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1
Quan, Yu Sheng, Lin Jie Fang, Zi Jian Wang und Pu Xin Shi. „Study of the Winding Temperature Distribution for Distribution Transformers“. Applied Mechanics and Materials 672-674 (Oktober 2014): 1380–83. http://dx.doi.org/10.4028/www.scientific.net/amm.672-674.1380.
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In this article, in order to provide a reference for determining the location of fiber optic temperature probe in saving distribution transformers,we analyze the internal transformer by the basic heat transfer theory and simulate via ANSYS simulation software, determining the location of the highest temperature separately of the high and low voltage winding and iron core. The simulation results will be as a reference value for the experimental results. Therefore, it is very significant for analyzing the hottest point distribution of distribution transformers and improving thermal design of dry type transformers and temperature monitoring that the numerical simulation of dry-type distribution transformers of temperature field.
2
Yang, Cheng Feng. „Research of Ageing and Life Assessment Methods of Power Transformers in Nuclear Power Plants“. Advanced Materials Research 614-615 (Dezember 2012): 1109–15. http://dx.doi.org/10.4028/www.scientific.net/amr.614-615.1109.
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The effective methods of the ageing and life assessment for large and medium-sized power transformers used in nuclear power plants are analyzed and described, including the thermal ageing life assessment method for transformer solid insulation, the gas analysis method of CO and CO2 in the transformer oil, the average degree of polymerization method, furfural content analysis method, and the analysis method based on the insulation ageing-related electrical parameters. The analysis results show that the methods used can reasonably assess the remaining life of the transformers. These methods have important reference value to the ageing and life management for the large and medium-sized power transformers in nuclear power plants.
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Poonnoy, Nitchamon, Cattareeya Suwanasri und Thanapong Suwanasri. „Fuzzy Logic Approach to Dissolved Gas Analysis for Power Transformer Failure Index and Fault Identification“. Energies 14, Nr. 1 (23.12.2020): 36. http://dx.doi.org/10.3390/en14010036.
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This research focuses on problem identification due to faults in power transformers during operation by using dissolved gas analysis such as key gas, IEC ratio, Duval triangle techniques, and fuzzy logic approaches. Then, the condition of the power transformer is evaluated in terms of the percentage of failure index and internal fault determination. Fuzzy logic with the key gas approach was used to calculate the failure index and identify problems inside the power transformer. At the same time, the IEC three-gas ratio and Duval triangle are subsequently applied to confirm the problems in different failure types covering all possibilities inside the power transformer. After that, the fuzzy logic system was applied and validated with DGA results of 244 transformers as reference cases with satisfactory accuracy. Two transformers were evaluated and practically confirmed by the investigation results of an un-tanked power transformer. Finally, the DGA results of a total of 224 transformers were further evaluated by the fuzzy logic system. This fuzzy logic is a smart, accurate tool for automatically identifying faults occurring within transformers. Finally, the recommendation of maintenance strategy and time interval is proposed for effective planning to minimize the catastrophic damage, which could occur with the power transformer and its network.
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Ku, Te-Tien, Chia-Hung Lin, Chung-Sheng Li, Yung-Ruei Chang und Yih-Der Lee. „Design of Micro-Phasor Measurement System to Identify Phasor of Distribution Transformers“. Applied Sciences 9, Nr. 18 (12.09.2019): 3831. http://dx.doi.org/10.3390/app9183831.
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In this paper, the micro-phasor measurement system is developed to support phasor identification of distribution transformers for the distribution mapping management system (DMMS) of Taiwan Power Company (TPC). The one pulse per second signal (1PPS) from the global positioning system (GPS) is used to synchronize the voltage sampling between reference and measurement sides. By receiving 1PPS from GPS, the phasor measurement of three-phase voltage at the reference site of the substation is stored in the master station with a time-stamp. This paper proposes a timing synchronous module with an embedded temperature compensated crystal oscillator (TCXO) to generate highly accurate timing for field measurement of underground distribution facilities. Mobile communication network is used to compare measurement results between reference and field sides of voltage angle that define distribution transformer phasor. This paper also designs and develops an application for mobile devices by importing DMMS database, which is used to search the attributes of the distribution transformers for measurement at the field. After the transformer phasor is identified, the results are stored in the mobile device to update the attributes of distribution transformers in DMMS.
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Bajwa, Rayan, und Murat Kaya Yapici. „Integrated On-Chip Transformers: Recent Progress in the Design, Layout, Modeling and Fabrication“. Sensors 19, Nr. 16 (13.08.2019): 3535. http://dx.doi.org/10.3390/s19163535.
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On-chip transformers are considered to be the primary components in many RF wireless applications. This paper provides an in-depth review of on-chip transformers, starting with a presentation on the various equivalent circuit models to represent transformer behavior and characterize their performance. Next, a comparative study on the different design and layout strategies is provided, and the fabrication techniques for on-chip implementation of transformers are discussed. The critical performance parameters to characterize on-chip transformers, such as the Q-factor, coupling factor (k), resonance frequency (fSR), and others, are discussed with reference to trade-offs in silicon chip real-estate. The performance parameters and area requirements for different types of on-chip transformers are summarized in tabular form and compared. Several techniques for performance enhancement of on-chip transformers, including the different types of micromachining and integration approaches stemming from MEMS (microelectromechanical systems) technologies are also analyzed. Lastly, the different uses and applications of on-chip transformers are discussed to highlight the evolution of on-chip transformer technology over the recent years and provide directions for future work in this field.
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Rana, Iqra, Murtaza Ali, Faheem Shafeeque Channar, Munsif Ali und Mustafa Memon. „PLC Based Load Sharing of Transformers“. IJEEIT International Journal of Electrical Engineering and Information Technology 3, Nr. 2 (02.02.2021): 25–30. http://dx.doi.org/10.29138/ijeeit.v3i2.1234.
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The transformer is very expensive and bulky power system equipment. It runs and feed the load for 24 hours a day. Sometimes the load on the transformer unexpectedly rises above its rated capacity in that situation the load on the transformer increases and it will be overloaded and current will increase and cause overheating which in results damage the insulation of transformer. That insulation failure resulting in interruption of power supply. The common problems which transformer face is overloading voltage fluctuations and heating effect. It takes lot of time to fix the transformer so that a device need to be introduced a device which would help in automatically sharing of these over voltages. We will try to build an automated transformer sharing system in this project where the transformer current is confined to auxiliary transformer and automatically enters system.
There are three transformers working as sources in this project, initially when the main switched ON the load that time load will be shared through the first transformer but when the load on first transformer suddenly increase above its reference value then immediately second transformer connected parallel with first transformer automatically through PLC by busing relay circuit.
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Guo, Zheng Wei, Xiang Li Liu, Xin Ju Guo, Cun Kai Liu, Chuan Jing, Yong Li und Min Tang. „Research on Pressure Relief Technology of Main Transformer in 220KV Indoor Substation“. Applied Mechanics and Materials 873 (November 2017): 279–84. http://dx.doi.org/10.4028/www.scientific.net/amm.873.279.
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Most indoor substations adopt oil-immersed transformers as voltage transformation device. In multiple disadvantage conditions, the flammable gases formed form transformer oil may explode in transformer room. Typical 220kV main transformer room of indoor substation was researched in this paper. An correlation of pressure relief area of the 220kV mail transformer room of indoor substation were presented based on the CFD tool FLACS modeling of the general designing schemes of the State Grid Corporation of China. This research may be used as reference of the pressure relief technology for main transformer rooms of indoor substations.
