its advantages like fast switching speeds and low cost. It then shows simulations of the system in MATLAB Simulink and Xilinx, including waveforms that demonstrate the stepped output waveform and reduced harmonics.
The document discusses short circuit currents and testing of transformers to withstand short circuits. It defines short circuits and short circuit current, and differentiates short circuits from overloads. Symmetrical and asymmetrical short circuit currents are calculated. Short circuit tests are done on distribution and power transformers to demonstrate their ability to withstand thermal and dynamic effects of short circuits without damage. The document outlines test procedures, current calculations, and setup for short circuit testing in the lab.
Hybrid transformer zvszcs dc–dc converter with optimized magnetics and improv...LeMeniz Infotech
Hybrid transformer zvszcs dc–dc converter with optimized magnetics and improved power devices utilization for photovoltaic module applications
To Get this projects Call : 9566355386 / 99625 88976
Visit : www.lemenizinfotech.com / www.ieeemaster.com
Mail : projects@lemenizinfotech.com
In this work, an accurate formulation and estimation of stray power losses in induction machines are proposed. Stray losses are estimated by derived formulas based on the leakage fluxes from the induction machine windings. These leakage fluxes induce voltage drops in the machine stator and rotor iron cores and eddy currents in the machine windings, causing stray power losses in the machine iron cores and windings. By adding these losses, a completed estimation of stray losses can be obtained and implemented in the equivalent machine circuit. The stray losses are represented by stray loss resistances connected in series with the stator and rotor circuits. Due to the stray loss in the rotor circuit depending largely on the machine slip this may be omitted without influencing the accuracy of stray loss calculations. The obtained formulas of stray loss estimation are practically satisfied. An accurate loss calculation in induction machines is very useful in the energy-saving issue.
This document is a technical seminar report submitted for the degree of Bachelor of Technology in Electrical and Electronics Engineering. It discusses short circuit study in electrical technology. Short circuit calculations are required to ensure equipment ratings are adequate to withstand fault currents. No substation equipment can be purchased without knowledge of complete short circuit values. Short circuit studies deliver short circuit calculations highlighting underrated equipment and suggested modifications. They also include protective device setting and coordination studies. Regularly maintaining and updating short circuit calculations helps protect equipment and safety.
Transient voltage distribution in transformer winding (experimental investiga...eSAT Journals
Abstract In this work, the non-liner voltage distribution in transformer winding is investigated that occurs due switching and lightning. Transformer winding is modeled in the alternative transients program (ATP) version of Electromagnetic transients program (EMTP-RV). EMTP software is used to simulate the very fast transient overvoltage. An experimental setup that consist of , Recurrent surge generator, CRO and transformer winding model has been developed and voltages measured at different point along the transformer winding. Simulation results show good agreement with the experimental result. Index Terms: Very fast transient overvoltages, internal resonance, impulse voltage distribution, disc winding
The document discusses modeling transformer response to surges. It describes how surges induce non-uniform voltage distributions in transformer windings, potentially damaging insulation. It presents two modeling approaches: classical distributed circuit models and field-based solutions. Distributed circuit models using ladder networks are feasible and provide voltages to input into field solutions for calculating electrical stresses. Proper modeling of network elements like inductances and capacitances requires considering effects of winding geometry, neighboring conductors, and the transformer core. Numerical simulations can help evaluate network parameters and model surge distribution for transformer insulation design.
Dr. Shamasundar spoke about the thermal management in transformers, different cooling methods and how simulation through JMAG can help you design an Efficient Transformer.
This paper addresses the approach to improve the efficiency of the quasi Z-source inverter. In order to increase the efficiency the reduction of conduction losses is one way to approach. Sequentially to decrease the conduction losses in the quasi z-source inverter the replacement of diode is replacing with switches is proposed which is also called as synchronous rectification. The paper represents basics of the approach, analysis and comparison of the power losses of the traditional and proposed designs of the grid connected PV-system with quasi z-source inverter system. The proposed approach validated on the computer simulations in the MATLAB environment.
Iaetsd placement of super conducting fault current limiters to mitigateIaetsd Iaetsd
This document discusses the use of superconducting fault current limiters (SFCLs) to mitigate fault currents in smart grids with different types of distributed generation sources like wind farms, solar panels, and diesel generators. The author models an SFCL and a smart grid system in MATLAB/Simulink. Simulation results show that locating an SFCL at the point where distributed generation connects to the grid (Location 3) provides the best performance, reducing fault currents from all distributed generation sources by 68-84% while also limiting fault current from the main grid. In contrast, placing SFCLs upstream in the distribution system can unexpectedly increase fault currents from some distributed generators.
Impact of Thyristor Controlled Series Capacitor Insertion on Short-circuit Ca...IJAPEJOURNAL
This research paper presents a study on phase to earth fault short-circuit calculation with fault resistance on a single transmission line 400 kV in eastern Algerian transmission networks at Algerian Company of Electricity and Gas (Sonelgaz Group) compensated by series Flexible AC Transmission System (FACTS) i.e. Thyristor Controlled Series Capacitor (TCSC) installed in midline. The facts are used for controlling transmission voltage, power flow, reactive power, and damping of power system oscillations at high power transfer levels. The direct impacts of TCSC insertion on the total impedance, active power and reactive power a electrical transmission line and also parameters of short-circuit : symmetrical currents, line currents, symmetrical voltages and line voltages are carried out. More the effects of injected voltage by TCSC for three case studies are presented.
This document discusses sheath voltage limiters (SVLs), which are surge arresters used to protect the outer jacket of underground high voltage cables. SVLs limit the voltage stress across the cable jacket during transient overvoltage events like faults, switching surges and lightning strikes to prevent puncture and moisture ingress. The document provides guidelines for selecting the proper rating for SVLs, including calculating the voltage that could appear on the cable sheath during faults based on cable characteristics, and ensuring the SVL's voltage rating is above this level so it does not conduct during faults. It also discusses using simulations and margins of protection to determine if the SVL can adequately protect the cable jacket from other transient overvoltages.
Concept of energy transmission & distribution ZunAib Ali
Downlaod is NOW Allowed (08/06/2016)
for more help: email me at zunaib_91@yahoo.com
Purpose of Electrical Transmission System
Main Parts of Power System
One-Line Diagram of Generating Station
Main Parts of Generating Station
Components of a Transmission Line
Grounding or earthing offers two principal advantages. First, it provides protection to the power system. Secondly, earthing of electrical equipment ensures the safety of the persons handling the equipment.
In today circumstance, rapid development of power system network cause the fault current of the system increased greatly .
The levels of fault current in many places have often exceeded the withstand capacity of existing power system equipment.
As implication to this matter ; security , stability and reliability of power system will be negatively affected .
Thus , limiting the fault current of the power system to a safe level can greatly reduce the risk of failure to the power system equipment due to high fault current flowing through the system. Because of that, there is no surprise to fault current limiter (FCL) become a most favourite research since this technology can limit the fault current .
EHV (extra high voltage) AC transmission refers to equipment designed for voltages greater than 345 kV. Higher transmission voltages increase efficiency by reducing transmission losses and current, decrease infrastructure costs, and increase transmission capacity. However, they also present safety and interference risks. New technologies like FACTS (flexible AC transmission systems) help maximize the benefits of EHV transmission by enabling voltage control and power flow management. There is growing support for expanding national EHV transmission grids to facilitate large-scale renewable energy integration and inter-regional power sharing.
