IEEE Transactions on Dielectrics and Electrical Insulation最新文献

{"title":"Two-Step Broadband Equivalent Circuit Modeling Method for Power Transformer Winding Based on Frequency Response Analysis and Bayesian Optimization","authors":"Yu Chen;Jiangnan Liu;Yuxuan Ding;Yaping Du;Binghao Li;Chenguo Yao;Zhongyong Zhao","doi":"10.1109/TDEI.2025.3635100","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3635100","url":null,"abstract":"Frequency response analysis (FRA) is a well-established technique to detect transformer winding deformation faults. Its diagnostic application is based on the principle that a transformer winding can be represented by an equivalent circuit consisting of resistors, inductors, and capacitors. However, rapidly obtaining an accurate and physically meaningful broadband equivalent circuit model for windings remains challenging, limiting both the understanding of fault mechanisms and the generation of data for data-driven fault diagnosis methods. To address these difficulties, this study proposes a two-step broadband equivalent circuit modeling method for the transformer winding based on FRA and Bayesian optimization (BO), considering long-distance mutual inductances and capacitances. The proposed method is validated in a specially designed 10-kV power transformer. Subsequently, two kinds of winding deformation faults, including interdisk short circuits (IDSCs) and disk space variations (DSVs), are simulated on the basis of the built model and compared with the experimental FRA data. The validation results confirm the accuracy and effectiveness of the proposed method in the construction of the equivalent winding circuit.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"33 5","pages":"3910-3919"},"PeriodicalIF":3.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149125481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tracking- and Erosion-Resistant Cellulose–Silica Co-Doped Silicone Rubber Composites for Oil-Filled Transformer Bushing Applications","authors":"Jatoth Varun;Palash Mishra;Pawel Rozga;Tariq Nazir;Mithun Mondal;R. Sarathi","doi":"10.1109/TDEI.2026.3685231","DOIUrl":"https://doi.org/10.1109/TDEI.2026.3685231","url":null,"abstract":"Silica-doped room-temperature-vulcanized (RTV) silicone rubber microcomposites are widely used as surface coatings for porcelain-based transformer bushings due to their excellent hydrophobicity and anti-pollution performance. However, prolonged exposure to transformer oil degrades these coatings making them susceptible tracking and erosion. Incorporation of cellulose fillers suppresses oil penetration by creating physical entanglements and tortuous diffusion pathways within the silicone rubber matrix. In this context, the present study investigates cellulose–silica co-doped RTV silicone rubber composites designed to mitigate tracking after aging in natural ester oil. Composite formulations were prepared with a fixed silica microparticle content of 30 wt.% and varying microsized cellulose loadings of 10, 15, and 20 wt.% along with unfilled silicone rubber as a reference. Accelerated aging was carried out in natural ester oil at <inline-formula> <tex-math>$80~^{circ }$ </tex-math></inline-formula>C for 200 h. Post-aging mass analysis and Fourier transform infrared (FTIR) spectroscopy revealed a progressive reduction in oil absorption and chain scission in both the silicone rubber backbone (Si–O–Si) and side chains (Si–CH₃) as the cellulose content increased from 10 to 15 wt.%. The composite containing 15 wt.% cellulose exhibited the lowest weight gain and minimal chemical degradation. Thermogravimetric analysis (TGA) and pyrolysis studies further demonstrated enhanced residual mass and smoother pyrolyzed surfaces with fewer cracks indicating improved thermal stability after aging. IEC 60587 inclined plane tracking (IPT) and erosion testing confirmed that the aged composite co-doped with 30 wt.% SiO₂ and 15 wt.% cellulose successfully passed the test, demonstrating its suitability for oil-exposed transformer bushing insulation applications.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"33 5","pages":"3396-3403"},"PeriodicalIF":3.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149125554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Breakdown Voltage Estimation of Hybrid Nitrogen–Barrier Insulation Gap Considering Surface Charge Effect at Different Pressures","authors":"Yilong Wang;Yuesheng Zheng;Huifen Huang;Zhaohui Lin","doi":"10.1109/TDEI.2026.3650886","DOIUrl":"https://doi.org/10.1109/TDEI.2026.3650886","url":null,"abstract":"The addition of an insulating barrier has an enhancing effect on breakdown voltages of the nitrogen-insulated gap at high gas pressures. However, the barrier surface charges distort the electric field distribution, leading to the difficulty of estimating the breakdown voltage. This study proposes a method to estimate the equivalent surface charge density under different gas pressures and analyzes the influence of the equivalent surface charge on the electric field distribution. The equivalent surface charge not only reduces the electric field strength near the rod electrode but also enhances the field strength between the barrier and the ground electrode. The effect of equivalent surface charge on the electric field is associated with the position of the barrier and the gas pressure. Moreover, the accuracy of the streamer criterion for the breakdown voltage estimation is analyzed. When the influence of equivalent surface charges on the electric field is considered, the calculated breakdown voltage agrees well with the experimental result, indicating the accuracy of the proposed method. The results show that the selection of the breakdown path has a significant influence on the breakdown voltage estimation at high pressures.