The paper presents a study on thermal behavior of a coil made of a hightemperature supercon-ducting tape representing operation of a superconducting device (for example, a transformer). Based on the results of a physical experiment, a mathematical model of superconducting coil operation under short circuit conditions at the load side was developed. Regimes of overheating by variable short circuit currents were investigated. In this case, short circuit current amplitudes ex-ceeded a critical current of a superconductor, and coil parameters (e.g. an average nonlinearity parameter of a current-voltage characteristic, a superconductor length, and others) were varied. Permissible overheating for a coil with the possibility of its return into the superconducting state after emergency conditions in a dead-time period of automatic reclosing was considered. A crite-rion for return of a superconducting device into the superconducting state within a dead-time period of automatic reclosing has been obtained.
Study of the Thermal Behavior of a Synchronous Motor With Permanent MagnetsCSCJournals
The present study deals with the thermal behavior of an electric motor used in naval propulsion. A permanent three-dimensional model based on a nodal approach was developed to predict the thermal behavior of the machine in permanent state. The various heat transfer modes playing a role (mainly the conduction, the convection and the mass transfer) are taken into account. The three dimensional developed model provides information (in terms of heat fluxes or temperatures) for the whole machine. A parametric study using this model is carried out aiming at two objectives. The first one consists in an evaluation of the influence of several factors on the temperature distribution. The second one aims at obtaining the inception of the thermal optimization and evaluating the more efficient cooling techniques or solutions.
Cable sizing to withstand short circuit currentLeonardo ENERGY
In a cable a short circuit causes very extreme stresses which are proportional to the square of the current:
• A temperature rise in the conducting components subjected to current flow such as conductor, screen, metal sheath, armour. Indirectly the temperature of adjoining insulation and protective covers also increases,
• electro-magnetic forces between the current-carrying components.
The temperature rise is important for its effect on ageing, heat pressure characteristics etc., and should be limited to a permissible short-circuit temperature. The thermo-mechanical effects of the current shall also be considered.
For a given short-circuit duty therefore the short-circuit capacity of a cable installation is to be investigated with respect to all these parameters. For multi-core cables in most instances the thermal effect - related to the magnitude of fault current and clearance time - is the critical parameter, since the cable will normally have enough mechanical strength. With single-core cables however, in addition, the mechanical effect - related to the magnitude of the peak short-circuit current - is of such significance that, next to the thermal, the mechanical with- stand of both cable and its supports is to be investigated.
Also accessories must be rated with respect to thermal and mechanical short-circuit stresses.
The short-circuit withstand of a cable system is not quantitatively defined with regard to permissible number of repeated short circuits, degree of deformation or destruction or impairment quality. It is expected, however, that a cable installation will remain safe in operation and that any deformation remains within tolerable limits even after several short circuits.
Study of the Thermal Behavior of a Synchronous Motor With Permanent MagnetsCSCJournals
The present study deals with the thermal behavior of an electric motor used in naval propulsion. A permanent three-dimensional model based on a nodal approach was developed to predict the thermal behavior of the machine in permanent state. The various heat transfer modes playing a role (mainly the conduction, the convection and the mass transfer) are taken into account. The three dimensional developed model provides information (in terms of heat fluxes or temperatures) for the whole machine. A parametric study using this model is carried out aiming at two objectives. The first one consists in an evaluation of the influence of several factors on the temperature distribution. The second one aims at obtaining the inception of the thermal optimization and evaluating the more efficient cooling techniques or solutions.
Cable sizing to withstand short circuit currentLeonardo ENERGY
In a cable a short circuit causes very extreme stresses which are proportional to the square of the current:
• A temperature rise in the conducting components subjected to current flow such as conductor, screen, metal sheath, armour. Indirectly the temperature of adjoining insulation and protective covers also increases,
• electro-magnetic forces between the current-carrying components.
The temperature rise is important for its effect on ageing, heat pressure characteristics etc., and should be limited to a permissible short-circuit temperature. The thermo-mechanical effects of the current shall also be considered.
For a given short-circuit duty therefore the short-circuit capacity of a cable installation is to be investigated with respect to all these parameters. For multi-core cables in most instances the thermal effect - related to the magnitude of fault current and clearance time - is the critical parameter, since the cable will normally have enough mechanical strength. With single-core cables however, in addition, the mechanical effect - related to the magnitude of the peak short-circuit current - is of such significance that, next to the thermal, the mechanical with- stand of both cable and its supports is to be investigated.
Also accessories must be rated with respect to thermal and mechanical short-circuit stresses.
The short-circuit withstand of a cable system is not quantitatively defined with regard to permissible number of repeated short circuits, degree of deformation or destruction or impairment quality. It is expected, however, that a cable installation will remain safe in operation and that any deformation remains within tolerable limits even after several short circuits.
Towards An Accurate Modeling of Frequency-dependent Wind Farm Components Unde...IJAPEJOURNAL
Frequency dependence complete model is set up for describing the lightning transient behavior of the wind turbines (WTs).To get an appropriate wind turbine model, a high frequency models of surge arrester protecting the boost transformer, transformer and ground electrode soil ionization are implemented. The transient responses and Ground Potential Rise (GPR) can be obtained at different locations in the WTs and connected grid in the time domain as well as in the frequency domain using Fast Fourier Transform (FFT). To check the validity of the model, Surge arresters protection level at different locations, at i.e. LV, MV and HV, is compared with ABB manufacture data sheet, Also a comparison has been made between simple and frequency dependence model of overall wind farm components using ATP/EMTP. This paper provides an accurate simulation of wind farm components under transient condition.
Compatibility Design of Non Salient Pole Synchronous Generatorijtsrd
This paper is focused design calculation of 30 MVA, 11 kV, 50 Hz, two pole non salient poles synchronous generator that use in gas turbine power plant. The choices of specific loadings are magnetic loading and electric loading are involved in that design calculation. The number of rotor slot selection main considered in order to avoid the undesirable effects of harmonics in the flux density wave forms. The rotors are cylindrical in shape having parallel slots on it to place rotor windings. The design system is compatibility based on where specific magnetic loading or specific electric loading with synchronous generator generate more electrical power and to get better performance. The relation between specific loading and volume of the generator, short circuit ratio and air gap length, comparison design data and efficiency due to load changing are mainly emphasized studying in this paper. Thant Zaw Oo | Aye Myo Thant ""Compatibility Design of Non-Salient Pole Synchronous Generator"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-4 , June 2019, URL: https://www.ijtsrd.com/papers/ijtsrd24026.pdf
Paper URL: https://www.ijtsrd.com/engineering/electrical-engineering/24026/compatibility-design-of-non-salient-pole-synchronous-generator/thant-zaw-oo
Harmonic currents can originate from systems that do not contain energy and in which the sign of the current matches that of the voltage throughout the cycle (e.g. a phase-angle controller for an incandescent lamp). The term ‘wattless current’ is sometimes applied to harmonic currents that do not have substantial voltage harmonics of the same orders to multiply them. The result is a product of current and voltage that is zero. Those harmonic currents have a lot in common with reactive currents and therefore it is possible to combat both reactive power and harmonics by similar means. This publication explains how it can be accomplished effectively and how dedicated filters can be created for individual frequencies.
In addition to the general principles and guidelines, this paper tackles the importance of using high-quality components for accurate filter tuning. It discusses whether to compensate centrally or dispersed, and how to choose the inductor for a given L/C ratio. Finally, it warns that special caution must be taken to (i) prevent the filtering out of sound frequencies used by utilities, and (ii) that despite filtering, harmonics should still be taken into account for rating cables and equipment.
Design and Simulation of Array of Rectangular Micro Cantilevers Piezoelectric...IJERA Editor
This paper presents the design, analysis and simulation of MEMS based array of bimorph rectangular microcantilever piezoelectric energy harvester structure with and without tip mass, to analyze their sensitivity. The microcantilever beams are made up of piezoelectric material and Aluminium as a substrate material. The analytical simulation of design is done by FEM (COMSOL Multiphysics). The simulation results of bimorph cantilever structure, applied force of 0.1 N and obtained end displacement and electric potential developed are given. The analytical model of the cantilever beam will be analyzed and the process of its construction will be discussed. The changes in the sensitivity of a cantilever beam with respect to change in its shape for the same applied force of 0.1N are denoted.
TRANSFORMER WINDING DEFORMATION ANALYSIS USING SFRA TECHNIQUEJournal For Research
The sweep rate response analysis is wide used technique for establish veiled fault and circumstance observance of power electrical device. The action is administrated by provide a coffee voltage signal of changeable frequencies to the electrical device windings and measures each the input and output signals. These 2 signals provide the specified response of the magnitude relation is named the transfer operate of the electrical device from that each the magnitude and section may be obtained. Frequency response is modification as deliberate by SFRA techniques might indicate a state change within the electrical device, so causes of fault recognized and examination is needed for root cause analysis.
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.
The transducer whose resistance varies because of the environmental effects such type of transducer is known as the resistive transducer. The change in resistance is measured by the ac or dc measuring devices. The resistive transducer is used for measuring the physical quantities like temperature, displacement, vibration etc.
The measurement of the physical quantity is quite difficult. The resistive transducer converts the physical quantities into variable resistance which is easily measured by the meters. The process of variation in resistance is widely used in the industrial applications.
The resistive transducer can work both as the primary as well as the secondary transducer. The primary transducer changes the physical quantities into a mechanical signal, and secondary transducer directly transforms it into an electrical signal.
Working Principle of Resistive Transducer
The resistive transducer element works on the principle that the resistance of the element is directly proportional to the length of the conductor and inversely proportional to the area of the conductor. equation-1
Where R – resistance in ohms.
A – cross-section area of the conductor in meter square.
