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Journal articles on the topic 'Electrical transformers'
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1
Kefalas, Themistoklis D., and Antonios Kladas. "Reduction of Power Grid Losses by Using Energy Efficient Distribution Transformers." Materials Science Forum 721 (June 2012): 269–74. http://dx.doi.org/10.4028/www.scientific.net/msf.721.269.
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The importance of distribution transformer no-load loss on the operation of modern electrical grids is often underestimated. Internationally, distribution transformer no-load loss constitutes nearly 25% of the transmission and distribution losses of electrical grids. The losses in European Union distribution transformers are estimated at about 33 TWh/year whereas, reactive power and harmonic losses add a further 5 TWh/year. In the Greek electrical grid the no-load losses of 140,000 distribution transformers are estimated at about 490 GWh/year. This paper has two goals the first one is to illustrate the significance of distribution transformer no-load loss in periods of high electric energy cost and the second goal is the presentation of a novel numerical methodology for wound core transformers no-load loss analysis, enabling to determine the economically and technically optimum transformer for every use.
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Banchuin, Rawid, and Roungsan Chaisricharoen. "Vector SDE Based Stochastic Analysis of Transformer." ECTI Transactions on Computer and Information Technology (ECTI-CIT) 15, no. 1 (January 5, 2021): 82–107. http://dx.doi.org/10.37936/ecti-cit.2021151.188931.
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In this research, the stochastic behaviours oftransformer have been analysed by using the stochasticdifferential equation approach where both noise in thevoltage source applied to the transformer and the randomvariations in elements and parameters of transformers havebeen considered. The resulting vector stochasticdifferential equations of the transformer have been bothanalytically and numerically solved in the Ito sense wherethe Euler-Maruyama scheme has been adopted fordetermining the numerical solutions which have been theirsample means have been used for verification. With theobtained analytical and numerical solutions, the stochasticproperties of the transformer’s electrical quantities havebeen studied and the influences of noise in the voltagesource and random variations in elements and parametersof transformers to those electrical quantities have beenanalysed. The causes of high and low frequency stochasticvariations of such electrical quantities in both transient andsteady state have been pointed out. Moreover, furtherextension of our stochastic differential equations and therelated mathematical formulations has also been given.
3
Alyunov, A. N., O. S. Vyatkina, I. G. Akhmetova, R. D. Pentiuc, and K. E. Sakipov. "Issues on optimization of operating modes of power transformers." E3S Web of Conferences 124 (2019): 02015. http://dx.doi.org/10.1051/e3sconf/201912402015.
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The article presents measure to optimize the operating modes of power transformers in order to minimize losses of electrical energy. The influence of actual voltage and service life of power transformers on electric power losses is shown. It was proposed to determine the economic capacity of power transformers taking into account the indicated factors, as well as taking into account the time of transformer switching on into the electric network and the form of the load schedule.
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Hanus, Oleksii, and Kostiantyn Starkov. "STUDY OF THE NATURE OF OVERVOLTAGES IN THE ELECTRICAL NETWORK ARISING FROM VOLTAGE TRANSFORMERS." Bulletin of the National Technical University "KhPI". Series: Energy: Reliability and Energy Efficiency, no. 1 (2) (July 2, 2021): 28–36. http://dx.doi.org/10.20998/2224-0349.2021.01.05.
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A non-linear dynamic mathematical model of voltage transformer has been considered and overvoltages arising on the elements of voltage transformer equivalent circuit during transient processes have been investigated. The influence of voltage transformer secondary circuit capacitance on overvoltage multiplicity in the primary circuits and the duration of transients has been determined. The advantages of approximation of nonlinearity of voltage transformers by hyperbolic sine are used. Mathematical expressions determining the nature of changes in the forced and free components of the transient process in an electrical network with a voltage transformer have been obtained. It is shown that with the increase of the electric network capacitance the duration of the transition process damping increases and the frequency of the forced oscillations and the level of overvoltage decrease. It is proved that even small, in comparison with the primary nominal sinusoidal voltage, aperiodic components of the voltage transient process can lead to significant overvoltages during voltage transformer outages. It has been substantiated that both the secondary resistance and the switching torque influence the overvoltage multiplicity arising in the primary winding of voltage transformers. It is shown that the closed secondary winding worsens the disconnection process of non-linear inductance of voltage transformers. The values to which overvoltages increase in this case are determined. According to the results of calculations it is determined that with open secondary winding of voltage transformers the duration of transient process significantly increases. It has been found that the decrease of frequency of forced oscillations, which occurs in this case, is accompanied by an increase of currents in the primary winding of the voltage transformer, which is dangerous in terms of thermal stability of the winding insulation. It is shown, that closing the secondary winding of voltage transformers leads to significant reduction of transient damping time. It is suggested that this algorithm can be used to provide a rapid breakdown (suppression) of ferroresonant processes. The effectiveness of such a measure of stopping of ferroresonance processes as short-term shunting of secondary winding of voltage transformers has been investigated. The correlation of parameters of electric networks (capacity of busbar sections, nonlinearity of characteristics of voltage transformers, disconnection torque, etc.) at which ferroresonance process may occur and consideration of which may allow, in terms of prevention of ferroresonance processes, to identify substations (electric networks) that require more detailed research has been determined. The results of analytical studies were tested in the electric networks of JSC "Kharkivoblenergo" and used in the electricity distribution system for the selection of specific voltage transformers for certain configurations of electrical networks.
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Changjiang, Zheng, Wang Qian, Wang Huai, Shen Zhan, and Claus Leth Bak. "Electrical Stress on the Medium Voltage Medium Frequency Transformer." Energies 14, no. 16 (August 19, 2021): 5136. http://dx.doi.org/10.3390/en14165136.
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This paper proposes an equivalent circuit model to obtain the transient electrical stress quantitatively in medium voltage medium frequency transformers in modern power electronics. To verify this model, transient simulation is performed on a 1.5 kV/1 kHz transformer, revealing voltage overshoot quantitatively between turns and layers of the transformer’s HV winding. Effects of rise time of the input pulse voltage, stray capacitance of the winding insulation, and their interactions on the voltage overshot magnitude are presented. With these results, we propose limiting the voltage overshoot and, thereafter, enhancing medium voltage medium frequency transformer’s insulation capability, which throws light on the transformer’s insulation design. Additionally, guidance on the future studies on aging and endurance lifetime of the medium voltage medium frequency transformer’s insulation could be given.
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Anh Khoi Pham, Dinh. "Application of Frequency Response Analysis for in-service power transformers." Science and Technology Development Journal 20, K1 (March 31, 2017): 58–66. http://dx.doi.org/10.32508/stdj.v20ik1.415.
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CIGRE, IEC and IEEE have recently approved the technique of Frequency Response Analysis (FRA) as an application tool for diagnosis of mechanical failures in power transformer’s active part, i.e., windings, leads and the core. The diagnosis is based on the discrepancy between frequency responses measured on power transformers mainly at different time points. In Vietnam, utilities such as Power Transmission Companies and Power Corporations are investigating this technique for application on their power transformers.
Mechanical failures in power transformers cause changes on measured frequency responses starting from a medium frequency range, from several hundreds of Hz or tens of kHz depending on transformer/winding type and power. For a reliable diagnosis, the understanding of transformer/winding structure on measured frequency responses is of importance; thus, the international standards suggested the simulation approach with physical distributed transformer circuits should be exploited.
The development of physical distributed circuits of power transformers normally needs availability of internal transformer structure and material properties for an analytical approach. However, for in-service power transformers, this task is challenging since the required data are not available.