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"33 5","pages":"3457-3465"},"PeriodicalIF":3.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149125548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electrical Treeing Resistance in Epoxy Resins With Varied Molecular Structures Under High-Frequency and High-Temperature Conditions","authors":"Yunxiao Zhang;Yingjian Cai;Wenxin Lin;Yuhao Liu;Hao Hu;Kangning Wu","doi":"10.1109/TDEI.2025.3648700","DOIUrl":"10.1109/TDEI.2025.3648700","url":null,"abstract":"As power electronics evolve toward high-frequency and high-power-density applications, conventional epoxy resin encapsulation materials face critical challenges in withstanding the combined stresses of high-frequency pulsewidth modulation voltages and elevated operating temperatures, posing substantial threats to system reliability. The relationship between the molecular structure of epoxy resins and their resistance to electrical treeing remains unclear. This study systematically evaluates the electrical treeing resistance of four commercially available epoxy resins with distinct molecular architectures under high-frequency (10 kHz) and high-temperature (<inline-formula> <tex-math>$90~^{circ }$ </tex-math></inline-formula>C) conditions. Through isothermal surface potential decay (ISPD) tests and quantum chemical calculations, we elucidate the mechanism of electrical treeing inhibition from microscopic perspectives of electron cloud polarization and trap distribution characteristics. Results demonstrate that densely distributed shallow traps in epoxy resins promote bush-like electrical tree growth patterns, homogenizing internal electric field and effectively suppressing tree propagation. This work establishes a theoretical framework for designing and evaluating insulation materials in high-frequency/high-temperature power electronic systems.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"33 5","pages":"3263-3272"},"PeriodicalIF":3.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147898729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electrical Tree Inhibition Characteristics of AOS Grafted Epoxy Resin Composites Considering the Coupling Effects of High Frequency and Temperature","authors":"Yunxiao Zhang;Yuanzhang Zhang;Wenxin Lin;Yuhao Liu;Hao Hu","doi":"10.1109/TDEI.2026.3656102","DOIUrl":"10.1109/TDEI.2026.3656102","url":null,"abstract":"Encapsulation insulation materials for high-frequency transformers endure coupled electrothermal stresses from sustained high-frequency pulsed voltages and elevated operational temperatures, exhibiting inherent limitations in electrical treeing resistance that trigger premature insulation degradation. To address this, 4-acetoxystyrene (AOS) is chemically grafted onto <inline-formula> <tex-math>$E$ </tex-math></inline-formula>-51 bisphenol-A epoxy resin (DGEBA) via free radical grafting, forming DGEBA-g-AOS composites with varied AOS contents. The electrical tree growth characteristics under high-frequency (10 kHz) conditions at both room temperature (<inline-formula> <tex-math>$25~^{circ }$ </tex-math></inline-formula>C) and high temperature (<inline-formula> <tex-math>$90~^{circ }$ </tex-math></inline-formula>C) are systematically investigated through physicochemical characterization, quantum chemical calculations, and trap property analysis. The results demonstrate that at <inline-formula> <tex-math>$25~^{circ }$ </tex-math></inline-formula>C and 10 kHz, AOS effectively delays electrical tree initiation and propagation by trapping high-energy electrons and increasing trap density. Under <inline-formula> <tex-math>$90~^{circ }$ </tex-math></inline-formula>C and 10 kHz conditions, although the electrical tree growth rate shows no significant reduction, branch complexity decreases, and the damage area diminishes. This study provides critical insights for the development of advanced encapsulation insulation materials in high-frequency/high-temperature transformers.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"33 5","pages":"3358-3367"},"PeriodicalIF":3.