A High-Speed and Power-Efficient Voltage Level Shifter for Dual-Supply Applic...JAYAPRAKASH JPINFOTECH
This document presents a fast and power-efficient voltage level shifter circuit that can convert low input voltages into high output voltages. The proposed circuit improves efficiency by reducing the strength of the pull-up device when the pull-down device is active, and by increasing the strength of the pull-down device using an auxiliary circuit. Post layout simulation results using a 0.18-μm technology show the circuit has a total energy per transition of 157 fJ, static power dissipation of 0.3 nW, and propagation delay of 30 ns when operating with supply voltages of 0.4V and 1.8V at an input frequency of 1 MHz. The paper analyzes logic size, area, and power consumption using the
This document discusses the use of vacuum circuit breakers (VCBs) in flexible AC transmission systems (FACTS). It explains that FACTS devices use power electronics to control parameters like voltage, impedance, and phase angle to enhance power grid stability and transfer capacity. VCBs are replacing power semiconductors in some FACTS applications due to lower cost. Specifically, VCBs can be used in mechanically switched series reactors to help damp power oscillations along with thyristor-controlled series compensators. VCBs can also stabilize voltages by connecting capacitors and reactors to load nodes in mechanically switched devices. This allows VCBs to support FACTS technologies in improving power system performance.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
A Study of Superconducting Transformer with Short-Circuit Current Limitation IJECEIAES
The paper presents physico-mathematical models for analyzing transient processes in electrical networks having transformers with a high temperature superconducting winding. One of the main purposes of the study is the investigation of the short circuit current limitation process with the use of a transformer with a high temperature superconducting winding, that allows the combination of two series-connected elements, transformer and reactor, in one device. The efficiency of this method for short circuit current limitation is provided by the fact that the critical value of superconducting winding temperature is exceeded under short circuit current flowing, then it passes into the normal state with a high impedance winding, thus limiting a short circuit current. It is important to know the moment when superconducting material passes into the normal state with the loss of superconductivity. For this purpose, the program for calculating the quantity of heat under short circuit current flowing before its interruption was developed. If a 40 MVA transformer with a high temperature superconducting winding is considered, short circuit should be cleared after 100 ms without transformer disconnection. It is proposed to use a hybrid winding in addition to the main winding for short circuit current limitation. Conducted investigations showed that the return of a winding into the superconducting state depends primarily on the ratio between a short circuit current and a rated load current. This represents the criterion for returning or not returning into the superconducting state for transformer windings.
Distribution System Voltage Drop and Power Loss CalculationAmeen San
Distribution System Voltage Drop and Power Loss
Calculation
Comparison of Overhead Versus Underground System
Power Loss Calculation,Voltage Drop Calculation
A Resonant Converter with LLC for DC-to-DC Converter Based ApplicationsIJMTST Journal
This document discusses a current mode control scheme for LLC series resonant DC-to-DC converters used for electric vehicle battery chargers. The proposed current mode control employs feedback from the resonant tank current to nullify effects of changes in power stage dynamics, improving performance over conventional voltage mode control. The LLC converter has multiple resonant modes depending on operating frequency and load. Experimental results show the current mode control achieves 97.96% peak efficiency for a 6.6 kW, 390V to 250-450V converter. Future work will focus on design optimization and a simpler design procedure.
IRJET- FPGA Controlled Three Level Diode Clamped Multilevel Inverter for Sola...IRJET Journal
This document discusses a three-level diode clamped multilevel inverter controlled by an FPGA for a solar PV system. It begins with an abstract that outlines the working principle and simulation of the FPGA-controlled three-level inverter fed by a solar PV DC bus. It then discusses the principles of two-level and multilevel inverters, focusing on the diode clamped topology. The document introduces the proposed three-level diode clamped inverter with FPGA control and discusses its advantages like fast switching speeds and low cost. It then shows simulations of the system in MATLAB Simulink and Xilinx, including waveforms that demonstrate the stepped output waveform and reduced harmonics.
The document discusses short circuit currents and testing of transformers to withstand short circuits. It defines short circuits and short circuit current, and differentiates short circuits from overloads. Symmetrical and asymmetrical short circuit currents are calculated. Short circuit tests are done on distribution and power transformers to demonstrate their ability to withstand thermal and dynamic effects of short circuits without damage. The document outlines test procedures, current calculations, and setup for short circuit testing in the lab.
Hybrid transformer zvszcs dc–dc converter with optimized magnetics and improv...LeMeniz Infotech
Hybrid transformer zvszcs dc–dc converter with optimized magnetics and improved power devices utilization for photovoltaic module applications
To Get this projects Call : 9566355386 / 99625 88976
Visit : www.lemenizinfotech.com / www.ieeemaster.com
Mail : projects@lemenizinfotech.com
In this work, an accurate formulation and estimation of stray power losses in induction machines are proposed. Stray losses are estimated by derived formulas based on the leakage fluxes from the induction machine windings. These leakage fluxes induce voltage drops in the machine stator and rotor iron cores and eddy currents in the machine windings, causing stray power losses in the machine iron cores and windings. By adding these losses, a completed estimation of stray losses can be obtained and implemented in the equivalent machine circuit. The stray losses are represented by stray loss resistances connected in series with the stator and rotor circuits. Due to the stray loss in the rotor circuit depending largely on the machine slip this may be omitted without influencing the accuracy of stray loss calculations. The obtained formulas of stray loss estimation are practically satisfied. An accurate loss calculation in induction machines is very useful in the energy-saving issue.
This document is a technical seminar report submitted for the degree of Bachelor of Technology in Electrical and Electronics Engineering. It discusses short circuit study in electrical technology. Short circuit calculations are required to ensure equipment ratings are adequate to withstand fault currents. No substation equipment can be purchased without knowledge of complete short circuit values. Short circuit studies deliver short circuit calculations highlighting underrated equipment and suggested modifications. They also include protective device setting and coordination studies. Regularly maintaining and updating short circuit calculations helps protect equipment and safety.
Transient voltage distribution in transformer winding (experimental investiga...eSAT Journals
Abstract In this work, the non-liner voltage distribution in transformer winding is investigated that occurs due switching and lightning. Transformer winding is modeled in the alternative transients program (ATP) version of Electromagnetic transients program (EMTP-RV). EMTP software is used to simulate the very fast transient overvoltage. An experimental setup that consist of , Recurrent surge generator, CRO and transformer winding model has been developed and voltages measured at different point along the transformer winding. Simulation results show good agreement with the experimental result. Index Terms: Very fast transient overvoltages, internal resonance, impulse voltage distribution, disc winding
The document discusses modeling transformer response to surges. It describes how surges induce non-uniform voltage distributions in transformer windings, potentially damaging insulation. It presents two modeling approaches: classical distributed circuit models and field-based solutions. Distributed circuit models using ladder networks are feasible and provide voltages to input into field solutions for calculating electrical stresses. Proper modeling of network elements like inductances and capacitances requires considering effects of winding geometry, neighboring conductors, and the transformer core. Numerical simulations can help evaluate network parameters and model surge distribution for transformer insulation design.
Dr. Shamasundar spoke about the thermal management in transformers, different cooling methods and how simulation through JMAG can help you design an Efficient Transformer.
Unit-II
Voltage Sag: Sources of voltage sag: motor starting, arc furnace, fault clearing etc; estimating voltage sag performance and principle of its protection; solutions at end user level- Isolation Transformer, Voltage Regulator, Static UPS, Rotary UPS, Active Series Compensator
This document discusses estimating the costs for a pole mounted substation. It defines estimating and lists the essential elements as specifying materials, knowing current market costs, calculating material and labor costs, and understanding purchasing systems. It describes substations as receiving high voltage energy and reducing it for distribution. Outdoor pole mounted substations have advantages over indoor types as they require less construction materials and equipment is easier to view and access for fault detection. The document provides an example estimate for components of an 11kV/440V pole mounted outdoor substation.
2003 09-08 joeck icefa fuse protection in transformer pole substationRemigiusz Joeck
This document summarizes the use of fuses to protect transformer pole substations in Poland. It discusses how expulsion fuses are commonly used on the medium-voltage side for transformers up to 400 kVA when short-circuit currents do not exceed 3.15 kA. Current-limiting fuses are used for larger transformers or higher short-circuit currents. On the low-voltage side, fuses with a time-current characteristic of gG or gF are typically used. The document also provides guidelines on properly selecting and coordinating fuses on both the MV and LV sides of transformer substations for effective protection against overloads and short-circuits.
This document provides an introduction and overview of gas insulated substations (GIS). It discusses the advantages of GIS over conventional substations, including their compact size, reliability, and maintenance benefits. It also outlines some challenges with GIS, such as the generation of very fast transient overvoltages (VFTOs) during switching operations. These VFTOs can cause flashovers and insulation issues. The document examines the factors that influence VFTO magnitudes, including contact speed and system voltage. It also discusses the potential effects of VFTOs on transformers connected to GIS systems.
The document is a thesis submitted by three students for their Bachelor of Technology degree in Mechanical Engineering. It discusses the design of an energy harvester that converts the vibration of railway tracks caused by passing trains into electricity. The harvester is intended to power trackside equipment requiring up to 100 Watts of power, making railroads less reliant on national power grids. The harvester uses a mechanical motion rectifier to efficiently convert the bidirectional vibration of the track into unidirectional rotational motion. Bench testing showed the prototype harvester can achieve up to 71% mechanical efficiency and produce a large amount of power.
