Article
Chemistry, Physical
Dorian Rabaud, Paul Dussart, Guylaine Ducouret, Pierre-Antoine Albouy, Jeremy Forte, Benjamin Isare, Laurent Bouteiller
Summary: This study explores the possibility of designing FDCA-based organogelators that self-assemble into fibrillar networks stabilized by hydrogen bonding. Gelation tests demonstrate the versatility of this gelator family with various gelled liquids, especially apolar ones. The structure of the gels was investigated using FTIR and CD spectroscopies, crystallography, powder X-ray diffraction, and rheology.
Article
Chemistry, Physical
Dorian Rabaud, Paul Dussart, Guylaine Ducouret, Pierre-Antoine Albouy, Jeremy Forte, Benjamin Isare, Laurent Bouteiller
Summary: This study explores the possibility of designing FDCA-based organogelators and investigates their gel structure. The results show that these gelators are versatile and can be used in a wide variety of applications, especially in non-polar liquids.
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.
Review
Engineering, Electrical & Electronic
Qingguo Chen, Wei Sun, Song Cheng, Guokai Huang
Summary: Insulation paper plays a crucial role in evaluating the insulation status of transformers. The traditional evaluation methods, such as dissolved gas component content analysis and furfural content analysis, have limitations in accuracy and field application. Recent research has explored methanol as a novel marker for aging evaluation of transformer insulating paper, which has shown better correlation with insulation aging state. This paper summarizes the current research status, detection methods, and development prospects of methanol in insulating oil, with the aim of providing reference for aging evaluation of oil immersed power transformer.
IET GENERATION TRANSMISSION & DISTRIBUTION
(2023)
Article
Chemistry, Physical
Binghao Chen, Ziming Su, Zhenbin Du, Mingyuan Ma, Junjie Zhang, Chao Tang
Summary: This study analyzes the kinematic viscosity and oxidation stability of mixed oils composed of rapeseed oil and palm fatty acid ester (PFAE). The results show that the addition of PFAE reduces the kinematic viscosity of the mixed oil. The presence of short chain oil molecules in the mixed system decreases the internal friction between oil molecules, resulting in improved performance.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Mechanics
Dongyuan Du, Chao Tang, Yujing Tang, Lu Yang, Jian Hao
Summary: This study used molecular dynamics simulation technology to investigate the impact of carbon nanowires on the thermodynamic properties of cellulose insulating paper. The results showed that different structures of carbon nanowires can improve the thermodynamic properties of cellulose, with hard chiral carbon nanowires having the most significant effect.
COMPOSITE STRUCTURES
(2021)
Article
Chemistry, Physical
Wenyu Ye, Jian Hao, Chenyu Gao, Qing Xu, Mengzhao Zhu, Ruijin Liao
Summary: This study investigates the molecular details about the dynamic behavior of hydrocarbons and ester insulating liquids on the surface of crystalline cellulose. The comparisons of microscopic differences between the two insulating liquids and cellulose interfaces provide insights into the development of environmentally friendly insulating materials. The theoretical basis provided in the study supports the more scientific application of natural esters in oil-immersed power transformers.
JOURNAL OF MOLECULAR LIQUIDS
(2021)
Article
Chemistry, Analytical
Jiajing Chen, Huan Huang, Dan Ouyang, Jiali Lin, Zhuling Chen, Zongwei Cai, Zian Lin
Summary: Analysis of cis-diol compounds is crucial due to their important roles in various fields. Researchers have developed a matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-MS) method to effectively analyse cis-diol compounds. This method utilizes a unique reactive matrix (BMQI) for in situ derivatization of cis-diol compounds, resulting in improved speed, reproducibility, and signal intensity, as well as reduced background interference. Additionally, the method has been successfully applied to the rapid screening and identification of sugar alcohols in different sugar-free foods.
Article
Energy & Fuels
Sherif S. M. Ghoneim
Summary: The aging of power transformers can cause various defects and damages in the insulating system, particularly in the insulating paper. Statistical tools can be used to establish a connection between the DP and testing parameters of transformer samples to determine the status of the insulating paper and the remaining life percentage.
Article
Chemistry, Applied
Chanoong Lim, Dong Soo Hwang, Dong Woog Lee
Summary: The degree of acetylation (DA) of chitosan is crucial for determining its physical, chemical, and biological properties. This study investigated the molecular interactions of chitosan thin films under different molecular weight and DA conditions. Results showed that the interactions of low molecular weight and high molecular weight chitosan were influenced by different factors.
CARBOHYDRATE POLYMERS
(2021)
Article
Energy & Fuels
Maciej Zdanowski
Summary: This paper presents research results on the use of fullerene C-60 to reduce the phenomenon of streaming electrification generated by liquid dielectrics. The influence of flow velocity and C-60 concentration on the electrification of different liquids was analyzed, and the optimal concentration of C-60 resulting in the highest reduction of the electrification phenomenon was identified.