L – Length of the conductor in meter square.
ρ – the resistivity of the conductor in materials in ohm meter.
The resistive transducer is designed by considering the variation of the length, area and resistivity of the metal.
Applications of Resistive Transducer
The following are the applications of the resistive transducer.
Potentiometer – The translation and rotatory potentiometer are the examples of the resistive transducers. The resistance of their conductor varies with the variation in their lengths which is used for the measurement of displacement.
Strain gauges – The resistance of their semiconductor material changes when the strain occurs on it. This property of metals is used for the measurement of the pressure, force-displacement etc.
Resistance Thermometer – The resistance of the metals changes because of changes in temperature. This property of conductor is used for measuring the temperature.
Thermistor – It works on the principle that the temperature coefficient of the thermistor material varies with the temperature. The thermistor has the negative temperature coefficient. The Negative temperature coefficient means the temperature is inversely proportional to resistance.
This presentation gives the information about:electrical resistance strain gauges, covering syllabus of Unit-1, Sub: Experimental stress analysis for BE course.
Circuit-based method for extracting the resistive leakage current of metal ox...journalBEEI
Resistive leakage current based condition assessment of metal oxide surge arrester (MOSA) is one of the most extensively employed technique to monitor its degradation. An extraction method is customarily required to extract the resistive component from the total leakage current. The existing methods to extract the resistive current are complex and less accurate. Therefore, this paper describes a simple and accurate circuit-based method to extract the resistive current using equivalent model and measured leakage current of the arrester. The accuracy of the proposed method is validated through experimental results on ABB’s 120 kV surge arrester, EMTP and QuickField software simulations. The performance of the method is also analyzed and verified experimentally on 72, 180 and 240 kV rated ABB’s surge arresters. The obtained results of resistive leakage current have shown the maximum error of 0.001%. Simple and easier computational steps with higher accuracy are the key benefits of the proposed technique.
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
Discussion of Bioelectrodes, types of electrodes, their materials, bio potentials and their electrodes used. Special electrodes and their designs are discussed.
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.
ethodology for determining the parameters of hightemperature superconducting...IJECEIAES
This paper substantiates a new adaptive method for determining parameters of high-temperature superconducting power transformers with current limiting function. The main focus is the design of current-limiting superconducting windings in the light of new restrictions on current density, magnetic induction, critical current and critical temperature. The presented method considers the nature of alternating current (AC) losses in a superconductor under nominal operating conditions, features of the dielectric medium (liquid nitrogen), as well as the reduced values of the short-circuit voltage (0.5 to 1.5%). The main design features of high-temperature superconducting (HTS) transformers are specified, and a prototype of a three-phase HTS transformer of 63 kVA with a short-circuit current limiting function is developed. It is shown that HTS units have some advantages over conventional transformers: a 90 to 95% active losses reduction, short-circuit current limitation function, explosion and fire safety, a 60% reduction in weight and size, and increased efficiency (up to 99.8%). Experimental studies confirm that the short-circuit current limitation function is safe and efficient. It is demonstrated that during the short-circuit current limitation, significant heat flows occur on the windings, which should not exceed the critical value above which the superconductor could not return to the superconducting state by itself.
Towards An Accurate Modeling of Frequency-dependent Wind Farm Components Unde...IJAPEJOURNAL
Frequency dependence complete model is set up for describing the lightning transient behavior of the wind turbines (WTs).To get an appropriate wind turbine model, a high frequency models of surge arrester protecting the boost transformer, transformer and ground electrode soil ionization are implemented. The transient responses and Ground Potential Rise (GPR) can be obtained at different locations in the WTs and connected grid in the time domain as well as in the frequency domain using Fast Fourier Transform (FFT). To check the validity of the model, Surge arresters protection level at different locations, at i.e. LV, MV and HV, is compared with ABB manufacture data sheet, Also a comparison has been made between simple and frequency dependence model of overall wind farm components using ATP/EMTP. This paper provides an accurate simulation of wind farm components under transient condition.
Compatibility Design of Non Salient Pole Synchronous Generatorijtsrd
This paper is focused design calculation of 30 MVA, 11 kV, 50 Hz, two pole non salient poles synchronous generator that use in gas turbine power plant. The choices of specific loadings are magnetic loading and electric loading are involved in that design calculation. The number of rotor slot selection main considered in order to avoid the undesirable effects of harmonics in the flux density wave forms. The rotors are cylindrical in shape having parallel slots on it to place rotor windings. The design system is compatibility based on where specific magnetic loading or specific electric loading with synchronous generator generate more electrical power and to get better performance. The relation between specific loading and volume of the generator, short circuit ratio and air gap length, comparison design data and efficiency due to load changing are mainly emphasized studying in this paper. Thant Zaw Oo | Aye Myo Thant ""Compatibility Design of Non-Salient Pole Synchronous Generator"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-4 , June 2019, URL: https://www.ijtsrd.com/papers/ijtsrd24026.pdf
Paper URL: https://www.ijtsrd.com/engineering/electrical-engineering/24026/compatibility-design-of-non-salient-pole-synchronous-generator/thant-zaw-oo
Harmonic currents can originate from systems that do not contain energy and in which the sign of the current matches that of the voltage throughout the cycle (e.g. a phase-angle controller for an incandescent lamp). The term ‘wattless current’ is sometimes applied to harmonic currents that do not have substantial voltage harmonics of the same orders to multiply them. The result is a product of current and voltage that is zero. Those harmonic currents have a lot in common with reactive currents and therefore it is possible to combat both reactive power and harmonics by similar means. This publication explains how it can be accomplished effectively and how dedicated filters can be created for individual frequencies.
In addition to the general principles and guidelines, this paper tackles the importance of using high-quality components for accurate filter tuning. It discusses whether to compensate centrally or dispersed, and how to choose the inductor for a given L/C ratio. Finally, it warns that special caution must be taken to (i) prevent the filtering out of sound frequencies used by utilities, and (ii) that despite filtering, harmonics should still be taken into account for rating cables and equipment.
Design and Simulation of Array of Rectangular Micro Cantilevers Piezoelectric...IJERA Editor
This paper presents the design, analysis and simulation of MEMS based array of bimorph rectangular microcantilever piezoelectric energy harvester structure with and without tip mass, to analyze their sensitivity. The microcantilever beams are made up of piezoelectric material and Aluminium as a substrate material. The analytical simulation of design is done by FEM (COMSOL Multiphysics). The simulation results of bimorph cantilever structure, applied force of 0.1 N and obtained end displacement and electric potential developed are given. The analytical model of the cantilever beam will be analyzed and the process of its construction will be discussed. The changes in the sensitivity of a cantilever beam with respect to change in its shape for the same applied force of 0.1N are denoted.
TRANSFORMER WINDING DEFORMATION ANALYSIS USING SFRA TECHNIQUEJournal For Research
The sweep rate response analysis is wide used technique for establish veiled fault and circumstance observance of power electrical device. The action is administrated by provide a coffee voltage signal of changeable frequencies to the electrical device windings and measures each the input and output signals. These 2 signals provide the specified response of the magnitude relation is named the transfer operate of the electrical device from that each the magnitude and section may be obtained. Frequency response is modification as deliberate by SFRA techniques might indicate a state change within the electrical device, so causes of fault recognized and examination is needed for root cause analysis.
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.
The transducer whose resistance varies because of the environmental effects such type of transducer is known as the resistive transducer. The change in resistance is measured by the ac or dc measuring devices. The resistive transducer is used for measuring the physical quantities like temperature, displacement, vibration etc.
The measurement of the physical quantity is quite difficult. The resistive transducer converts the physical quantities into variable resistance which is easily measured by the meters. The process of variation in resistance is widely used in the industrial applications.
The resistive transducer can work both as the primary as well as the secondary transducer. The primary transducer changes the physical quantities into a mechanical signal, and secondary transducer directly transforms it into an electrical signal.
Working Principle of Resistive Transducer
The resistive transducer element works on the principle that the resistance of the element is directly proportional to the length of the conductor and inversely proportional to the area of the conductor. equation-1
Where R – resistance in ohms.
A – cross-section area of the conductor in meter square.
L – Length of the conductor in meter square.
ρ – the resistivity of the conductor in materials in ohm meter.
The resistive transducer is designed by considering the variation of the length, area and resistivity of the metal.
Applications of Resistive Transducer
The following are the applications of the resistive transducer.
Potentiometer – The translation and rotatory potentiometer are the examples of the resistive transducers. The resistance of their conductor varies with the variation in their lengths which is used for the measurement of displacement.
Strain gauges – The resistance of their semiconductor material changes when the strain occurs on it. This property of metals is used for the measurement of the pressure, force-displacement etc.
Resistance Thermometer – The resistance of the metals changes because of changes in temperature. This property of conductor is used for measuring the temperature.
Thermistor – It works on the principle that the temperature coefficient of the thermistor material varies with the temperature. The thermistor has the negative temperature coefficient. The Negative temperature coefficient means the temperature is inversely proportional to resistance.
This presentation gives the information about:electrical resistance strain gauges, covering syllabus of Unit-1, Sub: Experimental stress analysis for BE course.
Circuit-based method for extracting the resistive leakage current of metal ox...journalBEEI
Resistive leakage current based condition assessment of metal oxide surge arrester (MOSA) is one of the most extensively employed technique to monitor its degradation. An extraction method is customarily required to extract the resistive component from the total leakage current. The existing methods to extract the resistive current are complex and less accurate. Therefore, this paper describes a simple and accurate circuit-based method to extract the resistive current using equivalent model and measured leakage current of the arrester. The accuracy of the proposed method is validated through experimental results on ABB’s 120 kV surge arrester, EMTP and QuickField software simulations. The performance of the method is also analyzed and verified experimentally on 72, 180 and 240 kV rated ABB’s surge arresters. The obtained results of resistive leakage current have shown the maximum error of 0.001%. Simple and easier computational steps with higher accuracy are the key benefits of the proposed technique.