This document presents a design for generating electricity from railway tracks. It introduces the concept of converting rotational energy from trains passing over tracks into electrical energy. The objectives are to use dynamos connected to the tracks to generate a voltage that can be used to charge lead-acid batteries. Some advantages are that a high electrical output can be achieved by increasing the gear ratio between the tracks and generators. The generated power could be used for applications like charging mobile phones and powering displays, lights, and equipment at train stations. It suggests implementing this system at entry and exit points of busy railway stations.
This document provides an overview of the typical components found in a gas insulated substation (GIS), including: enclosures made of aluminum alloy; conductors made of aluminum alloy; SF6 gas used for insulation and sealing; insulators that act as gas barriers; SF6 accessories like density sensors, valves, and pressure relief; circuit breakers; disconnectors; earthing switches; current and voltage transformers; and surge arresters. It also mentions gas insulated lines/bus and references further topics like GIS construction, maintenance, and its role in electric grid applications.
System and method for generating electric powershalsub
The document describes a system and method for generating electric power from the movement of rails. It uses a variable capacitor system comprising two capacitor plates that are driven together and apart by the passing of vehicles on the rail. This changes the capacitance between the plates and allows energy to be extracted from the power source and converted to electrical energy. The system is intended to power remote railway equipment without needing to run power lines to those locations.
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.
Modeling and analysis of power transformers under ferroresonance phenomenonGilberto Mejía
The document discusses modeling a Fernandez surge arrester on a 132kV transmission line using ATP simulation software. It first provides background on lightning, surge arresters, and issues lightning can cause for power systems. It then discusses different surge arrester models including the Fernandez model, and describes modeling the transmission line, tower, and surge arrester in ATP. Simulation results show the output waveform of lightning surge on the line with and without a surge arrester, comparing the standard and Fernandez models. The Fernandez model better represented the surge arrester's dynamic performance during fast lightning events.
COVERS THE LAYOUT AVAILABLE FOR ADOPTION WITH AN EYE ON EASY MAINTENANCE .The layouts were evolved by the author and his associate for use by power boards
The document proposes a system to generate electricity from railway tracks. It uses a generator powered by a variable capacitor that is primed by a power source. As trains pass over the tracks, the changing capacitance extracts significant electrical energy. Circuit diagrams show components like a reservoir, power tie line, motor, generator and processor that condition the power and control generation. Mathematical calculations demonstrate how capacitance and electrical potential vary based on factors like dielectric thickness and plate distance. The conclusion states that this approach economically produces sufficient power by increasing the capacitor's electrical energy by 2400 times through movements on the rail system.
power generation from railway track in an advanced technology by which the power can be generated with help of motion of the rail and can be stored in the form of generators or can reuse.
This document describes a project to generate electricity from railway tracks. A train model with a magnet passes over coils attached to the tracks, inducing voltage in the coils. This alternating current is rectified and stored in a battery. A charge controller protects the battery from overcharging. An inverter converts the direct current to alternating current that can power devices. The project aims to help address electricity shortages by generating power from passing trains without fuel inputs.
This document provides information about key components of a steam power plant, including boilers, steam turbines, condensers, and condensate pumps. It describes the basic operation and essential elements of steam turbines, including impulse and reaction turbines. It also lists some advantages of steam turbines over reciprocating engines, such as higher thermal efficiency and not requiring internal lubrication. The document is an informative overview of a steam power plant and the main equipment involved in the steam cycle.
Uttar pradesh power corparation ltd. training report19saurabh89
The document provides details about a 220/132 kV substation in Lucknow, Uttar Pradesh, India. It discusses the key components of the substation including transformers, bus bars, insulators, circuit breakers, metering equipment, and protection systems. Specifically, it notes that the main bus is connected to various transmission lines and has a total capacity of 320 MVA for 132 kV. Transformers step down the voltage from 220 kV to 132 kV and 33 kV. Various feeders transmit power from the substation to surrounding areas. Protection, metering, capacitors, and other equipment are also described.
Analysis of protection measures on equipment of gis for very fast transient o...eSAT Journals
Abstract Gas Insulated Substations (GIS) have found a broad range of applications in power systems because of their high reliability, easy maintenance, small ground space requirements etc. In a Gas insulated substations, the operation of disconnector switches and circuit breakers can cause Very Fast Transient Overvoltages (VFTOs), which will bring an instantaneous change in voltage with a very short rise time and it is normally followed by oscillation having high frequencies. For designing the insulation level of a substation, it is essential to know the maximum value of VFTO. Fast operating disconnector switches are usually used to reduce time of the breakdown; however, it cannot eliminate fully the effect of the VFTO. Very Fast Transient Overvoltages caused by disconnector switch operation of 1000 kv GIS is simulated and calculated in this paper using MATLAB. The various protection measures on equipment of GIS have been compared and analyzed by adding ferrite rings, opening and closing of resistor, metal oxide arrester and R-C absorber. Index Terms: Gas Insulated Substation, Very Fast Transient Overvoltage’s, Matlab/Simulink, Disconnector switch.
Vlsi implementation of a programmable low drop out voltage regulatoreSAT Journals
This document summarizes the VLSI implementation of a programmable low drop-out voltage regulator. It begins by introducing low drop-out voltage regulators and their importance in applications requiring low noise and high accuracy power rails. It then discusses key design considerations for low voltage, low power LDO regulators including fast transient response, high power supply rejection, and programmability. The document presents the schematic and CMOS layout of the proposed 32nm programmable LDO regulator design. The design uses an operational transconductance amplifier as the error amplifier, along with a common-source amplifier and current-sourcing PMOS transistor in the output stage to achieve fast transient response while operating below 1V with low power consumption and program
Abstract
This paper deals with the RF (Radio Frequency)-MEMS (Micro-Electro-Mechanical-System) switch design using the coventorware software and its superiority over the existing technologies like PIN Diodes and Field-Effect-Transistors regarding size, power, Isolation and Insertion loss, and graphically how Pull-in voltage affects on the deflection of the switch. Also this paper deals with the fabrication process of the cantilever switch.
Keywords: Etching, Sacrificial Layer, Actuation Voltage, Electrostatic Force, RF Switch, PIN Diodes, Stiction, Isolation and Insertion loss.
Modeling and Analysis of a 3-Phase 132kv GasInsulated SubstationIRJET Journal
1) The document discusses modeling and analysis of very fast transient overvoltages in a 3-phase 132kV gas insulated substation using MATLAB 7.8 software.
2) Equivalent circuits for different components of the substation were developed in MATLAB to simulate transient overvoltages caused by switching operations and faults.
3) Transient overvoltages were analyzed for different lengths of the gas insulated bus duct and various voltages on the source and load sides to determine maximum overvoltage levels.
IRJET- Integrated Variable Resistor using Switched Capacitor Circuit and Volt...IRJET Journal
The document proposes a method to fabricate a voltage-controlled variable resistor in an integrated circuit using a switched capacitor circuit with a varactor tuning circuit. It summarizes how switched capacitor circuits can simulate resistance using ideal switches and a capacitor. A varactor diode acts as a variable capacitor under reverse bias, allowing the capacitance and resistance to be controlled by voltage. The document simulates the proposed circuit in LTSPICE and shows that it achieves variable resistance by changing the control voltage and thus the capacitance of the tuning circuit.
Control analysis of a high frequency resonant inverter for induction cooking ...eSAT Journals
This document discusses control analysis of a high frequency resonant inverter for induction cooking applications. It studies the stability of three possible closed-loop control techniques for a series resonant inverter. Ultimately, it proposes a single closed-loop control that can ensure both power control and satisfactory zero voltage switching in a finite control range near the operating point. A phase shift controlled series resonant inverter is used as the power supply for an induction cooking system. Its linearized model is developed for small signal analysis and a PID controller is designed for the proposed closed-loop control. Controller performance is evaluated under various operating conditions using MATLAB/Simulink.
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.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Study and implementation of comparator in cmos 50 nm technologyeSAT Journals
Abstract This paper describes the comparator circuits used in FLASH Analog to digital converter (ADC). The performance of FLASH ADC is greatly influenced by the choice of comparator. In this paper, first a single ended “Threshold Inverter Quantizer” (TIQ) is presented. The TIQ comparator is based on a CMOS inverter cell, in which voltage transfer characteristics (VTC) are changed by systematic transistor sizing. However, TIQ comparator is very sensitive to power supply noise. Another comparator circuit presented in this paper is “Two stage open loop comparator”. It is implemented in 50 nm CMOS Technology. Pre-simulation of comparator is done in LT-Spice and post layout simulation is done in Microwind 3.1. Keywords: CMOS, Comparator, TIQ (Threshold Inverter Quantizer), LT-Spice.