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
Chemistry, Physical
Hanbo Zheng, Weijie Lv, Yang Wang, Yongji Feng, Hang Yang
Summary: In this paper, kinematic viscosity prediction models of triglyceride molecules based on sparse machine learning methods are proposed. Molecular dynamics simulations are used to obtain extensive characterization data for main 20 triglyceride molecules in natural ester insulating oil. Sparse feature selection methods are employed to identify the most relevant molecular descriptors, and quantitative structure-property relationship models are constructed for efficient and accurate kinematic viscosity prediction.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Article
Multidisciplinary Sciences
Jihoon Shin, Shinichiro Toyoda, Yosuke Okuno, Reiko Hayashi, Shigeki Nishitani, Toshiharu Onodera, Haruyo Sakamoto, Shinya Ito, Sachiko Kobayashi, Hirofumi Nagao, Shunbun Kita, Michio Otsuki, Atsunori Fukuhara, Kazuhiro Nagata, Iichiro Shimomura
Summary: HSP47 is identified as a key determinant of body adiposity, with abundant expression in adipose tissue. It is influenced by factors such as diet, exercise, hormones, and genetics. HSP47 affects body fat levels through its role in collagen dynamics, FAK signaling, and protection of PPAR gamma protein.
NATURE COMMUNICATIONS
(2023)
Article
Polymer Science
Jiajun Zhou, Mao Li, Jiadong Wu, Chongyin Zhang, Zidong He, Yan Xiao, Gangsheng Tong, Xinyuan Zhu
Summary: A new kind of hyperbranched semi-aromatic poly(ester-imide)s with hydroxyl terminated groups has been successfully synthesized by a simple one-pot melting polymerization method, possessing low glass transition temperature and high thermostability, as well as abundant terminal hydroxyl functional groups.
Article
Engineering, Electrical & Electronic
Thomas Koffi, Koutoua S. Kassi, Gbah Kone, Janvier S. N'Cho, Mensah Edoe, Jocelyne Bosson, Issouf Fofana, Jeremie Zoueu
Summary: The aging process of insulating oils in electrical transformers has a significant impact on power transmission and distribution networks. This study used SLIPI imaging technique to accurately determine the extinction coefficient of biodegradable oils, enabling early diagnosis and prevention of potential breakdowns. The results indicate that SLIPI is a reliable diagnostic tool for biodegradable oils in power transformers, offering an alternative solution to traditional monitoring methods.
IET GENERATION TRANSMISSION & DISTRIBUTION
(2022)
Article
Engineering, Electrical & Electronic
S. Tagzirt, D. Bouguedad, A. Mekhaldi, I Fofana
Summary: This article presents a multiscale analysis of the degradation of XLPE insulation in two harsh environments. The results show that the degradation rate is faster in the arid desert climate compared to the coastal environment.
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
(2022)
Article
Chemistry, Physical
Anahita Allahdini, Gelareh Momen, Frederick Munger, Stephan Brettschneider, Issouf Fofana, Reza Jafari
Summary: We have developed a novel non-fluorinated superhydrophobic coating in polymer science to improve the reliability and lifespan of high-voltage insulators. Through comprehensive testing, we found that the coating has high thermal stability and weathering resistance, and successfully increases the flashover voltage and reduces leakage currents under high humidity conditions.
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2022)
Review
Energy & Fuels
Samson Okikiola Oparanti, Ungarala Mohan Rao, Issouf Fofana
Summary: The use of mineral insulating oils for power transformer insulation and cooling is being questioned due to environmental concerns and the shift away from fossil fuels. Natural esters are a renewable and environmentally friendly alternative, but they have limitations that hinder their widespread acceptance. This article explores the state of the art of natural esters for transformers and discusses potential improvements in their performance and serviceability through additives and chemical modification. The authors hope that this report will be beneficial for transformer owners and contribute to the advancement of natural esters for power transformer applications.
Article
Engineering, Electrical & Electronic
Kandala N. V. P. S. Rajesh, U. Mohan Rao, I. Fofana, P. Rozga, Ashish Paramane
Summary: This article investigates the influence of data balancing approaches on transformer DGA fault classification, highlighting the importance of selecting suitable data sampling methods and machine learning algorithms for efficient classification.
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
(2023)
Article
Engineering, Electrical & Electronic
U. Mohan Rao, Issouf Fofana, Pawel Rozga, Patrick Picher, Dilip K. Sarkar, Rajan Karthikeyan
Summary: The focus of this study is on the oxidation aspects (gelling) of natural esters and its impact on the performance of transformer insulation systems. Even though natural esters are not suitable for breathing units, the scenario considered simulates a defect in the sealing system, allowing direct contact with atmospheric air. Commercially available natural ester liquids are thermally degraded under controlled aging conditions to observe the formation of sol and gel. The influence of sol and gel on the insulation is analyzed through physicochemical and electrical characterizations.
