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1
Charpentier, Michel, et K. Mani Chandy. « Specification transformers : a predicate transformer approach to composition ». Acta Informatica 40, no 4 (1 février 2004) : 265–301. http://dx.doi.org/10.1007/s00236-003-0130-y.
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Santos, Nuno, Miguel Chaves, Paulo Gamboa, Armando Cordeiro, Nelson Santos et Sónia Ferreira Pinto. « High Frequency Transformers for Solid-State Transformer Applications ». Applied Sciences 13, no 12 (18 juin 2023) : 7262. http://dx.doi.org/10.3390/app13127262.
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This paper focuses on the study of the high frequency transformer incorporated in solid- state transformers, specifically on the development of the steps that enable the design of an optimized high frequency transformer and its equivalent model based on the desired characteristics. The impact of operating a transformer at high frequency and the respective solutions that allow this impact to be reduced are analyzed, alongside the numerous advantages that the utilization of these transformers has over traditional 50/60 Hz transformers. Furthermore, the power scheme of the solid-state transformer is outlined, focusing on the power converters, which are immediately before and after the high frequency transformer (HFT). We also investigate a control technique that allows for correct operation and the existence of power bidirectionality. In a novel approach, this paper demonstrates the systematic steps for designing an HFT according to the desired specifications of each given project, helping students and engineers achieve their objectives in power-electronic applications. Moreover, this paper aims at increasing the knowledge of this area of power electronics and facilitating the development of new topologies with high power density, which are very important to the integration of renewable power sources and other applications. Finally, a simulation is presented to validate a high frequency transformer and its control technique.
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Wu, H. « All eyes on transformers [super grid transformer remote monitoring] ». Power Engineer 18, no 5 (2004) : 32. http://dx.doi.org/10.1049/pe:20040506.
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Desai, B. T., H. O. Gupta et M. K. Vasantha. « Current transformer performance for inrush current in power transformers ». Electric Power Systems Research 14, no 3 (juin 1988) : 237–41. http://dx.doi.org/10.1016/0378-7796(88)90057-0.
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Martin, Daniel, Tapan Saha, Richard Dee, Gary Buckley, Srinivasan Chinnarajan, Greg Caldwell, Jian Bin Zhou et Gary Russell. « Determining water in transformer paper insulation : analyzing aging transformers ». IEEE Electrical Insulation Magazine 31, no 5 (septembre 2015) : 23–32. http://dx.doi.org/10.1109/mei.2015.7214442.
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Kattel, Ruska, et Bhupendra Devkota. « PCBs Contamination among Distribution Transformers in the Kathmandu Valley ». International Journal of Environment 4, no 1 (22 février 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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Hazra, Nil Kamal, Pradip Kundu et Asok K. Nanda. « Some Reliability Properties of Transformed-Transformer Family of Distributions ». American Journal of Mathematical and Management Sciences 38, no 1 (18 décembre 2018) : 44–56. http://dx.doi.org/10.1080/01966324.2018.1482244.
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Jeckson, Jeckson, Azis Prayuda et Yenni Afrida. « ANALISIS DAMPAK OVERLOAD TRANSFORMATOR TERHADAP KUALITAS DAYA GARDU K622 PENYULANG PELANGI PT. PLN ( PERSERO ) ULP KARANG ». Jurnal Ilmiah Teknik Elektro 4, no 1 (31 mai 2022) : 10–12. http://dx.doi.org/10.36269/jtr.v4i1.986.
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Transformer overload occurs in one of the distribution transformers in PT. PLN (Persero) ULP Karang,namely the K622 Distribution Transformer at the Rainbow Feeder with a load of 110.16% exceeding the standard set by SPLN, which is 80%. This study aims to find out how to overcome the Overload problem in the K622 distribution substation transformer on The Rainbow and get the size of the K622 distribution substation transformer load before and after the Uprating Transformer. From the results of uprating, the percentage of transformer loading value before uprating transformers was carried out by 110.16% and after uprating transformers by 26.38% so that it decreased by 83.78%. This means that the uprating transformer is one of the methods that can be used to overcome excess loads.
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Thango, Bonginkosi A., et Pitshou N. Bokoro. « Stray Load Loss Valuation in Electrical Transformers : A Review ». Energies 15, no 7 (23 mars 2022) : 2333. http://dx.doi.org/10.3390/en15072333.
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The electricity production opus in South Africa has transformed over the last few years from predominantly coal power generation to a blend of renewable energy generation. The necessity emerges to ascertain whether electrical transformer design philosophies in local manufacturers are contemporary in reference to customer specifications, under increasing penetration of harmonics and distortion as a result of increasing deployment of decentralized power systems. Accurate computation of transformer stray load loss is imperative in localizing the hotspot regions and design of adequate insulation system and consequently cooling system. This loss must also be met by manufacturers based on the customer specifications to avoid penalties. The review of current scientific works affirms the ongoing interest in utilizing the advancement of computational power for painstaking evaluation and management of stray load loss in electric transformers. This article confers overview research, evolution and application of diverse computer-based tools for analyzing the stray load loss based on over 60 published scientific works. Mathematical formulations that can be practically employed by transformer designers during the design phase under normal and harmonic load current conditions are discussed.
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Demirović, Azelma, et Amir Kurtić. « Experiences and Analyses of Reconstruction and Commissioning of Medium Voltage Substation ». B&H Electrical Engineering 15, no 2 (1 décembre 2021) : 63–70. http://dx.doi.org/10.2478/bhee-2021-0019.
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Abstract The paper will present experiences in the reconstruction of the transformer station, which supplies the industrial factory. The previous version of the medium voltage (MV) substation with oil-filled transformers, and the new MV substation with dry and more energy efficient transformers, will be presented. An analysis of the operation and maintenance methods of oil transformers will be given. As oil transformers have many disadvantages, the reason, choice and cost-effectiveness of replacement with new dry transformers will be presented. Tests and measurements of insulation resistance of the winding and transformer protection during commissioning will also be presented. PT100 probes, which are connected to the thermostat, are installed in each low voltage winding of the dry transformer. Testing of this thermal protection of the transformer will be presented as well. Since transformers supply industrial consumers, mostly nonlinear ones, it is important to analyse the losses and life span of transformers. Nonlinear consumers lead to early aging of winding insulation, premature failures and reduction of transformer life. The newly designed and installed MV substation with Ring-main unit is ABB type SafePlus, and its installation and operating instructions will also be presented. The MV is equipped with a protection terminal, so settings and measurements of this terminal in transformer cells will be done. After the commissioning of the transformer station, the most important are diagnostics and periodic tests. Methods of periodic testing of MV substations will be presented in this paper.
