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.
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.
The document describes a project report on wireless power transfer submitted by a student for their Bachelor of Technology degree. It includes a cover page, certificate from the project guide, acknowledgements, declaration, table of contents, and sections describing the abstract, block diagram, hardware requirements including various electronic components, schematic diagram, hardware testing, results, future prospects, medical applications, and conclusion.
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.
A Study of Thermal Behaviour of HTS Devices at Alternating Current IJECEIAES
The paper presents a study on thermal behavior of a coil made of a hightemperature supercon-ducting tape representing operation of a superconducting device (for example, a transformer). Based on the results of a physical experiment, a mathematical model of superconducting coil operation under short circuit conditions at the load side was developed. Regimes of overheating by variable short circuit currents were investigated. In this case, short circuit current amplitudes ex-ceeded a critical current of a superconductor, and coil parameters (e.g. an average nonlinearity parameter of a current-voltage characteristic, a superconductor length, and others) were varied. Permissible overheating for a coil with the possibility of its return into the superconducting state after emergency conditions in a dead-time period of automatic reclosing was considered. A crite-rion for return of a superconducting device into the superconducting state within a dead-time period of automatic reclosing has been obtained.
High-efficiency 2.45 and 5.8 GHz dual-band rectifier design with modulated in...IJECEIAES
This document presents the design of a dual-band rectifier for radio frequency energy harvesting. The rectifier is designed to operate with both continuous wave and modulated input signals over a wide input power range without using active components. It achieves this through a Wilkinson power divider that distributes power to two branches, each with an impedance matching network and voltage doubler rectifier using different diodes suited to different power levels. Simulation results show the rectifier achieves peak efficiencies of 67.0% and 49.1% for 2.45 GHz and 5.8 GHz continuous wave signals respectively. With modulated 16QAM and 8PSK input signals, efficiencies within 3-5% of continuous wave signals are obtained, demonstrating modulated
An algorithm for selection and design of hybrid power supplies for MEMS with ...Kimberly Cook-Chennault
The document presents an algorithm for selecting and designing hybrid power supplies for microelectromechanical systems (MEMS). It evaluates three strategies for powering the Wireless Integrated Microsystems environmental monitor testbed (WIMS-EMT), a MEMS device: 1) a single power supply, 2) multiple power supplies divided by power range, and 3) flexible "power bundles" based on device space. Strategy 2 provided the best mass (0.032 kg) and volume (0.028 L) results. Strategies 2 and 3 provided the best battery lifetimes in excess of 2,000 hours. Future work will incorporate operational amplifier technologies to accommodate large voltage fluctuations and implement the algorithm into user-friendly software.
Control of Saturation level in the magnetic core of a welding transformer by ...IJERA Editor
The objective of this paper is to analyse the performances of two controllers such as Hysteresis control (HC) and proportional integral (PI) control to control saturation level in the magnetic core of a welding transformer in a middle-frequency direct current (MFDC) resistance spot welding system(RSWS). It consists of an input converter, welding transformer, and a full-wave rectifier mounted at the transformer secondary. The unequal ohmic resistances of the two transformer’s secondary circuits and the different characteristics of the diodes of output rectifier certainly lead to the magnetic core saturation which, consequently, causes the unwanted spikes in the transformer’s primary current and over-current protection switch-off. The goal is to analyse the performance of both controllers in terms of transients, total harmonic distortion(THD) and variations in primary current and flux in the magnetic core of a welding transformer of highly nonlinear system of RSWS. The simulation study has been done in Matlab/Simulink environment and presented performance analysis. The responses shows that from the aforementioned aspects, proportional integral Controller is the better choice for controlling the saturation level in magnetic core of a welding transformer which is widely used in automobile industry welding system.
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.
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.
The document describes a project report on wireless power transfer submitted by a student for their Bachelor of Technology degree. It includes a cover page, certificate from the project guide, acknowledgements, declaration, table of contents, and sections describing the abstract, block diagram, hardware requirements including various electronic components, schematic diagram, hardware testing, results, future prospects, medical applications, and conclusion.
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.
A Study of Thermal Behaviour of HTS Devices at Alternating Current IJECEIAES
The paper presents a study on thermal behavior of a coil made of a hightemperature supercon-ducting tape representing operation of a superconducting device (for example, a transformer). Based on the results of a physical experiment, a mathematical model of superconducting coil operation under short circuit conditions at the load side was developed. Regimes of overheating by variable short circuit currents were investigated. In this case, short circuit current amplitudes ex-ceeded a critical current of a superconductor, and coil parameters (e.g. an average nonlinearity parameter of a current-voltage characteristic, a superconductor length, and others) were varied. Permissible overheating for a coil with the possibility of its return into the superconducting state after emergency conditions in a dead-time period of automatic reclosing was considered. A crite-rion for return of a superconducting device into the superconducting state within a dead-time period of automatic reclosing has been obtained.
High-efficiency 2.45 and 5.8 GHz dual-band rectifier design with modulated in...IJECEIAES
This document presents the design of a dual-band rectifier for radio frequency energy harvesting. The rectifier is designed to operate with both continuous wave and modulated input signals over a wide input power range without using active components. It achieves this through a Wilkinson power divider that distributes power to two branches, each with an impedance matching network and voltage doubler rectifier using different diodes suited to different power levels. Simulation results show the rectifier achieves peak efficiencies of 67.0% and 49.1% for 2.45 GHz and 5.8 GHz continuous wave signals respectively. With modulated 16QAM and 8PSK input signals, efficiencies within 3-5% of continuous wave signals are obtained, demonstrating modulated
An algorithm for selection and design of hybrid power supplies for MEMS with ...Kimberly Cook-Chennault
The document presents an algorithm for selecting and designing hybrid power supplies for microelectromechanical systems (MEMS). It evaluates three strategies for powering the Wireless Integrated Microsystems environmental monitor testbed (WIMS-EMT), a MEMS device: 1) a single power supply, 2) multiple power supplies divided by power range, and 3) flexible "power bundles" based on device space. Strategy 2 provided the best mass (0.032 kg) and volume (0.028 L) results. Strategies 2 and 3 provided the best battery lifetimes in excess of 2,000 hours. Future work will incorporate operational amplifier technologies to accommodate large voltage fluctuations and implement the algorithm into user-friendly software.
Control of Saturation level in the magnetic core of a welding transformer by ...IJERA Editor
The objective of this paper is to analyse the performances of two controllers such as Hysteresis control (HC) and proportional integral (PI) control to control saturation level in the magnetic core of a welding transformer in a middle-frequency direct current (MFDC) resistance spot welding system(RSWS). It consists of an input converter, welding transformer, and a full-wave rectifier mounted at the transformer secondary. The unequal ohmic resistances of the two transformer’s secondary circuits and the different characteristics of the diodes of output rectifier certainly lead to the magnetic core saturation which, consequently, causes the unwanted spikes in the transformer’s primary current and over-current protection switch-off. The goal is to analyse the performance of both controllers in terms of transients, total harmonic distortion(THD) and variations in primary current and flux in the magnetic core of a welding transformer of highly nonlinear system of RSWS. The simulation study has been done in Matlab/Simulink environment and presented performance analysis. The responses shows that from the aforementioned aspects, proportional integral Controller is the better choice for controlling the saturation level in magnetic core of a welding transformer which is widely used in automobile industry welding system.
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.
Introduction gadgets have gained a lot of attention.pdfbkbk37
The document discusses the increasing need for ultra-low power electronic devices due to advances in mobile technology and the internet of things. It covers limitations in further reducing power consumption and scaling transistors according to Moore's Law. Transition metal dichalcogenides are discussed as a potential channel material for ultra-low power transistors due to their ability to achieve high ON/OFF ratios even at the monolayer level. The document also mentions using technology computer-aided design (TCAD) tools like the Quantum Transport Simulator to model and optimize new materials and device geometries.
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.