Application of single phase matrix converter topology to an uninterruptible p...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Temperature analysis of lna with improved linearity for rf receivereSAT Journals
Abstract In this paper we are fully integrated 5.5 GHz high-linearity low noise amplifier (LNA) is designing using post-linearization technique, in sub-120nm & sub-70nm technology. It developed using cascode amplifier with inductors. RC linearization circuit is designed to improve the linearity of the design. Cascode LNA circuit is designed for linearity improvement. In this work Temperature analysis is carried out for LNA circuit performance improvement fully integrated 5.5 GHz high-linearity low noise amplifier (LNA) is designing using post-linearization technique, in sub-120nm & sub-70nm technology. Temperature stability of the circuit is analysed for different temperature ranges our results prove that the proposed LNA design achieve high gain with good linearity. Although power dissipation of the circuit is high, good temperature stability is achieved. Temperature stability of the circuit is analysed for different temperature ranges our results prove that the proposed LNA design achieve high gain with good linearity. Although power dissipation of the circuit is high, we are able to achieve good temperature stability. The Low Noise Amplifier is a special type of electronic amplifier used in communication systems which amplifies very weak signals captured by an antenna. Keywords: Linearity improvement LNA circuit, DSCH and Microwind software.
Temperature analysis of lna with improved linearity for rf receivereSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
The document presents a study on estimating re-striking transient overvoltages in a 3-phase 132kV gas insulated substation (GIS). It discusses:
1) A MATLAB model was developed to simulate a GIS system comprising an input cable, spacer, disconnector switch, 10m busbar and load. Transient overvoltages generated during disconnector switch closing and opening operations and 3-phase faults were analyzed.
2) During disconnector switch operation, multiple re-strikes occur due to the slow contact speed, generating transient overvoltages. Each re-strike was modeled as a voltage collapse across the gas.
3) Simulation results show the magnitude and rise time of
This document discusses the estimation of very fast transient overvoltages (VFTOs) in a 3-phase 132kV gas insulated substation (GIS). It presents the modeling of a GIS system in MATLAB to analyze VFTOs generated during switching operations and 3-phase faults. Each re-strike of the disconnector switch during opening/closing generates high frequency transient overvoltages that can damage equipment. The paper develops an accurate electrical model of the GIS components using lumped parameters to simulate transient behavior and calculate overvoltage waveforms.
Novel technique in charactarizing a pv module using pulse width modulatoreSAT Journals
This document summarizes a novel technique for characterizing photovoltaic (PV) modules using a pulse width modulator. The technique uses an electronic load circuit with power MOSFETs controlled by a pulse width modulation signal generated using LABVIEW. Experimental results from a 150W polycrystalline PV module showed high accuracy when compared to simulations performed using COMSOL Multiphysics and MATLAB. The technique provides accurate characterization with lower cost and simplicity compared to previous methods.
Fuzzy logic approach to control the magnetization level in the magnetic 2IAEME Publication
This document describes a fuzzy logic approach to control the magnetization level in the magnetic core of a welding transformer. The goal is to prevent saturation of the core which can cause current spikes that lead to system shutdown. A fuzzy logic controller is proposed to maintain the magnetization level and welding current within optimal limits through closed-loop control of the transformer's primary voltage. Membership functions define the inputs of core flux level and welding current and the single output of primary voltage. Rules are defined so that if the flux or current exceed limits, the voltage direction is reversed to reduce the flux level. The Mamdani algorithm is used to implement the fuzzy logic controller as a replacement for one of the previously used hysteresis controllers.
Fuzzy logic approach to control the magnetization level in the magnetic 2IAEME Publication
This document describes a fuzzy logic approach to control magnetization levels in the magnetic core of a welding transformer. The fuzzy logic controller is proposed to work alongside an artificial neural network-based detector of magnetic saturation. Membership functions are defined for the controller inputs of flux and welding current, and output of transformer primary voltage. Rules are defined so that if flux or current exceed limits, the voltage direction is reversed to reduce flux. Simulation results show the controller maintains flux and current within limits, preventing current spikes that could cause overcurrent protection and system shutdown. The fuzzy logic approach provides an alternative to typically used hysteresis controllers.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
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
doubly fed induction generator (DFIG) based wind parks.
Similar to Analsis of very fast transient over voltages in gas insulated substations (20)
Mechanical properties of hybrid fiber reinforced concrete for pavementseSAT Journals
Abstract
The effect of addition of mono fibers and hybrid fibers on the mechanical properties of concrete mixture is studied in the present
investigation. Steel fibers of 1% and polypropylene fibers 0.036% were added individually to the concrete mixture as mono fibers and
then they were added together to form a hybrid fiber reinforced concrete. Mechanical properties such as compressive, split tensile and
flexural strength were determined. The results show that hybrid fibers improve the compressive strength marginally as compared to
mono fibers. Whereas, hybridization improves split tensile strength and flexural strength noticeably.
Keywords:-Hybridization, mono fibers, steel fiber, polypropylene fiber, Improvement in mechanical properties.
Material management in construction – a case studyeSAT Journals
Abstract
The objective of the present study is to understand about all the problems occurring in the company because of improper application
of material management. In construction project operation, often there is a project cost variance in terms of the material, equipments,
manpower, subcontractor, overhead cost, and general condition. Material is the main component in construction projects. Therefore,
if the material management is not properly managed it will create a project cost variance. Project cost can be controlled by taking
corrective actions towards the cost variance. Therefore a methodology is used to diagnose and evaluate the procurement process
involved in material management and launch a continuous improvement was developed and applied. A thorough study was carried
out along with study of cases, surveys and interviews to professionals involved in this area. As a result, a methodology for diagnosis
and improvement was proposed and tested in selected projects. The results obtained show that the main problem of procurement is
related to schedule delays and lack of specified quality for the project. To prevent this situation it is often necessary to dedicate
important resources like money, personnel, time, etc. To monitor and control the process. A great potential for improvement was
detected if state of the art technologies such as, electronic mail, electronic data interchange (EDI), and analysis were applied to the
procurement process. These helped to eliminate the root causes for many types of problems that were detected.
Managing drought short term strategies in semi arid regions a case studyeSAT Journals
Abstract
Drought management needs multidisciplinary action. Interdisciplinary efforts among the experts in various fields of the droughts
prone areas are helpful to achieve tangible and permanent solution for this recurring problem. The Gulbarga district having the total
area around 16, 240 sq.km, and accounts 8.45 per cent of the Karnataka state area. The district has been situated with latitude 17º 19'
60" North and longitude of 76 º 49' 60" east. The district is situated entirely on the Deccan plateau positioned at a height of 300 to
750 m above MSL. Sub-tropical, semi-arid type is one among the drought prone districts of Karnataka State. The drought
management is very important for a district like Gulbarga. In this paper various short term strategies are discussed to mitigate the
drought condition in the district.
Keywords: Drought, South-West monsoon, Semi-Arid, Rainfall, Strategies etc.
Life cycle cost analysis of overlay for an urban road in bangaloreeSAT Journals
Abstract
Pavements are subjected to severe condition of stresses and weathering effects from the day they are constructed and opened to traffic
mainly due to its fatigue behavior and environmental effects. Therefore, pavement rehabilitation is one of the most important
components of entire road systems. This paper highlights the design of concrete pavement with added mono fibers like polypropylene,
steel and hybrid fibres for a widened portion of existing concrete pavement and various overlay alternatives for an existing
bituminous pavement in an urban road in Bangalore. Along with this, Life cycle cost analyses at these sections are done by Net
Present Value (NPV) method to identify the most feasible option. The results show that though the initial cost of construction of
concrete overlay is high, over a period of time it prove to be better than the bituminous overlay considering the whole life cycle cost.
The economic analysis also indicates that, out of the three fibre options, hybrid reinforced concrete would be economical without
compromising the performance of the pavement.
Keywords: - Fatigue, Life cycle cost analysis, Net Present Value method, Overlay, Rehabilitation
Laboratory studies of dense bituminous mixes ii with reclaimed asphalt materialseSAT Journals
Abstract
The issue of growing demand on our nation’s roadways over that past couple of decades, decreasing budgetary funds, and the need to
provide a safe, efficient, and cost effective roadway system has led to a dramatic increase in the need to rehabilitate our existing
pavements and the issue of building sustainable road infrastructure in India. With these emergency of the mentioned needs and this
are today’s burning issue and has become the purpose of the study.