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
Discussion of Bioelectrodes, types of electrodes, their materials, bio potentials and their electrodes used. Special electrodes and their designs are discussed.
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.
ethodology for determining the parameters of hightemperature superconducting...IJECEIAES
This paper substantiates a new adaptive method for determining parameters of high-temperature superconducting power transformers with current limiting function. The main focus is the design of current-limiting superconducting windings in the light of new restrictions on current density, magnetic induction, critical current and critical temperature. The presented method considers the nature of alternating current (AC) losses in a superconductor under nominal operating conditions, features of the dielectric medium (liquid nitrogen), as well as the reduced values of the short-circuit voltage (0.5 to 1.5%). The main design features of high-temperature superconducting (HTS) transformers are specified, and a prototype of a three-phase HTS transformer of 63 kVA with a short-circuit current limiting function is developed. It is shown that HTS units have some advantages over conventional transformers: a 90 to 95% active losses reduction, short-circuit current limitation function, explosion and fire safety, a 60% reduction in weight and size, and increased efficiency (up to 99.8%). Experimental studies confirm that the short-circuit current limitation function is safe and efficient. It is demonstrated that during the short-circuit current limitation, significant heat flows occur on the windings, which should not exceed the critical value above which the superconductor could not return to the superconducting state by itself.
Simulation and Results of Static Var Compensator for Electric Arc Furnace No ...ijtsrd
Electric arc furnace is unbalanced, nonlinear and time varying loads, which can cause many problems in the power system. Voltage variation problem is the major focus of the power system because the loads can vary anytime. Power quality issue has a very high attractive for power system engineers and try to solve these problems by several effective ways. In this thesis, Static Var Compensator SVC , thyristor controlled reactor compensation with thyristor switched capacitor TCR TSC type is designed and its performance is simulated in the case studies. This unique design of this device SVC is used for reactive power compensation for nonlinear loads such as electric arc furnace EAF in an industrial plant. Moreover, the SVC is more effectively enhance the voltage stability. Single tuned passive harmonic filter can reduce total harmonic distortion THD caused by thyristor controlled reactor of SVC. The installation site for this thesis is No. 1 Iron and Steel Mill, Pyin Oo Lwin. And then, data is taken from this Steel Mill. Simulation results will be provided by using MATLAB SIMULINK. Dr. Thet Mon Aye "Simulation and Results of Static Var Compensator for Electric Arc Furnace (No 1 Iron and Steel Mill, Pyin Oo Lwin, Myanmar)" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd26613.pdfPaper URL: https://www.ijtsrd.com/engineering/electrical-engineering/26613/simulation-and-results-of-static-var-compensator-for-electric-arc-furnace-no-1-iron-and-steel-mill-pyin-oo-lwin-myanmar/dr-thet-mon-aye
Hotspot temperature analysis of distribution transformer under unbalanced har...IJECEIAES
In an electrical power distribution system, harmonic distortion is the most prominent power quality problem that causes long-term adverse effects such as failure of distribution transformers. Considering that most transformer problems are caused by heat losses due to the presence of harmonics, it was decided to use a numerical method with the highest accuracy, finite element method (FEM) to analyze the hot spot temperature (HST) of the thermal distribution transformer model. Through the use of COMSOL Multiphysics software, three phases of unbalanced harmonic loads are considered, which contribute to three different total harmonic distortion current (THDI) levels and five different insulation temperature classes. Using the IEEE C57.1102018 guidance, the simulation outputs are then verified with HST results from the HST mathematical model. The findings indicated that with the increased loadings, the unbalanced harmonic currents have impacted the HST increment and distinguished the HST values between the phases.
The purpose of this paper is to study and design of 230 kV twin bundle double circuit overhead transmission line. In design consideration, the selection of economic voltage, choice of conductor size, number of insulators, maximum sag of conductor and minimum height of conductor are considered. The electrical transfer of energy from one place to another over long distance with standard regulations is one of the major problems in the field of electrical power engineering. The parameters of overhead transmission line are resistance, inductance and capacitance. The bundle conductors are used for reducing the reactance on the line, corona losses, radio interference and surge impedance. Daw Hnin Yu Lwin | U Hla Myo Htay "Design of 230 kV Twin Bundle Double Circuit Overhead Transmission Line" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd27830.pdfPaper URL: https://www.ijtsrd.com/engineering/electrical-engineering/27830/design-of-230-kv-twin-bundle-double-circuit-overhead-transmission-line/daw-hnin-yu-lwin
PROJECT DESCRIPTION
DOWNLOAD
The main objective of this project is to develop a device for wireless power transfer. The concept of wireless power transfer was realized by Nikolas tesla. Wireless power transfer can make a remarkable change in the field of the electrical engineering which eliminates the use conventional copper cables and current carrying wires.
Based on this concept, the project is developed to transfer power within a small range. This project can be used for charging batteries those are physically not possible to be connected electrically such as pace makers (An electronic device that works in place of a defective heart valve) implanted in the body that runs on a battery.
The patient is required to be operated every year to replace the battery. This project is designed to charge a rechargeable battery wirelessly for the purpose. Since charging of the battery is not possible to be demonstrated, we are providing a DC fan that runs through wireless power.
This project is built upon using an electronic circuit which converts AC 230V 50Hz to AC 12V, High frequency. The output is fed to a tuned coil forming as primary of an air core transformer. The secondary coil develops a voltage of HF 12volt.
Thus the transfer of power is done by the primary(transmitter) to the secondary that is separated with a considerable distance(say 3cm). Therefore the transfer could be seen as the primary transmits and the secondary receives the power to run load.
Moreover this technique can be used in number of applications, like to charge a mobile phone, iPod, laptop battery, propeller clock wirelessly. And also this kind of charging provides a far lower risk of electrical shock as it would be galvanically isolated.
PROJECT DESCRIPTION
DOWNLOAD
The main objective of this project is to develop a device for wireless power transfer. The concept of wireless power transfer was realized by Nikolas tesla. Wireless power transfer can make a remarkable change in the field of the electrical engineering which eliminates the use conventional copper cables and current carrying wires.
Based on this concept, the project is developed to transfer power within a small range. This project can be used for charging batteries those are physically not possible to be connected electrically such as pace makers (An electronic device that works in place of a defective heart valve) implanted in the body that runs on a battery.
The patient is required to be operated every year to replace the battery. This project is designed to charge a rechargeable battery wirelessly for the purpose. Since charging of the battery is not possible to be demonstrated, we are providing a DC fan that runs through wireless power.
This project is built upon using an electronic circuit which converts AC 230V 50Hz to AC 12V, High frequency. The output is fed to a tuned coil forming as primary of an air core transformer. The secondary coil develops a voltage of HF 12volt.
Thus the transfer of power is done by the primary(transmitter) to the secondary that is separated with a considerable distance(say 3cm). Therefore the transfer could be seen as the primary transmits and the secondary receives the power to run load.
Moreover this technique can be used in number of applications, like to charge a mobile phone, iPod, laptop battery, propeller clock wirelessly. And also this kind of charging provides a far lower risk of electrical shock as it would be galvanically isolated.
Central Electric Field and Threshold Voltage in Accumulation Mode Junctionles...IJECEIAES
Transfer characteristics is presented using analytical potential distribution of accumulation-mode junctionless cylindrical surrounding-gate (JLCSG) MOSFET, and deviation of center electric field at threshold voltage is analyzed for channel length and oxide thickness. Threshold voltages presented in this paper is good agreement with results of other compared papers, and transfer characteristics is agreed with those of two-dimensional simulation. The most important factor to determine threshold voltage is center electric field at source because the greater part of electron flows through center axis of JLCSG MOSFET. As a result of analysis for center electric field at threshold voltage, center electric field is decreased with reduction of channel length due to drain induced barrier lowering. Center electric field is increased with decrease of oxide thickness, and deviation of center electric field for channel length is significantly occurred with decrease of oxide thickness.
IJRET-V1I2P1 -Measurement and FEMM Modelling of Experimentally Generated Stro...ISAR Publications
This work presents correlations between experimentally generated magnetic field strengths and computationally modeled field strengths. The experimental set-up comprised a C-shape structure designed to generate strong magnetic field strengths. The sections of the C-structure were individual solenoids made from copper-wound low carbon steel. These sections were connected such that the overall structure formed a continuous conduit for the magnetic flux and concentrated the magnetic field into an air gap. This experimental set-up could be used for magnetic annealing, or alternatively to measure the magnetostrictive strain properties of suitable materials, placed in the air gap. Magnetic field strengths of approximately 1.0 Tesla (T) were measured using a magnetic field strength meter. Finite Element Method Magnetics (FEMM) computational modeling software was used to model the design and predict field strengths. Modeled field strengths fell short of practical measurements. The efficiency of the apparatus in producing high fields is reduced due to effects related to drilling and machining of the steel core. Other reasons for discrepancies include the configuration of the C-shape, the properties of the core material, and skin effects. By building these considerations into the FEMM model, a more accurate representation of the workings of the C-shape set-up was achieved.
