Article
Engineering, Electrical & Electronic
Abraao G. C. Menezes, Mateus M. Araujo, Otacilio M. Almeida, Fabio R. Barbosa, Arthur P. S. Braga
Summary: This article introduces the use of a decision tree approach based on computational intelligence for analyzing and diagnosing incipient faults in power transformers. The method relies on measuring the concentration of combustible gas in the insulating oil. By using the gain ratio as an attribute selection metric, the decision tree algorithm is able to extract maximum information from each class and provide a solution for unsolved cases. Overall, the decision tree plays a significant role in improving the performance of dissolved gas analysis and can be combined with other traditional techniques.
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
(2022)
Article
Chemistry, Physical
Bo Gao, Yanan Fang, Kai Liu, Haojie Yin, Yonghong Zeng, Guangning Wu
Summary: In this paper, molecular dynamics simulations were performed to study the thermal decomposition mechanism and product distribution of synthetic ester oils. The results show that the initial decomposition reaction is ester bond cleavage, followed by decarboxylation reaction and beta-C bond cleavage. The main decomposition products are CO2, C2H4, and some C2 and C3 species. The study of the generation process of these dissolved gases provides a theoretical basis for the research on the DGA method of synthetic ester oil.
CHEMICAL PHYSICS LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Jose E. Contreras, Josue Rodriguez, Carlos Gaytan
Summary: Currently, the use of new biodegradable dielectric liquids as an alternative to conventional mineral oil in transformers is being considered. However, the higher viscosity of ester liquids compared to mineral oil requires modifications in the impregnation process of insulation materials.
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
(2022)
Article
Computer Science, Information Systems
Jaime Sanz, Oasis Sancibrian, Cristian Olmo, Cristina Mendez, Alfredo Ortiz, Carlos J. Renedo
Summary: The study focuses on the impregnation behavior of eight common dielectric solids with two esters and a traditional mineral oil. It identifies the key materials and properties to consider during impregnation as the rigid cellulosic materials present in the transformers and the viscosity of the dielectric oils. An adaptation of the current impregnation processes to the alternative oils have been proposed by increasing their temperature depending on the viscosity of the oil used.
Article
Chemistry, Analytical
Vijay V. Kondalkar, Jihoon Park, Keekeun Lee
Summary: This report introduces a MEMS gas sensor system for dissolved hydrogen gas analysis, providing effective monitoring of transformer operational status and maintenance of safety standards in the power grid.
SENSORS AND ACTUATORS B-CHEMICAL
(2021)
Article
Engineering, Electrical & Electronic
Teresa Buchacz, Jerzy Buchacz, Michel Duval
Summary: This article discusses the generation of gases in insulating oils at low temperatures, and how to distinguish this phenomenon from other potential faults. By comparing gas generation patterns in the laboratory and real transformers, the temperature range of possible defects can be evaluated.
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
(2021)
Article
Engineering, Electrical & Electronic
Shigeyoshi Yoshida, Masahiro Kozako, Masayuki Hikita
Summary: This study investigates the effect of white trace on partial discharge inception voltage (PDIV) of the composite insulation system using high-speed optical observation and electrical measurements. It reveals the impact of the white trace on discharge propagation and discusses the mechanism of discharge progression.
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
(2021)
Article
Engineering, Electrical & Electronic
Hanbo Zheng, Yongji Feng, Xufan Li, Hang Yang, Weijie Lv, Songjiang Li
Summary: Natural ester insulating oil, with a biodegradation rate of almost 100% and meeting carbon emission requirements, is considered a good substitute for mineral insulating oil. However, its higher kinematic viscosity in low-temperature environments limits its application in cold regions. This study establishes a model to predict the kinematic viscosity of natural ester insulating oil through experiments and molecular dynamics simulation. It provides a convenient tool for predicting and improving the low-temperature kinematic viscosity of the oil.