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
This paper presents a highly efficient power transfer system based on a co-design of a class-E power amplifier (PA) and a pair of inductively coupled Helical coils for through-metal-wall power transfer. Power is transferred wirelessly through a 3.1-mm thick aluminum barrier without any physical penetration and contact. Measurement results show that the class-E PA achieves a peak power gain of 25.2 dB and a maximum collector efficiency of 57.3%, all at 200 Hz. The proposed system obtains a maximum power transfer efficiency of 9% and it can deliver 5 W power to the receiver side through the aluminum barrier.
ECE 6030 Device Electronics discusses advances in low-power electronics and internet-connected devices. As transistors continue to shrink according to Moore's law, new challenges have emerged like increased OFF current. The document discusses approaches to overcoming these challenges, including new materials like transition metal dichalcogenides and their use in ultra-low power transistors. Device and circuit simulation tools are also discussed as important for optimizing new device designs without costly fabrication.
This document summarizes a research paper that proposes a solid-state transformer (S2T) using a single phase matrix converter (SPMC). The S2T aims to address limitations of conventional transformers such as size, weight, environmental issues. The proposed S2T design uses two SPMCs - one operating at 1 kHz to generate high frequency current on the primary side, and the other at 50 Hz to produce low frequency voltage on the secondary side. A switching algorithm is presented to address commutation problems when using inductive loads. The S2T design and switching control are simulated in MATLAB/Simulink. Results show the S2T design can help minimize size and losses while achieving optimal efficiency compared to conventional approaches
11.[21 28]voltage stability improvement using the 21st century power transformerAlexander Decker
This document summarizes a study on improving power system voltage stability using 21st century power transformers. The study used a 5-bus power network model to analyze how different transformer parameters affect voltage stability. It found that higher series resistance, flux leakage reactance, magnetizing conductance, and shunt conductance bring the system closer to voltage collapse. Higher shunt susceptance improves stability by moving the operating point farther from collapse. Replacing traditional transformers with cross-linked polyethylene cable-winding transformers, which have higher shunt susceptance, can enhance voltage stability.
IRJET- Evolution of a 1250-kVa Superconducting Transformer and its Exhibition...IRJET Journal
1) A three-phase 1250-kVA high temperature superconducting transformer operating at 10.5-kV and 0.4-kV has been designed and manufactured.
2) The windings are made of Bi2223 high temperature superconductor tape and the core is made of domain-refined high-induction silicon steel.
3) Testing showed the no-load loss was 2319.2 W, short-circuit impedance was 5.6% of rated value, and average load loss was 249.6 W, meeting grid requirements.
Modified dc dc converter for high input voltage applicationseSAT Journals
Abstract: This paper proposes a model for high input voltage applications using two fly-back converters. In this the components are arranged by using integrated magnetic techniques. To reduce the voltage stresses the input components are connected in series and to obtain the required output the output components are connected in parallel. The three cores of the fly-back transformers are air gaped to reduce the current spikes which are caused due to coupling and the secondary side of the transformers are inversely coupled for ripple cancellation. This is done by using a prototype which helps us to obtain output as we desired for certain input with certain transformation ratio. The components used are IGBT’s, capacitors and fly-back transformers. Keywords: Integrated magnetic techniques fly back converter, coupling, ripple reduction, interleaved operation.
This document describes a modified DC-DC converter design for high input voltage applications using two interleaved flyback converters integrated into a single magnetic core. The primary sides of the two flyback converters are connected in series to reduce voltage stresses on the primary components. The secondary sides are connected in parallel to obtain the required output voltage and for ripple cancellation. Simulation results show the output voltage and current waveforms for different firing pulse configurations. The proposed design addresses issues like current spikes caused by voltage mismatches between the secondary windings by using an air-gapped core configuration with weakened coupling between the transformers.
This document proposes and validates an equivalent circuit model for a wireless power transfer system capable of transferring 220W of power over a 30cm air gap with 95% efficiency. The model represents the transmitter and receiver coils as inductors with low mutual coupling. Analytical expressions for the model are derived and validated using finite element analysis and experimental results. Loss analysis is also performed to investigate skin effect and proximity effect losses at high operating frequencies. A new coil spatial design is proposed to reduce such losses compared to conventional coil designs.
ANALYSIS OF SOLID STATE TRANSFORMER WITH PERMANENT MAGNET SYNCHRONOUS GENERATOREditor IJMTER
In recent years the complexity of the grid systems has grown due to the increased
penetration of renewable energy and distributed generation sources. The increased complexity
requires new methods to quickly manage the changing sources and loads. This research focuses
on one of such technologies, called the SST. A SST uses power electronic devices to achieve
voltage conversion from one level to another. Several SST topologies have been proposed by
different research groups, without a clear idea on which is most suited for grid applications.To
ensure a proper choice of topology,a separate literature review is presented in this paper. The final
choice of topology is extremely modular. In this, conventional dc-dc converter of solid state transformer is replaced by SEPIC converter and the analysis is done using PMSG.
This document presents a new method for analyzing transient voltage distributions in transformer windings. It models the electric, magnetic, and current fields as equivalent circuits consisting of interconnected electric and magnetic networks.
The electric network models the voltage distribution within each winding section using resistances and emfs derived from the geometry. The magnetic network models the flux paths using reluctances, which is then converted to an equivalent inductance network. Capacitances model the electric fields within and between sections.
The electric, magnetic, and capacitance networks are coupled through ideal transformers to form a single overall mathematical model without mutual inductances. The model can analyze transient voltages inside the windings resulting from any applied terminal overvoltage waveform. An example application
This document discusses high voltage direct current (HVDC) transmission technology. It begins with a brief history of HVDC and explains the advantages it has over alternating current (AC) transmission, such as the ability to transmit power over long distances and between asynchronous AC networks. It then describes the main components of HVDC systems including converters, transmission lines, cables, and control systems. The two main types of HVDC configurations are also summarized - back-to-back converters for interconnecting AC networks and monopolar systems with ground or metallic return paths for long-distance bulk power transmission.
The conventional transformer in power infrastructure should be capable of meeting the demand for the load. The conventional transformer is structured and designed to handle high power. Also, the overload capacity of conventional transformers depends on the highest temperature and short-term overload. This paper represents the construction and working of the solid-state transformer which consists of AC to DC and DC to AC conversion which has low overload capability as compared to conventional transformers. Solid-state transformer finding applications in Solar and wind power generation electric vehicle battery management systems because of high-frequency operation, which is not possible in case of conventional transformers also smart transformer, provides flexible control of electric power distribution.
Cost savings by low-loss distribution transformers in wind power plantsLeonardo ENERGY
Highlights:
* National governments should promote energy-efficient components and provide incentives for energy-efficient measures.
* A European specification for a range of energy-efficient transformers is needed.
* The feasibility to get one EU specification should be studied.
Energy-efficient transformers should be promoted through education of customers.
* An energy-efficient transformer should be given a sensational name.
The document discusses the history and development of transformers over the past 130 years. It describes how transformers enabled the breakthrough of efficient long-distance AC power transmission systems. While the basic principle of a transformer remains unchanged, the technology has advanced tremendously, allowing for higher voltages, efficiencies, and power capacities. ABB is now the world's largest manufacturer of transformers, supplying products for power grids, buildings, industries, and transportation worldwide.
Application of single phase matrix converter topology to an uninterruptible p...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
This document summarizes a research paper on using a multilevel converter topology for AC-DC harmonic immunity in VSC HVDC transmission. Key points:
- Voltage-source converter (VSC) based HVDC systems use multilevel converters to achieve high voltage switching capabilities. Cascaded H-bridge converters allow utilization of different DC voltages on individual cells.
- Selective harmonic elimination pulse-width modulation (SHE-PWM) techniques offer the lowest possible number of switching transitions and losses for VSC HVDC. The paper discusses optimized modulation patterns providing controlled harmonic immunity between AC and DC sides for a two-level converter with a rippled DC link voltage.