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Braña, L., A. Costa und R. Lopes. „Development of a power transformer model for high-frequency transient phenomena“. Renewable Energy and Power Quality Journal 19 (September 2021): 217–21. http://dx.doi.org/10.24084/repqj19.260.
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In recent years, the proliferation of distributed renewable energy sources and the application of new rules for the exploitation of electrical networks imposed by the markets have dictated increasingly demanding operating conditions for electric power transformers, creating new challenges in their exploration and conservation. Transformers that, in addition to the transmission lines, are certainly the most important and critical element of any electrical energy system. Adequate models are necessary to accurately describe transformer behavior and internal response when submitted to different external requests imposed by the network, particularly during transient phenomena, as well as, to properly assess system vulnerabilities and network optimization. This effort is being carried out today by several research groups in the world, namely from Cigré and IEEE. In this work, a transformer model to be integrated into a timedomain equivalent circuit is developed and discussed. Results obtained with this model are compared with measurements obtained by the Cigré JWG A2/C4.52 in a power transformer used as a reference for the working group.
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Hu, Yang, und Hui Qi Li. „Experimental Study on Transformer under DC Bias“. Applied Mechanics and Materials 556-562 (Mai 2014): 2186–89. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.2186.
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As the voltage level to improve, DC bias problem of power transformers increasingly prominent. When the DC current affects the transformer, transformer laminated core magnetization characteristics inside will be affected by magnetic saturation increased. Aiming at this problem, the model of the load side and a smart experimental platform are established, for the measurement of related data such as the excitation current under DC bias. Based on MATLAB software, analysis summarized the laws of physics, to provide a reference for theoretical research.
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Mester, Christian. „Optimised calibration programmes for comparators for instrument transformers“. tm - Technisches Messen 88, Nr. 2 (15.01.2021): 122–31. http://dx.doi.org/10.1515/teme-2020-0086.
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Abstract Traditionally, instrument transformers are calibrated using bridges. By definition, bridges use the null method of measurement. The traditional calibration programme for instrument transformer bridges characterise namely this null measurement. Many new commercial comparators for instrument transformer use a very different method. They sample the secondary signals of reference and device under test (dut) transformer independently. Based on the samples, magnitude and phase of both signals are determined. Ratio error and phase displacement are calculated. Consequently, the significance of their calibration using the traditional calibration programme is limited. Moreover, the operating range of modern comparators is much larger than that of bridges. The additional versatility cannot be used without an adapted calibration programme. This article analyses the calibration programmes for both technologies. An experimental study confirms both the suitability of the new calibration programme and the need to chose the calibration programme depending on the technology of the device to be calibrated. The conclusion is very general and applies to all measurement problems where an operating principle is replaced by another – when changing the operating principle, it is important to check the calibration programme and adapt it if necessary.
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Djurdjevic, Ksenija, Mirjana Vojinovic-Miloradov und Slobodan Sokolovic. „Life cycle of transformer oil“. Chemical Industry 62, Nr. 1 (2008): 37–46. http://dx.doi.org/10.2298/hemind0801037d.
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The consumption of electric power is constantly increasing due to industrialization and population growth. This results in much more severe operating conditions of transformers, the most important electrical devices that make integral parts of power transmission and distribution systems. The designed operating life of the majority of worldwide transformers has already expired, which puts the increase of transformer reliability and operating life extension in the spotlight. Transformer oil plays a very important role in transformer operation, since it provides insulation and cooling, helps extinguishing sparks and dissolves gases formed during oil degradation. In addition to this, it also dissolves moisture and gases from cellulose insulation and atmosphere it is exposed to. Further and by no means less important functions of transformer are of diagnostic purpose. It has been determined that examination and inspection of insulation oil provide 70% of information on transformer condition, which can be divided in three main groups: dielectric condition, aged transformer condition and oil degradation condition. By inspecting and examining the application oil it is possible to determine the condition of insulation, oil and solid insulation (paper), as well as irregularities in transformer operation. All of the above-mentioned reasons and facts create ground for the subject of this research covering two stages of transformer oil life cycle: (1) proactive maintenance and monitoring of transformer oils in the course of utilization with reference to influence of transformer oil condition on paper insulation condition, as well as the condition of the transformer itself; (2) regeneration of transformer oils for the purpose of extension of utilization period and paper insulation revitalization potential by means of oil purification. The study highlights advantages of oil-paper insulation revitalization over oil replacement. Besides economic, there are advantages concerning environmental protection, starting from unrecoverable resources (petroleum) saving through power and energy saving to waste reduction. Adequate management of transformer oil life cycle, meaning timely and technologically updated regeneration process, prevents waste production. Regeneration by means of synthetic adsorbents in laboratory conditions as well as on site has ensured and provided satisfactory results with reference to oil quality improvement. It has also confirmed and substantiated the necessity of regeneration implementation before the paper insulation is damaged.
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Wang, Bo, Hai Sen Zhao und Shou Jun Lian. „Study on Precision Selection of Instrument Transformer and its Calibration for Automatic Test System“. Applied Mechanics and Materials 333-335 (Juli 2013): 2461–64. http://dx.doi.org/10.4028/www.scientific.net/amm.333-335.2461.
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System accuracy is an important assessment indicator for automatic test system, which is influenced by many factors such as instrument, person, and environment. The paper takes a set of automatic motor testing system for an example, the mathematic relationship between the system accuracy and the precision of instrument transformers was analyzed, which also provides a theoretical reference for the precision selection of instrument transformer when the system accuracy was known. Some improved measures such as the selection of measuring point and the calibration of transformer ratio and phase angle are put forward. Testing results verified its simplicity and efficiency, besides the novelty above, the paper also provides a new idea to improve the system accuracy of constructed test platforms without increasing the cost for exchanging a matched transformer.
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Arunkumar, S., M. Gopalakrishnan, K. Udayakumar, S. Shankar, V. Sandeep und V. Jayashankar. „Impulse testing of power transformers – a model reference approach“. IEE Proceedings - Science, Measurement and Technology 151, Nr. 1 (01.01.2004): 25–30. http://dx.doi.org/10.1049/ip-smt:20030761.
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Yu, Jicheng, Changxi Yue, Jun Li, Dengyun Li und He Li. „Error Calculating and Compensating Method of All-Optical Fiber Current Transformer in ± 10 kV DC Distribution Network“. Journal of Nanoelectronics and Optoelectronics 14, Nr. 11 (01.11.2019): 1606–15. http://dx.doi.org/10.1166/jno.2019.2680.
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Current transformer is one of the main equipment in ±10 kV DC distribution network. Traditional electromagnetic current transformer has poor anti-jamming capacity and poor insulation, so it cannot realize transient protection. The emergence of all-optical fiber current transformer brings solutions to these problems, which has attracted more and more attention. In this study, aiming at the problem of error and compensation of λ/4 waveform of all-fiber current transformer, the fabrication method of λ/4 waveform is studied, the mathematical model of the waveform is established, the influence of the waveform error on the scale factor is analyzed, and a calculating device of angle difference and ratio difference to compare the error is designed. The device adopts the principle of traceability of quantities to collect the state data of the wave plate. At the same time, in order to collect data for errors, database technology and network technology are used to realize remote transmission of monitoring data. The error of the λ/4 wave plate is compensated, the bidirectional principle generated by the birefringence in the fiber ring is analyzed, and the data logic description of the transformer sensitive ring is performed. The phase delay and the angle of the shaft are selected as the main factors causing the error. Compensation is performed by means of peak segmentation and variable cancellation. In the experimental process, compared with the error sampling of the traditional transformer, the error calculated by the current amplitude and phase angle parameters obtained by the all-fiber current transformer is more accurate, and the compensation scheme can suppress the size of the birefringence and improve sensing accuracy of fiber optic current transformers. This study provides a powerful reference for the error analysis of all-fiber current transformer λ/4 wave plates, which is beneficial to promote the better application of such current transformers.