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
(2022)
Article
Engineering, Electrical & Electronic
Huize Cui, Liuqing Yang, Yuanwei Zhu, Shengtao Li, A. Abu-Siada, Syed Islam
Summary: This paper investigates the effect of momentary small variations in transformer operating temperature on dissolved gas analysis (DGA) measurement through laboratory experiments. It is found that the gas evolution in transformer oil is greatly affected by these small variations, which may be caused by intermittent generation characteristics of renewable energy sources. The experimental results are explained through chemical equilibrium constant theory, suggesting a new paradigm for DGA process by correlating measurements with transformer operating temperature at the instant of oil sampling.
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
(2021)
Article
Energy & Fuels
Pawel Zukowski, Przemyslaw Rogalski, Tomasz N. Koltunowicz, Konrad Kierczynski, Marek Zenker, Alexander D. Pogrebnjak, Matej Kucera
Summary: This study investigated the conductivity and permittivity of electrical pressboard-insulating liquid-water composites and compared them to water. The presence of water increased the permeability of the composites below 100 Hz, and the conductivity of the composites exponentially increased with increasing water content. The activation energy of the composites' DC conductivity was higher than that of liquid water, and the dielectric relaxation times of the composites were significantly longer than those of water.
Article
Chemistry, Physical
Hongcheng Liu, Zhixin Tan, Yuxing Niu, Shigang Wang, Yao Wang
Summary: The gas-sensing properties of Ir-decorated MoS2 monolayer to methane, ethane, and acetylene dissolved in transformer oil were studied using density functional theory (DFT). The physical structure and adsorption parameters of Ir-decorated MoS2 were investigated, and it was found that Ir modification significantly enhances the conductivity of MoS2. The study also analyzed the electronic properties and adsorption strength of the material, showing that Ir-decorated MoS2 is more sensitive to ethane and acetylene gases compared to methane gas.
CHEMICAL PHYSICS LETTERS
(2023)
Review
Energy & Fuels
Ghada Gmati, Ungarala Mohan Rao, Issouf Fofana, Patrick Picher, Oscar Arroyo-Fernandez, Djamal Rebaine
Summary: The degradation of the insulation system in liquid-filled power transformers is a serious concern, as it is accelerated by moisture, acids, oxidation products, and other decay particles. Aging mechanisms of oil-paper insulation are complex, temperature-dependent, and involve moisture migration and bubble evolution. Existing standards mainly focus on insulation temperature as a key parameter, but there are various factors to consider when expanding the models to alternative liquids.
Article
Physics, Condensed Matter
Jincong Wang, Xiaoxing Zhang, Li Liu, Zengting Wang
Summary: Based on density functional theory, this study analyzed the adsorption characteristics of dissolved gases (H-2, C2H2, CH4) on Ni-doped GaN (Ni-GaN) and explored its potential as a gas sensor. The results showed that Ni-GaN has the largest adsorption energy for C2H2 and outstanding responses to H-2, C2H2, and CH4.
SUPERLATTICES AND MICROSTRUCTURES
(2021)
Article
Acoustics
Bakrutheen Moosasait, Willjuice Iruthayarajan Maria Siluvairaj
Summary: The study demonstrates that ultrasonic treatment can significantly reduce the pour point of vegetable oils, meeting the standard value for liquid insulation and providing a new pathway for the application of low pour point vegetable oils as liquid insulation in power transformers in cold climate areas.
ULTRASONICS SONOCHEMISTRY
(2021)
Article
Energy & Fuels
Kamil Lewandowski, Hubert Moranda, Radoslaw Szewczyk
Summary: One possible cause of transformer failures is high moisture in the winding insulation system, which can lead to a sudden release of water vapor, known as the bubble effect. This study analyzed the initiation temperature of the bubble effect in different solid insulation materials immersed in two electro-insulating liquids. The moisture content of the solid insulation was found to be the main factor affecting the initiation temperature, with high-temperature materials having slightly lower initiation temperatures compared to cellulose. However, the differences in initiation temperature among the tested materials were very small after considering uneven water absorption.