In the present study, the samples of existing bituminous layer materials were collected from NH-48(Devahalli to Hassan) site.The
mixtures were designed by Marshall Method as per Asphalt institute (MS-II) at 20% and 30% Reclaimed Asphalt Pavement (RAP).
RAP material was blended with virgin aggregate such that all specimens tested for the, Dense Bituminous Macadam-II (DBM-II)
gradation as per Ministry of Roads, Transport, and Highways (MoRT&H) and cost analysis were carried out to know the economics.
Laboratory results and analysis showed the use of recycled materials showed significant variability in Marshall Stability, and the
variability increased with the increase in RAP content. The saving can be realized from utilization of recycled materials as per the
methodology, the reduction in the total cost is 19%, 30%, comparing with the virgin mixes.
Keywords: Reclaimed Asphalt Pavement, Marshall Stability, MS-II, Dense Bituminous Macadam-II
Laboratory investigation of expansive soil stabilized with natural inorganic ...eSAT Journals
This document summarizes a study on stabilizing expansive black cotton soil with the natural inorganic stabilizer RBI-81. Laboratory tests were conducted to evaluate the effect of RBI-81 on the soil's engineering properties. The tests showed that with 2% RBI-81 and 28 days of curing, the unconfined compressive strength increased by around 250% and the CBR value improved by approximately 400% compared to the untreated soil. Overall, the study found that RBI-81 effectively improved the strength properties of the black cotton soil and its suitability as a soil stabilizer was supported.
Influence of reinforcement on the behavior of hollow concrete block masonry p...eSAT Journals
Abstract
Reinforced masonry was developed to exploit the strength potential of masonry and to solve its lack of tensile strength. Experimental
and analytical studies have been carried out to investigate the effect of reinforcement on the behavior of hollow concrete block
masonry prisms under compression and to predict ultimate failure compressive strength. In the numerical program, three dimensional
non-linear finite elements (FE) model based on the micro-modeling approach is developed for both unreinforced and reinforced
masonry prisms using ANSYS (14.5). The proposed FE model uses multi-linear stress-strain relationships to model the non-linear
behavior of hollow concrete block, mortar, and grout. Willam-Warnke’s five parameter failure theory has been adopted to model the
failure of masonry materials. The comparison of the numerical and experimental results indicates that the FE models can successfully
capture the highly nonlinear behavior of the physical specimens and accurately predict their strength and failure mechanisms.
Keywords: Structural masonry, Hollow concrete block prism, grout, Compression failure, Finite element method,
Numerical modeling.
Influence of compaction energy on soil stabilized with chemical stabilizereSAT Journals
This document summarizes a study on the influence of compaction energy on soil stabilized with a chemical stabilizer. Laboratory tests were conducted on locally available loamy soil treated with a patented polymer liquid stabilizer and compacted at four different energy levels. The study found that increasing the compaction effort increased the density of both untreated and treated soil, but the rate of increase was lower for stabilized soil. Treating the soil with the stabilizer improved its unconfined compressive strength and resilient modulus, and reduced accumulated plastic strain, with these properties further improved by higher compaction efforts. The stabilized soil exhibited strength and performance benefits compared to the untreated soil.
Geographical information system (gis) for water resources managementeSAT Journals
This document describes a hydrological framework developed in the form of a Hydrologic Information System (HIS) to meet the information needs of various government departments related to water management in a state. The HIS consists of a hydrological database coupled with tools for collecting and analyzing spatial and non-spatial water resources data. It also incorporates a hydrological model to indirectly assess water balance components over space and time. A web-based GIS portal was created to allow users to access and visualize the hydrological data, as well as outputs from the SWAT hydrological model. The framework is intended to facilitate integrated water resources planning and management across different administrative levels.
Forest type mapping of bidar forest division, karnataka using geoinformatics ...eSAT Journals
Abstract
The study demonstrate the potentiality of satellite remote sensing technique for the generation of baseline information on forest types
including tree plantation details in Bidar forest division, Karnataka covering an area of 5814.60Sq.Kms. The Total Area of Bidar
forest division is 5814Sq.Kms analysis of the satellite data in the study area reveals that about 84% of the total area is Covered by
crop land, 1.778% of the area is covered by dry deciduous forest, 1.38 % of mixed plantation, which is very threatening to the
environmental stability of the forest, future plantation site has been mapped. With the use of latest Geo-informatics technology proper
and exact condition of the trees can be observed and necessary precautions can be taken for future plantation works in an appropriate
manner
Keywords:-RS, GIS, GPS, Forest Type, Tree Plantation
Factors influencing compressive strength of geopolymer concreteeSAT Journals
Abstract
To study effects of several factors on the properties of fly ash based geopolymer concrete on the compressive strength and also the
cost comparison with the normal concrete. The test variables were molarities of sodium hydroxide(NaOH) 8M,14M and 16M, ratio of
NaOH to sodium silicate (Na2SiO3) 1, 1.5, 2 and 2.5, alkaline liquid to fly ash ratio 0.35 and 0.40 and replacement of water in
Na2SiO3 solution by 10%, 20% and 30% were used in the present study. The test results indicated that the highest compressive
strength 54 MPa was observed for 16M of NaOH, ratio of NaOH to Na2SiO3 2.5 and alkaline liquid to fly ash ratio of 0.35. Lowest
compressive strength of 27 MPa was observed for 8M of NaOH, ratio of NaOH to Na2SiO3 is 1 and alkaline liquid to fly ash ratio of
0.40. Alkaline liquid to fly ash ratio of 0.35, water replacement of 10% and 30% for 8 and 16 molarity of NaOH and has resulted in
compressive strength of 36 MPa and 20 MPa respectively. Superplasticiser dosage of 2 % by weight of fly ash has given higher
strength in all cases.
Keywords: compressive strength, alkaline liquid, fly ash
Experimental investigation on circular hollow steel columns in filled with li...eSAT Journals
Abstract
Composite Circular hollow Steel tubes with and without GFRP infill for three different grades of Light weight concrete are tested for
ultimate load capacity and axial shortening , under Cyclic loading. Steel tubes are compared for different lengths, cross sections and
thickness. Specimens were tested separately after adopting Taguchi’s L9 (Latin Squares) Orthogonal array in order to save the initial
experimental cost on number of specimens and experimental duration. Analysis was carried out using ANN (Artificial Neural
Network) technique with the assistance of Mini Tab- a statistical soft tool. Comparison for predicted, experimental & ANN output is
obtained from linear regression plots. From this research study, it can be concluded that *Cross sectional area of steel tube has most
significant effect on ultimate load carrying capacity, *as length of steel tube increased- load carrying capacity decreased & *ANN
modeling predicted acceptable results. Thus ANN tool can be utilized for predicting ultimate load carrying capacity for composite
columns.
Keywords: Light weight concrete, GFRP, Artificial Neural Network, Linear Regression, Back propagation, orthogonal
Array, Latin Squares
Experimental behavior of circular hsscfrc filled steel tubular columns under ...eSAT Journals
This document summarizes an experimental study that tested circular concrete-filled steel tube columns with varying parameters. 45 specimens were tested with different fiber percentages (0-2%), tube diameter-to-wall-thickness ratios (D/t from 15-25), and length-to-diameter (L/d) ratios (from 2.97-7.04). The results found that columns filled with fiber-reinforced concrete exhibited higher stiffness, equal ductility, and enhanced energy absorption compared to those filled with plain concrete. The load carrying capacity increased with fiber content up to 1.5% but not at 2.0%. The analytical predictions of failure load closely matched the experimental values.
Evaluation of punching shear in flat slabseSAT Journals
Abstract
Flat-slab construction has been widely used in construction today because of many advantages that it offers. The basic philosophy in
the design of flat slab is to consider only gravity forces; this method ignores the effect of punching shear due to unbalanced moments
at the slab column junction which is critical. An attempt has been made to generate generalized design sheets which accounts both
punching shear due to gravity loads and unbalanced moments for cases (a) interior column; (b) edge column (bending perpendicular
to shorter edge); (c) edge column (bending parallel to shorter edge); (d) corner column. These design sheets are prepared as per
codal provisions of IS 456-2000. These design sheets will be helpful in calculating the shear reinforcement to be provided at the
critical section which is ignored in many design offices. Apart from its usefulness in evaluating punching shear and the necessary
shear reinforcement, the design sheets developed will enable the designer to fix the depth of flat slab during the initial phase of the
design.