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Jalbert, Rodriguez-Celis, Arroyo-Fernández, Duchesne und Morin. „Methanol Marker for the Detection of Insulating Paper Degradation in Transformer Insulating Oil“. Energies 12, Nr. 20 (18.10.2019): 3969. http://dx.doi.org/10.3390/en12203969.
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This manuscript presents a comprehensive literature review with the aim to provide readers a reference document with up-to-date information on the field of methanol use as a chemical marker. It has been a little more than a decade since methanol was first introduced as a marker for assessing solid insulation condition in power transformers. It all started when methanol was identified in the laboratory during thermal ageing tests carried out with oil-immersed insulating papers and was subsequently also identified in transformer field samples. The first publication on the subject was released in 2007 by our research group. This review covers the methanol fundamentals such as the analytical methods for its determination in transformer oil, which is generally performed by headspace gas chromatography with mass spectrometry or flame ionization as a detector. Current standardization efforts for its determination include ASTM working group 30948 and IEC TC10. Kinetic studies have confirmed the relationship between methanol generation, the number of broken 1,4-β-glycosidic bonds of cellulose and changes in mechanical properties. Laboratory tests have confirmed its stability at different accelerated ageing temperatures. Several utilities have identified methanol during field measurements, case studies on power and some distribution transformers are presented, as well as transformer postmortem investigations. These field-testing results demonstrate its utility in monitoring cellulosic insulation degradation. Recently, a model of methanol interpretation has become available that allows for evaluation of the average degree of polymerization of core type transformer cellulose winding. Methanol has a role as an indicator of cellulosic solid insulation ageing in transformer mineral oil, and it is expected that in the future it will be in routine use by utilities.
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Cao, Mei Gen, und Juan Mo. „Parameter Analysis and Shaking Table Test Based on Mechanics Analysis in Seismic Isolation System of Transformer with Bushings“. Advanced Materials Research 859 (Dezember 2013): 33–42. http://dx.doi.org/10.4028/www.scientific.net/amr.859.33.
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Earthquake damage many times in history indicate thatthe destroy type of large power transformer is diverse in earthquake andvulnerability is very high. Isolationtechnology can effectively reduce seismic response of the transformer and bushings,but transformer isolation layer design and parameter selection have a largerimpact on the isolation effect. Firstly, one transformer model installing 220,500kV real bushings for testing and analysis is designed which its structural dimension is closer totrue transformer. Multi-particle analysis model of the transformer withbushings isolation system (TBIS)and the equations of motion are established, and calculationprocedures are compiled using MATLABprogram. Secondly, impacts analysis on equivalent horizontal stiffness and dampingratio of the isolation layer are carried out subjectedto earthquake. Reasonable ranges ofstiffness and damping parameters have been determined. Earthquake simulatortesting of the transformer with real bushings is implement which transformertank filled with water in the test. Acceleration, displacement and stressresponse of transformer and bushings with or without isolation bearings wereobtained. Analysis and experiments show that the rational designing isolationlayer parameters can effectively reduce the seismic response of transformers andbushings. In conclusion, mentioned above research have reference role toseismic isolation design and application for power transformer and bushings forthe future.
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Plotnikov, Sergey. „Analysis of the Resistances of the Equivalent Circuit of TM Series Transformers“. Известия высших учебных заведений. Электромеханика 64, Nr. 1 (2021): 43–47. http://dx.doi.org/10.17213/0136-3360-2021-1-43-47.
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An assessment of the ratio of active and reactive components of the resistances of the primary and secondary windings of transformers included in the simplified equivalent circuit is made. It is shown that the reactances of the primary and reduced secondary windings are the same. Based on the reference data of the TM series transformers, it has been established that the active resistance of the primary winding exceeds the reduced secondary resistance. The ratios of the resistances of the primary and reduced secondary windings of transformers with a capacity of 20 to 1000 kVA are obtained, taking into account the electrical skin effect and thermal change in the resistances of copper and aluminum windings
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Li, Xi Nian, und Yan Wen Wang. „Research of Voltage Sag Propagation through Transformers“. Advanced Materials Research 706-708 (Juni 2013): 1504–10. http://dx.doi.org/10.4028/www.scientific.net/amr.706-708.1504.
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Voltage sag is one of the most critical power quality problems. This paper calculates voltage sag propagation through YNd11 and Dyn11 winding connected transformers in series using symmetrical components, thus obtaining the voltage transfer matrix. Then the voltage sag propagation of single line-to-ground fault is computed using the transfer matrix. Simulation result proves the correctness of the analytical calculation, providing reference for the further study of voltage sag influence and estimation.
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Falvello, Larry R. „Crystalline transformers: more within than meets the eye“. Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 74, Nr. 5 (27.09.2018): 403–4. http://dx.doi.org/10.1107/s2052520618013203.
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Studies of phase transitions in molecular crystals are becoming more commonplace as improvements in instrumentation and technique enable more efficient exploration of the behavior of samples with varying external conditions, usually temperature. This scientific commentary provides contextual background on this type of study, with reference to an article on transformations in a ferrocenyl–acetylide–gold(I) complex [Makal (2018). Acta Cryst. B74, 427–435].
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Liu, Yunpeng, Xinye Li, Huan Li und Xiaozhou Fan. „Global Temperature Sensing for an Operating Power Transformer Based on Raman Scattering“. Sensors 20, Nr. 17 (30.08.2020): 4903. http://dx.doi.org/10.3390/s20174903.
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Traditional monitoring methods cannot obtain the overall thermal information for power transformers. To solve this problem, a distributed fiber optic sensor (DFOS) was creatively applied inside an operating 35 kV power transformer by highly integrating with the electromagnetic wires. Then, the transformer prototype with totally global sensing capability was successfully developed and it was qualified for power grid application through the strict ex-factory tests. The as designed optical fiber sensor works stably all the time with a temperature accuracy of ±0.2 °C and spatial positioning accuracy of 0.8 m. Based on the obtained internal temperature distribution, Gaussian convolution was further applied for the signal processing and hereby, the hotspots for all the windings and iron cores could be accurately traced. The hottest points were located at 89.1% (55 °C) of the high voltage winding height and 89.7% (77.5 °C) of the low voltage winding height. The actual precise hotspot location corrected the traditional cognition on the transformer windings and it would serve as an essential reference for the manufactures. This new nondestructive internal sensing and condition monitoring method also exhibits a promising future for the DFOS applying in the high-voltage electrical apparatus industry.
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Satish, L., und A. Jain. „Structure of Transfer Function of Transformers with Special Reference to Interleaved Windings“. IEEE Power Engineering Review 22, Nr. 5 (2002): 69–70. http://dx.doi.org/10.1109/mper.2002.4312222.
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Satish, L., und A. Jain. „Structure of transfer function of transformers with special reference to interleaved windings“. IEEE Transactions on Power Delivery 17, Nr. 3 (Juli 2002): 754–60. http://dx.doi.org/10.1109/tpwrd.2002.1022800.