For a feasible application of the simulation based FRA interpretation, this paper introduces an investigation on the development of a distributed equivalent circuit of an in-service 6.5 MVA 47/27.2 kV Yd5 power transformer. The result of this investigation is a feasible approach in determining electrical parameters in a physical distributed circuit, which supports analysis of frequency responses measured at transformer terminals for real application on in-service power transformers of utilities.
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Liu, Guo Bin, Ning Wang, Qing Hao Wang, Tian Shu Hai, Chuan Zong Zhao, Gui Bin Hu, Hong Zhi Jiao, Chuan Bing Bi, and Hui Yan Cao. "Chromatographic Analysis of Oil-Based Electrical Equipment Discharge Failure." Applied Mechanics and Materials 602-605 (August 2014): 2953–57. http://dx.doi.org/10.4028/www.scientific.net/amm.602-605.2953.
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Discharge of failure was the fault type are likely to occur in transformers, bushings, transformers, and the extent of damage to the equipment is a serious and direct impact on the stable operation of the system, first introduced the principle and gas chromatographic analysis its test methods, then gas chromatography equipment discharge failure is how to judge the conduct described. Through the analysis of transformer oil chromatographic method can be found as early as possible transformers and other equipment inside the existence of latent failures, thus chromatography is to oversee and guarantee the safe operation of an important means of transformer.
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Bogicevic, Zorica, Slobodan Bjelić, Petar Spalević, and Milan Mišić. "Graph-Analytical Method of Determining Impedance in Electrical Transformers." Mathematical Problems in Engineering 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/745629.
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This paper presents a graph-analytical method for determining the electrical impedance of alternate energy sources, especially small power transformers and current transformers in electric networks. Unlike conventional short-circuit and idle tests, according to proposed method, in this paper, transformer parameters are determined in a new way, which is based on measurement of voltages and currents on the active and reactive load (inductive or capacitive). The effectiveness of the proposed model was verified using an adapted simulation in the software package MATLAB Simulink. The simulation was performed for three types of ABB transformers with a 100% load. Simulation results were obtained for power transformers:Sn1=1 [MVA],Sn2=2 [MVA],Sn3=3.15 [MVA]. If we compare measurement result values ofRT,XT, which are contained in a brochure for ABB transformers and those obtained through simulation, different tolerances are obtained. For reactance results, deviations are up to 20% for all three tested transformers. For results of active resistance tolerances are up to 5% for all three tested transformers. This method can be used not only to determine the active and inductive AC power source parameters but also to determine and analyze the impendence of electrical sources with high frequencies.
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Orosz, Tamás, and István Vajda. "Design Optimization with Geometric Programming for Core Type Large Power Transformers." Electrical, Control and Communication Engineering 6, no. 1 (October 23, 2014): 13–18. http://dx.doi.org/10.2478/ecce-2014-0012.
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Abstract A good transformer design satisfies certain functions and requirements. We can satisfy these requirements by various designs. The aim of the manufacturers is to find the most economic choice within the limitations imposed by the constraint functions, which are the combination of the design parameters resulting in the lowest cost unit. One of the earliest application of the Geometric Programming [GP] is the optimization of power transformers. The GP formalism has two main advantages. First the formalism guarantees that the obtained solution is the global minimum. Second the new solution methods can solve even large-scale GPs extremely efficiently and reliably. The design optimization program seeks a minimum capitalized cost solution by optimally setting the transformer's geometrical and electrical parameters. The transformer's capitalized cost chosen for object function, because it takes into consideration the manufacturing and the operational costs. This paper considers the optimization for three winding, three phase, core-form power transformers. This paper presents the implemented transformer cost optimization model and the optimization results.
10
Gong, Chen Bin, Qing Hao Wang, Gang Chen, En Lu Wang, Tian Shu Hai, Xin Yu Li, Bo Li, Xue Wang, Chen Yang Liu, and Qi Dong Zhao. "Research on Harm of Harmonics on Electrical Equipment." Advanced Materials Research 986-987 (July 2014): 1846–49. http://dx.doi.org/10.4028/www.scientific.net/amr.986-987.1846.
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Through the analysis of harmonics caused by transformer, capacitor, electromagnetic voltage transformer and other accident, harmonics is an important indicator of power quality, which has been included in the “pollution" of power grid is found. In order to understand the harmonic, this paper from the concept of quality of electric energy, and then gradually extended to the field of harmonics. This paper firstly introduces the various reasons and equipment may produce harmonic, Secondly, illustrate harm of harmonic to operation of transformers, capacitors, electromagnetic voltage transformers and other electrical equipment, let more people know and understand the relevant knowledge of the harmonic, In order to save technical force and provide scientific basis for future effective harmonic.
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Lakehal, Abdelaziz, and Fouad Tachi. "Bayesian Duval Triangle Method for Fault Prediction and Assessment of Oil Immersed Transformers." Measurement and Control 50, no. 4 (May 2017): 103–9. http://dx.doi.org/10.1177/0020294017707461.
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Dissolved gas analysis of transformer insulating oil is considered the best indicator of a transformer’s overall condition and is most widely used. In this study, a Bayesian network was developed to predict failures of electrical transformers. The Duval triangle method was used to develop the Bayesian model. The proposed prediction model represents a transformer fault prediction, possible faulty behaviors produced by this transformer (symptoms), along with results of possible dissolved gas analysis. The model essentially captures how possible faults of a transformer can manifest themselves by symptoms (gas proportions). Using our model, it is possible to produce a list of the most likely faults and a list of the most informative gas analysis. Also, the proposed approach helps to eliminate the uncertainty that could exist, regarding the fault nature due to gases trapped in the transformer, or faults that result in more simultaneous gas percentages. The model accurately provides transformer fault diagnosis and prediction ability by calculating the probability of released gases. Furthermore, it predicts failures based on their relationships in the Bayesian network. Finally, we show how the approach works for five distinct electrical transformers of a power plant, by describing the advantages of having available a Bayesian network model based on the Duval triangle method for the fault prediction tasks.
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Florkowski, Marek, Jakub Furgał, Maciej Kuniewski, and Piotr Pająk. "Overvoltage Impact on Internal Insulation Systems of Transformers in Electrical Networks with Vacuum Circuit Breakers." Energies 13, no. 23 (December 2, 2020): 6380. http://dx.doi.org/10.3390/en13236380.
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Vacuum circuit breakers are increasingly used as switching apparatus in electric power systems. The vacuum circuit breakers (VCBs) have very good operating properties. VCBs are characterized by specific physical phenomena that affect overvoltage exposure of the insulation systems of other devices. The most important phenomena are the ability to chop the current before the natural zero crossing, the ability to switch off high-frequency currents, and the rapid increase in dielectric strength recovery. One of the devices connected directly to vacuum circuit breakers is the distribution transformer. Overvoltages generated in electrical systems during switching off the transformers are a source of internal overvoltages in the windings. The analysis of the exposure of transformers operating in electrical networks equipped with vacuum circuit breakers is of great importance because of the impact on the insulation systems of switching overvoltages (SO). These types of overvoltages can be characterized by high maximum values and atypical waveforms, depending on the phenomena in the circuit breaker chambers, system configuration, parameters of electrical devices, and overvoltage protection. Overvoltages that stress the internal insulation systems are the result of the windings response to overvoltages at transformer terminals. This article presents an analysis of overvoltages that stress the transformer insulation systems, which occur while switching off transformers in systems with vacuum circuit breakers. The analysis was based on the results of laboratory measurements of switching overvoltages at transformer terminals and inside the winding, in a model medium-voltage electrical network with a vacuum circuit breaker.