- Simulation and experimental results presented confirm the
Electric Field Analysis and Impact Study with Shrubbery on the 11 kV Distribu...IRJET Journal
This document analyzes the impact of vegetation growth on 11kV distribution systems using finite element modeling (FEM). It studies two scenarios: a clean distribution line with no vegetation, and an unclean line with varying levels of tree/shrub heights from 40-100% of the pole height.
For the clean line, FEM is used to model the electric field distribution. The maximum electric field intensities on three insulators are reported. For the unclean line, increasing the tree height from 4-10 meters causes the electric field stress to rise between the top of the tree and transmission line. FEM contours show the electric field distribution increases and is more intense near the higher vegetation. Analysis of insulator 2 at
Redefining brain tumor segmentation: a cutting-edge convolutional neural netw...IJECEIAES
Medical image analysis has witnessed significant advancements with deep learning techniques. In the domain of brain tumor segmentation, the ability to
precisely delineate tumor boundaries from magnetic resonance imaging (MRI)
scans holds profound implications for diagnosis. This study presents an ensemble convolutional neural network (CNN) with transfer learning, integrating
the state-of-the-art Deeplabv3+ architecture with the ResNet18 backbone. The
model is rigorously trained and evaluated, exhibiting remarkable performance
metrics, including an impressive global accuracy of 99.286%, a high-class accuracy of 82.191%, a mean intersection over union (IoU) of 79.900%, a weighted
IoU of 98.620%, and a Boundary F1 (BF) score of 83.303%. Notably, a detailed comparative analysis with existing methods showcases the superiority of
our proposed model. These findings underscore the model’s competence in precise brain tumor localization, underscoring its potential to revolutionize medical
image analysis and enhance healthcare outcomes. This research paves the way
for future exploration and optimization of advanced CNN models in medical
imaging, emphasizing addressing false positives and resource efficiency.
Embedded machine learning-based road conditions and driving behavior monitoringIJECEIAES
Car accident rates have increased in recent years, resulting in losses in human lives, properties, and other financial costs. An embedded machine learning-based system is developed to address this critical issue. The system can monitor road conditions, detect driving patterns, and identify aggressive driving behaviors. The system is based on neural networks trained on a comprehensive dataset of driving events, driving styles, and road conditions. The system effectively detects potential risks and helps mitigate the frequency and impact of accidents. The primary goal is to ensure the safety of drivers and vehicles. Collecting data involved gathering information on three key road events: normal street and normal drive, speed bumps, circular yellow speed bumps, and three aggressive driving actions: sudden start, sudden stop, and sudden entry. The gathered data is processed and analyzed using a machine learning system designed for limited power and memory devices. The developed system resulted in 91.9% accuracy, 93.6% precision, and 92% recall. The achieved inference time on an Arduino Nano 33 BLE Sense with a 32-bit CPU running at 64 MHz is 34 ms and requires 2.6 kB peak RAM and 139.9 kB program flash memory, making it suitable for resource-constrained embedded systems.
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Similar to ethodology for determining the parameters of hightemperature superconducting power transformers with current limiting function
Introduction gadgets have gained a lot of attention.pdfbkbk37
The document discusses the increasing need for ultra-low power electronic devices due to advances in mobile technology and the internet of things. It covers limitations in further reducing power consumption and scaling transistors according to Moore's Law. Transition metal dichalcogenides are discussed as a potential channel material for ultra-low power transistors due to their ability to achieve high ON/OFF ratios even at the monolayer level. The document also mentions using technology computer-aided design (TCAD) tools like the Quantum Transport Simulator to model and optimize new materials and device geometries.
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.
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
This paper presents a highly efficient power transfer system based on a co-design of a class-E power amplifier (PA) and a pair of inductively coupled Helical coils for through-metal-wall power transfer. Power is transferred wirelessly through a 3.1-mm thick aluminum barrier without any physical penetration and contact. Measurement results show that the class-E PA achieves a peak power gain of 25.2 dB and a maximum collector efficiency of 57.3%, all at 200 Hz. The proposed system obtains a maximum power transfer efficiency of 9% and it can deliver 5 W power to the receiver side through the aluminum barrier.
ECE 6030 Device Electronics discusses advances in low-power electronics and internet-connected devices. As transistors continue to shrink according to Moore's law, new challenges have emerged like increased OFF current. The document discusses approaches to overcoming these challenges, including new materials like transition metal dichalcogenides and their use in ultra-low power transistors. Device and circuit simulation tools are also discussed as important for optimizing new device designs without costly fabrication.
This document summarizes a research paper that proposes a solid-state transformer (S2T) using a single phase matrix converter (SPMC). The S2T aims to address limitations of conventional transformers such as size, weight, environmental issues. The proposed S2T design uses two SPMCs - one operating at 1 kHz to generate high frequency current on the primary side, and the other at 50 Hz to produce low frequency voltage on the secondary side. A switching algorithm is presented to address commutation problems when using inductive loads. The S2T design and switching control are simulated in MATLAB/Simulink. Results show the S2T design can help minimize size and losses while achieving optimal efficiency compared to conventional approaches
11.[21 28]voltage stability improvement using the 21st century power transformerAlexander Decker
This document summarizes a study on improving power system voltage stability using 21st century power transformers. The study used a 5-bus power network model to analyze how different transformer parameters affect voltage stability. It found that higher series resistance, flux leakage reactance, magnetizing conductance, and shunt conductance bring the system closer to voltage collapse. Higher shunt susceptance improves stability by moving the operating point farther from collapse. Replacing traditional transformers with cross-linked polyethylene cable-winding transformers, which have higher shunt susceptance, can enhance voltage stability.
IRJET- Evolution of a 1250-kVa Superconducting Transformer and its Exhibition...IRJET Journal
1) A three-phase 1250-kVA high temperature superconducting transformer operating at 10.5-kV and 0.4-kV has been designed and manufactured.
2) The windings are made of Bi2223 high temperature superconductor tape and the core is made of domain-refined high-induction silicon steel.
3) Testing showed the no-load loss was 2319.2 W, short-circuit impedance was 5.6% of rated value, and average load loss was 249.6 W, meeting grid requirements.
Modified dc dc converter for high input voltage applicationseSAT Journals
Abstract: This paper proposes a model for high input voltage applications using two fly-back converters. In this the components are arranged by using integrated magnetic techniques. To reduce the voltage stresses the input components are connected in series and to obtain the required output the output components are connected in parallel. The three cores of the fly-back transformers are air gaped to reduce the current spikes which are caused due to coupling and the secondary side of the transformers are inversely coupled for ripple cancellation. This is done by using a prototype which helps us to obtain output as we desired for certain input with certain transformation ratio. The components used are IGBT’s, capacitors and fly-back transformers. Keywords: Integrated magnetic techniques fly back converter, coupling, ripple reduction, interleaved operation.
This document describes a modified DC-DC converter design for high input voltage applications using two interleaved flyback converters integrated into a single magnetic core. The primary sides of the two flyback converters are connected in series to reduce voltage stresses on the primary components. The secondary sides are connected in parallel to obtain the required output voltage and for ripple cancellation. Simulation results show the output voltage and current waveforms for different firing pulse configurations. The proposed design addresses issues like current spikes caused by voltage mismatches between the secondary windings by using an air-gapped core configuration with weakened coupling between the transformers.
This document proposes and validates an equivalent circuit model for a wireless power transfer system capable of transferring 220W of power over a 30cm air gap with 95% efficiency. The model represents the transmitter and receiver coils as inductors with low mutual coupling. Analytical expressions for the model are derived and validated using finite element analysis and experimental results. Loss analysis is also performed to investigate skin effect and proximity effect losses at high operating frequencies. A new coil spatial design is proposed to reduce such losses compared to conventional coil designs.