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Lu, Yun Cai, Li Wei, Wei Chao et Wu Peng. « The New Development Trend of Distribution Transformer ». Applied Mechanics and Materials 672-674 (octobre 2014) : 831–36. http://dx.doi.org/10.4028/www.scientific.net/amm.672-674.831.
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Firstly, this paper introduces the development of new materials, new technology and new manufacture in power industry of China, energy-saving, low noise and smart distribution transformers are widely used in countryside power grid reconstruction. In this paper, application status and development trend of different types of distribution transformers were introduced and compared in terms of new material and new structure, such as oil-immersed distribution transformer, amorphous core transformer(AMT), dry-type transformer, SF6 insulated distribution transformer, composite transformer and other types of distribution transformers. The development of distribution transformer is mainly based on energy saving, miniaturization, wound core and amorphous alloy nowadays, but the class-H dry-type transformer and tridimensional toroidal-core amorphous alloy transformer are the future direction of development. The technology application of smart distribution grid, power electronics technology and dynamic reactive power compensation technique will also affect the safety and economic operation of distribution transformer.
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Kalita, Pankaj Kumar, Sujit Kumar Muduli, Loris D’Antoni, Thomas Reps et Subhajit Roy. « Synthesizing abstract transformers ». Proceedings of the ACM on Programming Languages 6, OOPSLA2 (31 octobre 2022) : 1291–319. http://dx.doi.org/10.1145/3563334.
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This paper addresses the problem of creating abstract transformers automatically. The method we present automates the construction of static analyzers in a fashion similar to the way yacc automates the construction of parsers. Our method treats the problem as a program-synthesis problem. The user provides specifications of (i) the concrete semantics of a given operation op , (ii) the abstract domain A to be used by the analyzer, and (iii) the semantics of a domain-specific language L in which the abstract transformer is to be expressed. As output, our method creates an abstract transformer for op in abstract domain A , expressed in L (an “ L -transformer for op over A ”). Moreover, the abstract transformer obtained is a most-precise L -transformer for op over A ; that is, there is no other L -transformer for op over A that is strictly more precise. We implemented our method in a tool called AMURTH. We used AMURTH to create sets of replacement abstract transformers for those used in two existing analyzers, and obtained essentially identical performance. However, when we compared the existing transformers with the transformers obtained using AMURTH, we discovered that four of the existing transformers were unsound, which demonstrates the risk of using manually created transformers.
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Jyothi, B., A. Pandian et P. Bhavana. « Fabrication and experimental analysis of multiple-winding transformers for multiphase supply ». Measurement and Control 53, no 3-4 (27 janvier 2020) : 662–78. http://dx.doi.org/10.1177/0020294019897086.
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This paper aims to fabricate multiple-winding transformers for polyphase supply that means more than the classical three-phase supply. Usually, transformers do not change the phase, that is, from single phase to three phase or vice versa, but according to the required power applications, transformer windings are connected in such a way to get the desired phase supply. Transformers are connected to implement three or more phases, which are generally referred as polyphase or multiphase transformers. In order to obtain three-phase transformers from one single unit with respect to the required phase supply of the transformer for the same kVA rating, the circuit becomes less expensive, smaller, and much lighter than when it is obtained from three single-phase individual transformers. In this work, the proposed multiphase supply is preferred as five, obtained from three individual transformers instead of five single-phase transformers. By properly connecting the secondary windings of the three multiwinding single-phase transformers, the required power output is obtained. Different multiple-winding transformer topologies are discussed and elaborated through both simulation and experimental analysis with the fabricated proposed five-phase multiple-winding transformer.
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Survilo, Josifs, et Antons Kutjuns. « Operation Modes of HV/MV Substations ». Scientific Journal of Riga Technical University. Power and Electrical Engineering 25, no 25 (1 janvier 2009) : 81–86. http://dx.doi.org/10.2478/v10144-009-0018-y.
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Operation Modes of HV/MV SubstationsA distribution network consists of high voltage grid, medium voltage grid, and low voltage grid. Medium voltage grid is connected to high voltage grid via substations with HV/MV transformers. The substation may contain one, mostly two but sometimes even more transformers. Out of reliability and expenditure considerations the two transformer option prevail over others mentioned. For two transformer substation, there may be made choice out of several operation modes: 1) two (small) transformers, with rated power each over 0.7 of maximum substation load, permanently in operation; 2) one (big) transformer, with rated power over maximum substation load, permanently in operation and small transformer in constant cold reserve; 3) big transformer in operation in cold season, small transformer-in warm one. Considering transformer load losses and no load losses and observing transformer loading factor β it can be said that the mode 1) is less advantageous. The least power losses has the mode 3). There may be singled out yet three extra modes of two transformer substations: 4) two big transformers in permanent operation; 5) one big transformer permanently in operation and one such transformer in cold reserve; 6) two small transformers in operation in cold season of the year, in warm season-one small transformer on duty. At present mostly two transformers of equal power each are installed on substations and in operation is one of them, hence extra mode 5). When one transformer becomes faulty, it can be changed for smaller one and the third operation mode can be practiced. Extra mode 4) is unpractical in all aspects. The mode 6) has greater losses than the mode 3) and is not considered in detail. To prove the advantage of the third mode in sense of power losses, the notion of effective utilization time of power losses was introduced and it was proven that relative value of this quantity diminishes with loading factor β. The use of advantageous substation option would make it possible to save notable amount of electrical energy but smaller transformer lifetime of this option must be taken into account as well.
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Aini, Zulfatri, Esa Mutari, Liliana Liliana et Oriza Candra. « Analysis of Imbalance Loads and Losses Based on The Largest Loading by 3 Units of 3 Phase Distribution Transformer ». JTEV (Jurnal Teknik Elektro dan Vokasional) 7, no 1 (2 avril 2021) : 69. http://dx.doi.org/10.24036/jtev.v7i1.111965.