Keywords: Flat slabs, punching shear, unbalanced moment.
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Analsis of very fast transient over voltages in gas insulated substations
1. IJRET: International Journal of Research in Engineering and Technology ISSN: 2319-1163
__________________________________________________________________________________________
Volume: 01 Issue: 03 | Nov-2012, Available @ http://www.ijret.org 415
ANALSIS OF VERY FAST TRANSIENT OVER VOLTAGES IN GAS
INSULATED SUBSTATIONS
A.Raghu Ram1
, Kamakshaiah2
1 Associate Professor, Department of EEE, JNTUH college of engineering, AP, India, raghuram_a@yahoo.co.in
2 professor (Retd.), Department of EEE, JNTUH College of engineering, AP, India
Abstract
Due to the opening or closing of circuit breakers and disconnect switches in Gas Insulated Substations (GIS), Very Fast Transient
Over-voltages (VFTO) are generated. This paper describes the 500 kV and 750 kV GIS of power system. The variations of VFTO
magnitudes at different points in 500 kV and 750 kV GIS during different switching operations have been calculated and compared by
using Matlab/Simulink.
In this paper the effective factors on the level of VFTO is investigated and the beneficial approaches for the industry to finding the
optimum approaches for VFT mitigation is presented. These factors are included residual charges, resistance, spark resistance and
entrance capacitance of transformer.
Index Terms: Gas Insulated Substation, Very Fast Transient Over voltages, Matlab/Simulink.
-----------------------------------------------------------------------***-----------------------------------------------------------------------
1. INTRODUCTION
The increase in demand for electricity and growing energy
density in metropolitan cities have made it necessary to extend
the existing high voltage networks right up to the consumers .
Stepping down the voltage from transmission to the
distribution level at the substation located near the actual
consumers not only produces economic advantages, but also
ensures reliable power supply. The following are the main
reasons for use of gas insulated substation,GIS has small
ground space requirements. Gas insulated Substations have
easy maintenance (nearly zero Maintenance) Less field
erection time & less erection cost. For underground power
house of Hydro electric power project where space constraint
is a major issue
This paper describes the 500 kV and 750 kV GIS of the power
system. The variations of VFTO magnitudes at different points
in 500 kV and 750 kV GIS during different switching
operations have been calculated and compared by using
Matlab/Simulink.
Very Fast Transients (VFT) belong to highest frequency range
of transients in power systems. These transients are originated
within a gas-insulated substation (GIS) any time there is an
instantaneous change in voltage. This generally occurs as the
result of the opening or closing of a disconnect switch, but
other events, such as the operation of a circuit breaker, the
closing of a grounding switch, or the occurrence of a fault, can
also cause VFT. These transients have a very short rise time,
in the range of 4 to 100 ns, and are normally followed by
oscillations having frequencies in the range of 1 to 50 MHz.
During the operation of the DS, a small capacitor connecting
to the breaker will be switched. The velocity of DS contacts is
small (generally more than 0.6s), before the completely
switching, the arc reignition or prestrike occurs, which is the
main cause of VFTO. Figure.1. shows the equivalent circuit of
VFTO during switching operation
Fig -1: The Equivalent Circuit of VFTO during switching
operation
Ls is the system equivalent reactance, Cs is the capacitor of
system, DL is the circuit breaker, Cm is the bus capacitor and
Rm is the leaking resistor of the bus.
During a dis connector operation a number of prestrikes-
restrikes occur due to the relatively low speed of the moving
contact. During closing as the contacts approach, the electric
field between them will rise until sparking occurs. The first
2. IJRET: International Journal of Research in Engineering and Technology ISSN: 2319-1163
__________________________________________________________________________________________
Volume: 01 Issue: 03 | Nov-2012, Available @ http://www.ijret.org 416
strike will almost occur at the crest of the power frequency
voltage, due to the slow operating speed. T here after
current will flow through the spark and charge the capacitive
load to the source voltage. As it does, the potential difference
across the contacts falls and the spark will extinguish.
2. EQUIVALENT MODELS
The quality of the simulation depends on the quality of the
model of each individual GIS component. In order to achieve
reasonable results even for longer time periods of some
microseconds or for very complex GIS structures highly
accurate models for each of the internal equipment and also
for components connected to the GIS are necessary. Due to
travelling wave nature of VFT, modeling of GIS components
make use of electrical equivalent circuits composed of lumped
elements and distributed parameters lines.
A GIS system comprising of an input cable, circuit breakers,
Dis-connector Switch, Bus bar, power transformer, surge
arrester. To simulate the Very Fast Transient over voltages
occur at Disconnect switch in GIS, Matlab is used. The
equivalent circuit of GIS is shown in figure 2.
Power transformer with bushing can be modeled by entrance
Capacitance where entrance capacitance has been calculated in
lightning test. Here the entrance capacitance of power
transformer should be kept as a 5000pF. The surge impedance
of a transmission Line is 350Ω and travel time is 300m/µs.
The GIS Bus Bar can be represented as a lossless π- line for a
50 Hz frequency. The surge impedance is 80 Ω and travel time
is 231m/µs [2]. The Cable can be represented as a lossless π-
line for a 50 Hz frequency. The surge impedance is 68.8 Ω
and travel time is 103.8m/µs. Metal Oxide surge arresters are
used to protect medium and high voltage systems and
equipment against lightning and switching over-voltages.
The surge impedance of a transmission line can be obtained
from the relation
60ln
b
Z
a
Ω
Capacitance
2
ln
o r
C
b
a
Inductance
ln
2
b
aL
H
Fig -2: The Equivalent Circuit used for simulation
The MO Arrester obeys the equation
I KV
, α>1
1
( ) ii i
i
ref ref
V I
K
V I
Where,
I current through arrester
V voltage across arrester
K ceramic constant (depending on arrester type)
α nonlinearity exponent (measure of nonlinearity).
The Characteristics of surge arresters are showed in Table 1
and Table 2
Table -1: Characteristics of 444kV surge arrester
Current(A) Voltage(kV)
0.003 20000.0
628.0 1161.0
3. IJRET: International Journal of Research in Engineering and Technology ISSN: 2319-1163
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Volume: 01 Issue: 03 | Nov-2012, Available @ http://www.ijret.org 417
Table -2: Characteristics of 420 kV surge arrester
Current(A) Voltage(kV)
0.008 594.0
20.0 674.5
10000 932.0
3. RESULTS AND DISCUSSIONS
Against the difference of switch operation mode and their
position in GIS sub-station, we take three conditions to
calculate Very Fast Transient Over-voltages [VFTO]. Such
operation mode has two forms when opened and closed. When
open recovery voltage between contacts is much higher and
VFTO is higher correspondingly since the other contacts have
residual charges. So followed operations are pointed to opened
operation of DS.
A. VFTO caused by DS-50543.
When the Disconnect switch-50543 is opened before that the
switches DS-50546 and CB-5054 are already opened then the
VFTO level at Different points is shown in Table 3&4.
1) For 500 kV GIS
Source voltage is 550 kV.
Table -3: VFTO caused by operating of DS-50543 for 500kV
GIS
Voltage to
ground of
bus-bar(kV)
V14s 535.1
V15s 572.4
V17s 706.3
Voltage to
ground of surge
arrester (kV)
V11UA 548.5
V12UA 630.7
V13UA 0.031
Voltage to
ground of
Transformer
(kV)
VTR1 472.5
VTR3 476.1
VTR4 473.2
From data in table 3, we know that when opening of DS-
50543 the maximal voltage to ground of bus bar near the
switch reaches 1.73p.u.;the maximal voltage to ground of
surge arrester reaches 1.54p.u.;the maximal voltage to ground
of transformer reaches 1.16p.u.and the corresponding results
are as follows.
Fig -3: Voltage to ground of bus bar at 14S.
Fig -4: Voltage to ground of bus bar at 17S
Fig -5: Voltage to ground of surge arrester at the end of
transformer unit3&4
Fig -6: Voltage to ground of surge arrester at the end of
transformer unit6
4. IJRET: International Journal of Research in Engineering and Technology ISSN: 2319-1163
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Volume: 01 Issue: 03 | Nov-2012, Available @ http://www.ijret.org 418
Fig -7 : Voltage to ground of transformer at unit 3
Fig -8: Voltage to ground of transformer at unit 4
2) For 750 kV GIS
Source voltage is 750 kV.