ANALYSIS OF SOLID STATE TRANSFORMER WITH PERMANENT MAGNET SYNCHRONOUS GENERATOREditor IJMTER
In recent years the complexity of the grid systems has grown due to the increased
penetration of renewable energy and distributed generation sources. The increased complexity
requires new methods to quickly manage the changing sources and loads. This research focuses
on one of such technologies, called the SST. A SST uses power electronic devices to achieve
voltage conversion from one level to another. Several SST topologies have been proposed by
different research groups, without a clear idea on which is most suited for grid applications.To
ensure a proper choice of topology,a separate literature review is presented in this paper. The final
choice of topology is extremely modular. In this, conventional dc-dc converter of solid state transformer is replaced by SEPIC converter and the analysis is done using PMSG.
This document presents a new method for analyzing transient voltage distributions in transformer windings. It models the electric, magnetic, and current fields as equivalent circuits consisting of interconnected electric and magnetic networks.
The electric network models the voltage distribution within each winding section using resistances and emfs derived from the geometry. The magnetic network models the flux paths using reluctances, which is then converted to an equivalent inductance network. Capacitances model the electric fields within and between sections.
The electric, magnetic, and capacitance networks are coupled through ideal transformers to form a single overall mathematical model without mutual inductances. The model can analyze transient voltages inside the windings resulting from any applied terminal overvoltage waveform. An example application
This document discusses high voltage direct current (HVDC) transmission technology. It begins with a brief history of HVDC and explains the advantages it has over alternating current (AC) transmission, such as the ability to transmit power over long distances and between asynchronous AC networks. It then describes the main components of HVDC systems including converters, transmission lines, cables, and control systems. The two main types of HVDC configurations are also summarized - back-to-back converters for interconnecting AC networks and monopolar systems with ground or metallic return paths for long-distance bulk power transmission.
The conventional transformer in power infrastructure should be capable of meeting the demand for the load. The conventional transformer is structured and designed to handle high power. Also, the overload capacity of conventional transformers depends on the highest temperature and short-term overload. This paper represents the construction and working of the solid-state transformer which consists of AC to DC and DC to AC conversion which has low overload capability as compared to conventional transformers. Solid-state transformer finding applications in Solar and wind power generation electric vehicle battery management systems because of high-frequency operation, which is not possible in case of conventional transformers also smart transformer, provides flexible control of electric power distribution.
Cost savings by low-loss distribution transformers in wind power plantsLeonardo ENERGY
Highlights:
* National governments should promote energy-efficient components and provide incentives for energy-efficient measures.
* A European specification for a range of energy-efficient transformers is needed.
* The feasibility to get one EU specification should be studied.
Energy-efficient transformers should be promoted through education of customers.
* An energy-efficient transformer should be given a sensational name.
The document discusses the history and development of transformers over the past 130 years. It describes how transformers enabled the breakthrough of efficient long-distance AC power transmission systems. While the basic principle of a transformer remains unchanged, the technology has advanced tremendously, allowing for higher voltages, efficiencies, and power capacities. ABB is now the world's largest manufacturer of transformers, supplying products for power grids, buildings, industries, and transportation worldwide.
Application of single phase matrix converter topology to an uninterruptible p...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
This document summarizes a research paper on using a multilevel converter topology for AC-DC harmonic immunity in VSC HVDC transmission. Key points:
- Voltage-source converter (VSC) based HVDC systems use multilevel converters to achieve high voltage switching capabilities. Cascaded H-bridge converters allow utilization of different DC voltages on individual cells.
- Selective harmonic elimination pulse-width modulation (SHE-PWM) techniques offer the lowest possible number of switching transitions and losses for VSC HVDC. The paper discusses optimized modulation patterns providing controlled harmonic immunity between AC and DC sides for a two-level converter with a rippled DC link voltage.
- Simulation and experimental results presented confirm the
Electric Field Analysis and Impact Study with Shrubbery on the 11 kV Distribu...IRJET Journal
This document analyzes the impact of vegetation growth on 11kV distribution systems using finite element modeling (FEM). It studies two scenarios: a clean distribution line with no vegetation, and an unclean line with varying levels of tree/shrub heights from 40-100% of the pole height.
For the clean line, FEM is used to model the electric field distribution. The maximum electric field intensities on three insulators are reported. For the unclean line, increasing the tree height from 4-10 meters causes the electric field stress to rise between the top of the tree and transmission line. FEM contours show the electric field distribution increases and is more intense near the higher vegetation. Analysis of insulator 2 at
Similar to ethodology for determining the parameters of hightemperature superconducting power transformers with current limiting function (20)
Redefining brain tumor segmentation: a cutting-edge convolutional neural netw...IJECEIAES
Medical image analysis has witnessed significant advancements with deep learning techniques. In the domain of brain tumor segmentation, the ability to
precisely delineate tumor boundaries from magnetic resonance imaging (MRI)
scans holds profound implications for diagnosis. This study presents an ensemble convolutional neural network (CNN) with transfer learning, integrating
the state-of-the-art Deeplabv3+ architecture with the ResNet18 backbone. The
model is rigorously trained and evaluated, exhibiting remarkable performance
metrics, including an impressive global accuracy of 99.286%, a high-class accuracy of 82.191%, a mean intersection over union (IoU) of 79.900%, a weighted
IoU of 98.620%, and a Boundary F1 (BF) score of 83.303%. Notably, a detailed comparative analysis with existing methods showcases the superiority of
our proposed model. These findings underscore the model’s competence in precise brain tumor localization, underscoring its potential to revolutionize medical
image analysis and enhance healthcare outcomes. This research paves the way
for future exploration and optimization of advanced CNN models in medical
imaging, emphasizing addressing false positives and resource efficiency.
Embedded machine learning-based road conditions and driving behavior monitoringIJECEIAES
Car accident rates have increased in recent years, resulting in losses in human lives, properties, and other financial costs. An embedded machine learning-based system is developed to address this critical issue. The system can monitor road conditions, detect driving patterns, and identify aggressive driving behaviors. The system is based on neural networks trained on a comprehensive dataset of driving events, driving styles, and road conditions. The system effectively detects potential risks and helps mitigate the frequency and impact of accidents. The primary goal is to ensure the safety of drivers and vehicles. Collecting data involved gathering information on three key road events: normal street and normal drive, speed bumps, circular yellow speed bumps, and three aggressive driving actions: sudden start, sudden stop, and sudden entry. The gathered data is processed and analyzed using a machine learning system designed for limited power and memory devices. The developed system resulted in 91.9% accuracy, 93.6% precision, and 92% recall. The achieved inference time on an Arduino Nano 33 BLE Sense with a 32-bit CPU running at 64 MHz is 34 ms and requires 2.6 kB peak RAM and 139.9 kB program flash memory, making it suitable for resource-constrained embedded systems.
Advanced control scheme of doubly fed induction generator for wind turbine us...IJECEIAES
This paper describes a speed control device for generating electrical energy on an electricity network based on the doubly fed induction generator (DFIG) used for wind power conversion systems. At first, a double-fed induction generator model was constructed. A control law is formulated to govern the flow of energy between the stator of a DFIG and the energy network using three types of controllers: proportional integral (PI), sliding mode controller (SMC) and second order sliding mode controller (SOSMC). Their different results in terms of power reference tracking, reaction to unexpected speed fluctuations, sensitivity to perturbations, and resilience against machine parameter alterations are compared. MATLAB/Simulink was used to conduct the simulations for the preceding study. Multiple simulations have shown very satisfying results, and the investigations demonstrate the efficacy and power-enhancing capabilities of the suggested control system.
Neural network optimizer of proportional-integral-differential controller par...IJECEIAES
Wide application of proportional-integral-differential (PID)-regulator in industry requires constant improvement of methods of its parameters adjustment. The paper deals with the issues of optimization of PID-regulator parameters with the use of neural network technology methods. A methodology for choosing the architecture (structure) of neural network optimizer is proposed, which consists in determining the number of layers, the number of neurons in each layer, as well as the form and type of activation function. Algorithms of neural network training based on the application of the method of minimizing the mismatch between the regulated value and the target value are developed. The method of back propagation of gradients is proposed to select the optimal training rate of neurons of the neural network. The neural network optimizer, which is a superstructure of the linear PID controller, allows increasing the regulation accuracy from 0.23 to 0.09, thus reducing the power consumption from 65% to 53%. The results of the conducted experiments allow us to conclude that the created neural superstructure may well become a prototype of an automatic voltage regulator (AVR)-type industrial controller for tuning the parameters of the PID controller.