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Urquiza, Domingo, Belen Garcia und Juan Carlos Burgos. „Statistical study on the reference values of furanic compounds in power transformers“. IEEE Electrical Insulation Magazine 31, Nr. 4 (Juli 2015): 15–23. http://dx.doi.org/10.1109/mei.2015.7126070.
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Cao, Jian, Hao Jun Zhou und Su Xiang Qian. „Research on the 3D Temperature Field of Transformer Winding Based on Finite Element Analysis“. Advanced Materials Research 129-131 (August 2010): 353–57. http://dx.doi.org/10.4028/www.scientific.net/amr.129-131.353.
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Power transformer is one of the most important electric equipments in power network, its running state has a direct effect on its safe operation of power network. Fault’s occurrence of power transformer probably result in vast hazards or accidents. According to statistics, its over-temperature operation of winding often result in different fault patterns, such as aging, breakdown and its burnt, etc, which has a large proportion in its accidents of power transformer. In this paper, based on the thermal analysis theory, a 3D thermal field model of transformer’s winding and core is respectively established in ANSYS software environment. And its 3D temperature field distribution of power transformer, including winding and core is simulated. Numerical simulated results provide a reliable and convenient reference for its thermal performance analysis of power transformer.is simulated. Numerical simulated results provide a reliable and convenient reference for its thermal performance analysis of power transformer.
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Gayibov, Tulkin, Sherkhon Latipov und Davron Abdurashidov. „Optimization of Electrical Networks Modes on Transformation Coefficients of Transformers“. E3S Web of Conferences 216 (2020): 01095. http://dx.doi.org/10.1051/e3sconf/202021601095.
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Optimization of modes of electrical networks provides for the determination of rational values of reactive powers of controlled sources, voltages of reference nodes and transformation coefficients of adjustable loop transformers, at which the minimum costs associated with the production, transmission and distribution of electricity are ensured and all the specified operating and technological constraints are met. As a result of a lot of work performed by specialists from all over the world on the development of methods and algorithms for optimization the modes of electrical networks, at present, the methods for optimization of reactive powers and voltages of nodes are quite developed. At the same time, the algorithms for optimization of transformation coefficients of transformers, taking into account the provision of permissible voltage levels and minimum energy losses in closed electric networks by ensuring the optimal distribution of power flows in them, requires corresponding improvement. In this regard, this work proposes a new algorithm for optimization of modes of electrical networks on transformation coefficients of adjustable loop transformers. The results of researched the effectiveness of the proposed algorithm are presented.
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Guerrero, Jose M., Alejandro E. Castilla, José Ángel Sánchez-Fernández und Carlos A. Platero. „Fluid Degradation Measurement Based on a Dual Coil Frequency Response Analysis“. Sensors 20, Nr. 15 (26.07.2020): 4155. http://dx.doi.org/10.3390/s20154155.
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Electrical industry uses oils for cooling and insulation of several machines, such as power transformers. In addition, it uses water for cooling some synchronous generators. To avoid malfunctions in these assets, fluid quality should be preserved. To contribute to this aim, a sensor that detects changes in fluid composition is presented. The designed sensor is like a single-phase transformer whose magnetic core is the fluid whose properties will be measured. The response of this device to a frequency sweep is recorded. Through a comparison between any measurement and a reference one corresponding to a healthy state, pollutants presence, such as water in oil or salt in water, can be measured. The performance of the sensor was analyzed through simulation. In addition, a prototype was built and tested measuring water concentration in oil and salt content in water. The correlation between pollutant concentration measured with the sensor and known pollutant concentrations is good.
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Zhang, Yiyi, Yi Li, Shizuo Li, Hanbo Zheng und Jiefeng Liu. „A Molecular Dynamics Study of the Generation of Ethanol for Insulating Paper Pyrolysis“. Energies 13, Nr. 1 (05.01.2020): 265. http://dx.doi.org/10.3390/en13010265.
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Cellulosic insulation paper is usually used in oil-immersed transformer insulation systems. In this study, the molecular dynamics method based on reaction force field (ReaxFF) was used to simulate the pyrolysis process of a cellobiose molecular model. Through a series of ReaxFF- Molecular Dynamics (MD) simulations, the generation path of ethanol at the atomic level was studied. Because the molecular system has hydrogen bonding, force-bias Monte Carlo (fbMC) is mixed into ReaxFF to reduce the cost of calculation by reducing the sampled data. In order to ensure the reliability of the simulation, a model composed of 20 cellobioses and a model composed of 40 cellobioses were respectively established for repeated simulation in the range of 500–3000 K. The results show that insulating paper produced ethanol at extreme thermal fault, and the intermediate product of vinyl alcohol is the key to the aging process. It is also basically consistent with others’ previous experiment results. So it can provide an effective reference for the use of ethanol as an indicator to evaluate the aging condition of transformers.
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Joosten, A. P. B., J. Arrillaga, C. P. Arnold und N. R. Watson. „Simulation of HVDC system disturbances with reference to the magnetizing history of the convertor transformers“. IEEE Transactions on Power Delivery 5, Nr. 1 (1990): 330–36. http://dx.doi.org/10.1109/61.107293.
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Siegel, Martin, Sebastian Coenen, Michael Beltle, Stefan Tenbohlen, Marc Weber, Pascal Fehlmann, Stefan Hoek et al. „Calibration Proposal for UHF Partial Discharge Measurements at Power Transformers“. Energies 12, Nr. 16 (08.08.2019): 3058. http://dx.doi.org/10.3390/en12163058.
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The continuous, non-intermitted service of electrical grids relies on the reliability of their assets, e.g., power transformers. Local insulation defects can result in serve failures such as breakdowns with severe subsequent costs. The prevention of such events is crucial. Hence, partial discharge (PD) activity at power transformers is evaluated directly in the factory before shipment. Additionally, PD activity can be monitored during service using the ultra-high frequency (UHF) method. In this contribution, a calibration procedure is proposed for the UHF method. The calibration process is required to ensure both, reproducibility and comparability of UHF measurements: Only a calibrated UHF measurement procedure can be introduced supplementary to IEC 60270 in acceptance tests of power transformers. The proposed calibration method considers two factors: The influence of the UHF-antenna’s sensitivity and the PD recorder characteristics including accessories such as cable damping, pre-amplifier, etc. The former is addressed by a characterization of UHF sensors using the standard antenna factor (AF) in a gigahertz transverse electromagnetic (GTEM) cell. The PD recorder’s influence is corrected by using a defined, invariable test signal as reference for all recording devices. A practical evaluation of the proposed calibration procedure is performed in a laboratory setup using different UHF recording devices and UHF sensors using artificial PD signals and real voltage-driven PD sources.
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Fofana, Issouf, Yohan Bergeron, Marie-Pier Gagnon, Jonathan Tremblay, Luc Loiselle, Kouba Marie Lucia Yapi und Mohan Rao Ungarala. „Fullers Earth Treatment for Esters Liquids used in Power Apparatuses: Inferences and Arguments“. ENP Engineering Science Journal 1, Nr. 1 (22.07.2021): 38–42. http://dx.doi.org/10.53907/enpesj.v1i1.33.