13
Gracheva, E. I., A. N. Gorlov, and Z. M. Shakurova. "Calculation of the economy of electric energy in industrial electrical supply systems." Power engineering: research, equipment, technology 22, no. 2 (May 15, 2020): 65–74. http://dx.doi.org/10.30724/1998-9903-2020-22-2-65-74.
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The article examines the main features of the layout of electrical equipment for shop networks of internal power supply with the definition of indicators for a group of shop customers connected to a single power center, affecting the choice of the structure of schemes for shop network sites. The parameters characterizing the circuit topology are revealed. A study is presented of the influence of the load factor of workshop transformers on their reactive power factor, it is proved by calculation by technical and economic criteria the feasibility of replacing a workshop transformer with two with a lower total power. The calculation of energy savings in the in-plant power supply systems. The type of dependences tgφ of transformers ТМ and ТСЗ with various rated powers in the function of loading transformers is established. The most significant factors of the growth of idle power losses during operation are presented. With determination of losses of active and reactive power and electricity in transformers and losses of active power in a high voltage distribution network A feasibility study was carried out on the options for internal power supply schemes with two transformers of lower power installed instead of one, and the feasibility of such a replacement to increase the efficiency of the equipment was proved and the estimated payback period for the investment capital was determined. A comparative analysis of the studied power supply schemes of industrial enterprises with the identification of their advantages and disadvantages.
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Vinogradov, A. V., A. V. Vinogradova, V. E. Bolshev, M. O. Ward, N. V. Makhiyanova, and L. V. Dolomaniuk. "Justification for creating a mobile complex to assess electric energy loss in power transformers during the operation process." E3S Web of Conferences 124 (2019): 02009. http://dx.doi.org/10.1051/e3sconf/201912402009.
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The paper analyzes the statistical data on the transformers of the Kromsky branch of Oreloblenergo OJSC including the average lifetime of the transformers and no-load losses measured in accordance with the requirements of Russian standard GOST 3484.1. The analysis indicates that the declared passport data differ from the measured data. There is also the analysis of technical solutions to improve the power transformer design including to development of new types of electrical steel used in transformer cores, superconducting materials for winding. The article gives an understanding of the advantages and disadvantages of using these technologies as well as the possible reduction of electrical losses. In conclusion there is the justification for creating the mobile measuring complex to assess electric energy loss in power transformers during operation without disconnecting the load. The paper describes the result achieved using such a mobile measuring complex along with the economic effect of creating the project.
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Kulesz, Barbara. "RECTIFIER TRANSFORMERS IN ELECTRIC TRACTION SUBSTATIONS ‐ DIFFERENT DESIGNS." TRANSPORT 20, no. 2 (April 20, 2005): 66–72. http://dx.doi.org/10.3846/16484142.2005.9637998.
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Electric traction in Poland is supplied with dc voltage which is obtained from the power grid via traction substations equipped with transformers and rectifiers. The paper gives the results of the investigation of different designs of these transformer‐rectfier sets ‐ namely, 12‐ and 24‐pulse systems. The comparison of electrical quantities such as ripple content, harmonic content of supply current and output voltage and utilisation of transformer secondary windings is provided.
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Kattel, Ruska, and Bhupendra Devkota. "PCBs Contamination among Distribution Transformers in the Kathmandu Valley." International Journal of Environment 4, no. 1 (February 22, 2015): 16–29. http://dx.doi.org/10.3126/ije.v4i1.12175.
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Transformer is the crucial part in any electrical system, however there are many risks associated with its use. Thus this study was focused on assessing the status of PCBs contamination and distribution of transformers in Distribution Centre-North of the Kathmandu valley along with PCBs contamination in them. Each transformer within the study area was closely observed to obtain information about all transformers. The dielectric oil samples from the transformers were collected, safely stored and analyzed in Test Kits (L2000DX Chloride Analyzer System, recommended by UNEP). Among 111 samples of transformer oil analyzed, 4 transformers were found PCBs contaminated and they were manufactured before 1990s. The total amount of PCBs contaminated transformer oil in these transformers was 479.6 Kg. Seven transformers were found leaking, four transformers located at residential area were found emitting a low frequency tonal noise, two transformers were located within school compound, nine transformers were located near water body and around 1.44 square meters of soil surface was found contaminated by transformer oil. Though there is no way to eliminate all the risk and consequences of operating oil filled transformers, scientific distribution and proper handling could be the reasonable approaches to reduce the risks.DOI: http://dx.doi.org/10.3126/ije.v4i1.12175International Journal of Environment Volume-4, Issue-1, Dec-Feb 2014/15, Page: 16-29
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Lankin, Anton, Alexey Baklanov, and Igor Lankin. "Analysis of diagnostic methods and functional state monitoring of power oil transformers in electrical substations." E3S Web of Conferences 135 (2019): 01021. http://dx.doi.org/10.1051/e3sconf/201913501021.
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In this paper, we analyze the methods of diagnosis and control the functional state of power oil transformers in electrical substations. Oil transformers are the most efficient converters of electrical energy, which is reflected in a higher efficiency in comparison with dry transformers. Oil transformers are designed to work with power grids in large industrial complexes where energy conversion is required to protect equipment from sudden voltage surges. The high loads associated with this work require timely diagnosis and maintenance of transformers. The article discusses the most commonly used methods for diagnosing deviations of the technical parameters of electrical substations in the process of their operation. The authors proposed a method of impedance series-parallel identification, which allows not only to determine the equivalent circuit of the power oil transformer, but also to diagnose possible malfunctions. Functional circuits of the device for impedance series-parallel identification of faults in power oil transformers have been developed.
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Trần, Ngọc Thạch, Thanh Phương Nguyễn, Trọng Huy Nguyễn, and Đình Anh Khôi Phạm. "A new method in determination of electrical parameters and geometrical structure of a power transformer applicable to failure diagnosis." Science & Technology Development Journal - Engineering and Technology 3, no. 4 (December 27, 2020): first. http://dx.doi.org/10.32508/stdjet.v3i4.744.
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In transmission and distribution networks throughout the world and in Vietnam nowadays, power transformers that are operating in the networks often are in black-box condition, i.e. there is no internal information available in terms of geometrical structure and material parameters. Geometrical structure of power transformers includes mainly winding structure and additional parts such as a static end ring or a would-in shield coil, if any whereas main materials in power transformers consists of conductive, insulating and magnetic materials… This makes difficulties in faults diagnosis that is based on the approach of physical modeling in general and the so-called electrical equivalentcircuit based modeling in particular since the physical approach requires internal information of power transformers for calculating electrical parameters. In case the electrical equivalent-circuit approach is used, the diagnosis is then conducted based on the change of values of electrical parameters in the circuit before and after an alarm or a suspicious fault that happens when power transformers are in operation. Relevant international investigations conducted recently have mainly focused on test objects as power transformers in grey- or white-box condition, i.e. during manufacturing phase, since they have available geometrical structure and material properties. To show a possibility that blackbox power transformers could be investigated in a physical manner, this article introduces a new method in determining electrical parameters and geometrical structure applied on a black-box power transformer. The research is based on the Frequency Response Analysis technique and has developed recent relevant investigations of the authors. This enables investigations of the value change of electrical equivalent parameters of this transformer on its simulated frequency responses for the purpose of physical fault diagnosis of power transformers later on.
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Abdikulova, Z. K., and E. O. Zhaparov. "СALCULATION AND CHOICE OF ELECTRIC CHART OF SUBSTATION OF THE КENTAU TRANSFORMER PLANT." BULLETIN Series of Physics & Mathematical Sciences 70, no. 2 (June 30, 2020): 141–48. http://dx.doi.org/10.51889/2020-2.1728-7901.21.