An improved modulation technique suitable for a three level flying capacitor ...IJECEIAES
This research paper introduces an innovative modulation technique for controlling a 3-level flying capacitor multilevel inverter (FCMLI), aiming to streamline the modulation process in contrast to conventional methods. The proposed
simplified modulation technique paves the way for more straightforward and
efficient control of multilevel inverters, enabling their widespread adoption and
integration into modern power electronic systems. Through the amalgamation of
sinusoidal pulse width modulation (SPWM) with a high-frequency square wave
pulse, this controlling technique attains energy equilibrium across the coupling
capacitor. The modulation scheme incorporates a simplified switching pattern
and a decreased count of voltage references, thereby simplifying the control
algorithm.
A review on features and methods of potential fishing zoneIJECEIAES
This review focuses on the importance of identifying potential fishing zones in seawater for sustainable fishing practices. It explores features like sea surface temperature (SST) and sea surface height (SSH), along with classification methods such as classifiers. The features like SST, SSH, and different classifiers used to classify the data, have been figured out in this review study. This study underscores the importance of examining potential fishing zones using advanced analytical techniques. It thoroughly explores the methodologies employed by researchers, covering both past and current approaches. The examination centers on data characteristics and the application of classification algorithms for classification of potential fishing zones. Furthermore, the prediction of potential fishing zones relies significantly on the effectiveness of classification algorithms. Previous research has assessed the performance of models like support vector machines, naïve Bayes, and artificial neural networks (ANN). In the previous result, the results of support vector machine (SVM) were 97.6% more accurate than naive Bayes's 94.2% to classify test data for fisheries classification. By considering the recent works in this area, several recommendations for future works are presented to further improve the performance of the potential fishing zone models, which is important to the fisheries community.
Electrical signal interference minimization using appropriate core material f...IJECEIAES
As demand for smaller, quicker, and more powerful devices rises, Moore's law is strictly followed. The industry has worked hard to make little devices that boost productivity. The goal is to optimize device density. Scientists are reducing connection delays to improve circuit performance. This helped them understand three-dimensional integrated circuit (3D IC) concepts, which stack active devices and create vertical connections to diminish latency and lower interconnects. Electrical involvement is a big worry with 3D integrates circuits. Researchers have developed and tested through silicon via (TSV) and substrates to decrease electrical wave involvement. This study illustrates a novel noise coupling reduction method using several electrical involvement models. A 22% drop in electrical involvement from wave-carrying to victim TSVs introduces this new paradigm and improves system performance even at higher THz frequencies.
Electric vehicle and photovoltaic advanced roles in enhancing the financial p...IJECEIAES
Climate change's impact on the planet forced the United Nations and governments to promote green energies and electric transportation. The deployments of photovoltaic (PV) and electric vehicle (EV) systems gained stronger momentum due to their numerous advantages over fossil fuel types. The advantages go beyond sustainability to reach financial support and stability. The work in this paper introduces the hybrid system between PV and EV to support industrial and commercial plants. This paper covers the theoretical framework of the proposed hybrid system including the required equation to complete the cost analysis when PV and EV are present. In addition, the proposed design diagram which sets the priorities and requirements of the system is presented. The proposed approach allows setup to advance their power stability, especially during power outages. The presented information supports researchers and plant owners to complete the necessary analysis while promoting the deployment of clean energy. The result of a case study that represents a dairy milk farmer supports the theoretical works and highlights its advanced benefits to existing plants. The short return on investment of the proposed approach supports the paper's novelty approach for the sustainable electrical system. In addition, the proposed system allows for an isolated power setup without the need for a transmission line which enhances the safety of the electrical network
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%.
Supermarket Management System Project Report.pdfKamal Acharya
Supermarket management is a stand-alone J2EE using Eclipse Juno program.
This project contains all the necessary required information about maintaining
the supermarket billing system.
The core idea of this project to minimize the paper work and centralize the
data. Here all the communication is taken in secure manner. That is, in this
application the information will be stored in client itself. For further security the
data base is stored in the back-end oracle and so no intruders can access it.
Software Engineering and Project Management - Software Testing + Agile Method...Prakhyath Rai
Software Testing: A Strategic Approach to Software Testing, Strategic Issues, Test Strategies for Conventional Software, Test Strategies for Object -Oriented Software, Validation Testing, System Testing, The Art of Debugging.
Agile Methodology: Before Agile – Waterfall, Agile Development.
Software Engineering and Project Management - Introduction, Modeling Concepts...Prakhyath Rai
Introduction, Modeling Concepts and Class Modeling: What is Object orientation? What is OO development? OO Themes; Evidence for usefulness of OO development; OO modeling history. Modeling
as Design technique: Modeling, abstraction, The Three models. Class Modeling: Object and Class Concept, Link and associations concepts, Generalization and Inheritance, A sample class model, Navigation of class models, and UML diagrams
Building the Analysis Models: Requirement Analysis, Analysis Model Approaches, Data modeling Concepts, Object Oriented Analysis, Scenario-Based Modeling, Flow-Oriented Modeling, class Based Modeling, Creating a Behavioral Model.
Tools & Techniques for Commissioning and Maintaining PV Systems W-Animations ...Transcat
Join us for this solutions-based webinar on the tools and techniques for commissioning and maintaining PV Systems. In this session, we'll review the process of building and maintaining a solar array, starting with installation and commissioning, then reviewing operations and maintenance of the system. This course will review insulation resistance testing, I-V curve testing, earth-bond continuity, ground resistance testing, performance tests, visual inspections, ground and arc fault testing procedures, and power quality analysis.
Fluke Solar Application Specialist Will White is presenting on this engaging topic:
Will has worked in the renewable energy industry since 2005, first as an installer for a small east coast solar integrator before adding sales, design, and project management to his skillset. In 2022, Will joined Fluke as a solar application specialist, where he supports their renewable energy testing equipment like IV-curve tracers, electrical meters, and thermal imaging cameras. Experienced in wind power, solar thermal, energy storage, and all scales of PV, Will has primarily focused on residential and small commercial systems. He is passionate about implementing high-quality, code-compliant installation techniques.
Accident detection system project report.pdfKamal Acharya
The Rapid growth of technology and infrastructure has made our lives easier. The
advent of technology has also increased the traffic hazards and the road accidents take place
frequently which causes huge loss of life and property because of the poor emergency facilities.
Many lives could have been saved if emergency service could get accident information and
reach in time. Our project will provide an optimum solution to this draw back. A piezo electric
sensor can be used as a crash or rollover detector of the vehicle during and after a crash. With
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Generative AI Use cases applications solutions and implementation.pdfmahaffeycheryld
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Digital Twins Computer Networking Paper Presentation.pptxaryanpankaj78
A Digital Twin in computer networking is a virtual representation of a physical network, used to simulate, analyze, and optimize network performance and reliability. It leverages real-time data to enhance network management, predict issues, and improve decision-making processes.
ethodology for determining the parameters of hightemperature superconducting power transformers with current limiting function
1. International Journal of Electrical and Computer Engineering (IJECE)
Vol. 13, No. 1, February 2023, pp. 238~248
ISSN: 2088-8708, DOI: 10.11591/ijece.v13i1.pp238-248 238
Journal homepage: http://ijece.iaescore.com
Methodology for determining the parameters of high-
temperature superconducting power transformers with current
limiting function
Vadim Zinovievich Manusov1
, Dmitriy Mihailovich Ivanov1
, Arseniy Valerievich Semenov1
,
Gennady Viktorovich Ivanov2
1
Department of Power Supply Systems, Novosibirsk State Technical University, Novosibirsk, Russian Federation
2
Department of Radio Electronics and Electrical Engineering, Surgut State University, Surgut, Russian Federation
Article Info ABSTRACT
Article history:
Received Sep 9, 2021
Revised Aug 12, 2022
Accepted Sep 3, 2022
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.