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Insulating Liquids are widely used for their electrical and thermal properties in power apparatuses, particularly at the level of liquid-filled transformers. With the shift in engineering aspects towards sustainable development, it is important to find a sustainable solution with ecofriendly nature. Therefore, alternative (biodegradable) liquids are of high importance in the global transformer communities. In the present study, the alternative dielectric fluids (ester-based) feasibility for potential regeneration with Fuller’s earth is investigated. The experimental results are confined to the reclamation temperature as well as the ratio of Fuller's earth (the sorbent) and the liquid. A suitable laboratory treatment apparatus is designed and is adopted in this study. Promising measurements to comment on the effectiveness of the treatment have been performed at controlled treatment temperature and sorbent-liquid ratio with the ASTM 7150-13 as a reference norm.The results of this study allowed 80°C and 1 g/30 ml as affirmative conditions for the present experimental conditions. Diagnostic measurements include turbidity, particle counter, and UV spectrophotometry before and after treatments. It is inferred that fuller’s earth is not a promising sorbent for the reclamation of ester liquids.
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Bezuk, Steve. „Challenges and Directions in Mobile Device Packaging“. Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2014, DPC (01.01.2014): 1–32. http://dx.doi.org/10.4071/2014dpc-keynote_t1_bezuk.
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Mobile devices such as phones, tablets and subnotebooks are driving innovation in device packaging. These devices currently are jammed full of advanced capabilities, such as HD video, GPS, WLAN, cellular, touchscreens, Bluetooth, and dual cameras - with significantly more functionality than “sophisticated” notebooks. These features drive demand for mobile devices and provide significant challenges to the packaging community for solutions such as thinner packages while still controlling warpage, new materials, both polymers and solders, as well as innovative structures moving into 2.5 and 3D. Solving these challenges allows innovation to drive demand for mobile devices, providing a providing a platform for many innovative uses that are still being tapped, such as entertainment, video recording, web access, computer vision, augmented reality, all readable, recognizable, locatable, addressable, and controllable through the internet, the Internet of Things (IOT) concept. This talk will discuss current and future innovations to address these formidable issues in the mobile environment. Many extreme temperature applications such as power converters and motor drivers operate from power rails that are floating, noisy and have extremely high voltages. Typically the logic signal is only a few volts but is must be transmitted in an environment with hundreds or thousands of volts of common mode voltage. In some cases isolation is required for safety reasons to prevent leakage currents that could present an electrical shock hazard. For example the ground reference for a high side driver of an all N channel half bridge is referenced to the switch pin and switches between ground and the power rail within a few nanoseconds. At normal operating temperatures there are many specialized components such as opto-isolators, capacitive coupled devices and devices with integrated high frequency transformers that transmit logic signals across the isolation barrier. These specialized integrated circuits that provide isolation may not function reliably at elevated temperatures; those that do tend to be expensive. With special consideration of the system partitioning, it may be possible to avoid the need for galvanic isolation at extreme temperatures. It may be possible to provide the isolation in a remote more benign environment and send the isolated signal down a cable with appropriate impedance matching. When galvanic isolation at extreme temperatures is necessary, there must be temperature considerations for the components used. For example, when designing pulse transformers, the temperature effects on the magnetic core material properties such as permeability and frequency response must be considered as well as the Curie temperature. Modulation of the logic signals can help to reduce transformer size. Since the isolated driver functions typically require power, a novel method of winding the transformer is discussed; this method allows the drive signal to be transferred across the isolation barrier in the same transformer core that is used to provide isolated power to the driver. This paper addresses these topics and provides several alternative solutions to the problem of galvanic signal isolation at extreme temperatures.
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Dong, Huanyu, Xiaohui Yang, Anyi Li, Zihao Xie und Yuanlong Zuo. „Bio-Inspired PHM Model for Diagnostics of Faults in Power Transformers Using Dissolved Gas-in-Oil Data“. Sensors 19, Nr. 4 (18.02.2019): 845. http://dx.doi.org/10.3390/s19040845.
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Prognostics and Health Management (PHM) is an emerging technique which can improve the availability and efficiency of equipment. A series of related optimization of the PHM system has been achieved due to the growing need for lowering the cost of maintenance. The PHM system highly relies on data collected from its components. Based on the theory of machine learning, this paper proposes a bio-inspired PHM model based on a dissolved gas-in-oil dataset (DGA) to diagnose faults of transformes in power grids. Specifically, this model applies Bat algorithm (BA), a metaheuristic population-based algorithm, to optimize the structure of the Back-propagation neural network (BPNN). Furthermore, this paper proposes a modified Bat algorithm (MBA); here the chaos strategy is utilized to improve the random initialization process of BA in order to avoid falling into local optima. To prove that the proposed PHM model has better fault diagnostic performance than others, fitness and mean squared error (MSE) of Bat-BPNN are set as reference amounts to compare with other power grid PHM approaches including BPNN, Particle swarm optimization (PSO)-BPNN, as well as Genetic algorithm (GA)-BPNN. The experimental results show that the BA-BPNN model has increased the fault diagnosis accuracy from 77.14% to 97.14%, which is higher than other power transformer PHM models.
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Zukowski, Pawel, Przemyslaw Rogalski, Konrad Kierczynski und Tomasz N. Koltunowicz. „Precise Measurements of the Temperature Influence on the Complex Permittivity of Power Transformers Moistened Paper-Oil Insulation“. Energies 14, Nr. 18 (14.09.2021): 5802. http://dx.doi.org/10.3390/en14185802.
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The reference characteristics of complex permittivity of the transformers insulation solid component were determined for use in the precise diagnostics of the power transformers insulation state. The solid component is a composite of cellulose, insulating oil and water nanoparticles. Measurements were made in the frequency range from 10−4 Hz to 5000 Hz at temperatures from 293.15 to 333.15 K. Uncertainty of temperature measurements was less than ±0.01 K. Pressboard impregnated with insulating oil with a water content of (5.0 ± 0.2) by weight moistened in a manner maximally similar to the moistening process in power transformers was investigated. It was found that there are two stages of changes in permittivity and imaginary permittivity components, occurring for low and high frequency. As the temperature increases, the frequency dependencies of the permittivity and imaginary permittivity component shifts to the higher frequency region. This phenomenon is related to the change of relaxation time with the increase in temperature. The values of relaxation time activation energies of the permittivity ΔWτε′ ≈ (0.827 ± 0.0094) eV and the imaginary permittivity component ΔWτε″ = 0.883 eV were determined. It was found that Cole-Cole charts for the first stage are asymmetric and similar to those described by the Dawidson–Cole relaxation. For stage two, the charts are arc-shaped, corresponding to the Cole-Cole relaxation. It has been established that in the moistened pressboard impregnated with insulating oil, there is an additional polarization mechanism associated with the occurrence of water in the form of nanodrops and the tunneling of electrons between them.
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Bin Asrokin, Azhari, und Mohamad Kamal Bin A. Rahim. „Performance Evaluation of Two Port and Four Port Measurement for Twisted Pair Cable“. International Journal of Electrical and Computer Engineering (IJECE) 8, Nr. 4 (01.08.2018): 2624. http://dx.doi.org/10.11591/ijece.v8i4.pp2624-2632.
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A balance-unbalance (balun) transformer is commonly used to connect the balance 100 Ohm twisted pair cable to the unbalance 50 Ohm network analyzer ports, but due to the limitations of the core (i.e. ferrite) inside the balun, the balun can only effectively operates at a certain band of frequencies. This limitation can be eliminated by using a 4-port vector network analyzer (VNA) which is done by connecting the VNA’s ports to each conductor end. The extracted S-parameters will then be transformed to a 2-port S-parameters in differential mode at both ports. To validate the measurement technique, S-parameter measurement by using the 4-Port Network Analyzer without any balun will be compared to the measurement which used the 2-Port Network Analyzer with the balun transformers. Two twisted pair cable distances are selected as reference which are 500, and 1000 meters with nominal copper diameter of 0.5mm. Based on the measurement results, the 4-ports measurement shows good correlation with the 2-ports measurement especially at 500m distance. This shows that the 4-ports measurement setup is suitable to be used to measure twisted pair copper cable and possible to measure at a higher frequency band such as up to 500 MHz but at a shorter twisted pair cable distance.