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Electric supply system in enterprises must provide with electrical supply continuity and reliability as in normal and accidental regimes, quality electro energetic, production efficiency, so in connection with these in the article there have been analyzed work regimes of substations, studied electrical net scheme for Kentau Transformer Plant’s substation, calculated plant’s loads and short circuit currents and on the base of the calculated results curried out inspection for the chosen equipment. The number of connections, reliability of power supply and prospects for development are the determining factors for choosing the electrical scheme of high-voltage switchgears. You also need to take into account the need to conduct audits and tests of switches without interruption. In our case, we have four connections: two communication lines with electrical systems and two transformers. The distribution devices of the substation of the Kentau transformer plant are connected to the transformers according to a block scheme. Electrical installations are connected to the network transformer unit or receive backup power from another substation, since in case of failure of one network, both transformers can not work with the rest of the network. Based on this, measures are proposed for the reconstruction of the substation, with the replacement of the block diagram of the switchgear with the circuit for connecting the power transformer to the switchgear by a bus bridge. Offered measurements on reconstruction of the substation by replacing block scheme of switchgears to scheme of power transformer connection with DD bus bridge. Worked out main modernization problems of the substation switchgear, done calculation and selection of distributing bus bars for arranging switchgear.
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DeCristofaro, Nicholas. "Links of Science & Technology." MRS Bulletin 23, no. 5 (May 1998): 50–56. http://dx.doi.org/10.1557/s0883769400030451.
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On April 13, 1982, the Duke Power Company energized an experimental pad-mount distribution transformer in Hickory, North Carolina. The transformer, manufactured by General Electric, provided electric power to a local residence. That same month, the Georgia Power Company installed a similar transformer, made by Westinghouse Electric, atop a utility pole in Athens, Georgia. It supplied electricity for the exterior lights at the Westinghouse Newton Bridge Road plant. These devices shown in Figure 1 were unique among the nearly 40 million distribution transformers in service in the United States because their magnetic cores were made from an Fe–B–Si amorphous-metal alloy. This new material, produced by Allied-Signal (formerly Allied Chemical), was capable of magnetizing more efficiently than any electrical steel. By replacing grain-oriented silicon steel in the transformer cores, the amorphous metal reduced the core losses of the transformers by 75%.Although distribution transformers are relatively efficient devices, often operating at efficiencies as high as 99% at full load, they lose a significant amount of energy in their use. Because of the number of units in service, coupled with the fact that the core material is continuously magnetized and demagnetized at line frequency, transformers account for the largest portion of the energy losses on electric power distribution systems. It is estimated that over 50 × 109 kWh are dissipated annually in the United States in the form of distribution transformer core losses. At today's average electricity generating cost of $0.035/kWh, that energy is worth over $1,500 million.
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Adi Wirajaya, I. Putu, I. Wayan Rinas, and I. Wayan Sukerayasa. "Studi Analisa Pengaruh Total Harmonic Distortion (THD) terhadap Rugi-Rugi, Efisiensi, dan Kapasitas Kerja Transformator pada Penyulang Kerobokan." Jurnal SPEKTRUM 6, no. 2 (June 1, 2019): 121. http://dx.doi.org/10.24843/spektrum.2019.v06.i02.p17.
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Kerobokan feeder supply electrical energy in the area of Kerobokan. This feeder supplies 67 distribution transformers that serve a variety of customers with nonlinier electrical loads. Nonlinier electrical loads cause harmonics which adversely affect customers and power system equipment, especially distribution transformers. In Kerobokan feeder, only 3 (4.5%) of the 67 transformers has THDi content that according with the IEEE 519-2014 standard and 64 (95.5%) of the 67 transformers has a high THDi content and exceed the IEEE 519-2014 standard. For this reason, the power losses, efficiency, and work capacity of the transformer are analyzed due to the effect of THDi. This study uses a direct measurement method in all transformers in the Kerobokan feeder and simulation on the ETAP Powerstation program. The results of the analysis showed that total power losses without being affected by THDi for all transformers were 49.4 kW and after being affected by THDi were 591.71 kW. The highest THDi content is in the KA 0992 transformer is 24.8% which results in an increased in power losses is 12.02 kW or 12.02% of its capacity and a decreased in efficiency is 12.66% and has a decreased in work capacity is 19.9%. While the smallest THDi content is found in the DB 449 transformer is 6.8% which results in an increased in power losses is 2.2 kW or 0.88% of its capacity and a decreased efficiency is 1.01% and has a decreased in work capacity is 2.7%.
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CAZACU, Emil, Laurentiu-Marius DUMITRAN, and Lucian PETRESCU. "EVALUAREA SOLICITĂRILOR TERMICE ȘI A DURATEI DE VIAȚĂ A TRANSFORMATOARELOR DE DISTRIBUȚIE AFLATE ÎN REGIM PERIODIC NESINUSOIDAL." "ACTUALITĂŢI ŞI PERSPECTIVE ÎN DOMENIUL MAŞINILOR ELECTRICE (ELECTRIC MACHINES, MATERIALS AND DRIVES - PRESENT AND TRENDS)" 2020, no. 1 (February 10, 2021): 1–13. http://dx.doi.org/10.36801/apme.2020.1.7.
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Electrical transformers are some of the most important equipment in the entire electricity distribution chain. Their operation with optimal values of the parameters (electrical, thermal and mechanical) ensures the continuous supply of consumers. The modern electrical loads of power distribution transformers are often nonlinear and generate several power quality problems, especially the distortion of the waveform of the current that flows through the windings of the transformer. This generates additional stresses (electrical and thermal) of the various components of the transformer (originally designed to operate in pure sinusoidal mode) which can cause abnormal (faulty) operation of the transformer and ultimately reducing its life (estimated by the manufacturer for permanent sinusoidal regime). In order to prevent or diminish the negative effects of the nonsinusoidal regime on the transformer, a deliberate limitation (reduction) of its maximum load is performed. The procedure is known as transformer derating. Its main aim is to establish the most appropriate declassification factors (denomination), resulting from the correlation of the nominal and constructive data of the transformer with the power quality parameters, measured in its secondary part (usually, these are the current distortion level and the corresponding spectrum harmonic). This paper analyzes qualitatively and quantitatively these aspects and proposes a downgrading procedure for in-service transformers which it illustrates in a case study.
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Anishchenko, V. A., and I. V. Gorokhovik. "Influence of Oil-Filled Transformers Overload Capacity on the Throughput Capacity of the Electrical Network." ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 61, no. 4 (July 20, 2018): 310–20. http://dx.doi.org/10.21122/1029-7448-2018-61-4-310-320.
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During the operation of the electric power system, there is often a need to overload its individual elements (generators, power transformers, overhead and cable power lines, switching electric devices) for a period lasting from several dozens of minutes to a day. The overloads can be caused by intentional disconnection of parallel elements of the system because of scheduled preventive repairs, post-accident disconnections, as well as an unexpected increase in electricity consumption due to the impact of various factors. The overload capacity of the system elements makes it possible to increase operational reliability of power supply to consumers without additional expenditures while maintaining, in most cases, the almost normal service life of electrical equipment. Oil-filled transformers have the greatest potential overload capacity power, which makes it possible to consider them as a significant source of increasing the capacity of the transmission and distribution networks of the electric power system. Excessive over-current of power oil-filled transformers significantly reduces reliability and reduces their normal service life. This is due to the accelerated process of wear of the insulation material of the transfer windings as a result of overheating of the transformer oil, that causes structural changes and, as a consequence, to mechanical damage to the insulation of the windings; the latter can cause an electrical puncture. On the other hand, underestimation of the permissible overload of transformers might result in economic losses due to under-produced products when the functioning of the part of the transformers connected in parallel are ceased for scheduled preventive maintenance or as a result of forced emergency shutdowns. Therefore, there is a need to assess the potential of reasonable increase in the throughput capacity of the electrical network and, accordingly, the reliability of the power supply system, taking into account the requirements for the permissible loads of transformers when the electrical network and various operating modes are being designed.