Keywords:
Design methodology
Energy efficiency
High-temperature
superconductivity
High-temperature
superconducting transformers
Liquid nitrogen
Short-circuit current limitation
This is an open access article under the CC BY-SA license.
Corresponding Author:
Dmitriy Mihailovich Ivanov
Department of Power Supply Systems, Novosibirsk State Technical University
20, Karl Marx prospekt, Novosibirsk, 630073, Russian Federation
Email: mrdemasi123@gmail.com
1. INTRODUCTION
High-temperature superconducting (HTS) transformers are the most innovative solution when it
comes to electric power systems modernization and improved energy efficiency. The design and research of
transformers with high-temperature superconducting windings are of great interest and are described in
publications of scientists from leading world institutes [1], [2]. Attempts are made to optimize the design and
technical characteristics of HTS transformers from the side of energy efficiency, energy saving and reduction
of weight and size [3]. In [4], the results of the work of many design and research teams that developed about
20 HTS transformers in the power range of 25 to 5,000 kVA were collected and analyzed. However, despite
the considerable interest of the scientific community in HTS transformers, there are no well-founded methods
and principles of designing such electric machines. That is why developing a novel methodology for
2. Int J Elec & Comp Eng ISSN: 2088-8708
Methodology for determining the parameters of high-temperature … (Vadim Zinovievich Manusov)
239
determining parameters and designing HTS transformers, taking into account the superconductor’s particular
properties, is an important contemporary challenge.
General research approach of HTS transformers is characterized as systematic due to the wide
coverage of various design processes when using HTS technologies for voltage transformation and their
interaction with other elements or electric power system objects. This study’s main purpose is to determine
the basic requirements and conditions for the engineering and design of HTS transformers. Special attention
is paid to searching for optimal and economically feasible designs of windings, cryostat and magnetic core of
the transformer, exemplified by a three-phase prototype of a 63 kVA HTS transformer with a current limiting
function. A case study of voltage transformation and the short-circuit currents limitation, as the two most
essential components of the performance of an electric power system, is carried out, based on a single device.
Results of computer models as well as experiments are provided and confirmed the benefit of our
methodology. Our focus lies on studying the possibility of the HTS transformer to limit the fault current due
to a sharp increase in the conductor’s resistance when the critical current or temperature is exceeded.
2. PROPOSED METHOD FOR DETERMINING THE ELECTRICAL PARAMETERS OF HTS
TRANSFORMERS
Transformers have significant resistances and affect the energy losses in the mains, the voltage
deviations at consumer locations, and therefore play a crucial role in the calculations and analysis of the
operation of electric power systems. Currently, there is no established methodology for determining
parameters of HTS transformers. The analysis of the designed experimental models [5]–[9] allows adapting
the classical methods for new method for determining the parameters of transformers to HTS machines with
current limiting function. Our study is aimed at developing a HTS transformer for reliable current limitation
in the light of new restrictions on current density, magnetic induction, critical current and critical temperature
of superconductor.
2.1. Current density and core induction
The main difference between HTS and conventional transformers is the windings. The windings
consist of HTS wires made of second-generation superconductors. The thickness of the second-generation
HTS wires manufactured by the company “S-Innovations” is only 0.1 to 0.2 mm. However, the average
operating current density of such a wire at a temperature of 77 K is 200 to 400 A/mm2
, which is two orders of
magnitude higher than in a copper wire. When choosing the values of current density and magnetic induction
during the transformer designing, it is necessary to consider the dependence of the critical current density 𝐽𝑐
on the magnetic induction B [10]. Figure 1 shows the 𝐽𝑐(𝐵) dependences for Yttrium barium copper oxide
(YBCO) superconductors for the temperature range 10 to 77 K [11].
The above dependence allows determining an optimal range for choosing the transformer core
magnetic induction when a sufficient critical current density is maintained. This current ensures a high
performance of the HTS wire under the nominal operating conditions without loss of superconductivity.
When analyzing the dependences of 𝑗𝑐(𝐵) for different cross-sections of HTS YBCO wires, it is proposed to
accept a range of inductances of the magnetic core rod equal to 1.1 to 2 T. This range ensures high values of
the critical current density and obtains optimal values of the idle current and magnetic losses in the core.
Furthermore, it allows experimentally achieving a wide range of the calculated inductions for magnetic
systems of HTS transformers for various grades of hot-rolled, cold-rolled and amorphous steels. If required,
the induction can be selected to provide lower critical current values to optimize the transformer for regions
with a large number of two-phase and single-phase short circuits. The lower critical current effectively
protects the transformer from short circuits. However, it is unnecessary to overestimate the value of
induction. The reason is idle losses, since they are prevalent in HTS transformers due to the lack of resistance
in the windings under nominal operating conditions.
Figure 1. Critical current density Jcm as a function of the magnetic induction at different temperatures
3. ISSN: 2088-8708
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240
2.2. HTS transformers losses
The main losses in transformers are losses in the windings-electrical losses, and losses in the steel
core-magnetic losses or core losses. Short-circuit losses (SC) in HTS transformers are in stark contrast to the
conventional ones. There are various theories and methods how to characterize alternating current (AC)
losses in superconductors [12]–[15]. The authors of such papers specify the dependence of the losses on the
value and direction of the alternating magnetic field. Depending on the source of the alternating magnetic
field, the losses are split into two components: i) losses from self-induced field-caused by the magnetic field
from the flowing current and ii) losses from the external field-are determined by the leakage field of the
windings. Losses from self-induced field are determined as [16]:
2
0
1( ) 2 2 1 ln 1
2
C T T T T
SF T
C C C C
f I I I I I
P I
I I I I
= − + − −
(1)
where 𝐼𝐶 is the critical current, 𝐼𝑇 is the transport current (the maximum current in the conductor), 𝜇0 is the
magnetic constant, 𝑓 is the frequency.
However, expression (1) is valid only for windings made of a single wire. Laying parallel-connected
conductors in windings changes the distribution of the magnetic field inside the superimposed wires. The
dependence shown in Figure 2 [17] indicates a significant increase in losses, coming from the magnetic
self-induced field, with an increase in the number of parallel wires in the windings.
Figure 2. Dependence of the loss factor on the number of parallel wires
The total losses from the self-induced field in the windings are:
1 1
3( ( ) ( ))
SF pHV SF THV pLW SF TLW
P n k P I n k P I
= + (2)
where 𝑛𝑝𝐻𝑣 and 𝑛𝑝𝐿𝑊 are the numbers of parallel wires in the high voltage (HV) and low voltage (LV)
windings, k is the loss factor, 𝐼𝑇𝐻𝑉 and 𝐼𝑇𝐿𝑊 are the transport currents in HW and LW windings.
In wire superconductors, an external perpendicular magnetic field leads to higher losses than a field
parallel to the plane of the conductor. In general, the losses from the external field can be split into two
components. On the one hand, the hysteresis losses in superconductors are determined by (3) [18]:
H С HTS
P I a Bf
= (3)
where 𝑎𝐻𝑇𝑆 is the width of the wire superconducting layer.
On the other hand, Eddy current losses induced in non-superconducting layers of the HTS wire are [19]:
2 3
2
( )
6
Ме Ме
Eddy
b a
P Bf
= (4)
where 𝑏𝑀𝑒 is the thickness of the metal layers of the superconducting tape, 𝑎𝑀𝑒 is the width of the wire’s
metal layer, and 𝜌 is the resistivity.
fo=23.4
cL=27.9
nc=6.01
4. Int J Elec & Comp Eng ISSN: 2088-8708
Methodology for determining the parameters of high-temperature … (Vadim Zinovievich Manusov)
241
Besides the losses due to the magnetic field, explained above, resistive losses in transformer current
leads are also present. They are determined according to the equation given in (5) [16]:
2
. . . . . . . .