Table-4: VFTO caused by operating of DS-50543 for 750kV
GIS
From data in table 4, we know that when opening of DS-
50543 the maximal voltage to ground of bus bar near the
switch reaches 1.57p.u; the maximal voltage to ground of
surge arrester reaches 1.40p.u.;the maximal voltage to ground
of transformer reaches 1.06p.u.and the corresponding results
are as follows.
Fig -9: Voltage to ground of bus bar at 14S.
Fig -10: Voltage to ground of bus bar at 17S
Fig -11: Voltage to ground of surge arrester at the end of
transformer unit3&4
Fig -12: Voltage to ground of surge arrester at the end of
transformer unit6
Voltage to ground
of bus bar (kV)
V14s 729.7
V15s 780.5
V17s 963.1
Voltage to ground
of surge arrester
(kV)
V11UA 748
V12UA 860.1
V13UA 0.032
Voltage to ground
of Transformer
(kV)
VTR1 644.3
VTR3 649.3
VTR4 645.2
5. IJRET: International Journal of Research in Engineering and Technology ISSN: 2319-1163
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Volume: 01 Issue: 03 | Nov-2012, Available @ http://www.ijret.org 419
Fig -13: Voltage to ground of transformer at unit 3
Fig -14: Voltage to ground of transformer at unit 4
B. VFTO caused by DS-50121 when DS-50122 open
When the Disconnect switch-50121 is opened before that the
switches DS-50122 and CB-5012 are already opened then the
VFTO level at Different points is shown in Table 5&6.
1) For 500 kV GIS
Table-5: VFTO caused by opening of DS-50121 open for
500kV GIS
Voltage to ground of
bus bar (kV)
V14s 712.5
Voltage to ground of
surge arrester (kV)
V11UA 676
Voltage to ground of
transformer(kV)
VTR1 493.9
From data in table 5, we know that when opening of DS-
50121 level of over voltages is much higher due to few current
shunts circuit. The maximal voltage to ground of bus bar near
the switch reaches 1.75p.u;the maximal voltage to ground of
surge arrester reaches 1.65p.u.;the maximal voltage to ground
of transformer reaches 1.20p.u
2) For 750 kV GIS
Source voltage is 750 kV
Table-6: VFTO caused by opening of DS-50121 open for
750kV GIS
From data in table-6, the maximal voltage to ground of bus bar
near the switch reaches 1.58p.u;the maximal voltage to ground
of surge arrester reaches 1.50p.u.;the maximal voltage to
ground of transformer reaches 1.09p.u.
C. VFTO caused by DS-50121 when DS-50122 closed
When the Disconnect switch-50121 is opened before that the
switches DS-50122 is closed and CB-5012 is already opened
then the VFTO level at Different points is shown in Table
7&8.
1) For 500 kV GIS
Source voltage is 550 kV.
From data in table 7, we know that when DS-50122 is still
closed VFTO caused by opening DS-50121 will spread all
over 500kv GIS.
Table-7: VFTO caused by opening of DS-50121 open when
DS-50122 is closed for 500kV GIS
Voltage to ground
of bus bar (kV)
V14s 562.5
V15s 555.6
V17s 517.1
Voltage to ground
of surge arrester
(kV)
V11UA 540.4
V12UA 552.8
V13UA 512.1
Voltage to ground
of Transformer
(kV)
VTR1 470
VTR3 457.1
VTR4 457.1
VTR6 458.4
Voltage to ground of
bus bar (kV)
V14s 971.5
Voltage to ground of
surge arrester (kV)
V11UA 921.9
Voltage to ground of
transformer(kV)
VTR1 673.5
6. IJRET: International Journal of Research in Engineering and Technology ISSN: 2319-1163
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Volume: 01 Issue: 03 | Nov-2012, Available @ http://www.ijret.org 420
1) For 750 kV GIS
Source voltage is 750 kV.
From data in table 8, we know that when DS-50122 is still
closed VFTO caused by opening DS-50121 will spread all
over 750kv GIS.
Table-8: VFTO caused by opening of DS-50121 open when
DS-50122 is closed for 750kV GIS
Voltage to
ground of bus
bar (kV)
V14s 767
V15s 757.7
V17s 705.2
Voltage to
ground of surge
arrester (kV)
V11UA 736.9
V12UA 753.8
V13UA 698.4
Voltage to
ground of
Transformer (kV)
VTR1 640.9
VTR3 623.3
VTR4 623.3
VTR6 625.2
From the above tables we can observe that if we increase the
supply voltage the transient voltage levels also increased.
4. EFFECTIVE FACTORS
The level of VFTO is determined by the factors including
residual charges, series resistance, spark resistance, entrance
capacitance of transformer.
A. Influence of Residual Charges.
When DS opens on line, it may be have some charges residual
on the line that will influence the level of VFTO. Consider the
first condition i.e. when DS-50543 is opened then the residual
charges voltages of line side of transformer range from -1.0p.u
to 0.5p.u,then the VFTO levels at different points are shown in
Table 9,10,11,12
1) For 500 kV
Table-9: Simulation result of residual charges influence on
VFTO at bus bars
In table-9, we can observe that the residual charges voltage of
transformer range -1.0p.u. to 0.5p.u then the voltage to ground
of bus bar levels are decreased. The maximal voltage to
ground of bus bar at 17s range from 690.6 kV to 504.7 kV. So,
the level of VFTO decreases along with the reduction of
recovery voltage between contacts. The residual charges has
function of suppression of VFTO.
From data in table-10, we can observe that The maximal
voltage to ground of transformer at TR4 range from 469.2 kV
to 447.9 kV. So, the level of VFTO decreases
Table-10: Simulation result of residual charges influence on
VFTO at Transformers
1) For 750kV
Table-11: Simulation result of residual charges influence on
VFTO at bus bars
From data in table 11, we can observe that the maximal
voltage to ground of bus bar at 17s range from 949.9 kV to
688.2 kV. So, the level of VFTO decreases along with the
vary of residual charges. So, the residual charges has function
of suppression of VFTO.
Residual
Charges(p.u.)
VTR1
[kV]
VTR3
[kV]
VTR4
[kV]
-1.0 472.5 472.2 469.2
-0.5 464.6 464.3 462.1
0 456.6 456.5 455
0.5 448.6 448.7 447.9
Voltage to ground of Bus-bar
(kV)
Residual
Charges(p.u.)
V14s V15s V17s
-1.0 535.1 572.4 690.6
-0.5 511.5 539.4 632.6
0 488 506.5 568.7
0.5 464.4 473.7 504.7
Voltage to ground of Bus-bar
(kV)
Residual
Charges(p.u.) V14s V15s V17s
-1.0 729.7 780.5 949.9
-0.5 697.5 735.5 862.6
0 665.5 690.7 775.5
0.5 633.2 646 688.2
7. IJRET: International Journal of Research in Engineering and Technology ISSN: 2319-1163
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Volume: 01 Issue: 03 | Nov-2012, Available @ http://www.ijret.org 421
Table-12: Simulation result of residual charges influence
on VFTO at Transformers
The maximal voltage to ground of transformer at TR4 range
from 639.9 kV to 610.7 kV. So, the level of VFTO decreases.
B. Influence of Resistance
1) For 500 kV GIS
Table-13: Simulation result of resistance influence on VFTO
at bus bars
From table 13, we can observe that if the resistance is
changed from 100 Ω to 1000 Ω, then the maximal voltage to
ground of bus bar at 17S varied from 8486 MV to 849.1 MV.
So, the level of VFTO decreases along with the increasing of
resistance.
Table-14: Simulation result of resistance influence on VFTO
at Transformers
From table 14, we can observe that if the resistance is
changed from 100 Ω to 1000 Ω, then the maximal voltage to
ground of transformers at TR4 varied from 951.7 MV to 95.58
MV. So, the level of VFTO decreases along with the
increasing of resistance.
2) For 750kV
Similarly for 750kV for increasing the series resistance the
VFTO levels decreased. The simulation results are shown in
the tables 15 &16.
Table-15: Simulation result of resistance influence on VFTO
at bus bars
Table16: Simulation result of resistance influence on VFTO
at Transformers
T
a
b
l
e
-
C. INFLUENCE OF SPARK RESISTANCE
When restriking transient happens, spark resistance can have
effect on damping over voltages. Spark resistance is an
exponentially decaying resistance. Table 17, 18, 19 and 20 are
the simulation results of the spark resistance influence of
VFTO.
1) For 500 kV GIS
Source voltage is 550 kV.