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Van Cuong, Ngo, and Lidiia I. Kovernikova. "Predicting the influence of the non-sinusoidal network mode on power transformers." E3S Web of Conferences 114 (2019): 04005. http://dx.doi.org/10.1051/e3sconf/201911404005.
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The parameters of electrical network modes often do not meet the requirements of Russian GOST 32144-2013 and the guidelines of Vietnam. In the actual operating conditions while there is the non-sinusoidal mode in electrical networks voltage and current harmonics are present. Harmonics result in overheating and damage of power transformers since they cause additional active power losses. Additional losses lead to the additional heat release, accelerating the process of insulating paper, transformer oil and magnetic structure deterioration consequently shortening the service life of a power transformer. In this regard there arises a need to develop certain scientific methods that would help demonstrate that low power quality, for instance could lead to a decrease in the electrical equipment service life. Currently we see a development of automated systems for continuous monitoring of power quality indices and mode parameters of electrical networks. These systems could be supplemented by characteristics calculating programs that give out a warning upon detection of the adverse influence of voltage and current harmonics on various electrical equipment of both electric power providers and electric power consumers. A software program presented in the article may be used to predict the influence of voltage and current harmonics on power transformers.
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Braña, L., A. Costa, and 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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Anitha Kumari, K., Avinash Sharma, S. Nivethitha, V. Dharini, V. Sanjith, R. Vaishnavi, G. Jothika, and K. Shophiya. "Automated Outlier Detection for Electrical Motors and Transformers." Journal of Computational and Theoretical Nanoscience 17, no. 9 (July 1, 2020): 4703–8. http://dx.doi.org/10.1166/jctn.2020.9304.
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Electrical appliances most commonly consist of two electrical devices, namely, electrical motors and transformers. Typically, electrical motors are normally used in all sort of industrial purposes. Failures of such motors results in serious problems, such as overheat, shut down and even burnt, in their host systems. Thus, more attention have to be paid in detecting the outliers. In a similar way, to avoid the unexpected power reliability problems and system damages, the prediction of the failures in the transformers is expected to quantify the impacts. By predicting the failures, the lifetime of the transformers increases and unnecessary accidents is avoided. Therefore, this paper presents the detection of the outliers in electrical motors and failures in transformers using supervised machine learning algorithms. Machine learning techniques such as Support Vector Machine (SVM), Random Forest (RF) and regression techniques like Support Vector Regression (SVR), Polynomial Regression (PR) are used to analyze the use cases of different motor specifications. Evaluation and the efficiency of findings are proved by considering accuracy, precision, F-measure, and recall for motors. Mean Absolute Error (MAE), Mean Squared Error (MSE), Root Mean Square Error (RMSE) and R-squared Error (R2) are considered as metrics for transformers. The proposed approach helps to identify the anomalies like vibration loss, copper loss and overheating in the industrial motor and to determine the abnormal functioning of the transformer that in turn leads to ascertain the lifetime. The proposed system analyses the behaviour of the electrical machines using the energy meter data and reports the outliers to users. It also analyses the abnormalities occurring in the transformer using the parameters involved in the degradation of the paper-oil insulation system and the voltage of operation as a whole leads to the predict the lifetime.
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Krishna, A. Prudhvi, P. Srinivasa Varma, R. B. R. Prakash, and V. Kiran Babu. "Prioritization of network transformers in electrical distribution system by considering social welfare index." Indonesian Journal of Electrical Engineering and Computer Science 16, no. 1 (October 1, 2019): 25. http://dx.doi.org/10.11591/ijeecs.v16.i1.pp25-32.
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<span lang="EN-US">To supply a meshed distribution system, network transformers are required. When few transformers are not in service, they must be repaired or replaced. A method is proposed for prioritizing the transformers considering the critical loads. Repair or replacement of transformers can be done by giving priority based on risk reduction. By addressing the possibility of network collapse due to failure of the feeder and impacted customers, risk can be predicted where the loads are extremely used at feeders section, network transformers and secondary mains. To select the transformer that needs to be replaced quickly and economically, an algorithm is proposed and it was tested on IEEE test system using GridLAB-D, MATLAB softwares. An index is proposed to give priority to emergency needs like hospitals and water pumping stations. Replacement or repair can be done by prioritizing network transformers incorporating social welfare index. </span>
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Simons, Philip, and Andries Habraken. "Simulation of Electrical Heating with Multiple Transformers." Advanced Materials Research 39-40 (April 2008): 469–74. http://dx.doi.org/10.4028/www.scientific.net/amr.39-40.469.
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In the simulation package GTM-X two methods are available that approximate the electric potentials in the glass melt in the presence of multiple transformers. Both methods control the grouped electrodes in such a way that power consistency is guaranteed, also for complicated electrode groupings and transformer systems. By power consistency we mean that the total heat release, as calculated from the potentials and currents at the electrodes, matches the power that is released in the volume cells. The first method approximates two scalar potentials; it may violate the constraint that electrical currents are conserved per electrode group. The second method solves for two scalar potentials per electrode group (or transformer); the result is that also this additional constraint can be satisfied. In this article, we discuss these two methods and show results for a model problem.
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Sharma, R. Rajesh. "Design of Distribution Transformer Health Management System using IoT Sensors." September 2021 3, no. 3 (September 16, 2021): 192–204. http://dx.doi.org/10.36548/jscp.2021.3.005.
Full textAbstract:
Transformers are one of the primary device required for an AC (Alternating Current) distribution system which works on the principle of mutual induction without any rotating parts. There are two types of transformers are utilized in the distribution systems namely step up transformer and step down transformer. The step up transformers are need to be placed at some regular distances for reducing the line losses happening over the electrical transmission systems. Similarly the step down transformers are placed near to the destinations for regulating the electricity power for the commercial usage. Certain regular check-ups are must for a distribution transformer for increasing its operational life time. The proposed work is designed to regularize such health check-ups using IoT sensors for making a centralized remote monitoring system.
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Chisepo, Hilary Kudzai, Leslie David Borrill, and Charles Trevor Gaunt. "Measurements show need for transformer core joint details in finite element modelling of GIC and DC effects." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 37, no. 3 (May 8, 2018): 1011–28. http://dx.doi.org/10.1108/compel-11-2016-0511.
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Purpose This paper aims to improve the finite element modelling of transformers subjected to DC excitation, by including core joint details. Design/methodology/approach Geomagnetically induced currents (GICs) or leakage DC can cause part-cycle, half wave saturation of a power transformer’s core. Practical measurements and finite element matrix (FEM) simulation were carried out using three laboratory-scale, untanked single-phase four limb transformers resembling real power transformers in terms of the core steel and parallel winding assemblies. “Equivalent air gaps” at the joints, based on AC measurements, were applied to the FEM models for simultaneous AC and DC excitation. Findings Measurements confirm that introducing equivalent air gaps at the joints improves the FEM simulation of transformers carrying DC. Research limitations/implications The FEM simulations based on the laboratory transformers are exemplary, showing the difference between modelling core joints as solid or including equivalent air gaps. They show that, for more representative results, laboratory transformers used for research should have mitred core joints (like power transformers). Originality/value This research shows why joint details are important in FEM models for analysing transformer core saturation in the presence of DC/GICs. Extending this, other core structures of power transformers with mitred joints should improve the understanding of the leakage flux during half-wave saturation.