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The imbalance load of distribution transformers often occurs.This is due to the fact that the load time amongst consumers is not the same, so that there is a difference in the value for each R, S, and T phase. The value difference of the phase causes overload in several phases so as the current emerges in neutral transformers. The current flowing in the neutral transformers causes the losses. In this research, the identification of the overload and the calculation of the distribution transformer load with the IEC reference standard which is allowed for 80% and the calculation of the imbalance transformer load with the 5% standard, then the losses resulting from the presence of neutral currents were carried out. There are three transformers in the Hangtuah feeder that have a load exceeded the standard, namely the DRI 0157, DRI 0241, and DRI 0065 transformers. The calculations for the three transformers are taken from measurement data in the form of voltage and current values for each phase during the daytime and nighttime and are simulated using ETAP 12.6.0 software. The symmetrical component method was used to obtain the imbalance value of the transformer load based on the measurement results and the ETAP simulation. The result of this research is the imbalance load occured in the three transformers. DRI 0241 is the transformer that has the largest percentage of an imbalance load at night. At nighttime, based on the measurement results of the DRI 0241, the transformer load is 80% and 65% at daytime, while for the imbalance load at nighttime and daytime are 32.2% and 29.8%, respectively. The greater the loading of the transformer, the larger the imbalance loading of transformer becomes. The current in neutral transformer generated losses in the amount of 45 A and 2.4% at nighttime while for 33 A and 1.2% at daytime. The neutral current affects the values of losses that the higher it is, the bigger the losses appear in a transformer.
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Oktavianus Rikardus Waro et Aris Heriandriawan. « Analisis Umur Pakai Transformator Distribusi 800 Dan 1600 kVA Di PDAM Ngagel Surabaya ». Venus : Jurnal Publikasi Rumpun Ilmu Teknik 2, no 2 (9 mars 2024) : 01–17. http://dx.doi.org/10.61132/venus.v2i2.234.
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Distribution transformers have a very important role in the electric power system. The lifespan of transformers in electric power systems will decrease over time. The reduced service life of distribution transformers is caused by several factors, including loading, ambient temperature, transformer winding temperature and transformer oil temperature. The author uses quantitative and qualitative research types. This research was conducted to determine the remaining useful life of distribution transformers. The data used in this research are transformer template data and peak load data during the day and night. The results of data processing obtained state that the first transformer's estimated remaining life with a load > 80% is 18 years starting from 2023, the second transformer's estimated remaining life with a load > 80% is 16 years starting from 2023, for the third and fourth transformers it is not calculated because it has been used since 1982 or is around 41 years old. For the winding temperature on the first transformer LBP 84 ℃ and BP 89 ℃, on the second transformer the winding temperature LBP 81 ℃ and BP 96 ℃. Both transformers are still considered good because the hot spot temperature is below the maximum limit set by the IEEE in 1955, namely a temperature of 98 ℃.
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Lancon, Leo, Hugo Vallee, Gilles Montoriol, Fabien Brunelli et Thierry Taris. « Integrated-Transformer-Based Impedance Matching Method : Impedance Matching With Transformers ». IEEE Microwave Magazine 23, no 9 (septembre 2022) : 40–56. http://dx.doi.org/10.1109/mmm.2022.3158033.
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Saravanakumar, K., J. Samson Issac, J. Dhanaselvam, R. Rajesh, Ajith B. Singh et K. Geetha. « Fe3O4/TiO2/Graphene Hybrid Nanocomposite to Improve the Lifespan of Distribution Transformers ». Journal of Physics : Conference Series 2325, no 1 (1 août 2022) : 012016. http://dx.doi.org/10.1088/1742-6596/2325/1/012016.
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Abstract The actual lifetime of a transformer is between 30-50 years, while a foundation can be in service for 100 years. The aim of this research is to get the exact remaining lifetime of the transformers and to suggest a method to improve it. Hybrid nanoparticles are used to improve the thermal properties and dielectric strength of transformer oil. Titanium oxide (TiO2), Iron oxide (Fe3O4), and Graphene is used in specific concentration to prepare the hybrid nanoparticles. Energy Dispersive X-Ray Analysis (EDX), X-Ray Diffraction Analysis (XRD), Fourier Transform Infrared Spectroscopy (FTIR) are carried out to know whether the nanoparticles are properly synthesized. Initially Infrared thermography analysis using Fluke TiX-580 is being carried out to measure the surface temperature of the transformers and transformers under analysis are grouped. Nanofluid Transformer oil is prepared and Break Down Voltage (BDV) Test is taken to analyse the strength. Transformers are filled with nanofluid transformer oil and Infrared Thermography analysis is performed again to analyse the surface temperature. It is showing that lifetime of transformers is increased from 6 to 8% after using nanofluid transformer oil.
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Kuncoro, Rohmanu Dwi. « Analisis Resetting Relay Dan Load Presentase Terhadap Pola Pelaksanaan Dan Pemeliharaan Pada Gardu Induk 150 Kv Saketi Banten ». ELPOSYS : Jurnal Sistem Kelistrikan 8, no 2 (2 juillet 2021) : 16–22. http://dx.doi.org/10.33795/elposys.v8i2.46.
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Abstrac: The Saketi substation has three 150/70 kV power transformers with a capacity of 3x60 MVA with a frequency of 50 Hz where all three transformers have the capacity, transformer 1 60 MVA (PAUWELS TRAFO) has 3 feeders with an average load of 300 A, 10 MW, transformer 2 60 MVA (UNINDO) has 3 feeders with an average load of 200 A, 6.9 MW and transformer 3 60 MVA (UNINDO) has 4 feeders with an average load of 300 A, 10 MW. This calculation and simulation analysis is carried out aiming to find out the relay settings on each transformer under normal conditions and in a maintenance state on one of the transformers for a long period of time. From the results of the analysis and calculation, it was found that the OCR relay setting under normal conditions of the incoming 150 kV transformer transformers 1, 2, and 3 has a current setting value of 0.92 A and a time setting of 0.36 seconds. On the outgoing side the 20 kV transformers 1, 2, and 3 have a setting of 1,039 A and a time setting of 0.166 seconds.
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Kuncoro, Rohmanu Dwi, Ahmad Hermawan et Rhezal Agung Ananto. « Analisis Resetting Relay Dan Load Presentase Terhadap Pola Pelaksanaan Dan Pemeliharaan Pada Gardu Induk 150 Kv Saketi Banten ». Elposys : Jurnal Sistem Kelistrikan 8, no 2 (30 juin 2021) : 50–56. http://dx.doi.org/10.33795/elposys.v8i2.632.