From data in table 17, we can observe that if the spark
resistance is varied from 0.1 to 200 Ω then the maximum
voltage to ground of bus bar at 17s varied from 701.3 to 436.7
kV. similarly the maximum voltage to ground of transformer
Voltage to ground of
Transformer(kV)
Residual
Charges(p.u.) VTR1 VTR3 VTR4
-1.0 644.3 643.9 639.9
-0.5 633.5 633.2 630.1
0 622.6 622.5 620.5
0.5 611.8 611.8 610.7
Voltage to ground of Bus-bar
(MV)
Resistance(Ω)
V14s V15s V17s
100 3127 4373 8486
200 1564 2187 4243
300 1043 1458 2829
500 625.7 875 1698
1000 313.1 437.7 849.1
Voltage to ground of
Transformer (MV)
Resistance(Ω) VTR1 VTR3 VTR4
100 1051 1044 951.7
200 525.6 522.4 476.1
300 350.5 348.4 317.5
500 210.5 209.2 190.7
1000 105.5 104.8 95.58
Voltage to ground of Bus-bar
(MV)
Resistance(Ω)
V14s V15s V17s
100 4264 5963 11570
200 2132 2982 5786
300 1422 1988 3858
500 853.3 1193 2315
1000 427 595.9 1158
Voltage to ground of
Transformer (MV)
Resistance(Ω) VTR1 VTR3 VTR4
100 1433 1424 1298
200 715.7 712.3 649.2
300 478 475.1 433
500 287.1 285.3 260.1
1000 143.8 143 130.3
8. IJRET: International Journal of Research in Engineering and Technology ISSN: 2319-1163
__________________________________________________________________________________________
Volume: 01 Issue: 03 | Nov-2012, Available @ http://www.ijret.org 422
varied from 478.4 to 445.9 kV. So, the VFTO levels decreased
along with the increasing the spark resistance.
Table -17: Simulation result of spark resistance influence on
VFTO at bus bars
Table -18: Simulation result of spark resistance
influence on VFTO at transformers
2) For 750 kV
Table -19: Simulation result of spark resistance influence
on VFTO at bus bars
Table -20: Simulation result of spark resistance
influence on VFTO at transformers
D.INFLUENCE OF ENTRANCE CAPACITANCE
OF TRANSFORMER
The simulation results transformer entrance capacitance
influence of VFTO is shown in tables 21,22,23,24.
1) When DS-50543 opened
a) For 500 kV GIS.
Table-21:Simulation result of transformer entrance
capacitance influence on VFTO when DS-50543 opened.
Voltage to ground of
Transformer(kV)
Transformer
Entrance
Capacitance(pF)
VTR1 VTR3 VTR4
5000 453.3 458.2 456.6
10000 455.8 461.2 458.9
15000 472.4 472.2 469.2
20000 450.9 455.1 454.2
25000 448.4 452 451.9
From data in table-21, we can observe that the entrance
capacitance is changed from 5000 to 25000 pF, then the max.
voltage to ground of transformer is changed from 456.6 kV to
451.9 kV, So, the VFTO levels decreased along with the
increasing the entrance capacitance of transformer.
b) For 750 kV
Similarly in 750kV, the VFTO levels decreased along with the
increasing the entrance capacitance of transformer.
Voltage to ground of
Bus-bar (kV)
Spark
Resistance(Ω) V14s V15s V17s
0.1 537.4 574.4 701.3
25 535.1 572.4 696.7
10 528.9 566.4 683.4
50 505.9 541.9 631.5
100 477 511.2 566.6
200 419.4 449.9 436.7
Voltage to ground of
Transformer(kV)
Spark
Resistance(Ω)
VTR1 VTR3 VTR4
0.1 472.8 472.7 478.4
25 472.5 472.2 469.3
10 471.4 470.9 468.2
50 466.6 465.5 463.5
100 460.0 458.8 457.6
200 448.6 445.3 445.9
Voltage to ground of
Bus-bar (kV)
Spark
Resistance(Ω) V14s V15s V17s
0.1 732.8 783.2 956.3
25 729.7 780.5 950
10 721.3 772.4 931.9
50 689.8 738.8 861.1
100 650 697.1 772.6
200 571.9 613.4 595.5
Voltage to ground of
Transformer(kV)
Transformer
Entrance
Capacitance(pF)
VTR1 VTR3 VTR4
5000 644.2 643.9 639.8
10000 621.5 628.9 625.8
15000 618.2 624.8 622.6
20000 614.8 620.6 619.4
25000 611.5 616.4 616.2
9. IJRET: International Journal of Research in Engineering and Technology ISSN: 2319-1163
__________________________________________________________________________________________
Volume: 01 Issue: 03 | Nov-2012, Available @ http://www.ijret.org 423
Table-22: Simulation result of transformer entrance
capacitance influence on VFTO when DS-50543 opened
2) When DS-50121 opened(DS-50122 closed)
a) For 500 kV
Table-23: Simulation result of transformer entrance
capacitance influence on VFTO when DS-50543 opened
b) For 750 kV
Table-24:Simulation result of transformer entrance
capacitance influence on VFTO when DS-50543 opened
CONCLUSIONS
The 500 kV and 750 kV Gas Insulated Substation system had
been modeled and studied for VFTO‟s by using
Matlab/simulink. It can be concluded that as the source
voltage is increased the VFTO levels also increased and also
conclude that the factors residual charges, Spark resistance,
resistance and the entrance capacitance have functions of
Suppression of VFTO.
REFERENCES:
[1]. Lu Tiechen, Zhang Bo,”Calculation of Very Fast
Transient Overvoltage in GIS”, IEEE/PES Conference
on Transmission and Distribution,Vol.4,2005, pp.1-5.
[2]. J.A. Martinez, P. Chowdhuri, R. Iravani, A. Keri, D.
Povh,” Modelling guidelines for very fast transients in
Gas Insulated substations”, IEEE working group on
modeling and analysis of system transients
[3]. Christos A. Christodoulou, Fani A. Assimakopoulou,
Ioannis F. Gonos, Ioannis A. Stathopulos,”
Simulation of Metal Oxide Surge Arresters Behavior”
IEEE Transactions on High voltage, Vol.1,pp. 1862-
1866, 2008.
[4]. V. Vinod Kumar, Joy Thomas M. and M. S. Naidu,
“VFTO Computation in a 420kV GIS”, Eleventh
International Symposium on High Voltage Engineering,
(Conf. Publ. No. 467),Vol.1,pp.319-322,1999.
[5]. J. Meppelink, K. Diederich, K. Feser and D.W. Pfaff,
"Very fast transients in GIS", IEEE Transactions On
Power Delivery, vol. 4, no. 1, pp. 223-233, January
1989.
[6]. Boggs S.A., Chu F.Y and Fujimoto N., „Disconnect
Switch Induced Transients and Trapped charge in GIS‟,
IEEE Trans. PAS, Vol. PAS-101, No.10, PP.3593-
3601,1982
[7]. Y. Shibuya, S. Fuji, and N. Hosokawa, “ Analysis of
very fast transient over voltage in transformer
winding”, IEE Proc. Generation transmission and
distribution, Vol.144,No.5,1997,pp.461-468.
BIOGRAPHIES:
A. Raghu Ram, is working as an
Associate Professor in Jawaharlal
Nehru Technological University
Hyderabad, College of Engineering
since 2003. He obtained Ph.D from
JNTUH, Hyderabad, A.P, INDIA. He
has published National and
International papers in High Voltage
Engineering and areas of interest are
High Voltage Engineering and Electrical
Spark
Resistance(Ω)
VTR1
[kV]
VTR3
[kV]
VTR4
[kV]
0.1 644.7 644.6 652.4
25 644.3 643.9 639.9
10 642.8 642.2 638.4
50 636.3 634.8 632
100 628.1 625.6 624.1
200 611.7 607.2 608.1
Voltage to ground of Transformer(kV)
C (pF) VTR1 VTR3 VTR4 VTR6
5000 470 457.1 457.1 458.4
10000 458.9 449.7 449.7 451.2
15000 456.6 447 446.9 448.7
20000 454.3 444.2 444 446.3
25000 452 441.4 441.2 443.8
Voltage to ground of
Transformer(kV)
C(pF) VTR1 VTR3 VTR4 VTR6
5000 640.9 623.3 623.3 625.1
10000 625.8 613.3 613.2 615.3
15000 622.7 609.5 609.4 611.9
20000 619.5 605.7 605.5 608.6
25000 616.3 601.9 601.6 605.2