Development of magnetic pulse crimping process for highdurability connection ...IJERA Editor
Generally, hand-operated and hydraulic compressors use crimping of connection terminals. However, this equipment often causes compressed defects because non-uniform pressure is applied in the circumferential direction of the terminal during crimping. A defective terminal often leads to fire in electric equipment due to overheating. Therefore, there is a need to develop a new crimping process for manufacturing highly durable terminals. MPC (magnetic pulse crimping) uses uniform electromagnetic pressure by a high magnetic field interaction between coil and terminal. This process uses only electromagnetic pressure for crimping, so the terminal can be crimped without physical contact, thereby producing a highly durable connection terminal. In this study, a MPC process was developed to fabricate a prototypical terminal. The result was compared with other crimping processes in terms of durability. The crimped part using MPC has a lower rising temperature and higher tensile strength than those using other crimping process. It is inferred from the experimental results that an optimal charging voltage exists in the MPC process
Resonant-tunneling-diode effect in Si-based double-barrier structure sputtere...IJRES Journal
This paper presents the resonant-tunneling-diode (RTD) effect in a SiO2/n-Si/SiO2/p-Si double-barrier structural thin films fabricated using radio frequency (RF) magnetron sputtering at room temperature (300 K). The implementation of a circuit prototype is first accomplished by modulating a Si-based RTD with a solar-cell bias voltage. The important electrical properties of the peak current density and peak-to-valley current ratio (PVCR) are 184 nA/cm2 and 1.67, respectively. The connection between the two RTDs in series is biased by a solar cell. The value of the switching transition time is 24.37 μs; oscillation occurs with an operating frequency of 41.6 KHz. In semiconductor applications, the developed RTD is characterized by stability, enduring environmentally elevated temperature and relative humidity.
HEAT ABSORPTION IN FLUID USING INDUCTION HEATING TECHNOLOGYelelijjournal
Induction heating (IH) is a technique of heating electrically conducting materials by the application of electromagnetic induction.The heat generated in the object using eddy current itself in the object , instead of by an external heat source via heat conduction. This technique obeys contactless heating. Using this technique objects can be heated very rapidly. Ferromagnetic material and its alloys like iron, stainless steel responds best to induction heating. This technique has good efficiency up to 94%. This technique is in practice at industries for annealing, brazing, welding, melting of metals. Due to the large evolution in technology this technique became much popular food processing at day to day life.
Analysis of Modeling of Current Differential ProtectionIJPEDS-IAES
Analysis of transients in longitudinal differential protection schemes is given
basing on results obtained by simulation. Simulation diagram for modeling
differential protection with current transformers with non-linear cores is
proposed. Main shortcomings of using current transformers as measuring
transducers are shown. Solutions of the problem revealed are proposed.
Fea of pcb multilayer stack up high voltage planar transformer for aerospace...elelijjournal
High voltage planar transformer is a technology which can replace conventional transformer with its distinct advantages of saturation and cost efficiency. This paper includes, study and solution methods for PCB winding configuration in planar magnetic elements with multilayer
stack up of PCB Cu-tracks, producing High voltage power supply for aerospace application.With finite element analysis (FEA) simulations, different simulation outcomes are discussed for inspecting flux intensity and current density distribution with computing Electric field strength
and Magnetic fields. In principal conclusion of study, complete analysis and some practical design guidelines for
multilayer PCB stack up are discussed in this paper.
Similar to A Study of Thermal Behaviour of HTS Devices at Alternating Current (20)
Bibliometric analysis highlighting the role of women in addressing climate ch...IJECEIAES
Fossil fuel consumption increased quickly, contributing to climate change
that is evident in unusual flooding and draughts, and global warming. Over
the past ten years, women's involvement in society has grown dramatically,
and they succeeded in playing a noticeable role in reducing climate change.
A bibliometric analysis of data from the last ten years has been carried out to
examine the role of women in addressing the climate change. The analysis's
findings discussed the relevant to the sustainable development goals (SDGs),
particularly SDG 7 and SDG 13. The results considered contributions made
by women in the various sectors while taking geographic dispersion into
account. The bibliometric analysis delves into topics including women's
leadership in environmental groups, their involvement in policymaking, their
contributions to sustainable development projects, and the influence of
gender diversity on attempts to mitigate climate change. This study's results
highlight how women have influenced policies and actions related to climate
change, point out areas of research deficiency and recommendations on how
to increase role of the women in addressing the climate change and
achieving sustainability. To achieve more successful results, this initiative
aims to highlight the significance of gender equality and encourage
inclusivity in climate change decision-making processes.
Voltage and frequency control of microgrid in presence of micro-turbine inter...IJECEIAES
The active and reactive load changes have a significant impact on voltage
and frequency. In this paper, in order to stabilize the microgrid (MG) against
load variations in islanding mode, the active and reactive power of all
distributed generators (DGs), including energy storage (battery), diesel
generator, and micro-turbine, are controlled. The micro-turbine generator is
connected to MG through a three-phase to three-phase matrix converter, and
the droop control method is applied for controlling the voltage and
frequency of MG. In addition, a method is introduced for voltage and
frequency control of micro-turbines in the transition state from gridconnected mode to islanding mode. A novel switching strategy of the matrix
converter is used for converting the high-frequency output voltage of the
micro-turbine to the grid-side frequency of the utility system. Moreover,
using the switching strategy, the low-order harmonics in the output current
and voltage are not produced, and consequently, the size of the output filter
would be reduced. In fact, the suggested control strategy is load-independent
and has no frequency conversion restrictions. The proposed approach for
voltage and frequency regulation demonstrates exceptional performance and
favorable response across various load alteration scenarios. The suggested
strategy is examined in several scenarios in the MG test systems, and the
simulation results are addressed.
Enhancing battery system identification: nonlinear autoregressive modeling fo...IJECEIAES
Precisely characterizing Li-ion batteries is essential for optimizing their
performance, enhancing safety, and prolonging their lifespan across various
applications, such as electric vehicles and renewable energy systems. This
article introduces an innovative nonlinear methodology for system
identification of a Li-ion battery, employing a nonlinear autoregressive with
exogenous inputs (NARX) model. The proposed approach integrates the
benefits of nonlinear modeling with the adaptability of the NARX structure,
facilitating a more comprehensive representation of the intricate
electrochemical processes within the battery. Experimental data collected
from a Li-ion battery operating under diverse scenarios are employed to
validate the effectiveness of the proposed methodology. The identified
NARX model exhibits superior accuracy in predicting the battery's behavior
compared to traditional linear models. This study underscores the
importance of accounting for nonlinearities in battery modeling, providing
insights into the intricate relationships between state-of-charge, voltage, and
current under dynamic conditions.
Smart grid deployment: from a bibliometric analysis to a surveyIJECEIAES
Smart grids are one of the last decades' innovations in electrical energy.
They bring relevant advantages compared to the traditional grid and
significant interest from the research community. Assessing the field's
evolution is essential to propose guidelines for facing new and future smart
grid challenges. In addition, knowing the main technologies involved in the
deployment of smart grids (SGs) is important to highlight possible
shortcomings that can be mitigated by developing new tools. This paper
contributes to the research trends mentioned above by focusing on two
objectives. First, a bibliometric analysis is presented to give an overview of
the current research level about smart grid deployment. Second, a survey of
the main technological approaches used for smart grid implementation and
their contributions are highlighted. To that effect, we searched the Web of
Science (WoS), and the Scopus databases. We obtained 5,663 documents
from WoS and 7,215 from Scopus on smart grid implementation or
deployment. With the extraction limitation in the Scopus database, 5,872 of
the 7,215 documents were extracted using a multi-step process. These two
datasets have been analyzed using a bibliometric tool called bibliometrix.
The main outputs are presented with some recommendations for future
research.
Use of analytical hierarchy process for selecting and prioritizing islanding ...IJECEIAES
One of the problems that are associated to power systems is islanding
condition, which must be rapidly and properly detected to prevent any
negative consequences on the system's protection, stability, and security.
This paper offers a thorough overview of several islanding detection
strategies, which are divided into two categories: classic approaches,
including local and remote approaches, and modern techniques, including
techniques based on signal processing and computational intelligence.
Additionally, each approach is compared and assessed based on several
factors, including implementation costs, non-detected zones, declining
power quality, and response times using the analytical hierarchy process
(AHP). The multi-criteria decision-making analysis shows that the overall
weight of passive methods (24.7%), active methods (7.8%), hybrid methods
(5.6%), remote methods (14.5%), signal processing-based methods (26.6%),
and computational intelligent-based methods (20.8%) based on the
comparison of all criteria together. Thus, it can be seen from the total weight
that hybrid approaches are the least suitable to be chosen, while signal
processing-based methods are the most appropriate islanding detection
method to be selected and implemented in power system with respect to the
aforementioned factors. Using Expert Choice software, the proposed
hierarchy model is studied and examined.
Enhancing of single-stage grid-connected photovoltaic system using fuzzy logi...IJECEIAES
The power generated by photovoltaic (PV) systems is influenced by
environmental factors. This variability hampers the control and utilization of
solar cells' peak output. In this study, a single-stage grid-connected PV
system is designed to enhance power quality. Our approach employs fuzzy
logic in the direct power control (DPC) of a three-phase voltage source
inverter (VSI), enabling seamless integration of the PV connected to the
grid. Additionally, a fuzzy logic-based maximum power point tracking
(MPPT) controller is adopted, which outperforms traditional methods like
incremental conductance (INC) in enhancing solar cell efficiency and
minimizing the response time. Moreover, the inverter's real-time active and
reactive power is directly managed to achieve a unity power factor (UPF).
The system's performance is assessed through MATLAB/Simulink
implementation, showing marked improvement over conventional methods,
particularly in steady-state and varying weather conditions. For solar
irradiances of 500 and 1,000 W/m2
, the results show that the proposed
method reduces the total harmonic distortion (THD) of the injected current
to the grid by approximately 46% and 38% compared to conventional
methods, respectively. Furthermore, we compare the simulation results with
IEEE standards to evaluate the system's grid compatibility.