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The Saketi substation has three 150/70 kV power transformers with a capacity of 3x60 MVA with a frequency of 50 Hzwhere all three transformers have the capacity, transformer 1 60 MVA (PAUWELS TRAFO) has 3 feeders with an average load of 300 A, 10 MW, transformer 2 60 MVA (UNINDO) has 3 feeders with an average load of 200 A, 6.9 MW and transformer 3 60 MVA (UNINDO) has 4 feeders with an average load of 300 A, 10 MW. This calculation and simulation analysis is carried out aiming to find out the relay settings on each transformer under normal conditions and in a maintenance state on one of the transformers for a long period of time. From the results of the analysis and calculation, it was found that the OCR relay setting under normal conditions of the incoming 150 kV transformer transformers 1, 2, and 3 has a current setting value of 0.92 A and a time setting of 0.36 seconds. On the outgoing side the 20 kV transformers 1, 2, and 3 have a setting of 1,039 A and a time setting of 0.166 seconds.
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Zhao, Xinyue, Fangxu Gui, Heng Chen, Lanxin Fan et Peiyuan Pan. « Life Cycle Cost Estimation and Analysis of Transformers Based on Failure Rate ». Applied Sciences 14, no 3 (31 janvier 2024) : 1210. http://dx.doi.org/10.3390/app14031210.
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Transformers, as the hub equipment of the power system, are highly valued by engineering and scientific researchers in production practice and scientific research. The goal of transformer research is to ensure the safe operation of transformers while considering their economic benefits, arrange transformer inspections reasonably to reduce inspection costs, and save labor and maintenance costs reasonably. This study first provides a brief analysis of the life cycle cost of transformers. The life cycle of transformers is divided into initial cost, operating cost, maintenance cost, fault cost, and scrap cost. Based on the distribution of transformer failure rate, the corresponding life cycle cost of transformers is calculated. Taking 110 kV transformers as an example, the differences in the impact of key factors on the full life cycle cost are analyzed to achieve high quality, high reliability, economically optimal equipment procurement.
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Su, Biao, Li Xue Li, Yi Hui Zheng, Xin Wang, Yan Liu et Chang Li Dang. « Design and Analysis of PCB Rogowski Coil Current Transformer ». Applied Mechanics and Materials 672-674 (octobre 2014) : 984–88. http://dx.doi.org/10.4028/www.scientific.net/amm.672-674.984.
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Electronic current transformers are more suitable for the development of power system compared with traditional electromagnetic current transformers. Rogowski coil current transformer is one of three electric current transformers. According to the measurement principle of Rogowski coils, the equivalent circuit of PCB Rogowski coils is analyzed. By using four PCB Rogowski coils combined, a PCB Rogowski coil current transformer is designed and tested. The results show that the designed PCB Rogowski coil transformer has good linearity and high sensitivity and measurement accuracy and it can meet the requirement of power system.
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Xie, Qing, Shan Shan Hou, Feng Liao et Wei Tao Hu. « Study on the Power Transformers Deterioration State Evaluation Index System ». Advanced Materials Research 732-733 (août 2013) : 954–57. http://dx.doi.org/10.4028/www.scientific.net/amr.732-733.954.
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Large power transformers as the the hub of power system equipment, its operation reliability directly related to the security and stability of the power system. When we have to make a more comprehensive and accurate judgment for running health status of the power transformer,we must get the characteristics of the transformer state. In this paper, we can pick out representative indicators from the existing power transformers deterioration state elements. Thereby, we can study more systematic and targeted the deteriorated state of the power transformer. Keywords: power transformers; deterioration state ;evaluation
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BOLSHEV, V. E., B. V. PAPKOV, A. V. BUKREEV et D. V. KONKIN. « ALGORITHM FOR USING TWO TRANSFORMERS INSTEAD OF ONE AT 10/0.4 KV TRANSFORMER SUBSTATIONS IN ORDER TO REDUCE ELECTRICITY LOSSES ». Elektrotekhnologii i elektrooborudovanie v APK 71, no 1 (2024) : 24–30. http://dx.doi.org/10.22314/2658-4859-2024-71-1-24-30.
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According to statistics, losses in electrical networks of power supply organizations in the Russian Federation amount to 10 percent, while the world average is 8 percent. The Energy Strategy for the period until 2035, approved by the Government of the Russian Federation in 2020, sets the goal of achieving a reduction in electrical energy losses to 7.3 percent by 2035. One of the effective ways to reduce electricity losses is to replace underloaded transformers at substations in order to increase the transformer load factor. For this purpose, a method was developed for using two transformers instead of one at 10/0.4 kilovolt transformer substations. (Research purpose) is to develop an algorithm for implementing a method of using two transformers instead of one at 10/0.4 kilovolt transformer substations in order to reduce electricity losses. (Materials and methods) General scientific research methods, methods for constructing algorithms, control and data transmission systems, and analysis of scientific and technical information were used as the methodological basis for the research. (Results and discussion) This paper presents an algorithm for implementing the method of using two transformers instead of one at 10/0.4 kilovolt transformer substations. The algorithm allows automatically controlling the connection and disconnection of power transformers at a transformer substation depending on their load and season, while recording these actions and sending the corresponding signals to the dispatcher of the power supply organization. (Conclusions) Based on the results of the study, it was found that the developed algorithm for implementing the method of using two transformers instead of one at 10/0.4 kilovolt transformer substations makes it possible to achieve a reduction in electricity losses by increasing the load factor of transformers.
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Fernández, Inmaculada. « The Need for Experimental and Numerical Analyses of Thermal Ageing in Power Transformers ». Energies 15, no 17 (1 septembre 2022) : 6393. http://dx.doi.org/10.3390/en15176393.