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
(2023)
Article
Energy & Fuels
Regelii Suassuna de Andrade Ferreira, Patrick Picher, Fethi Meghnefi, Issouf Fofana, Hassan Ezzaidi, Christophe Volat, Vahid Behjat
Summary: Frequency response analysis (FRA) is widely used for internal condition assessment of transformers, but interpretation of FRA measurements is challenging due to lack of complete data. This research proposes a new method using simulation and laboratory models to obtain FRA traces and improve parameter estimation. The results show good agreement between measured and simulated FRA traces, supporting the use of this method for fault classification and localization in transformer windings. This approach can generate a larger and unique database of FRA traces with industrial importance and academic significance.
Review
Energy & Fuels
Andrew Adewunmi Adekunle, Samson Okikiola Oparanti, Issouf Fofana
Summary: Insulation cellulose paper is commonly used in power transformers due to its low cost and good electrical and mechanical properties. However, it deteriorates over time due to chemical reactions, affecting its degree of polymerization. Collecting paper samples from operational transformers is difficult, so alternative methods using chemicals dissolved in the dielectric liquid have been explored. Online measurement of polymerization degree using optical sensors has been proposed but not widely used. Additionally, the addition of nanoparticles has been found to enhance the insulating performance of oil-impregnated paper insulation.
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
Polymer Science
Akre Anne Simone Adja, Sarah Sobhani, Gelareh Momen, Issouf Fofana, Julie Carriere
Summary: This study presented the fabrication of an icephobic coating for steel using a silicone-epoxy hybrid resin. The coating exhibited good mechanical properties and weathering resistance for outdoor applications. Through various tests, the correlation between ice adhesion strength and Young modulus was examined, and the best-performing matrix was obtained by altering the surface energy characteristics with fluorinated silicone additives. The optimized coating showed a significant reduction in ice adhesion strength for steel substrates.
JOURNAL OF APPLIED POLYMER SCIENCE
(2023)
Article
Chemistry, Analytical
Simplice Akre, Issouf Fofana, Zie Yeo, Stephan Brettschneider, Peter Kung, Bekibenan Sekongo
Summary: This paper proposes a fiber optic sensor system to monitor the temperature, vibration, and moisture content in power transformers, aiming to improve their reliability and efficiency.
Article
Engineering, Electrical & Electronic
Arnaud Nanfak, Samuel Eke, Fethi Meghnefi, Issouf Fofana, Gildas Martial Ngaleu, Charles Hubert Kom
Summary: Power transformers are crucial for electrical power transmission grids, and dissolved gas analysis (DGA) has proven to be an effective tool for early fault detection. This article proposes a hybrid method that combines traditional and intelligent approaches using a genetic algorithm-based clustering algorithm and human expertise for DGA data interpretation and fault diagnosis. The proposed method outperforms existing traditional, intelligent, and hybrid methods in terms of diagnostic accuracy.
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
(2023)
Article
Chemistry, Analytical
Fataneh Dabaghi-Zarandi, Vahid Behjat, Michel Gauvin, Patrick Picher, Hassan Ezzaidi, Issouf Fofana
Summary: The early detection of On-Load Tap-Changer (OLTC) faults is crucial for maintaining power transformers, the most important component of power network substations. Vibro-acoustic signal analysis is a reliable method to detect various types of OLTC faults. This research focuses on developing a methodology to detect, locate, and track changes in vibro-acoustic signal envelopes based on main peaks extraction and Euclidean distance analysis.
Article
Green & Sustainable Science & Technology
Mounia Hendel, Fethi Meghnefi, Mohamed El Amine Senoussaoui, Issouf Fofana, Mostefa Brahami
Summary: This paper proposes a new intelligent system based on DGA to improve the efficiency of transformer diagnosis and overcome the weaknesses of traditional methods.
Article
Energy & Fuels
Ahmed Sayadi, Djillali Mahi, Issouf Fofana, Lakhdar Bessissa, Sid Ahmed Bessedik, Oscar Henry Arroyo-Fernandez, Jocelyn Jalbert
Summary: The aim of this research is to predict the mechanical properties and behaviors of insulation paper used in power transformers under thermal aging. An artificial neural network model trained with a multiple regression model and a particle swarm optimization model is applied. The aging of the paper insulation is monitored directly and indirectly using chemical markers. A mathematical model is developed to simulate the mechanical properties of the aged insulation paper. The proposed model shows accurate results when compared to experimental data.