Enhancing photovoltaic system maximum power point tracking with fuzzy logic-b...IJECEIAES
Photovoltaic systems have emerged as a promising energy resource that
caters to the future needs of society, owing to their renewable, inexhaustible,
and cost-free nature. The power output of these systems relies on solar cell
radiation and temperature. In order to mitigate the dependence on
atmospheric conditions and enhance power tracking, a conventional
approach has been improved by integrating various methods. To optimize
the generation of electricity from solar systems, the maximum power point
tracking (MPPT) technique is employed. To overcome limitations such as
steady-state voltage oscillations and improve transient response, two
traditional MPPT methods, namely fuzzy logic controller (FLC) and perturb
and observe (P&O), have been modified. This research paper aims to
simulate and validate the step size of the proposed modified P&O and FLC
techniques within the MPPT algorithm using MATLAB/Simulink for
efficient power tracking in photovoltaic systems.
Adaptive synchronous sliding control for a robot manipulator based on neural ...IJECEIAES
Robot manipulators have become important equipment in production lines, medical fields, and transportation. Improving the quality of trajectory tracking for
robot hands is always an attractive topic in the research community. This is a
challenging problem because robot manipulators are complex nonlinear systems
and are often subject to fluctuations in loads and external disturbances. This
article proposes an adaptive synchronous sliding control scheme to improve trajectory tracking performance for a robot manipulator. The proposed controller
ensures that the positions of the joints track the desired trajectory, synchronize
the errors, and significantly reduces chattering. First, the synchronous tracking
errors and synchronous sliding surfaces are presented. Second, the synchronous
tracking error dynamics are determined. Third, a robust adaptive control law is
designed,the unknown components of the model are estimated online by the neural network, and the parameters of the switching elements are selected by fuzzy
logic. The built algorithm ensures that the tracking and approximation errors
are ultimately uniformly bounded (UUB). Finally, the effectiveness of the constructed algorithm is demonstrated through simulation and experimental results.
Simulation and experimental results show that the proposed controller is effective with small synchronous tracking errors, and the chattering phenomenon is
significantly reduced.
Remote field-programmable gate array laboratory for signal acquisition and de...IJECEIAES
A remote laboratory utilizing field-programmable gate array (FPGA) technologies enhances students’ learning experience anywhere and anytime in embedded system design. Existing remote laboratories prioritize hardware access and visual feedback for observing board behavior after programming, neglecting comprehensive debugging tools to resolve errors that require internal signal acquisition. This paper proposes a novel remote embeddedsystem design approach targeting FPGA technologies that are fully interactive via a web-based platform. Our solution provides FPGA board access and debugging capabilities beyond the visual feedback provided by existing remote laboratories. We implemented a lab module that allows users to seamlessly incorporate into their FPGA design. The module minimizes hardware resource utilization while enabling the acquisition of a large number of data samples from the signal during the experiments by adaptively compressing the signal prior to data transmission. The results demonstrate an average compression ratio of 2.90 across three benchmark signals, indicating efficient signal acquisition and effective debugging and analysis. This method allows users to acquire more data samples than conventional methods. The proposed lab allows students to remotely test and debug their designs, bridging the gap between theory and practice in embedded system design.
Detecting and resolving feature envy through automated machine learning and m...IJECEIAES
Efficiently identifying and resolving code smells enhances software project quality. This paper presents a novel solution, utilizing automated machine learning (AutoML) techniques, to detect code smells and apply move method refactoring. By evaluating code metrics before and after refactoring, we assessed its impact on coupling, complexity, and cohesion. Key contributions of this research include a unique dataset for code smell classification and the development of models using AutoGluon for optimal performance. Furthermore, the study identifies the top 20 influential features in classifying feature envy, a well-known code smell, stemming from excessive reliance on external classes. We also explored how move method refactoring addresses feature envy, revealing reduced coupling and complexity, and improved cohesion, ultimately enhancing code quality. In summary, this research offers an empirical, data-driven approach, integrating AutoML and move method refactoring to optimize software project quality. Insights gained shed light on the benefits of refactoring on code quality and the significance of specific features in detecting feature envy. Future research can expand to explore additional refactoring techniques and a broader range of code metrics, advancing software engineering practices and standards.
Smart monitoring technique for solar cell systems using internet of things ba...IJECEIAES
Rapidly and remotely monitoring and receiving the solar cell systems status parameters, solar irradiance, temperature, and humidity, are critical issues in enhancement their efficiency. Hence, in the present article an improved smart prototype of internet of things (IoT) technique based on embedded system through NodeMCU ESP8266 (ESP-12E) was carried out experimentally. Three different regions at Egypt; Luxor, Cairo, and El-Beheira cities were chosen to study their solar irradiance profile, temperature, and humidity by the proposed IoT system. The monitoring data of solar irradiance, temperature, and humidity were live visualized directly by Ubidots through hypertext transfer protocol (HTTP) protocol. The measured solar power radiation in Luxor, Cairo, and El-Beheira ranged between 216-1000, 245-958, and 187-692 W/m 2 respectively during the solar day. The accuracy and rapidity of obtaining monitoring results using the proposed IoT system made it a strong candidate for application in monitoring solar cell systems. On the other hand, the obtained solar power radiation results of the three considered regions strongly candidate Luxor and Cairo as suitable places to build up a solar cells system station rather than El-Beheira.
An efficient security framework for intrusion detection and prevention in int...IJECEIAES
Over the past few years, the internet of things (IoT) has advanced to connect billions of smart devices to improve quality of life. However, anomalies or malicious intrusions pose several security loopholes, leading to performance degradation and threat to data security in IoT operations. Thereby, IoT security systems must keep an eye on and restrict unwanted events from occurring in the IoT network. Recently, various technical solutions based on machine learning (ML) models have been derived towards identifying and restricting unwanted events in IoT. However, most ML-based approaches are prone to miss-classification due to inappropriate feature selection. Additionally, most ML approaches applied to intrusion detection and prevention consider supervised learning, which requires a large amount of labeled data to be trained. Consequently, such complex datasets are impossible to source in a large network like IoT. To address this problem, this proposed study introduces an efficient learning mechanism to strengthen the IoT security aspects. The proposed algorithm incorporates supervised and unsupervised approaches to improve the learning models for intrusion detection and mitigation. Compared with the related works, the experimental outcome shows that the model performs well in a benchmark dataset. It accomplishes an improved detection accuracy of approximately 99.21%.
Developing a smart system for infant incubators using the internet of things ...IJECEIAES
This research is developing an incubator system that integrates the internet of things and artificial intelligence to improve care for premature babies. The system workflow starts with sensors that collect data from the incubator. Then, the data is sent in real-time to the internet of things (IoT) broker eclipse mosquito using the message queue telemetry transport (MQTT) protocol version 5.0. After that, the data is stored in a database for analysis using the long short-term memory network (LSTM) method and displayed in a web application using an application programming interface (API) service. Furthermore, the experimental results produce as many as 2,880 rows of data stored in the database. The correlation coefficient between the target attribute and other attributes ranges from 0.23 to 0.48. Next, several experiments were conducted to evaluate the model-predicted value on the test data. The best results are obtained using a two-layer LSTM configuration model, each with 60 neurons and a lookback setting 6. This model produces an R 2 value of 0.934, with a root mean square error (RMSE) value of 0.015 and a mean absolute error (MAE) of 0.008. In addition, the R 2 value was also evaluated for each attribute used as input, with a result of values between 0.590 and 0.845.
A review on internet of things-based stingless bee's honey production with im...IJECEIAES
Honey is produced exclusively by honeybees and stingless bees which both are well adapted to tropical and subtropical regions such as Malaysia. Stingless bees are known for producing small amounts of honey and are known for having a unique flavor profile. Problem identified that many stingless bees collapsed due to weather, temperature and environment. It is critical to understand the relationship between the production of stingless bee honey and environmental conditions to improve honey production. Thus, this paper presents a review on stingless bee's honey production and prediction modeling. About 54 previous research has been analyzed and compared in identifying the research gaps. A framework on modeling the prediction of stingless bee honey is derived. The result presents the comparison and analysis on the internet of things (IoT) monitoring systems, honey production estimation, convolution neural networks (CNNs), and automatic identification methods on bee species. It is identified based on image detection method the top best three efficiency presents CNN is at 98.67%, densely connected convolutional networks with YOLO v3 is 97.7%, and DenseNet201 convolutional networks 99.81%. This study is significant to assist the researcher in developing a model for predicting stingless honey produced by bee's output, which is important for a stable economy and food security.
A trust based secure access control using authentication mechanism for intero...IJECEIAES
The internet of things (IoT) is a revolutionary innovation in many aspects of our society including interactions, financial activity, and global security such as the military and battlefield internet. Due to the limited energy and processing capacity of network devices, security, energy consumption, compatibility, and device heterogeneity are the long-term IoT problems. As a result, energy and security are critical for data transmission across edge and IoT networks. Existing IoT interoperability techniques need more computation time, have unreliable authentication mechanisms that break easily, lose data easily, and have low confidentiality. In this paper, a key agreement protocol-based authentication mechanism for IoT devices is offered as a solution to this issue. This system makes use of information exchange, which must be secured to prevent access by unauthorized users. Using a compact contiki/cooja simulator, the performance and design of the suggested framework are validated. The simulation findings are evaluated based on detection of malicious nodes after 60 minutes of simulation. The suggested trust method, which is based on privacy access control, reduced packet loss ratio to 0.32%, consumed 0.39% power, and had the greatest average residual energy of 0.99 mJoules at 10 nodes.