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Most power transformers are oil-immersed transformers for which its insulation system consists of oil and cellulosic solid. The insulation liquid impregnates the solid-covering air spaces, which improves the efficiency of the insulation system. Not only does the oil ensure electrical insulation but it also works as coolants transferring the heat generated during transformer operation to the exterior of the transformer. Throughout normal operation conditions, transformers experience multiple stresses that degrade their insulation. Since the lifetime of oil-immersed transformers is defined mainly by the state of the insulation paper, it is critical to understand the behavior and degradation mechanisms of new insulation systems that try to overcome the drawbacks of mineral oil as well as to improve power transformer performances. The current increased prevalence of the nonlinear loads additionally stresses power transformers, which generates their premature ageing or even failure. Consequently, new materials and assessment methods are required to guarantee the suitable management of power transformer populations. In this Special Issue “Experimental and Numerical Analysis of Thermal Ageing in Power Transformers”, four papers have been published. The guest editor also describes briefly some challenges involved beyond the coverage of this Special Issue.
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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 (31 mars 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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Poonnoy, Nitchamon, Cattareeya Suwanasri et Thanapong Suwanasri. « Fuzzy Logic Approach to Dissolved Gas Analysis for Power Transformer Failure Index and Fault Identification ». Energies 14, no 1 (23 décembre 2020) : 36. http://dx.doi.org/10.3390/en14010036.
Texte intégralRésumé :
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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Yahaya, Muhammad, Norhafiz Azis, Amran Mohd Selva, Mohd Ab Kadir, Jasronita Jasni, Emran Kadim, Mohd Hairi et Young Yang Ghazali. « A Maintenance Cost Study of Transformers Based on Markov Model Utilizing Frequency of Transition Approach ». Energies 11, no 8 (2 août 2018) : 2006. http://dx.doi.org/10.3390/en11082006.
Texte intégralRésumé :
In this paper, a maintenance cost study of transformers based on the Markov Model (MM) utilizing the Health Index (HI) is presented. In total, 120 distribution transformers of oil type (33/11 kV and 30 MVA) are examined. The HI is computed based on condition assessment data. Based on the HI, the transformers are arranged according to its corresponding states, and the transition probabilities are determined based on frequency of a transition approach utilizing the transformer transition states for the year 2013/2014 and 2012/2013. The future states of transformers are determined based on the MM chain algorithm. Finally, the maintenance costs are estimated based on future-state distribution probabilities according to the proposed maintenance policy model. The study shows that the deterioration states of the transformer population for the year 2015 can be predicted by MM based on the transformer transition states for the year 2013/2014 and 2012/2013. Analysis on the relationship between the predicted and actual computed numbers of transformers reveals that all transformer states are still within the 95% prediction interval. There is a 90% probability that the transformer population will reach State 1 after 76 years and 69 years based on the transformer transition states for the year 2013/2014 and 2012/2013. Based on the probability-state distributions, it is found that the total maintenance cost increases gradually from Ringgit Malaysia (RM) 5.94 million to RM 39.09 million based on transformer transition states for the year 2013/2014 and RM 37.56 million for the year 2012/2013 within the 20 years prediction interval, respectively.
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Yuchao, Ma, Mo Juan, Yu Jinshan, Li Xiang et Zheng Zhongyuan. « Study on Sound Field Distribution Rule for Tank Structures of Large Oil-immersed Transformers ». E3S Web of Conferences 233 (2021) : 01021. http://dx.doi.org/10.1051/e3sconf/202123301021.
Texte intégralRésumé :
Large oil-immersed transformers are an important part of the transmission and distribution network in power systems. Power transformers are the main noise source of substations. Because of the uneven manufacturing process, aging equipment, long-term operation, and close distance from sensitive points, the problem of transformer noise pollution has become increasingly prominent. In this paper, the transmission and analysis model is established for transformer sound waves on the interface between insulating oil and tank body according to the sound wave propagation rule in complicated medium, and the simplified acoustic simulation model is constructed for large oil-immersed transformers by simulating the vibration noise of transformer core with monopole sound source, with which, the sound field distribution rule inside and outside the transformer tank structure is obtained, and finally, the influence factors for noise distribution are given. The results of the study provide control basis for reducing transformer noise.
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T, Thoyyibah, Wasis Haryono, Achmad Udin Zailani, Yan Mitha Djaksana, Neny Rosmawarni et Nunik Destria Arianti. « Transformers in Machine Learning : Literature Review ». Jurnal Penelitian Pendidikan IPA 9, no 9 (25 septembre 2023) : 604–10. http://dx.doi.org/10.29303/jppipa.v9i9.5040.
Texte intégralRésumé :
In this study, the researcher presents an approach regarding methods in Transformer Machine Learning. Initially, transformers are neural network architectures that are considered as inputs. Transformers are widely used in various studies with various objects. The transformer is one of the deep learning architectures that can be modified. Transformers are also mechanisms that study contextual relationships between words. Transformers are used for text compression in readings. Transformers are used to recognize chemical images with an accuracy rate of 96%. Transformers are used to detect a person's emotions. Transformer to detect emotions in social media conversations, for example, on Facebook with happy, sad, and angry categories. Figure 1 illustrates the encoder and decoder process through the input process and produces output. the purpose of this study is to only review literature from various journals that discuss transformers. This explanation is also done by presenting the subject or dataset, data analysis method, year, and accuracy achieved. By using the methods presented, researchers can conclude results in search of the highest accuracy and opportunities for further research.
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Barseghyan, Sarkis, Arman Hayrapetyan et Armen Kirakosyan. « Ecological assessment of noise impact of dry transformer substations on the environment ». E3S Web of Conferences 265 (2021) : 02011. http://dx.doi.org/10.1051/e3sconf/202126502011.
Texte intégralRésumé :
At present, special attention is paid to assessing the negative impact of power facilities on the environment, including the impact of noise generated by power equipment. Power transformers are one of the sources of noise for industrial areas and the surrounding area. The noise of transformers is caused both by the vibration of its active part and by the fans of the cooling system, which is amplified by resonance phenomena in its individual elements. The presented work provides an environmental assessment of the noise impact of transformer substations. The noise impact of a transformer substation is considered on the example of three dry transformers in the area immediately adjacent to the living space. A new corrected approach was developed and tested for calculating the sound power level for dry transformers with the MatLab software package. An assessment of the noise impact of the projected transformer substation to install three dry transformers was the voltage class of which is 400 kVA, and one has 1000 kVA for the territory immediately adjacent to the living area was made. In our researches, the regulated noise characteristic for transformers is the corrected sound power level, which is indicated in the technical characteristics of the transformer. Calculations on non-standard nominal rated powers were carried out.