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Bastiaens, Koen, Mitrofan Curti, Dave Krop, Sultan Jumayev und Elena Lomonova. „Spectral Element Method Modeling of Eddy Current Losses in High-Frequency Transformers“. Mathematical and Computational Applications 24, Nr. 1 (21.02.2019): 28. http://dx.doi.org/10.3390/mca24010028.
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This paper concerns the modeling of eddy current losses in conductive materials in the vicinity of a high-frequency transformer; more specifically, in two-dimensional problems where a high ratio between the object dimensions and the skin-depth exists. The analysis is performed using the Spectral Element Method (SEM), where high order Legendre–Gauss–Lobatto polynomials are applied to increase the accuracy of the results with respect to the Finite Element Method (FEM). A convergence analysis is performed on a two-dimensional benchmark system, for both the SEM and FEM. The benchmark system consists of a high-frequency transformer confined by a conductive cylinder and is free of complex geometrical shapes. Two different objectives are investigated. First, the discretizations at which the relative error with respect to a reference solution is minimized are compared. Second, the discretizations at which the trade-off between computational effort and accuracy is optimized are compared. The results indicated that by applying the SEM to the two-dimensional benchmark system, a higher accuracy per degree of freedom and significantly lower computation time are obtained with respect to the FEM. Therefore, the SEM is proven to be particularly useful for this type of problem.
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Widyastuti, Christine, und Rakai Alvin Wisnuaji. „Analisis Tegangan Tembus Minyak Transformator Di PT. PLN (Persero) Bogor“. Elektron : Jurnal Ilmiah 11, Nr. 2 (05.12.2019): 75–78. http://dx.doi.org/10.30630/eji.11.2.128.
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PT.PLN (Persero) adalah penyedia listrik yang ada di Indonesia. Dalam penyaluran daya listrik, tidak seluruhnya dapat disalurkan kepada konsumen, karena akan hilang dalam bentuk rugi-rugi energi. Dengan melakukan pengujian tegangan tembus pada minyak transformator diharapkan menjadi bahan acuan untuk menjaga kinerja atau umur transformator. Pengujian dengan menggunakan Alat uji Breakdown Voltage merek Megger OTS80PB. Kelayakan minyak transformator dilihat dari hasil pengujian tegangan tembus dan kadar airnya sebagai hasil simulasi kelayakan berdasarkan standar internasional untuk meningkatkan kehandalan dan dalam perawatan transformator daya dalam melayani penyaluran tenaga listrik kepada konsumen. Dengan nilai tegangan tembus yang semakin besar menunjukkan bahwa minyak transformator tersebut masih layak pakai. Sesuai standar uji PLN (SPLN) 49-1/1982 suatu minyak transformator sebagai bahan isolasinya harus memiliki tegangan tembus minimal 30kV/2,5mm. Dalam penelitian ini hasil pengujian dari transformator 1, transformator 2 dan transformator 3 memiliki tegangan tembus masing-masing adalah 49,4kV/2,5mm, 44,3 kV/2,5mm, 41,1 kV/2,5mm. Dari hasil tersebut dapat di katakan bahwa nilai tegangan tembus dari minyak transformator masih di atas minimal standar tegangan tembusnya sehingga masih dapat dipergunakan sebagai isolasi pada transformator.
Kata kunci : Minyak Transformator , Tegangan Tembus , Breakdown Voltage Tester Merk Megger Seri Ots80pb
PT.PLN (Persero) is a provider of electricity in Indonesia. In the distribution of electric power, not all of it can be distributed to consumers, because it will be lost in the form of energy losses. By testing the breakdown voltage on transformer oil is expected to be a reference material to maintain the performance or life of the transformer. Testing using the Megger OTS80PB Breakdown Voltage test tool. The feasibility of transformer oil can be seen from the results of testing the breakdown voltage and water content as a result of the feasibility simulation based on international standards to improve the reliability and maintenance of power transformers in serving the distribution of electricity to consumers. With a greater breakdown voltage value indicates that the transformer oil is still suitable for use. According to the PLN test standard (SPLN) 49-1 / 1982 a transformer oil as an insulating material must have a breakdown voltage of at least 30kV / 2.5mm. In this study the test results of transformer 1, transformer 2 and transformer 3 have a breakdown voltage of 49.4kV / 2.5mm, 44.3 kV / 2.5mm, 41.1 kV / 2.5mm respectively. From these results it can be said that the breakdown voltage value of the transformer oil is still above the minimum breakdown voltage standard so that it can still be used as insulation on the transformer.
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Bouchiba, Bousmaha, Abdeldjebar Hazzab, Hachemi Glaoui, Fellah Med-Karim, Ismaïl Bousserhane und Pierre Sicard. „Control of multi-machine using adaptive fuzzy“. Serbian Journal of Electrical Engineering 8, Nr. 2 (2011): 111–26. http://dx.doi.org/10.2298/sjee1102111b.
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An indirect Adaptive fuzzy excitation control (IAFLC) of power systems based on multi-input-multi-output linearization technique is developed in this paper. The power system considered in this paper consists of two generators and infinite bus connected through a network of transformers and transmission lines. The fuzzy controller is constructed from fuzzy feedback linearization controller whose parameters are adjusted indirectly from the estimates of plant parameters. The adaptation law adjusts the controller parameters on-line so that the plant output tracks the reference model output. Simulation results shown that the proposed controller IAFLC, compared with a controller based on tradition linearization technique can enhance the transient stability of the power system.
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Giussani, Andrea. „Machine Learning for Dissimulating Reality“. Proceedings 77, Nr. 1 (27.04.2021): 17. http://dx.doi.org/10.3390/proceedings2021077017.
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In the last decade, advances in statistical modeling and computer science have boosted the production of machine-produced contents in different fields: from language to image generation, the quality of the generated outputs is remarkably high, sometimes better than those produced by a human being. Modern technological advances such as OpenAI’s GPT-2 (and recently GPT-3) permit automated systems to dramatically alter reality with synthetic outputs so that humans are not able to distinguish the real copy from its counteracts. An example is given by an article entirely written by GPT-2, but many other examples exist. In the field of computer vision, Nvidia’s Generative Adversarial Network, commonly known as StyleGAN (Karras et al. 2018), has become the de facto reference point for the production of a huge amount of fake human face portraits; additionally, recent algorithms were developed to create both musical scores and mathematical formulas. This presentation aims to stimulate participants on the state-of-the-art results in this field: we will cover both GANs and language modeling with recent applications. The novelty here is that we apply a transformer-based machine learning technique, namely RoBerta (Liu et al. 2019), to the detection of human-produced versus machine-produced text concerning fake news detection. RoBerta is a recent algorithm that is based on the well-known Bidirectional Encoder Representations from Transformers algorithm, known as BERT (Devlin et al. 2018); this is a bi-directional transformer used for natural language processing developed by Google and pre-trained over a huge amount of unlabeled textual data to learn embeddings. We will then use these representations as an input of our classifier to detect real vs. machine-produced text. The application is demonstrated in the presentation.