Fuzzy linear programming with the intuitionistic polygonal fuzzy numbersIJECEIAES
In real world applications, data are subject to ambiguity due to several factors; fuzzy sets and fuzzy numbers propose a great tool to model such ambiguity. In case of hesitation, the complement of a membership value in fuzzy numbers can be different from the non-membership value, in which case we can model using intuitionistic fuzzy numbers as they provide flexibility by defining both a membership and a non-membership functions. In this article, we consider the intuitionistic fuzzy linear programming problem with intuitionistic polygonal fuzzy numbers, which is a generalization of the previous polygonal fuzzy numbers found in the literature. We present a modification of the simplex method that can be used to solve any general intuitionistic fuzzy linear programming problem after approximating the problem by an intuitionistic polygonal fuzzy number with n edges. This method is given in a simple tableau formulation, and then applied on numerical examples for clarity.
The performance of artificial intelligence in prostate magnetic resonance im...IJECEIAES
Prostate cancer is the predominant form of cancer observed in men worldwide. The application of magnetic resonance imaging (MRI) as a guidance tool for conducting biopsies has been established as a reliable and well-established approach in the diagnosis of prostate cancer. The diagnostic performance of MRI-guided prostate cancer diagnosis exhibits significant heterogeneity due to the intricate and multi-step nature of the diagnostic pathway. The development of artificial intelligence (AI) models, specifically through the utilization of machine learning techniques such as deep learning, is assuming an increasingly significant role in the field of radiology. In the realm of prostate MRI, a considerable body of literature has been dedicated to the development of various AI algorithms. These algorithms have been specifically designed for tasks such as prostate segmentation, lesion identification, and classification. The overarching objective of these endeavors is to enhance diagnostic performance and foster greater agreement among different observers within MRI scans for the prostate. This review article aims to provide a concise overview of the application of AI in the field of radiology, with a specific focus on its utilization in prostate MRI.
Seizure stage detection of epileptic seizure using convolutional neural networksIJECEIAES
According to the World Health Organization (WHO), seventy million individuals worldwide suffer from epilepsy, a neurological disorder. While electroencephalography (EEG) is crucial for diagnosing epilepsy and monitoring the brain activity of epilepsy patients, it requires a specialist to examine all EEG recordings to find epileptic behavior. This procedure needs an experienced doctor, and a precise epilepsy diagnosis is crucial for appropriate treatment. To identify epileptic seizures, this study employed a convolutional neural network (CNN) based on raw scalp EEG signals to discriminate between preictal, ictal, postictal, and interictal segments. The possibility of these characteristics is explored by examining how well timedomain signals work in the detection of epileptic signals using intracranial Freiburg Hospital (FH), scalp Children's Hospital Boston-Massachusetts Institute of Technology (CHB-MIT) databases, and Temple University Hospital (TUH) EEG. To test the viability of this approach, two types of experiments were carried out. Firstly, binary class classification (preictal, ictal, postictal each versus interictal) and four-class classification (interictal versus preictal versus ictal versus postictal). The average accuracy for stage detection using CHB-MIT database was 84.4%, while the Freiburg database's time-domain signals had an accuracy of 79.7% and the highest accuracy of 94.02% for classification in the TUH EEG database when comparing interictal stage to preictal stage.
Analysis of driving style using self-organizing maps to analyze driver behaviorIJECEIAES
Modern life is strongly associated with the use of cars, but the increase in acceleration speeds and their maneuverability leads to a dangerous driving style for some drivers. In these conditions, the development of a method that allows you to track the behavior of the driver is relevant. The article provides an overview of existing methods and models for assessing the functioning of motor vehicles and driver behavior. Based on this, a combined algorithm for recognizing driving style is proposed. To do this, a set of input data was formed, including 20 descriptive features: About the environment, the driver's behavior and the characteristics of the functioning of the car, collected using OBD II. The generated data set is sent to the Kohonen network, where clustering is performed according to driving style and degree of danger. Getting the driving characteristics into a particular cluster allows you to switch to the private indicators of an individual driver and considering individual driving characteristics. The application of the method allows you to identify potentially dangerous driving styles that can prevent accidents.
Hyperspectral object classification using hybrid spectral-spatial fusion and ...IJECEIAES
Because of its spectral-spatial and temporal resolution of greater areas, hyperspectral imaging (HSI) has found widespread application in the field of object classification. The HSI is typically used to accurately determine an object's physical characteristics as well as to locate related objects with appropriate spectral fingerprints. As a result, the HSI has been extensively applied to object identification in several fields, including surveillance, agricultural monitoring, environmental research, and precision agriculture. However, because of their enormous size, objects require a lot of time to classify; for this reason, both spectral and spatial feature fusion have been completed. The existing classification strategy leads to increased misclassification, and the feature fusion method is unable to preserve semantic object inherent features; This study addresses the research difficulties by introducing a hybrid spectral-spatial fusion (HSSF) technique to minimize feature size while maintaining object intrinsic qualities; Lastly, a soft-margins kernel is proposed for multi-layer deep support vector machine (MLDSVM) to reduce misclassification. The standard Indian pines dataset is used for the experiment, and the outcome demonstrates that the HSSF-MLDSVM model performs substantially better in terms of accuracy and Kappa coefficient.
Forklift Classes Overview by Intella PartsIntella Parts
Discover the different forklift classes and their specific applications. Learn how to choose the right forklift for your needs to ensure safety, efficiency, and compliance in your operations.
For more technical information, visit our website https://intellaparts.com
Courier management system project report.pdfKamal Acharya
It is now-a-days very important for the people to send or receive articles like imported furniture, electronic items, gifts, business goods and the like. People depend vastly on different transport systems which mostly use the manual way of receiving and delivering the articles. There is no way to track the articles till they are received and there is no way to let the customer know what happened in transit, once he booked some articles. In such a situation, we need a system which completely computerizes the cargo activities including time to time tracking of the articles sent. This need is fulfilled by Courier Management System software which is online software for the cargo management people that enables them to receive the goods from a source and send them to a required destination and track their status from time to time.
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
TECHNICAL TRAINING MANUAL GENERAL FAMILIARIZATION COURSEDuvanRamosGarzon1
AIRCRAFT GENERAL
The Single Aisle is the most advanced family aircraft in service today, with fly-by-wire flight controls.
The A318, A319, A320 and A321 are twin-engine subsonic medium range aircraft.
The family offers a choice of engines
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
COLLEGE BUS MANAGEMENT SYSTEM PROJECT REPORT.pdfKamal Acharya
The College Bus Management system is completely developed by Visual Basic .NET Version. The application is connect with most secured database language MS SQL Server. The application is develop by using best combination of front-end and back-end languages. The application is totally design like flat user interface. This flat user interface is more attractive user interface in 2017. The application is gives more important to the system functionality. The application is to manage the student’s details, driver’s details, bus details, bus route details, bus fees details and more. The application has only one unit for admin. The admin can manage the entire application. The admin can login into the application by using username and password of the admin. The application is develop for big and small colleges. It is more user friendly for non-computer person. Even they can easily learn how to manage the application within hours. The application is more secure by the admin. The system will give an effective output for the VB.Net and SQL Server given as input to the system. The compiled java program given as input to the system, after scanning the program will generate different reports. The application generates the report for users. The admin can view and download the report of the data. The application deliver the excel format reports. Because, excel formatted reports is very easy to understand the income and expense of the college bus. This application is mainly develop for windows operating system users. In 2017, 73% of people enterprises are using windows operating system. So the application will easily install for all the windows operating system users. The application-developed size is very low. The application consumes very low space in disk. Therefore, the user can allocate very minimum local disk space for this application.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
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safety, lower mass and dimensional parameters, possibility of continuous double overloading, reduced short
circuit losses.
However, adding the possibility of short circuit current limitation into a transformer specifies
requirements to the transformer construction caused by the features of existing regimes of the power system.
For example, SCT operation during successful automatic reclosing is of interest. In this case,
superconducting wires are overheated due to short circuit conditions with the initial short circuit current
limitation due to the rise of superconducting wire resistance. The following problem will be discussed in the
paper: which combinations of SCT winding parameters are required for the process of heating at current
limitation that it does not result in failures of normal operation of the transformer after successful short
circuit clearing in the automatic reclosing cycle.
The present study is performed with the help of the mathematical model for the process of
transformer winding overheating under short circuit conditions in the circuit based on the results of the full-
scale experiment on a small superconducting coil made of HTS wire of the 2nd generation produced by
SuperOxTM
[6]. It is assumed that processes in the coil, which represents a real transformer in a first
approximation, will be similar to processes in a large SCT. For that reason, terms “coil” and “transformer”
used in the paper will be equivalent.
2. PROBLEM DEFINITION
The starting point of the study is the investigation of the current limitation process with the use of a
coil made of a HTS tape (SuperOxTM
) having the length of 3m, width of 4mm and critical current of 80 A
(see Figure 1).
Figure 1. HTS coil connected to the power source in the polystyrene bath for liquid nitrogen filling
The full test circuit is illustrated in Figure 2. The circuit includes the load assembled from nichrome
wires and the short-circuit switch, which is represented by a common automatic circuit breaker. The
oscillogram of current in the moment of short circuit was recorded with the use of a current clamp
(see Figure 3).
The curve of current change versus time is shown as a black solid line in the oscillogram. The noisy
curve illustrates voltage drop at the coil. Curve distortion is caused by low resolution of voltage measuring by
FLUKE 435-II. Figure 3 shows that the current curve has some distortion caused by nonlinearity of the
current-voltage characteristic (the I-V curve) of the superconducting coil. The maximum value of current
reaches 132 A with limitation and 175 A without limitation. The conducted full-scale experiment and
obtained information can be used for the development of a mathematical model for a transient process in the
case of short circuit at the load side.
The oscillogram of limited current for various HTS current limiting devices given in Figure 4 [7] is
different from the oscillogram obtained during our experiment (see Figure 3). There are no any distortions
after the first half-cycle, then the signal becomes sinusoidal. It can be explained in the following way.