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Denisova, A. R., D. P. Spasov, A. R. Galyautdinova, and V. R. Ivanova. "The study of health and quality of operation of the transformer equipment electrical systems." Power engineering: research, equipment, technology 22, no. 3 (September 8, 2020): 23–35. http://dx.doi.org/10.30724/1998-9903-2020-22-3-23-35.
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Detection of defects at an early stage of their occurrence, especially for power transformers that have worked out the standard term, is an acute problem. This article discusses the possibility of using the system of monitoring, control and diagnosis of transformer equipment (SMUID) electrical systems in conjunction with the automated control system of electrical equipment (ASU ETO) and automated information-measuring system of commercial electricity metering (AIIS KUE) with the use of QR-code, as well as using TeamViewer for the operational elimination of accidents and identify abnormal operation of transformer equipment. Transformer monitoring system is designed for monitoring isolation, recording and analysis of partial discharges, monitoring of technical condition ensuring maximum fault-free service life of transformers. In addition, the introduction of automated diagnostics and electrical equipment is a necessary condition for the introduction of SmartGrid technology in industrial electric networks, contributes to the reduction of capital investments in the renewal of the equipment fleet. The methods currently used do not detect dangerous insulation degradation, are not sensitive to its aging, and in some cases mistakenly assess the isolation condition. The work analyses the operability and quality of the systems under consideration, shows the hierarchical structure of SMUID. By applying the proposed idea with the QR-code, it is possible to speed up the process of searching for information about the current technical state of electrical equipment.
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Hassani, Mahdi, Seyed Siavash Karimi Madahi, Hassan Feshki Farahani, and Hossein Sarabadani. "A New Method to Improve the Voltage Distribution and Electric Field Control for Conceder Bushing." Applied Mechanics and Materials 110-116 (October 2011): 5184–88. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.5184.
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Capacitor bushings are one of the key components in power transformers. Although their price is a negligible part of the total price of the power transformer, their quality has a significant effect on performance and reliability of power transformers. In high voltage capacitor bushings, the intensity of voltage and electric field on bushing abacus is very high. This high intensity is also observed in flange parts. The amount of multi layer insulator among the electrodes or floating plates in capacitor bushing make equi-potential surfaces and reduction of electric field in these areas can greatly improve the capacitor bushing performance. In this paper, we investigate the reduction of field intensity and electrical tension and also improvement in voltage control by displacing floating plates which are in the form of aluminum foils stick to impregnated paper. To calculate the field intensity, we used the MAXWELL software using FEM (Finite element method). Using this new method of placing capacitor core its effect on voltage profile reduction and field electrical tension is shown. Over voltage and pollution effects are also investigate on power transformer bushings.
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Malažinskas, Vilius, Renaldas Raišutis, Alfonsas Morkvėnas, Saulius Gudžius, Audrius Jonaitis, Jonas Vaičys, and Gediminas Daukšys. "EVALUATION OF THE INSULATION CONDITION OF HIGH-VOLTAGE TRANSFORMERS BY DETECTING PARTIAL DISCHARGES USING THE ELECTROMAGNETIC WAVE RADIATION METHOD." Materiali in tehnologije 55, no. 2 (April 15, 2021): 253–61. http://dx.doi.org/10.17222/mit.2020.175.
Full textAbstract:
High-voltage transformers are among the most important elements in an electric-power system. Each one of them is affected by various external factors: overvoltage, partial discharge (PD), overheating, vibrations, etc., which are created by a strong electric field, thermal effect, humidity, impurities, factory defects, dissolved water and gas in oil-type-transformer insulation. These and other factors, caused by the environment, reduce the life of a device. Thus, the evaluation of the device condition is one of the most important factors for a system-safety evaluation, which ensures a reliable and economical electrical-network operation. This work reviews different contact and non-contact methods, used to evaluate the conditions of transformers by measuring the level of PD. The selected method, i.e., the non-contact measurement of electromagnetic-wave radiation was used to evaluate the voltage-transformer status. The experiment was performed at a 110 kV substation. The authors discuss the efficiency of the selected method to evaluate the voltage-transformer insulation condition.
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Gutten, Miroslav, Daniel Korenciak, Matej Kucera, Richard Janura, Adam Glowacz, and Eliasz Kantoch. "Frequency and time fault diagnosis methods of power transformers." Measurement Science Review 18, no. 4 (August 1, 2018): 162–67. http://dx.doi.org/10.1515/msr-2018-0023.
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Abstract The authors describe experimental and theoretical analyses of faults of power transformer winding. Faults were caused by mechanical effect of short-circuit currents. Measurements of transformer were carried out in high-voltage laboratory. Frequency and time diagnostic methods (method SFRA - Sweep Frequency Response Analysis, impact test) were used for the analyses. Coils of transformer windings were diagnosed by means of the SFRA method and the time impact test. The analyzed methods had a significant sensitivity to a relatively small deformation of coil. In the analysis a new technique for analyzing the effects of short-circuit currents is introduced. This technique is developed for high-voltage transformers (different types of power). The proposed analyses show that it is necessary to analyze the value of short-circuit current. Short-circuit current represents a danger for the operation of the power transformer. The proposed approach can be used for other types of transformers. Moreover, the presented techniques have a potential application for fault diagnosis of electrical equipment such as: transformers and electrical machines.
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LIU, HUA-SHU, LIN MA, YUAN-TONG GU, and SHAWN NIELSEN. "NUMERICAL INVESTIGATION OF MECHANICAL AND THERMAL DYNAMIC PROPERTIES OF THE INDUSTRIAL TRANSFORMER." International Journal of Computational Methods 11, supp01 (November 2014): 1344012. http://dx.doi.org/10.1142/s021987621344012x.
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Industrial transformer is one of the most critical assets in the power and heavy industry. Failures of transformers can cause enormous losses. The poor joints of the electrical circuit on transformers can cause overheating and results in stress concentration on the structure which is the major cause of catastrophic failure. Few researches have been focused on the mechanical properties of industrial transformers under overheating thermal conditions. In this paper, both mechanical and thermal properties of industrial transformers are jointly investigated using finite element analysis (FEA). Dynamic response analysis is conducted on a modified transformer FEA model, and the computational results are compared with experimental results from literature to validate this simulation model. Based on the FEA model, thermal stress is calculated under different temperature conditions. These analysis results can provide insights to the understanding of the failure of transformers due to overheating, therefore are significant to assess winding fault, especially to the manufacturing and maintenance of large transformers.
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Manabat*, Carmela Mady B., Marielle C. Alejo, Loraine V. Dela Cruz, Joseph M. Apan, and Renato D. Erasquin Jr. "Cost Benefit Analysis for Electrical Loading System for Transformers of a Barangay." International Journal of Engineering and Advanced Technology 10, no. 4 (April 30, 2021): 82–88. http://dx.doi.org/10.35940/ijeat.d2325.0410421.
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The study assessed the cost and benefit of electrical loading management of transformers. There is a serious occurrence of over and under loaded transformer which deeply affects the power quality or system loss and reliability of the distribution lines. Initially, the percent loading of the 27 transformers of Feeder 21 were identified using Microsoft Excel 2016. Then, the identified transformers were classified into three categories; overload (greater than 70%), under loaded (less than 40%) and normal loaded (40-70%). Through this process, three (3) solutions were identified: Solution I - change the transformer rating, Solution II – merge and transfer transformer loadsand Solution III - combine solution I and II. The three-solution used to identify the new percent loading to meet the normal percent loading (40-69%). Subsequently, the reduced Core and Copper Losses, Annual Energy Save, Savings and Benefit/Cost Ratio were computed and analyzed to determine the impact of loadingmanagement. The results show that there was an accumulated savings of Php 332,060.08 for Solution I, Php 92,043.09 for Solution II and Php 252,045.78 for Solution III. In the case of Benefit/Cost ratio it should be greater than 1 (>1) for a project to be economically feasible and justifiable; Solution I was 1.22, Solution II was 687.3 and 1.93 for Solution III. Based on the results of the study, SolutionIII was best among the three, for it has met the criteria of all transformers were all in normal loaded (40-70%) condition, and greater than 1 benefit/cost ratio.