. . 0
( ) ( )
l
C L C L C L C L
C L
I dT
P x dx A Т
A dx
= +
(5)
where I is the current flowing in the current lead, 𝐴𝐶.𝐿 is the cross-sectional area of the lead, l is the length
of the lead, 𝜌𝐶.𝐿 is the resistivity of the lead, 𝜆𝐶.𝐿 is the coefficient of thermal conductivity of the lead, 𝑇 is the
temperature.
It is worth noting that also heat losses ΔPcryo pass through the surface of the cryostat. Depending on
the cryostat material, the heat leakage should not exceed 2.5 W/m2
[6], [16]. Adding up all losses, the total
losses in the windings of the HTS transformer become (6).
. .
SC SF H Eddy C L cryo
P P P P P P
= + + + + (6)
Core losses Δ𝑃𝑐𝑜𝑟𝑒, depending on the square of the magnetic induction 𝐵, are similar for HTS
transformers as well as for conventional ones. Figure 3 shows a general comparison of all the losses in
conventional Figure 3(a) and HTS Figure 3(b) transformers [16], [20]. The total loss of a superconducting
transformer is ultra-low compared to conventional transformers. In the idle state, the losses of a superconducting
transformer are 50%, and in the full load state, only 10% of the losses of conventional transformers.
Most of the losses (about 75%) of conventional transformers are caused by resistive losses in the
windings, whereas about 25% are the result of the iron core work. The main portion of the losses of a
superconducting transformer are the core losses (~67.2%). Because the losses in the HTS transformer
windings do not depend on the current density, it can be concluded that the transformers can operate with
nearly highest efficiency at any load factor. Figure 4 shows the dependence of the efficiency on the load
factor for conventional and HTS transformers. When fully loaded, the efficiency of the HTS device can reach
99.9%, exceeding the efficiency of the conventional one by 0.3 to 0.4%.
(a) (b)
Figure 3. Dependence of losses on the load factor for (a) conventional transformers and (b) HTS transformers
Figure 4. Dependence of the efficiency on the load for HTS and conventional transformers
5. ISSN: 2088-8708
Int J Elec & Comp Eng, Vol. 13, No. 1, February 2023: 238-248
242
The obtained results of the study of the types and magnitudes of losses in the transformers windings
make it possible to establish the optimal range of Usc. The superconducting transformers can raise the
efficiency of power transformers from 99.6 to 99.9%. Due to the zero active losses in the windings and the
ability of the HTS transformers to operate with high efficiency regardless of the load, it becomes possible to
reduce the Usc to values of 0.5 to 2%, depending on the rated power and the selected parameters of the
superconducting windings of the transformer.
2.3. Critical parameters of a superconductor and the current limiting function
The most important parameters for the normal operation of HTS transformers with a current limiting
function are the superconductor’s critical parameters: critical current, critical temperature, and critical field.
Since it is impossible to increase the magnetic fields close to the critical value in the transformer, only
temperature and current will affect the transformer engineering and design. The critical current 𝐼𝑐(𝑡)
determines the maximum allowable current that can flow through a superconductor without switching to a
resistive state. When choosing the rated current IRated of the superconducting winding, let us assume a current
margin factor of 𝐶𝑀, which will provide the necessary protection of the superconductor from quench
(unexpected failure in the resistive state).
𝐼𝑅𝑎𝑡𝑒𝑑 =
𝐼𝑐(𝑇)
𝐶𝑀
(7)
The value of the margin factor will be determined based on the operation conditions of the
transformer under the overload mode set for the design. The existing superconducting wires, with high values
of critical currents up to 439 A [21] at an operating temperature of 77 K, allow setting the safety factor in the
range of 1.25 to 2. This allows operating the HTS transformer in the overload mode, in excess of the rated
current up to 90% without loss of superconductivity.
The use of second generation HTS wires as transformer windings, in the superconducting state at a
temperature of 77 K, has a significant effect on electromagnetic transients due to the “switching effect”
(mode of transition from the superconducting state to the resistive state). This property of a superconductor
allows to instantly limit the most dangerous surge current. At the initial moment of the transition to the
resistive state, the current is pushed into the non-superconducting layers of the wire, thereby causing
significant heat release. After the short circuit is eliminated due to the increased resistivity, the
superconducting wire begins to cool. Assume the temperature difference between the winding and the
cryomedium is large (about 30 K). In that case, liquid nitrogen can transfer to the film boiling mode, which
results in minimal heat removal from the winding Figure 5 [22]. This mode of nitrogen boiling is
unacceptable since it can lead to a thermal failure of the winding, which can only be prevented by a forced
transformer shutdown.
The return of the superconductor to the superconducting state after the failure elimination depends
on the correlation between the ratio of the short-circuit current to the rated current, ISC/IRated, and the ratio of
the operating current to the rated current, Ioper/IRated, Figure 6 [23], [24]. In generally, the ratio of the operating
current to the limited short-circuit current must be such that the heat released on the windings in the current-
limiting mode does not exceed the critical value 𝑄𝐶𝑟, above which the superconductor could not return to the
superconducting state by itself.
Figure 5. Dependence of the heat flux density on
the temperature difference between the cooled
surface and the cooling liquid
Figure 6. Criterion for the winding to return to the
superconducting state
6. Int J Elec & Comp Eng ISSN: 2088-8708
Methodology for determining the parameters of high-temperature … (Vadim Zinovievich Manusov)
243
3. DESIGN OF AN EXPERIMENTAL THREE-PHASE HTS TRANSFORMER
The theory presented in section 2 allow create the novel method for determining the parameters of
HTS transformers. Our method allows to design HTS transformers with high stability to winding overheating
and the "quench" phenomenon. Below, the process of designing and assembling the main parts of a HTS
transformer is explained: windings, magnetic circuit, cryostat. Concrete design decisions and values are
provided for an experimental transformer. Experimental results obtained with this transformer are discussed
in section 4.
3.1. Windings
The layered cylindrical winding design is optimal for transformers with a power of less than
1 MVA. The advantages of this type include minimal AC losses; reduces deviation of the leakage magnetic
field, which improves the characteristics of HTS wires. In addition, this type of windings is ideal for the
design of a transformer with a current limiting function [4], [25]. The windings of our experimental
transformer are made of a 2G HTS tapes. The conductor is a thin multi-layer wire with a non-magnetic metal
substrate and a layer of superconducting material-yttrium-barium-copper oxide Y1Ba2Cu3O7-X (YBCO-123),
which is covered with a protective layer of silver, as well as other auxiliary layers. Since the desired
transformation ratio is equal to three, HTS wires of 4 mm width for the high voltage side and 12 mm width
for the low voltage side are selected for the windings. The use of a larger wire cross-section on the LV side is
due to the need for a current margin for the safe operation of a transformer with a high current density under
the overload mode. The parameters of the designed windings are shown in Table 1.
Table 1. Parameters of HTS windings of experimental transformer
Parameter HV Winding LV winding
Material Y1Bа2Cu3O7
Tensile strength, MPa 500
Critical temperature, K 93
HTS wire width, mm 4 12
Minimum critical current, A 131 439
Voltage, V 380 127
Rated current, A 95.7 287.2
Number of turns, pc 33 11
Length of one winding phase, m 28.1 8.4
Length of three winding phases, m 84.3 25.2
Winding height, mm 198 154
Winding diameter, mm 271 243
Insulation Polyimide
3.2. Magnetic core
For the magnetic core design, the Unicore technology was chosen. The magnetic core is assembled
from laminated plates of electrical steel, located parallel to the magnetic core. It provides an easy way of
assembly and disassembly, which is important for the prototype since it is planned to optimize the design of
the windings.
Figure 7 shows the assembly process and the final version of the laminated magnetic core. To provide
insulation, varnish was applied to the plates. In our calculations, the value of the induction is assumed to be 1.65 T.
The space factor is 0.883. The weight of the magnetic core is 430 kg, including fasteners.