Current limiting devices are designed in such a manner that flowing of high values of short circuit currents
causes “jumping” over the nonlinear area of the I-V curve of a superconducting wire, then steady state
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conditions of short circuit will be fully determined by resistances of resistive materials of a current limiting
device (for example, copper of a superconducting tape). However, the present study is devoted to
investigations of thermal operating regimes of the superconducting coil in the nonlinear area of the
superconductor I-V curve.
Figure 2. Test circuit
Figure 3. Oscillogram of transient process at short circuit
on the load side
Figure 4. Operating regimes of a current limiting
device
The circuit given in Figure 2 can be described by a simple differential equation for an inductive
circuit:
(1)
where L – inductance of the superconducting coil, H; i – current in the circuit, A; U – source voltage, V; R –
load resistance or short circuit resistance, depending on the considered regime, Ohm; Rsup.c – resistance of the
superconducting coil, Ohm.
Nonlinear character of superconducting coil resistance should be considered in the equation. It
depends on the modulus of instantaneous current in accordance with the following equation derived by
transforming the I-V curve expression for a superconducting tape (by division of equation parts by current):
( ) (2)
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where Ic – current, which is conventionally chosen as a critical current for a superconductor, A. As a rule,
current is considered to be critical if electric field strength in a superconductor at this current is equal to 1
µV/cm (this criterion is proposed by a HTS tape manufacturer); E0 – voltage at the coil tape at critical current
flowing, V; n – exponent of the I-V curve of the superconducting tape. At the same time, a critical current Ic
from (2) is determined by the following equation [8]:
( ) (3)
where Ic0 – critical current in a self-field at 77 K, A; T– ambient temperature, K. It should be noted that a
critical current is considered to be equal to zero at temperatures above 90 K. Equation (3) shows that the
process of winding heating should be taken into account when developing an adequate model of current
limitation. To consider the heating process of the superconducting coil, the heat balance equation can be
formulated:
( )
(4)
where Q – the quantity of heat released in the coil passing into the resistive state at current flowing per unit
time, W; A – surface area of the coil, m2
; q – density of heat flow passing into liquid nitrogen from the coil
surface per unit time, W/m2
; СΣ – total heat capacity of the HTS coil depending on the temperature, J/K. The
quantity of heat produced during current flowing through the HTS coil can be calculated as:
( ) ∫ (5)
where tsc and tclear – time of occurrence and time of clearance of a short circuit respectively.
Density of heat flow q has a complex dependence on the temperature difference between a cooling
surface and liquid nitrogen that is illustrated in Figure 5. As is shown, if the superconducting coil is
considerably overheated, the process of heat removal will be ineffective, that will cause further overheating
up to HTS wire burnout.
Figure 5. Heat flow density versus the temperature difference between a cooling surface and
liquid nitrogen [9]
Equations (1) to (5) need to be combined into the system of equations to be solved simultaneously.
This solution can be performed numerically in Matlab Simulink. As stated before, using the proposed model,
it is necessary to determine with which combinations of regime and design parameters a superconducting
transformer can be operated well after the successful automatic reclosing cycle. In other words, it is
necessary to find such impermissible values of parameters for overheating of transformer windings that a
superconducting transformer does not return into the superconducting state after successful automatic
reclosing. It means that a winding, being heated during the transition into the normal state, could not be
cooled within the automatic reclosing cycle.
The present study aims at showing rather qualitative character of thermal processes in the HTS
device, because the developed mathematical model has been verified previously by only a current behaviour
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in the circuit with the small superconducting coil. However, some of obtained results are supposed to be
generalized to more complex devices as superconducting transformers.
The combinations of such parameters as a short circuit duration and a dead-time period determine
conditions for a transformer winding to be cooled enough after overheating by short circuit currents, then a
transformer can return into the superconducting state.
An exponent of the I-V curve of the superconducting tape has the deeper meaning. An exponent n of
the current-voltage characteristic of the superconductor determines the level of short circuit current limitation
that, evidently, will influence directly on the value of overheating. As was shown in [10], the nonlinearity
parameter of the I-V curve generally will be different in different parts of the superconducting device (e.g.
the coil). This fact is not considered in the study. The nonlinearity parameter of the I-V curve is assumed to
be of the average value along the superconducting wire. The necessity of varying values of this parameter is
determined by the hypothesis that the exponent of the I-V curve will be changed in the result of mechanical
and thermomagnetic impacts on the superconductor, thus changing the form of a current signal and,
consequently, a value of heating.
3. INFLUENCE OF THE NONLINEARITY PARAMETER OF THE I-V CURVE ON THE
LEVEL OF CURRENT LIMITATION
The aim of this section is to demonstrate that the nonlinearity parameter of the I-V curve has a
considerable influence on the level of current limitation.
The circuit given in Figure 2 can be reduced to the classical form of the single line diagram
(Figure 6). Elements of the equivalent circuit have real values determined in the physical experiment
described above. Circuit parameters and some calculated values are given in Table 1.
Figure 6. Single line equivalent circuit for simulation of short circuit at the load side
Table 1. Circuit Parameters and some Calculated Values
Circuit parameters
Source voltage amplitude Umax 5 V
Frequency of power supply voltage 50 Hz
Inductance L 8 µH
Load resistance Rload 0.45 Ohm
Short circuit resistance Rsc 0.029 Ohm
Calculated parameters
Current amplitude under normal conditions Iload 11.1 A
Short circuit current amplitude (without limitation) Isc 175 A
Isc / Iload 15.8
Solution of the system of Equations (1) to (5) with F(t) switch closing and with real test circuit
parameters gives the following current oscillogram of the transient process shown in Figure 7.
Figure 7 shows good coincidence between the curve of limited current and the experimentally
obtained curve that implicitly demonstrates the adequacy of the model. It is observed from the presented
oscillogram that current is limited from 175 A to 132 A (or the ratio Isc / Iload decreases from 15.8 to 11.9) that
corresponds to the exponent n (see Equation (2)) being equal to 15.5. It should be noted that if unlimited and
limited current is known, under all other conditions being equal, the average n can be determined for any
device made of HTS wire. Then, the dependence of the maximum current in the circuit on the n parameter
will be considered (Figure 8).
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Figure 7. Oscillogram of short circuit current with
and without current limitation
Figure 8. Maximum limited short circuit current level
versus the nonlinearity parameter of the I-V curve
Under real experimental conditions, the n parameter for HTS wires does not usually exceed 15
(being more than 30 for low-temperature superconducting wires) [11]. The curve given in Figure 8 shows
insignificant current limitation at low values of n. This fact is important because, as was stated above,
thermomagnetic and mechanical impacts may change the exponent n of the device made of HTS wires. If the
average n of the I-V curve for this device is low, the device will be inefficient in current limitation.
Then, consider the curve of the dependence of maximum overheating on the exponent n for the
specified case (Figure 9). However, it should be noted that the curve of maximum overheating has a
considerable dependence on circuit parameters, such as short circuit resistance and HTS device resistance in
the normal state. Nevertheless, the obtained curve demonstrates the explicit dependence of overheating on
nonlinearity of the I-V curve. This fact will be considered in detail below.
Figure 9. Maximum temperature of HTS device heating versus the nonlinearity parameter of the I-V curve
4. INFLUENCE OF THE DEAD-TIME PERIOD AFTER SHORT CIRCUIT CLEARING ON
THE DEGREE OF COOLING FOR A HTS DEVICE
Since a HTS transformer is intended to be used in real power systems, then its operation should not
result in the loss of power system stability. One of such regulated regimes is the cycle of automatic reclosing
which includes a dead-time period required for self-clearance of short circuit at a power transmission line.
According to [12], a time setting for the first cycle of automatic reclosing in 6-10 kV networks is usually set
to not more than 2 s. The minimum setting for these networks varies in the wide range and depends on many
factors. As a first approximation, the minimum setting is assumed to be 0.4 s.
Since the process of heat release from a winding surface is stopped in a dead-time period, a
temperature change will be fully determined by heat removal into a cooling liquid that depends on the
characteristic shown in Figure 5. Transformer cooling does not also depend on a method of preliminary
heating. In other words, it does not depend on short circuit resistance, source voltage and other parameters.
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Therefore, the task is to determine the minimum temperature for cooling of the superconducting coil
depending on the maximum temperature of preliminary heating resulting from short circuit current flowing.
Simulation of these processes will be also performed with the use of the circuit presented in Figure 6 with the
parameters from Table 1 except the short circuit resistance, Rsc, now being equal to zero. Zero short circuit
resistance gives the regime with the maximum short circuit current, and, consequently, with the maximum
coil heating.
The results of simulation are presented in Figure 10 to Figure 13. Figure 10 and Figure 11 show the
characteristics of temperature versus time with the following sequence of events:
Time t = 0..125 ms – normal regime;
125..325 ms – short circuit;
325..725 ms – short circuit clearance and the dead-time period of the automatic reclosing cycle;
725..1000 ms – successful automatic reclosing and return to steady state conditions.
Figure 10 illustrates the case of successful thermal return of the superconducting coil into the
superconducting state after 0.4 s of the dead-time period, and the characteristic of heat flow versus time.
Figure 11 shows the case of NOT RETURNING of the coil into the superconducting state.
Therefore, the question has arisen: which factors influences on the process of returning or not
returning of a supercoducting device into the superconducting state after overheating? It is evident to assume
that in the case of the constant dead-time period the success of thermal returning will depend on the
temperature reached during short circuit. In other words, it is necessary for the device to be cooled below the
specific temperature within the dead-time period. This temperature will be determined by a current amplitude
of the further steady state regime in the case of successful automatic reclosing. If it is assumed that a current
amplitude in the steady state regime does not exceed 40 A (with the critical current of the HTS coil of 80 A),
then using this value in (3) and deriving an unknown T, the required temperature for thermal returning can be
found, being equal to 85 K.