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Maximov, Serguei, Manuel A. Corona-Sánchez, Juan C. Olivares-Galvan, Enrique Melgoza-Vazquez, Rafael Escarela-Perez, and Victor M. Jimenez-Mondragon. "Mathematical Calculation of Stray Losses in Transformer Tanks with a Stainless Steel Insert." Mathematics 9, no. 2 (January 18, 2021): 184. http://dx.doi.org/10.3390/math9020184.
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At present it is claimed that all electrical energy systems operate with high values of efficiency and reliability. In electric power systems (EPS), electrical power and distribution transformers are responsible for transferring the electrical energy from power stations up to the load centers. Consequently, it is mandatory to design transformers that possess the highest efficiency and reliability possible. Considerable power losses and hotspots may exist in the bushing region of a transformer, where conductors pass through the tank. Most transformer tanks are made of low-carbon steel, for economical reasons, causing the induction of high eddy currents in the bushing regions. Using a non-magnetic insert in the transformer tank can reduce the eddy currents in the region and as a consequence avoid overheating. In this work, analytical formulations were developed to calculate the magnetic field distribution and the stray losses in the transformer region where bushings are mounted, considering a stainless steel insert (SSI) in the transformer tank. Previously, this problem had only been tackled with numerical models. Several cases were analyzed considering different non-magnetic insert sizes. Additionally, a numerical study using a two dimensional (2D) finite element (FE) axisymmetric model was carried out in order to validate the analytical results. The solved cases show a great concordance between models, obtaining relative errors between the solutions of less than two percent.
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LARIN, Vasily S., and Daniil A. MATVEEV. "Approximation of Transient Resonance Voltages and Currents in Power Transformer Windings to Determine Their Natural Frequencies and Damping Factors." Elektrichestvo 12, no. 12 (2020): 44–54. http://dx.doi.org/10.24160/0013-5380-2020-12-44-54.
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Transient interaction between power transformers and power cable lines may give rise to resonance overvoltages in the transformer primary windings. To develop protection measures against resonance overvoltages and to design transformers resistant to resonance overvoltages, it is necessary to know the natural frequencies of the transformer windings. Recent years have seen very rapid development of transformer windings high-frequency models. However, the mathematical models used in practice, which came from calculations of impulse overvoltages in transformer windings, reproduce the frequency dependences of losses and damping at natural frequencies with insufficient accuracy. To verify and improve the mathematical models used for analyzing high-frequency processes in transformer windings, it is necessary to have sufficient experimental data on the values of natural frequencies and damping factors. Methods for experimentally determining the natural frequencies and damping factors of power transformer windings are considered. Theoretical principles and analytical expressions for transient voltages and currents obtained for simplified equivalent circuits of windings with lumped parameters are given. An approach is proposed, according to which the transient voltages and currents in the winding are represented as the sum of steady-state and free components. The free component is then approximated using the theoretical expressions obtained for the equivalent circuits of the windings. The results of applying the approach to approximating the transient voltage at the midpoint and the current in the neutral of a dry-type transformer’s high-voltage winding are presented.
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Yang, Cheng Feng. "Research of Ageing and Life Assessment Methods of Power Transformers in Nuclear Power Plants." Advanced Materials Research 614-615 (December 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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Stork, Milan, and Daniel Mayer. "Direct currents in power transformers." Journal of Electrical Engineering 70, no. 1 (February 1, 2019): 69–73. http://dx.doi.org/10.2478/jee-2019-0010.
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Abstract The article is devoted to the physical nature of geomagnetism, magnetic storms and methods of predicting their origin and deals with geomagnetic induced currents called GIC (Geomagnetically Induced Currents) and their effect on power transformers. A simplified, single-phase transmission system is described mathematically and its analysis was performed. Also the phenomenon of periodic semi-saturation of the magnetic circuit of the transformers resulting in current overload of the transformer windings, which can lead to thermal damage of the windings is explained. In addition, there is a significant deformation of the currents in the electrical system. The numerical solution of the system was verified by measurement on an electrical model.
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Xiang, Dong, and Fei Yu. "Characteristic Analysis of Ship Transformer Magnetizing Inrush Current and its Suppression Method." Advanced Materials Research 1070-1072 (December 2014): 1154–58. http://dx.doi.org/10.4028/www.scientific.net/amr.1070-1072.1154.
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Medium voltage in the electric power system of ship typically is powered by a large capacity transformer for low voltage electrical apparatus. When switching on, the primary side of transformer will produce very large current, which would endanger the safe operation of power for ships. The mechanism and characteristics of magnetizing inrush current is analyzed when the transformer switches with no load. We think that the reason caused magnetizing inrush current is transformers saturation. Pre-excitation is presented through a small volume transformer magnetizing method of suppressing the inrush current of transformer and validated by simulation and experiment.
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Pham, Khoi Dinh Anh. "Measurement -based electrical parameters of power transformers for Frequency Response Analysis interpretation - Part I: Core analysis." Science and Technology Development Journal 20, K3 (June 30, 2017): 5–10. http://dx.doi.org/10.32508/stdj.v20ik3.1074.
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Although the standard Frequency Response Analysis (FRA) test has been approved as an efficient tool to diagnose mechanical failures in power transformers, the demand to interpret FRA traces in practical and physical way is still requested. That means physical electrical parameters of transformers should be determined reasonably based on real measurements and afterwards are applicable for the interpretation. For purpose of FRA interpretation in practical manner, electrical parameters of power transformers in a physical equivalent circuit should be determined. As a first step, the paper introduces a new approach in determining frequency dependent core impedances of a distribution transformer based on the combination of circuit analysis of a duality-based model, measurements of driving-point impedances and experimental formulas. From that, two important contributions can be drawn. Firstly, frequency dependent core impedances are ready as available components in the circuit for FRA interpretation in broad frequency range. Secondly, the core parameters could be useful indicators for detecting relevant failures in cases there is no more failure on transformer windings.
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Liang, An Qi, Wen Ying Liu, Pei Dong Du, and Hui Yong Li. "Analysis of Busbar-Line Transformer Economic Operation Mode." Advanced Materials Research 1070-1072 (December 2014): 647–50. http://dx.doi.org/10.4028/www.scientific.net/amr.1070-1072.647.
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Power transformer is a extensively-used electrical equipment in our national economy. Generally speaking, there exists 6~8 times of transformation from electricity generation, power supply to power utilization. As is known to all, transformer itself generates power loss, so, because there are so many transformers and the whole capacity is very big, the economic operation of transformers proves of great importance. This article finds effective energy-saving method by analyzing a mode of busbar-line transformer economic operation. In the end, a practical case is added to prove the correctness and validity of this mode.
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Nazarov, Artyom, Vitaliy Savelev, and Dennis Frogh. "The investigation of frequency response analysis for power transformers winding condition." E3S Web of Conferences 139 (2019): 01023. http://dx.doi.org/10.1051/e3sconf/201913901023.