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Wu, Jing, Kun Li, Jing Sun et Li Xie. « A Novel Integrated Method to Diagnose Faults in Power Transformers ». Energies 11, no 11 (5 novembre 2018) : 3041. http://dx.doi.org/10.3390/en11113041.
Texte intégralRésumé :
In a smart grid, many transformers are equipped for both power transmission and conversion. Because a stable operation of transformers is essential to maintain grid security, studying the fault diagnosis method of transformers can improve both fault detection and fault prevention. In this paper, a data-driven method, which uses a combination of Principal Component Analysis (PCA), Particle Swarm Optimization (PSO), and Support Vector Machines (SVM) to enable a better fault diagnosis of transformers, is proposed and investigated. PCA is used to reduce the dimension of transformer fault state data, and an improved PSO algorithm is used to obtain the optimal parameters for the SVM model. SVM, which is optimized using PSO, is used for the transformer-fault diagnosis. The diagnostic-results of the actual transformers confirm that the new method is effective. We also verified the importance of data richness with respect to the accuracy of the transformer-fault diagnosis.
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Dai, Jing, et Zhi Hua Li. « Analysis of the Energy Efficiency Grades Detection for Power Transformers ». Advanced Materials Research 328-330 (septembre 2011) : 1003–7. http://dx.doi.org/10.4028/www.scientific.net/amr.328-330.1003.
Texte intégralRésumé :
There is a lot of power loss in the power transmission, and the loss comes from power transformers contribute very much to this. So the implement of energy efficiency grade for power transformers has great significance to the development of power transformer, which can wash out the high energy-consuming transformer, decrease the power loss, and increase the efficiency of power transmission. The energy consumption of transformer consists of no load loss and load loss. In this test, I analyze the experiments for no load loss and load loss with the “Minimum allowable values of energy efficiency and energy efficiency grades for power transformers”, ascertaining the transformer’s efficiency grade.
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Sharma, R. Rajesh. « Design of Distribution Transformer Health Management System using IoT Sensors ». September 2021 3, no 3 (16 septembre 2021) : 192–204. http://dx.doi.org/10.36548/jscp.2021.3.005.
Texte intégralRésumé :
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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Liu, Yijie. « High-frequency transformers optimized design for power electronic transformers ». Applied and Computational Engineering 10, no 1 (25 septembre 2023) : 196–202. http://dx.doi.org/10.54254/2755-2721/10/20230174.
Texte intégralRésumé :
Because of its small size, high frequency transformers are widely used to maximize energy transfer. However, the leakage inductance and distributed capacitance of high frequency transformer can not only cause resonance, but also lead to transient changes of voltage and current in high frequency, which can lead to voltage spike, so that the switch tube is damaged. For transformers with the same output power, high-frequency transformers are much smaller and have lower calorific value than low-frequency transformers. Therefore, at present, many consumer electronics and network product power adapters are switching power supplies, and the internal high-frequency transformer is the most important component of switching power supplies. The basic principle is to turn the input alternating current into DC first, and then turn it into high frequency through a transistor or FET, etc., through a high-frequency transformer to change voltage, and then rectify the output again, plus other control parts, and stabilize the output DC voltage. In this thesis, we choose a more rational and cost effective winding structure, choose a more appropriate core material based on the comparison of different core materials, research on the insulation and cooling properties of transformer so as to improve the insulation properties of the transformer, make it safer and more efficient. The study has important significance to decrease the power loss of high frequency transformer and decrease the size of high frequency transformer.
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Yao, Feng, Zhong Hui Zhang et Le Zhang He. « Comprehensive Assessment of Power Transformer Condition Based on the Fault Tree and the Analytic Hierarchy Process ». Advanced Materials Research 805-806 (septembre 2013) : 793–800. http://dx.doi.org/10.4028/www.scientific.net/amr.805-806.793.
Texte intégralRésumé :
Transformers state comprehensive assessment to provide the basis for the repair and maintenance of power transformers .Based on the fault tree analysis (FTA) to find out the impact of the failure of the power transformer factors, and the establishment of the index system to assess the state of the power transformer, application 3 scale analytic hierarchy process assessment model for the establishment of the state of the transformer , and thus the transformer state is divided into five levels. Through the classification of the more conducive to the staff to understand the transformer condition, reasonable arrangements for the maintenance plan .Case analysis to prove, based on the comprehensive assessment of the fault tree and power transformer condition of the Analytic Hierarchy Process method is reasonable and effective.
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Bachtiar, Raditya Fahmi. « Pemilihan Skala Prioritas Lokasi Pemasangan Sisip Trafo Distribusi dengan Metode Ahp – Topsis di PT. PLN ULP Pangkalan Bun ». Syntax Literate ; Jurnal Ilmiah Indonesia 8, no 12 (30 décembre 2023) : 6633–47. http://dx.doi.org/10.36418/syntax-literate.v8i12.14217.
Texte intégralRésumé :
In this study, a total of 57 transformers with a load measurement status above 95% (overload) were recorded in the year 2022 and require transformer insertions. Every year, PLN ULP Pangkalan, on average, carries out a transformer insertion program of 10 transformers due to budget limitations. With this number, it is necessary to prioritize locations based on 6 criteria: transformers with overloads >95%, maneuvering up to 50% of existing transformers, a waiting list of ready-to-connect customers, business tariff (B) customers, landowner permits required, and the need for adding new network extensions. The Analytic Hierarchy Process (AHP) method is used for weighting the criteria, followed by the Technique for Other Preference by Similarity of Ideal Solution (TOPSIS) method to determine the priority sequence of distribution transformer insertion locations. The results of the AHP method show that the highest weight is assigned to the criteria of transformers with overloads >95%, with a weight of 59.3%. The lowest weight is assigned to the criteria of having business tariff (B) customers, with a weight of 3.8%. Using the TOPSIS method, the top priority location for distribution transformer insertion is at substation PBN-0262, with a preference value of 0.721038962870702. Meanwhile, the lowest priority location is found at transformer PBH-0054, with a preference value of 0.157302058325342. The sensitivity analysis results show that the priority sequence of distribution transformer insertion locations remains consistent and does not significantly change, indicating that the TOPSIS method's prioritization results in this study are consistent.