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Song, Liang, Jian Feng Sheng und Jun Liu. „A Comparative Study on the Performance of Domestic Cellulose Based Pressboards for Use in Transformers“. Advanced Materials Research 887-888 (Februar 2014): 865–68. http://dx.doi.org/10.4028/www.scientific.net/amr.887-888.865.
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The cellulose based pressboards from four well-known suppliers in China, which areChangzhou HuaDian Insulation Material Co., Ltd (HD), TaiZhou XinYuan Electrical EquipmentCo., Ltd (XY), Hunan GuangXin Electrical Technology (GX) and ShangHai YaZhong TradeDevelopment Co., Ltd (YZ) were analyzed and compared. The guarantee value of Figeholm’spressboard was taken as a reference. Mechanical results show that most pressboards have excellenttensile, compressive and flexural properties except for YZ pressboards. The ply adhesion was alsostudied by simple loading method to verify the bonding effect and only XY pressboard show nosliding. Electrical results show that all pressboards have a similar electrical strength while HD andXY pressboards show relatively lower dissipation factor value. Based on the mechanical andelectrical performance, XY pressboards are considered to be better as compared to others andcompetitive to Figeholm’s products.
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Kong, Jin Jiao, Feng Wang, Yong Liang Li, Xu Tao Wu und Jian Gang Bi. „Review of Condition Assessment for Power Transformer“. Applied Mechanics and Materials 681 (Oktober 2014): 160–63. http://dx.doi.org/10.4028/www.scientific.net/amm.681.160.
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Transformer is one of the most important equipment in power system, and accurate condition assessment for transformer is the key for condition based maintenance (CBM). So the study of condition assessment is particularly important. In this paper, the function, role and steps of condition assessment, research status, existing problems and future directions are analyzed and summarized. And this paper can be a reference for transformer’s condition assessment.
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Arboleya, Pablo, Cristina Gonzalez-Moran und Manuel Coto. „Unbalanced Power Flow in Distribution Systems With Embedded Transformers Using the Complex Theory in $\alpha \beta 0\;$ Stationary Reference Frame“. IEEE Transactions on Power Systems 29, Nr. 3 (Mai 2014): 1012–22. http://dx.doi.org/10.1109/tpwrs.2013.2292112.
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Uchida, S., K. Mochizuki, K. Araki, I. Kaku, Y. Sakuraba, T. Takeshina und S. Shirakawa. „Relation of insulation resistance and deteriorated ratio of reference voltage of oil-immersed surge arrester elements enclosed in pole transformers“. IEEE Transactions on Power Delivery 13, Nr. 2 (April 1998): 453–58. http://dx.doi.org/10.1109/61.660914.
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Waluyo, Siti Saodah und Yogi Wibisono. „Arduino Mega Based Current Recorder Prototype Implementation“. ECTI Transactions on Electrical Engineering, Electronics, and Communications 19, Nr. 1 (25.02.2021): 59–70. http://dx.doi.org/10.37936/ecti-eec.2021191.222588.
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Current measurements in electric power systems are important aspects, both for monitoring and protection. The researchers have designed, created and tested a digital current measuring and recording prototype instrument. The current signals were sensed by the split-core current transformers, entered to the signal conditioning, to the main Arduino Mega 2560 microcontroller, and finally to the three outputs, namely a PC monitor, SD card data logger and LCD. It was tested and the results were compared to the computation results and the clamp ammeter readings, as the reference instrument. On both single and three phase systems, the absolute deviations would considerably rise and the relative deviations would slightly reduce as the load currents increased. Nevertheless, the values on both systems were not exactly same. For the single phase, the average absolute and relative deviation slopes were 0.156548 A/kW and -0.0020772 %/kW respectively. On other hand, for the three phase system, they were 0.12372 A/kW and -0.04176 %/kW respectively. The relative deviations to the computation results were under 6%, tended to be 3%, and the relative deviations to the reference instrument readings were under 3%, tended to be 1%, as the load increased.
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Oyeleye, M. O. „Evaluation of Lightning Protection Efficacy on Nigerian Installations High Voltage Installations Using Screen and Cone of Protection Methods“. European Journal of Engineering Research and Science 4, Nr. 7 (09.07.2019): 1–10. http://dx.doi.org/10.24018/ejers.2019.4.7.1401.
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This study evaluated lightning protective system efficacy on 11kV-132kV substation-power line installation in Ikorodu, Lagos State, Nigeria with reference to cloud to ground(C-G) lightning strike (LS) events. It focus on interception of lightning strikes and its protection with reference to direct lightning strike (DLS) and indirect lightning strike (IDLS). Data were collected from Ikorodu 132/33 kV Transmission Substation and its four major injection stations. This work was carried out using physical measurement of raw data obtained from the high voltage substation. Installations were scaled down and modelled dimensionally using AutoCAD software in order to measure spatial parameters in order to measure the screening of the existing substations and connected lines, as well as the existing cone angles of protection. Probability of lightning efficiency of lightning protective level (LPL) are used for screening evaluation while spike and sky wire angle of protection are used for cone of protection evaluation. Physical measurement of six substations (33/11 kV and 132/33 kV substations) in the studied area were also carried out to evaluate the effectiveness of the installed lightning arresters with respect to the protected devices using applicable standard. The results under the prevailing lightning protective system, LPS, (screening method), revealed that the existing 33/11 kV and 132/33 kV substations are not adequately protected against lightning strike; 132/33 kV substation is more vulnerable to lightning strike than 33/11kV substation and that the incoming 132kV power lines to the substation are adequately protected. The evaluation of the installed distances of all lightning arresters are within standard range and would adequately protect substation transformers against travelling waves (Indirect Stroke) events. The installed lightning arresters (LAs) would adequately protect substation transformers against travelling waves (Indirect Stroke) events. The adequate protection should be reinforced with proposed design scheme in further study in order to mitigate the disastrous effects of lightning strike. Any proposed design of protective system for electric power installations in Nigeria should be simulated using computer aided design software for scaled validation of dimensional and spatial design values in order to mitigate reported failures and uncertainties in identifying causes of observed failures in the system.
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Chen, Pei-Fu, Ssu-Ming Wang, Wei-Chih Liao, Lu-Cheng Kuo, Kuan-Chih Chen, Yu-Cheng Lin, Chi-Yu Yang, Chi-Hao Chiu, Shu-Chih Chang und Feipei Lai. „Automatic ICD-10 Coding and Training System: Deep Neural Network Based on Supervised Learning“. JMIR Medical Informatics 9, Nr. 8 (31.08.2021): e23230. http://dx.doi.org/10.2196/23230.
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Background The International Classification of Diseases (ICD) code is widely used as the reference in medical system and billing purposes. However, classifying diseases into ICD codes still mainly relies on humans reading a large amount of written material as the basis for coding. Coding is both laborious and time-consuming. Since the conversion of ICD-9 to ICD-10, the coding task became much more complicated, and deep learning– and natural language processing–related approaches have been studied to assist disease coders. Objective This paper aims at constructing a deep learning model for ICD-10 coding, where the model is meant to automatically determine the corresponding diagnosis and procedure codes based solely on free-text medical notes to improve accuracy and reduce human effort. Methods We used diagnosis records of the National Taiwan University Hospital as resources and apply natural language processing techniques, including global vectors, word to vectors, embeddings from language models, bidirectional encoder representations from transformers, and single head attention recurrent neural network, on the deep neural network architecture to implement ICD-10 auto-coding. Besides, we introduced the attention mechanism into the classification model to extract the keywords from diagnoses and visualize the coding reference for training freshmen in ICD-10. Sixty discharge notes were randomly selected to examine the change in the F1-score and the coding time by coders before and after using our model. Results In experiments on the medical data set of National Taiwan University Hospital, our prediction results revealed F1-scores of 0.715 and 0.618 for the ICD-10 Clinical Modification code and Procedure Coding System code, respectively, with a bidirectional encoder representations from transformers embedding approach in the Gated Recurrent Unit classification model. The well-trained models were applied on the ICD-10 web service for coding and training to ICD-10 users. With this service, coders can code with the F1-score significantly increased from a median of 0.832 to 0.922 (P<.05), but not in a reduced interval. Conclusions The proposed model significantly improved the F1-score but did not decrease the time consumed in coding by disease coders.