Figure 10. Characteristics of temperature (T) and heat flow density (q) versus time; thermal returning is
observed
Figure 12 and Figure 13 present characteristics of the minimum temperature reached in the dead-
time period versus the maximum temperature reached under the previous short circuit conditions. Figure 12
has the characteristic for the dead-time period of tdt = 0.4 s, while Figure 13 – for tdt = 2 s. These cases
consider two variants of the tape length in the HTS coil being equal to 3 m and 6 m.
The temperature limit required for thermal returning of the coil, made of the tape with the length of
3m, is marked with the black solid line in figures. As is shown, it is important for thermal returning of the
coil that the temperature of the previous regime (short circuit) does not exceed 100 K at the dead-time period
of 0.4s and 193 K at the dead-time period of 2s. These results are planned to be verified experimentally on
the real HTS coil shown in Figure 1.
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Figure 11. Characteristics of temperature (T) and heat flow density (q) versus time; thermal returning is not
observed
Figure 12. Characteristic of the minimum temperature
of cooling in the dead-time period versus the
maximum temperature of the preliminary winding
heating at tdt = 0.4 s
Figure 13. Characteristic of the minimum
temperature of cooling in the dead-time period
versus the maximum temperature of the preliminary
winding heating at tdt = 2 s
For comparison, Figure 12 also shows the characteristic for the coil with the tape of 6m, which is
heated slowly and cooled slowly, that is correct because the total weight of the HTS tape and, consequently,
heat capacity increases. This fact may have a positive aspect, as well as a negative aspect. On the one hand, a
large HTS device is heated slowly by currents exceeding the critical. On the other hand, it is also cooled
slowly after current interruption. Therefore, there is a problem of optimizing processes of heating and cooling
for large HTS devices, such as transformers. Discussion and solution of this optimization problem is planned
in further investigations.
5. INFLUENCE OF DIFFERENT PARAMETERS OF THE HTS DEVICE ON THE DEGREE OF
OVERHEATING
This section considers the degree of overheating for the HTS coil with variation of different
parameters of the coil and the circuit (Figure 6), and regime parameters, such as the short circuit duration.
The study will be performed by the series of calculation experiments with variation of the given parameters.
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5.1. Experiment 1 – Dependence of the maximum temperature of HTS coil overheating on the
exponent of the I-V curve and the short circuit duration
Figure 14 presents the series of surfaces representing the dependence of the maximum temperature
of coil overheating on the n parameter of the I-V curve (Equation (2)), the short circuit duration, and the short
circuit resistance. Other parameters of the circuit are presented in Table 2.
Table 2. Equivalent Circuit Parameters for Experiment 1
Source voltage amplitude Umax 5 V
Frequency of power supply voltage 50 Hz
Inductance L 8 µH
Load resistance Rload 0.45 Ohm
Short circuit resistance Rsc 0.0001 .. 0.0286 Ohm
Short circuit duration, tsc 0.1..0.2 s
Nonlinearity parameter of the I-V curve, n 1..20
Tape length of the HTS coil, m 3
Surfaces from Figure 14 are structured in a special way to demonstrate some considerable effects.
Firstly, the maximum temperature has a weak dependence on the short circuit duration almost at all surfaces
becoming stronger at last two surfaces (Rsc=0.02 Ohm and Rsc=0.0286 Ohm). This is explained by the fact
that a time constant of superconducting coil heating is smaller than the short circuit duration. When short
circuit resistance increases, current in the circuit begins decreasing. Then, energy for coil heating decreases
proportionally to the squared current, thus increasing a time constant for coil heating that determines the
dependence of the maximum temperature on the short circuit duration.
Figure 14. Characteristic of the maximum temperature of HTS coil overheating versus the exponent of the
I-V curve (n) and the short circuit duration (tsc) with various short circuit resistances (Rsc)
Secondly, the top graphs in Figure 13 illustrate the evident extremum of the maximum temperature
depending on the n parameter. This extremum is caused by complex interrelation between the current in the
circuit and the HTS coil resistance influencing each other. Their combination with the specified n results in
the maximum energy release from the HTS wire surface. The bottom graphs in Figure 14 show that the
temperature maximum is not explicitly observed. It is due to the short circuit resistance being commensurable
with the coil resistance in the resistive state. It is important to note that this maximum is shifted to the area of
higher n with the increase of the short circuit resistance.
Thirdly, it should be noted that each surface has the area of sharp temperature increase after the
specified n. If the nonlinearity parameter of the I-V curve is fixed, for example, at the level experimentally
obtained (n=15.5), the dependence of maximum temperatures on two other parameters will be as shown in
Figure 15. It can be seen that the short circuit duration at low values of Rsc does not have a great influence on
the maximum temperature, because steady-state thermal conditions are reached much faster than relay
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protection operates. At high values of short circuit resistance short circuit currents are not sufficient to cause
considerable overheating.
Figure 15. Characteristic of the maximum temperature of HTS coil overheating versus the short circuit
duration (tsc) and the short circuit resistance (Rsc) at n=15.5
However, explanations given above are correct under conditions of the real experiment for the small
coil. As for large devices, it is expected that the time constant will have greater influence on the level of
maximum temperatures, because larger devices are difficult to be heated. In addition, short circuit currents in
large devices are considerably higher.
5.2. Experiment 2 – Dependence of the maximum temperature of HTS coil overheating on the
exponent of the I-V curve and the source voltage
Consider coil behaviour under intentional overheating by high values of power taking into account
the nonlinearity parameter of the I-V curve. Regulation of the source power is performed by the change of its
voltage. Circuit parameters and regime parameters are given in Table 3. Simulation results in the form of the
surface are shown in Figure 16.
The plotted surface represents the importance of high values of n for HTS devices (in the range of
5...15), because the temperature increase in the case of the voltage rise becomes critical at low values of n
(lower than 5). This assumption should be verified at the model of a large HTS device. However,
undoubtedly, heat release will be maximum at low values of the nonlinearity parameter of the I-V curve due
to not so fast current limitation with rather fast increase of resistance.
Table 3. Equivalent Circuit Parameters for Experiment 2
Source voltage amplitude Umax 10..25 V
Frequency of power supply voltage 50 Hz
Inductance L 8 µH
Load resistance Rload 0.45 Ohm
Short circuit resistance Rsc 0.0001 Ohm
Short circuit duration, tsc 0.2 s
Nonlinearity parameter of the I-V curve, n 1..20
Tape length of the HTS coil, m 3
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Figure 16. Characteristic of the maximum temperature of HTS coil overheating versus the nonlinearity
parameter of the I-V curve and the source voltage
6. CONCLUSION
Using the physical model of current limitation with the use of the coil made of superconducting wire
SuperOxTM
, the mathematical model of the transient process in the nonlinear active-inductive circuit with
consideration of thermal heating was developed on the basis of two differential (1 and 4) and three algebraic
(2, 3 and 5) equations.
Based on the developed model, different aspects of thermal behaviour of the superconducting coil
with variation of its parameters and regime parameters in the wide range were studied. The following
conclusions can be made:
a. As shown in Section 3, based on known values of limited and NOT limited short circuit current, the
average nonlinearity parameter of the I-V curve can be uniquely determined for a superconducting
device;
b. It was shown that the level of current limitation considerably increases with the rise of the nonlinearity
parameter of the I-V curve;
c. As shown in Section 4, the possibility for returning an HTS device into the superconducting state in the
dead-time period of the automatic reclosing cycle is fully determined by cooling conditions and the
temperature reached under the previous short circuit regime;
d. The criterion for determination of the permissible temperature of overheating was proposed. It is based on
the current level in the further steady state regime (with assumption of successful automatic reclosing in
the first cycle) with the fixed dead-time period;
e. Direct influence of the nonlinearity parameter of the I-V curve on the level of maximum temperatures of
HTS device overheating was found: at low values of n, the combination of insufficient current limitation
and sufficiently increased resistance results in the maximum heat release in the HTS device. This allows
making an assumption that HTS devices with low average nonlinearity parameters of the I-V curve
should not be used for short circuit current limitation that needs to be verified by a physical experiment.
For further investigations, it is planned to adjust the proposed model by full-scale experiments, with
the consideration of the temperature change in HTS devices caused by current flowing exceeding critical
values. Statement and solution of the optimization problem is also planned based on conclusions given in
Section 3: which combination of the dead-time period and the maximum overheating temperature is
sufficient for returning an HTS device into the superconducting state.
ACKNOWLEDGEMENTS
The research was carried out under the State Assignment of the Ministry of Education and Science
of the Russian Federation, Project 8.6809.2017/8.9.
REFERENCES
[1] Amelichev V. A., “Methods of manufacture of the 2d generation HTS wire: Brief overview,” Global scientific
potential, 2012.
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[2] Fisher L. M., et al., “Superconducting fault current limiter for railway transport,” Physics of Atomic Nuclei, vol. 78,
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[8] Manusov V. Z. and Aleksandrov N. V., “Limitation of short circuit currents with the use of transformers with high
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BIOGRAPHIES OF AUTHORS
Vadim Z. Manusov. Novosibirsk State Technical University, Department of Power Supply Systems,
D. Eng, Professor. Main directions of investigations: methods of artificial intelligence for planning and
optimization of operating regimes of power systems.
E-mail: manusov@corp.nstu.ru
Dmitry O. Krjukov. Novosibirsk State Technical University, Department of Power Supply Systems,
student, Assistant of the department. Main directions of investigations: Application of superconductors
in the electric power industry
E-mail: fire-paladin@mail.ru