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David Chigozie Madumere, Evans C. Ashigwuike et N.B. Gafai. « Expert system for improving and controlling insulation system of service transformers using fuzzy logic controller ». Global Journal of Engineering and Technology Advances 18, no 3 (30 mars 2024) : 066–74. http://dx.doi.org/10.30574/gjeta.2024.18.3.0194.
Texte intégralRésumé :
Implementation of the smart transformer concept is critical for the deployment of IOT-based smart grids. Top manufacturers of power electrics develop and adopt online monitoring systems. Such systems become part of high-voltage grid and unit transformers. However, furnace transformers are a broad category that this change does not affect yet. At the same time, adoption of diagnostic systems for furnace transformers is relevant because they are a heavy-duty application with no redundancy. Creating any such system requires a well-founded mathematical analysis of the facility’s condition, carefully selected diagnostic parameters, and set points thereof, which serve as the condition categories. The goal hereof was to create an expert system to detect insulation breach and its expansion as well as to evaluate the risk it poses to the system; the core mechanism is mathematical processing of trends in partial discharge (PD). This research work examined the acidity of distribution transformer oil in service through laboratory tests using a case study of installed distribution transformers at Abuja metropolis network comprising ten Feeders. The result shows the minimum breakdown voltage of 40KV/mm and maximum breakdown voltage of 58KV/mm. The maximum transformer oil Acidity is 0.1143mgKOH/g and the minimum transformer oil Acidity level is 0.0954mgKOH/g. The transformer efficiency without fuzzy is 82.89% and transformer efficiency with fuzzy controller is 98.10%.
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Senoussaoui, Mohammed El Amine, Mostefa Brahami et Issouf Fofana. « Transformer Oil Quality Assessment Using Random Forest with Feature Engineering ». Energies 14, no 7 (24 mars 2021) : 1809. http://dx.doi.org/10.3390/en14071809.
Texte intégralRésumé :
Machine learning is widely used as a panacea in many engineering applications including the condition assessment of power transformers. Most statistics attribute the main cause of transformer failure to insulation degradation. Thus, a new, simple, and effective machine-learning approach was proposed to monitor the condition of transformer oils based on some aging indicators. The proposed approach was used to compare the performance of two machine-learning classifiers: J48 decision tree and random forest. The service-aged transformer oils were classified into four groups: the oils that can be maintained in service, the oils that should be reconditioned or filtered, the oils that should be reclaimed, and the oils that must be discarded. From the two algorithms, random forest exhibited a better performance and high accuracy with only a small amount of data. Good performance was achieved through not only the application of the proposed algorithm but also the approach of data preprocessing. Before feeding the classification model, the available data were transformed using the simple k-means method. Subsequently, the obtained data were filtered through correlation-based feature selection (CFsSubset). The resulting features were again retransformed by conducting the principal component analysis and were passed through the CFsSubset filter. The transformation and filtration of the data improved the classification performance of the adopted algorithms, especially random forest. Another advantage of the proposed method is the decrease in the number of the datasets required for the condition assessment of transformer oils, which is valuable for transformer condition monitoring.
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Wang, Xiao Fang. « Transformer Inrush Current Identification Based on EMD+TEO Methods ». Applied Mechanics and Materials 556-562 (mai 2014) : 3129–33. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.3129.
Texte intégralRésumé :
Transformers is one of the most important power system components, its role is to carry power conversion and transmission, transformer manufacturing technology continues to develop, but there is a surge of its problems, factors that have caused the transformer inrush load switching, transformers string parallel operation and fault lines, etc, as a transformer inrush phenomenon often can lead to malfunction of its protection, the correct identification is particularly important means of this paper, the combination of EMD and TEO transformer inrush and fault operation effective identification, theory and simulation confirms the validity and reliability of the algorithm.
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Kefalas, Themistoklis D., et Antonios Kladas. « Reduction of Power Grid Losses by Using Energy Efficient Distribution Transformers ». Materials Science Forum 721 (juin 2012) : 269–74. http://dx.doi.org/10.4028/www.scientific.net/msf.721.269.
Texte intégralRésumé :
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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S, Kumaran. « Transformer Fault Condition Prognosis Using Vibration Signals Over Cloud Environment ». International Scientific Journal of Engineering and Management 03, no 04 (23 avril 2024) : 1–9. http://dx.doi.org/10.55041/isjem01631.
Texte intégralRésumé :
he Automatic Area Transformer Fault Message Indicator is an innovative system designed to detect and report faults in transformers. It utilizes potential and current transformers, precision rectifiers, and sensors to monitor high/low voltage, current, frequency, and transformer temperature. The data is processed by a microcontroller, displayed on an LCD, and transmitted to the electric utility station via GSM, enabling timely identification and communication of transformer issues for efficient maintenance and grid reliability. This system offers several key benefits. First, its use of advanced sensors and precision rectifiers ensures accurate measurement of critical parameters, allowing for early detection of potential faults. Keywords—GSM, Step down transformer, potential and current transformer, Temperature sensor.
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Liang, Zhengping, Yan Fang, Hao Cheng, Yongbin Sun, Bo Li, Kai Li, Wenxuan Zhao, Zhongxu Sun et Yiyi Zhang. « Innovative Transformer Life Assessment Considering Moisture and Oil Circulation ». Energies 17, no 2 (16 janvier 2024) : 429. http://dx.doi.org/10.3390/en17020429.
Texte intégralRésumé :
Power transformers are one of the most expensive and important equipment in the power system. Significant differences exist in the insulation lifespan of transformers that have been in operation for more than 20 years, and using identical maintenance or scrapping methods may result in significant economic losses. However, most existing transformer life assessment methods only consider the impact of moisture content on the life decay rate without considering the impact of oil circulation cooling modes, which leads to some evaluation errors. In this study, we established a new transformer life assessment method that considers the influence of moisture content and oil circulation cooling modes, which is more accurate than most life assessment methods. Then, the proposed life evaluation method was validated on the on-site transformers, demonstrating its accuracy and effectiveness. The novelty of this study is that it establishes a new on-site transformer life assessment method that considers the comprehensive effect of moisture content and oil circulation cooling mode, which helps to evaluate the remaining lifespan of power transformers more accurately and thus extends the transformer lifespan systematically.
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Melnikova, O. S., et V. S. Kuznetsov. « Method of calculating the electric strength of oil channels of the main insulation of power transformers ». Vestnik IGEU, no 5 (30 décembre 2020) : 48–55. http://dx.doi.org/10.17588/2072-2672.2020.5.048-055.