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In modern electrical transmission and distribution systems, power transformers are critical components within the network. In the event that a failure occurs in service, the impact can be far reaching. The majority of mechanical deformation within power transformers is due to short circuit faults. The ageing transformer population increases the likelihood of failure so a reliable diagnostic tools required to determine the remaining life of these assets. Although, frequency response analysis (FRA) has been recently recognized as the most reliable detection tool for mechanical deformation in transformers, in the event of minor fault, the current FRA interpretation approach may not able to detect any variations between healthy and faulty FRA signatures. This paper focuses on FRA tests for power transformer and interpretation of obtained FRA signatures.
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Azhari Zakri, Azriyenni, Mohd Wazir Mustafa, Hari Firdaus, and Ibim Sofimieari. "ASSESS THE RISK LEVEL OF POWER TRANSFORMER DUE SHORT-CIRCUIT FAULTS BASED ON ANFIS." SINERGI 23, no. 2 (July 12, 2019): 99. http://dx.doi.org/10.22441/sinergi.2019.2.002.
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A power transformer is an electrical machine that converts electrical power at different voltage levels. Faults, occur in power transformers, inhibit electrical power distribution to the consumer. Protection, therefore, of the power transformers is essential in power systems reliability. The power system can be reliable if the protection devices work well when there is a fault. A hybrid intelligent technique, which is a combination of Artificial Neural Network (ANN) and Fuzzy known as Adaptive Neuro-Fuzzy Inference Systems (ANFIS), was used in this research. The objective of this paper is the simulation of differential relays as a protection device on power transformers using Matlab/Simulink. Performance of differential relays for power transformers protection is carried out with internal and external fault scenarios. The input data were classified into three different input for ANFIS such as internal and external 1, internal and external 2, internal, external 1, and external 2, respectively. The error results of ANFIS training for the type of fault internal and external 1 is 9.46*10-7, and types of fault internal and external 2 is 1.09*10-6 internal, external 1 and external 2 are 8.59*10-7. The results obtained from the simulation were accurate and shows that the ANFIS technique is an efficient method that gives less error and a great value. Finally, the technique can minimize faults with power transformers. Finally, to prove this method can reduce faults in the power transformer, the assess of this model has been carried out through the RMSE that has been generated which is zero.
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Henriques, Henrique Oliveira, Carlos Eduardo Vizeu, Paulo Cesar Souza, Mauricio Caldora Costa, Guilherme Gonçalves Sotelo, Jonaylton Moura Sousa, Marcio Zamboti Fortes, and Vitor Hugo Ferreira. "COUPLED ELECTROMAGNETIC-THERMAL SIMULATION OF A POWER TRANSFORMER BY 3D FEM." Acta Polytechnica 60, no. 5 (November 16, 2020): 400–409. http://dx.doi.org/10.14311/ap.2020.60.0400.
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Power transformers are the most common equipment in an electric power system, which has been manufactured in the last decade. However, overheating can damage them, considerably reducing their operation lives, which may cause economic losses to the power utilities. The motivation of this paper is to investigate the time and power overload limits that a power transformer can be subjected to and how it will impact its temperature. Investments in the grid can be delayed if a transformer can support some overload during some momentary load demand increase. In this context, this paper presents a study of a 30/40MVA power transformer by 3D finite element method (FEM) for coupled thermal-electromagnetic simulations to investigate its thermal behaviour when it is submitted to its nominal load at a steady-state operation and a variable load during a period of one day. The simulations were performed with the commercial software packages Flux 3D and AcuSolve, for electromagnetic and thermal modelling, respectively. The modelled equipment was based on a power transformer installed in the Light Serviços de Eletricidade S.A, the utility that supplies electrical energy to the city of Rio de Janeiro, in Brazil. Since the literature doesn’t present many works simulating coupled thermal-electromagnetic power transformers in 3D-FEM, this paper has the goal to bring new contributions to this field. Three study cases were modelled, and some simplifications in transformer’s geometry were made in some of them to reduce the computation time usually required for such a simulation. The obtained results are presented and compared with the measured values for the temperature in the hot spot of the transformer and in the top of the oil, to investigate the impact of these simplifications in the calculated results.
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Zdanowski, Maciej. "Streaming Electrification Phenomenon of Electrical Insulating Oils for Power Transformers." Energies 13, no. 12 (June 22, 2020): 3225. http://dx.doi.org/10.3390/en13123225.
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The subject matter of this study was the problem of the ECT (electrostatic charging tendency) of mineral insulation oils during their flow. The electrostatic charges generated may lead to partial discharges, and as a consequence, to the breakdown of a power transformer insulation system. In this study, the results of the ECT of mineral oils used in transformers were compared. The method of streaming electrification of insulation liquids using a flow-through system was used. The influence of flow speed, temperature, and the pipe material on the values of the electrification current and volume charge density qw were analyzed. The results obtained in this study should be taken into account regarding the operation of power transformers.
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Petrescu, L., E. Cazacu, V. Ioniţă, and Maria-Cătălina Petrescu. "An Experimental Device for Measuring the Single-Phase Transformers Inrush Current." Scientific Bulletin of Electrical Engineering Faculty 19, no. 1 (April 1, 2019): 18–22. http://dx.doi.org/10.1515/sbeef-2019-0004.
Full textAbstract:
AbstractElectrical transformers are essential parts of power supply networks and it is important that their life-time to be preserved. The inrush current of this devices could determine malfunctioning of the transformers or even others component of the network. For this reason, determining the inrush current for single-phase transformers is an important issue in power quality analysis of electrical grids. In this paper we presented an experimental device (hardware set-up and software program) that can measure this in rush current features for small transformers (up to 10 kVA). Also, the device affords the users to measure inrush current knowing the geometry of the transformer, the dimensions and the magnetic characteristic of the core.
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Bulucea, Cornelia A., Doru A. Nicola, Nikos E. Mastorakis, and Carmen A. Bulucea. "Three-phase power transformer modelling in AC/DC traction substations." MATEC Web of Conferences 292 (2019): 01006. http://dx.doi.org/10.1051/matecconf/201929201006.
Full textAbstract:
Three-phase power transformer is one of the most important elements in the electric power systems, and it plays a significant role in terms of energy savings. Since the efficiency standards can be expressed in terms of electrical efficiency, in an attempt to improve the transformer efficiency, in this study an enhancement of three-phase power transformer modelling with space phasors is presented. There are established the equations with space phasors of the three-phase transformer with symmetrical compact core. This equations system can be used to analyze the dynamic regimes of three-phase transformers. In this paper have been analyzed some aspects of three-phase power transformer operation in a AC/DC traction substation.
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Sun, Wen Xing, Zhao Hui Li, and Shi Jie Cheng. "A Highly Reliable Online Monitoring and Real-Time Alarm System for the Insulation Condition of Power Transformers." Advanced Materials Research 971-973 (June 2014): 1045–50. http://dx.doi.org/10.4028/www.scientific.net/amr.971-973.1045.
Full textAbstract:
Many successful applications for the online monitoring of the insulation condition for electric power transformers have been reported over last thirty years. However, false or unsolved alarms have been quite frequently generated by those condition monitoring systems. Failures and some occasionally catastrophic accidents involving transformers have still occurred. A highly reliable insulation condition online monitoring and real-time alarm system has been developed, to help resolve these problems. An electric power transformer has strongly linked mechanical, electrical, magnetic, chemical and thermal characteristics, and is also directly linked to circuit breakers and generators. Team Intelligence (TI) was employed to integrate all the monitoring modules of the various different aspects of the transformer into one unique system. This system could also be integrate with the condition monitoring systems of various linked facilities, such as the monitoring systems of the turbine and the generator in a Optimal Maintenance Information System for Hydropower Plant (HOMIS). Highly reliable monitoring and real-time alarms of transformer insulation condition could be achieved, due to highly coordinated and rapid response features. This system has been deployed in several hydropower plants. The industrial application examples are demonstrated.