Figure 7. Assembly process of the magnetic core of experimental three-phase HTS transformer
7. ISSN: 2088-8708
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244
3.3. Cryostat
A key feature of HTS transformers is the need to design a cryostat-a container for liquid nitrogen in
direct contact with the HTS wires. It is possible to distinguish two options of the cryostat design relative to
the magnetic system-HTS transformer with a “cold” and “warm” magnetic core [4], [26], [27]. The “Cold”
magnetic core is in direct contact with liquid nitrogen, and the cryostat covers the entire transformer. The
advantages are the simplicity of the cryostat, as well as a lower magnetic leak. The disadvantages include
additional heat losses for cooling the entire system. The “Warm” magnetic core is not in direct contact with
liquid nitrogen and only the windings are immersed in the cryostat. Its operating temperature is
approximately equal to room temperature. The advantages and disadvantages are the opposite of the “cold”
magnetic core. Practical experience from around the world shows that the “warm” magnetic core design is
superior [1]–[9], [28], [29]. The cryostat of our experimental transformer was made out of carbon fiber with
an intermediate filling of the wall cavity with aerogel. Carbon fiber is a composite material and is carbon
fiber with a binder-polyester resin. This material provides strength and non-shrinkage over a wide
temperature range, which is critical for a cryostat. The developed cryostat is shown in Figure 8.
Figure 8. Cryostat of experimental 63 kVA HTS transformer
Tests confirmed that the cryostat meets the requirements for the strength of the material and does
not affect the electromagnetic field induced by the transformer windings. The thermal insulation allows
conducting physical experiments of up to 1.5 hours duration, which is sufficient for the purposes of the
experiments. When further designing the prototype for pilot operation, a thermal insulation margin should be
provided, since pilot operation involves a longer (continuous) mode of operation of the transformer, in
contrast to experiments (one-time short-term operation).
3.4. Physical model of experimental three-phase HTS transformer
The designed prototype of a three-phase HTS transformer of 63 kVA as shown in Figure 9 allows
for experimental studies, analysis of the transients during current limitation and of the influence of the HTS
device on improving the energy efficiency of mains. One of the most important problems is to investigate the
influence of HTS transformers on the dynamic and static stability of electric power systems. To the best of
our knowledge, such studies have not been carried out yet. The basic parameters of the developed HTS
transformer of 63 kVA, with a voltage ratio of 380/127, are shown in Table 2.
Figure 9. Three-phase prototype of HTS transformer
8. Int J Elec & Comp Eng ISSN: 2088-8708
Methodology for determining the parameters of high-temperature … (Vadim Zinovievich Manusov)
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Table 2. Key electrical parameters of experimental HTS transformer
Parameter Value
Power, kVA 63
Number of phases 3
Frequency, Hz 50
Voltage ratio 380/127
Operating temperature, K 77
Winding arrangement Y-Y
Rated current of the HV winding, A 95.7
Rated current of the LV winding, A 287.2
Idle current, % 6%
Core induction, B 1.65
Operating current density, A/mm2
239
USC, % 1
4. EXPERIMENTAL VERIFICATION OF THE POSSIBILITY OF SHORT-CIRCUIT
CURRENT LIMITATION
The short-circuit current is limited due to the transition of the HTS winding from the
superconducting state. This, in turn, occurs when the short-circuit current exceeds the value of the critical
current of the HTS conductor. In addition, the failure of superconductivity may occur due to the excess of the
critical temperature. The short-circuit current is limited in the first half-wave of the sinusoidal current
wave-so during the first 0.01 s (that is faster than relay protection devices in mains can react) [28]–[31]. The
limiting function allows preventing the negative consequences of short circuits-damage to equipment,
disconnection of consumers. Our experimental studies include determining the characteristics of short-circuit
transients to test the ability of the HTS windings to limit the short-circuit current. The equivalent-circuit of
the experimental studies is shown in Figure 10.
Figure 10. Experiment equivalent-circuit model
In the equivalent-circuit model, R1 and R2 reflect the resistances of the external circuits and current
leads of the primary and secondary windings, L1, L2 are the self-inductances of the primary and secondary
windings, RHTS1, RHTS2 are the nonlinear resistances of the HTS windings of the transformer, U is the voltage
amplitude of the supply source, RL is the load. A series of experiments with line voltage supplied to the HTS
transformer with short-circuited terminals of the LV windings was performed. Using the FLUKE 435-II
recorder, current waveforms on the HV windings of phase A were obtained in Figure 11. They correlate with
the high-accuracy results of computer modelling.
Figure 11. Current in the primary winding phase A of the HTS transformer
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The simulation was performed on a previously developed mathematical model verified on a single-
phase prototype of an HTS transformer [23], [27]. The waveforms obtained as a result of modeling a three-
phase short circuit in the HV windings, check Figure 12, indicate a 2.53-fold decrease in the short-circuit
shock current. In this case, the temperature of the superconductor does not exceed the critical temperature (it
is only 80.9 K), which contributes to its fast return to the superconducting state and further normal operation
of the HTS transformer and the entire mains.
(a) (b)
Figure 12. Current waveforms in the windings during the short circuit (a) in mains without HTS transformer,
and (b) in mains with HTS transformer
5. CONCLUSION
The developed methodology for designing HTS transformers can be adopted as a new, adaptive
solution in the design of HTS devices. Our method allows to design HTS transformers with high stability to
winding overheating and the "quench" phenomenon. Our scientific results include the adoption of new
regulatory requirements for the current density (200 to 400 A/mm2
), short-circuit voltage (0.5 to 1.5%),
magnetic induction of the rod, the nature of losses in superconducting windings, as well as critical parameters
of the superconductor (critical current and temperature). The absence of active losses in the windings under
the nominal operating conditions allows increasing the efficiency by an average of 0.3%.
A physical prototype of a three-phase HTS transformer of 63 kVA was constructed for the study of
the current limiting processes, based on YBCO second-generation HTS wire. The results of theoretical and
experimental studies presented in this work indicate the effectiveness of using an HTS transformer for the
purpose of current limitation. The designed and constructed superconducting transformer reduces the first
peak of the short-circuit current by 2.53 times, thus protecting the transformer and the entire supply mains
from thermal and electrodynamic damage. During the transient process, the heat flow in the winding did not
exceed the critical value and the superconductor returned to the superconducting state, which indicates the
correct design of the transformer with the current limiting function.
In an electrical grid with an HTS transformer operating under an active load, in case of a three-phase
short-circuit, there is an instantaneous limitation of the short-circuit surge current. The use of electrical
equipment based on the phenomenon of high-temperature superconductivity should be considered as a new
innovative solution to the issue of improving the reliability, energy efficiency and stability of electrical grids.
ACKNOWLEDGEMENTS
This research was carried out under the Novosibirsk State Technical University development
program, scientific project NoС21-24.
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BIOGRAPHIES OF AUTHORS
Vadim Zinovievich Manusov Novosibirsk State Technical University,
Department of Power Supply Systems, doctor of technical science, professor. Main direction
of research: application of artificial intelligence methods for planning and optimizing modes of
electric power systems. He can be contacted at email: manusov36@mail.ru.
Dmitriy Mihailovich Ivanov Novosibirsk State Technical University,
Department of Power Supply Systems, PhD student. The main direction of research:
Optimization of processes in HTS transformers using artificial intelligence techniques. He can
be contacted at email: mrdemasi123@gmail.com.
Arseniy Valerievich Semenov Department of Power Supply Systems, PhD
student. The main direction of research: optimization of power system operation modes,
study of power system stability with HTS transformers. He can be contacted at email:
ars100500@ya.ru.
Gennady Viktorovich Ivanov Surgut State University, Department of Radio
Electronics and Electrical Engineering, PhD in Technical Science, Associate Professor. The
main direction of research: investigation of modes and characteristics of power grid equipment
with a cryogenic dielectric medium. He can be contacted at email: gennad-ivanov@yandex.ru.