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Molla, Emiyamrew Minaye, und Cheng-Chien Kuo. „Voltage Quality Enhancement of Grid-Integrated PV System Using Battery-Based Dynamic Voltage Restorer“. Energies 13, Nr. 21 (02.11.2020): 5742. http://dx.doi.org/10.3390/en13215742.
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The advancement of power electronic-based sensitive loads drives the power utilities’ devotion to power quality issues. The voltage disturbance could be happening due to fault conditions, switching of loads, energizing of transformers, or integration of highly intermittent energy sources such as PV systems. This research work attempts to enhance the voltage fluctuation of a sensitive load connected to a grid-integrated PV system using a battery-based dynamic voltage restorer (DVR). The proposed battery energy storage-based DVR has two separate controlling stages that are implemented at the DC–DC buck/boost converter of the battery and voltage source converter (VSC) system. Charging and discharging of the battery is operated based on the state-of-charge (SOC) value of the battery and the measured root mean square (RMS) voltage at the point of common coupling (PCC). The VSC of the DVR detection and reference generation control is done appropriately. In the detection control of the VSC, a combination of RMS and dq0 measurement techniques is used, whereas in the reference generation control, pre-fault strategy is implemented to restore both phase jump and magnitude distortions. Symmetrical and asymmetrical voltage sags scenarios are considered and the compensation demonstration is carried out using power system computer-aided design (PSCAD/EMTDC) software.
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Maurice, Olivier, Alain Reineix, Philippe Durand, François Dubois und Eric Beaussart. „Projection of Sensitive Reality into Cellular Topology“. Acta Europeana Systemica 4 (14.07.2020): 181–94. http://dx.doi.org/10.14428/aes.v4i1.57363.
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The purpose of this paper is to discuss about the abstract representation of some reality in a given referential into a cellular topology[1]. From this projection, tensorial algebra can then be employed to translate mathematically the behavior of this perceptible reality[2]. The first discussion wears on an experience realized on some object. We speak firstly of the perception of the object. How it can be seen, identified depending on various point of views. It fixes the reference frame where the observation is made. In this reference frame, environment involves domains for which parameters are defined: temperature, pressure, etc. A stimulus can be applied on known conditions in this environment and defined observable can be measured. From this pragmatic but stilling complex experience, a law can be extracted giving a relation between the stimulus and the observable. This law can be seen as a function, part of a non-linear metric when the same object is enclosed in a larger system[3]. Conditions on the domains and experiences must be detailed in order to control the system behavior, but masked parameters can influence the evolution of the system, being possible explanations for emergences. The whole system is modeling using “gamma matrices”, transformers and “tenfolds”.
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Sun, Zeyu, Qihao Zhu, Yingfei Xiong, Yican Sun, Lili Mou und Lu Zhang. „TreeGen: A Tree-Based Transformer Architecture for Code Generation“. Proceedings of the AAAI Conference on Artificial Intelligence 34, Nr. 05 (03.04.2020): 8984–91. http://dx.doi.org/10.1609/aaai.v34i05.6430.
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A code generation system generates programming language code based on an input natural language description. State-of-the-art approaches rely on neural networks for code generation. However, these code generators suffer from two problems. One is the long dependency problem, where a code element often depends on another far-away code element. A variable reference, for example, depends on its definition, which may appear quite a few lines before. The other problem is structure modeling, as programs contain rich structural information. In this paper, we propose a novel tree-based neural architecture, TreeGen, for code generation. TreeGen uses the attention mechanism of Transformers to alleviate the long-dependency problem, and introduces a novel AST reader (encoder) to incorporate grammar rules and AST structures into the network. We evaluated TreeGen on a Python benchmark, HearthStone, and two semantic parsing benchmarks, ATIS and GEO. TreeGen outperformed the previous state-of-the-art approach by 4.5 percentage points on HearthStone, and achieved the best accuracy among neural network-based approaches on ATIS (89.1%) and GEO (89.6%). We also conducted an ablation test to better understand each component of our model.
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Moser, Susanne. „Tugend als Wert: Christoph Halbig und Max Scheler im Vergleich“. Labyrinth 18, Nr. 2 (30.12.2016): 158. http://dx.doi.org/10.25180/lj.v18i2.52.
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Virtue as Value: A Comparison between Christoph Halbig and Max SchelerThe aim of the following contribution is to compare the virtue conceptions of Christoph Halbig and Max Scheler in order to scrutinize their common positions and differences and thus to answer two questions: Firstly, is it true that Scheler's approach is based on the basic assumptions of the recursive theory of virtues, as Halbig asserts this? Secondly, can the virtues be defined as attitudes (Thomas Hurka, Christopher Halbig), or should they be conceived as qualities of the person (Max Scheler)? In addition, the author examines the connection of virtues and emotions more closely and shows that virtues can be regarded as a kind of transformers from the negative to the positive, because they fix the right way of dealing with negative emotions and because they switch over the negative basic mood into a positive and joyful one. The reflection of these questions is embedded in a constant reference to Aristotle's understanding of virtues.
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Aguero, Marlon, Ali Ozdagli und Fernando Moreu. „Measuring Reference-Free Total Displacements of Piles and Columns Using Low-Cost, Battery-Powered, Efficient Wireless Intelligent Sensors (LEWIS2)“. Sensors 19, Nr. 7 (30.03.2019): 1549. http://dx.doi.org/10.3390/s19071549.
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Currently, over half of the U.S.’s railroad bridges are more than 100 years old. Railroad managers ensure that the proper Maintenance, Repair, and Replacement (MRR) of rail infrastructure is prioritized to safely adapt to the increasing traffic demand. By 2035, the demand for U.S. railroad transportation will increase by 88%, which indicates that considerable expenditure is necessary to upgrade rail infrastructure. Railroad bridge managers need to use their limited funds for bridge MRR to make informed decisions about safety. Consequently, they require economical and reliable methods to receive objective data about bridge displacements under service loads. Current methods of measuring displacements are often expensive. Wired sensors, such as Linear Variable Differential Transformers (LVDTs), require time-consuming installation and involve high labor and maintenance costs. Wireless sensors (WS) are easier to install and maintain but are in general technologically complex and costly. This paper summarizes the development and validation of LEWIS2, the second version of the real-time, low-cost, efficient wireless intelligent sensor (LEWIS) for measuring and autonomously storing reference-free total transverse displacements. The new features of LEWIS2 include portability, accuracy, cost-effectiveness, and readiness for field application. This research evaluates the effectiveness of LEWIS2 for measuring displacements through a series of laboratory experiments. The experiments demonstrate that LEWIS2 can accurately estimate reference-free total displacements, with a maximum error of only 11% in comparison with the LVDT, while it costs less than 5% of the average price of commercial wireless sensors.