Texte intégralRésumé :
The most damage-sensitive unit of power transformers is the main insulation of the oil barrier type. The breakdown of such insulation occurs as a result of the breakdown of the oil channel near the high voltage winding. In accordance with traditional methods of calculating the dielectric strength of insulation, the value of the breakdown strength is determined by empirical formulas depending on the selected width of the oil channel. The existing methods do not consider the influence of the oil channel volume, of the electric strength the statistical characteristics of the oil, the design features of the insulation of power transformers, and do not contain recommendations for creating design models. Thus, to improve the calculation accuracy, it is relevant to develop the evaluation method of dielectric strength of the main insulation of power transformers taking into account the volume and parameters of the breakdown voltage distribution of transformer oil, design features. The research results of the breakdown tension in oil channels with different volumes of transformer oil were used. To improve the accuracy of the calculation and taking into account the design features, the model of the main insulation of power transformers was made in the ANSYS program. Boundary data and assumption of linear stress distribution of transformer coils were considered. A method for calculating the dielectric strength of oil channels of the main insulation of power transformers, considering the volume and parameters of the breakdown voltage distribution of transformer oil was proposed. Unlike the existing methods, when calculating the minimum breakdown strength in the model of the main insulation, the design features of power transformers are taken into account and assumptions are justified to improve the accuracy of the calculation. In accordance with the methodology, the parameters of the dielectric strength of the transformer oil in the oil channel of the high voltage winding of the transformer were calculated. It was concluded that with increase of relative value of breakdown tension, dielectric strength of oil channel is decreasing, and it corresponds to physical sense of breakdown. The method for calculating the dielectric strength of transformer oil can be used when choosing the main insulation of power transformers in design.
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Tikhonov, A. I., A. A. Karzhevin, A. V. Stulov, D. M. Tikhomirov et V. E. Rozin. « Technology for simulation models of power transformers with arbitrary design of active part ». Vestnik IGEU, no 4 (31 août 2023) : 28–35. http://dx.doi.org/10.17588/2072-2672.2023.4.028-035.
Texte intégralRésumé :
Existing simulation models of power transformers that operate, for example, in the MATLAM Simulink SimPowerSystem environment, are based on an ideal transformer model. It allows using this model as an autonomous link in a complex electrical circuit. The main disadvantage of such models is the difficulty to consider non-standard versions of the magnetic circuit and special schemes for connecting winding elements when modeling. Particularly significant problems arise when modeling special transformers of the certain classes. At the same time, traditionally, when modeling the transient modes of transformers, a different approach is used. It is based on the use of inductance matrices which allows considering all the design features of the active part of the transformer. The disadvantage of this approach is the need to describe an external electrical circuit in addition to the transformer. Therefore, the problem to develop a modern technology for simulation models of transformers with an arbitrary design of the active part is topical. This model meets the requirement for the autonomy of the transformer model from the external circuit model. The authors have used the methods of modeling electrical and magnetic circuits based on the theory of ordinary differential equations, and simulation method using the MatLab Simulink SimPowerSystems package. A technology has been developed for simulation models of transformers with an arbitrary design of the active part based on the use of typical subsystems. An algorithm for matrix of inductances based on the main magnetic field of the transformer with the existing equivalent circuit of the magnetic circuit is given. The authors have presented a diagram of a three-phase transformer model developed using the proposed technology, as well as the results of comparing the current curves in the primary and secondary windings of the transformer when it is turned on at idle and with a resistive load. The results are obtained using the existing and new models. The results of the study can be used to design general industrial and special transformers in design companies and in manufacturing environment. The developed technology can give a special effect when it is used at the R&D stage to study the operating modes of transformers in case the enterprise has no experience to design and manufacture them.
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Mogorovic, Marko, et Drazen Dujic. « Sensitivity Analysis of Medium-Frequency Transformer Designs for Solid-State Transformers ». IEEE Transactions on Power Electronics 34, no 9 (septembre 2019) : 8356–67. http://dx.doi.org/10.1109/tpel.2018.2883390.
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Laka, Aitor, Jon Andoni Barrena, Javier Chivite-Zabalza, Miguel Angel Rodríguez Vidal et Gorka Calvo. « Novel Zero-Sequence Blocking Transformer (ZSBT) Using Three Single-Phase Transformers ». IEEE Transactions on Energy Conversion 28, no 1 (mars 2013) : 234–42. http://dx.doi.org/10.1109/tec.2012.2229282.
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Saha, T. K., M. Darveniza, D. J. T. Hill et T. T. Le. « Electrical and chemical diagnostics of transformers insulation. A. Aged transformer samples ». IEEE Transactions on Power Delivery 12, no 4 (1997) : 1547–54. http://dx.doi.org/10.1109/61.634174.
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Bracale, Antonio, Guido Carpinelli et Pasquale De Falco. « Probabilistic risk-based management of distribution transformers by dynamic transformer rating ». International Journal of Electrical Power & ; Energy Systems 113 (décembre 2019) : 229–43. http://dx.doi.org/10.1016/j.ijepes.2019.05.048.
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Khalina, Tat’yana, et Vanik Ovsepyan. « Analysis of the occurrence of magnetic flux surges and magnetizing current when the transformer is turned on at idle ». Energy Systems 7, no 4 (20 décembre 2022) : 46–53. http://dx.doi.org/10.34031/es.2022.4.005.
Texte intégralRésumé :
This article discusses the transients that occur in power transformers when they are turned on at idle. The main negative consequences arising from magnetizing current surges and their impact on the quality of electrical equipment, in particular, false alarms of relay protection devices and deformation of transformer structural elements by electrodynamic forces, are given. The mathematical derivation of physical quantities determining the process of occurrence of magnetic flux and magnetizing current surges is presented on the example of switching on a power single-phase transformer in idle mode. As a result of mathematical analysis, the main factors affecting the flow of the transient process when the power transformer is switched on in idle mode were identified. A mathematical expression was obtained that allows determining the phase of the mains voltage for a favorable moment of switching on a single-phase transformer, depending on the magnitude of the residual magnetic flux in the steel core of the transformer. Based on the analysis of transients that occur when transformers are switched on at idle, methods or algorithms for switching on power transformers can be developed that allow for a smooth start of the transformer and avoid or minimize negative consequences.