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147882645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assimilation of the Different Layers of Lossy-FSS, Switchable-FSS, and Air Spacers for Polarization-Insensitive Wideband Absorber With Band-Notch","authors":"Sachin Kalraiya;Shreya Pourush;Raghvendra Kumar Chaudhary","doi":"10.1109/TDEI.2026.3724553","DOIUrl":"https://doi.org/10.1109/TDEI.2026.3724553","url":null,"abstract":"A polarization-independent wideband electromagnetic absorber along with switchable band-notch characteristics is demonstrated in this article. The geometrical design encompasses a triple-layered structure comprising a top surface for lossy behavior achieved via resistor-loaded frequency-selective surface (FSS), a switchable middle layer with p-i-n diodes, and a bottom metallic ground plane. In the <sc>on</small> state of the diode, the absorber exhibits broadband absorption due to the top layer. When the diode is switched off, the middle layer introduces a band-notch response without affecting the rest of the absorption band. The proposed absorber exhibits a compact unit-cell size of <inline-formula> <tex-math>$0.14lambda _{text {L}}$ </tex-math></inline-formula>, achieves a relative absorption bandwidth (RAB) of 106%, and demonstrates a switchable notch band ranging from 5.02 to 6.05 GHz while maintaining polarization insensitivity and angular stability up to 45°. An equivalent circuitry study, current pattern analysis, and effect of dimensional variations are provided to validate the absorber’s operation. A specimen of the presented geometry is manufactured and experimental validation is carried out, showing agreeable matching with the simulation results.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"33 5","pages":"3574-3581"},"PeriodicalIF":3.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149124479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Detection Transformer-Based Deep Learning for Multisource Partial Discharge Recognition in High-Voltage Rotating Machine Insulation","authors":"Ciptian Weried Priananda;Hazlee Azil Illias;Jee Keen Raymond Wong;Abdelmoumene Hechifa;I. Made Yulistya Negara","doi":"10.1109/TDEI.2025.3648258","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3648258","url":null,"abstract":"Partial discharge (PD) is a critical early indicator of insulation degradation in high-voltage rotating machines. Minor undetected defects during manufacturing, combined with operational stresses, often trigger PD activity that accelerates insulation aging. The elongated structure of stator windings increases the possibility of multiple PD sources occurring simultaneously, each generating a distinct phase-resolved PD (PRPD) pattern. However, when multiple defects are present, these patterns overlap, leading to challenges such as occlusion, nesting, and the multisource PD horizontal flattening effect (MPD-HFE), where weaker discharges are visually suppressed, which challenge conventional classifiers due to signal occlusion and distortion effects. This work proposes a detection transformer (DETR)-based deep learning approach, enhanced with flattening augmentation to replicate dominant pattern distortions. The method enables simultaneous detection and classification of overlapping PRPD patterns by utilizing DETR’s global self-attention to mitigate discharge dominance and feature suppression. Evaluated on a multisource PRPD dataset comprising six defect types and 63-class combinations, the proposed model achieved 97.4% accuracy on single-source PD defects and 90.9% on multisource cases, with an overall accuracy of 93.7%.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"33 5","pages":"3686-3694"},"PeriodicalIF":3.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149124535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Influence of Hydrolytic and Oxidative Aging on the Properties and Chemical Structure of Natural Ester Used in Power Transformer","authors":"Dominika Szcześniak;Piotr Przybylek","doi":"10.1109/TDEI.2026.3711057","DOIUrl":"https://doi.org/10.1109/TDEI.2026.3711057","url":null,"abstract":"The article presents research findings that enabled a comprehensive evaluation of the effects of hydrolytic and oxidative aging on the physicochemical and dielectric properties of a natural ester, which are critical for the reliable operation of power transformers. The natural ester subjected to controlled hydrolytic and oxidative aging was also examined to assess changes in its chemical structure. For this purpose, spectrophotometric measurements and fatty acid profile analyzes were employed. The results obtained indicate that hydrolytic aging is significantly less detrimental to the natural ester than oxidative aging. The investigations demonstrated a beneficial effect of hydrolytic aging in the case of high-moisture ester, manifested by a reduction in water content and an improvement in breakdown voltage. It was further shown that, under hydrolytic aging conditions, the increase in ester acidity is not associated with a deterioration of its dielectric properties. The presented test results may constitute the basis for considering the need to change the limit values of ester acidity included in IEC 62975. In addition, the study proposes the use of fatty acid profile analysis as a complementary diagnostic tool for assessing the insulation condition of power transformers.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"33 5","pages":"3599-3606"},"PeriodicalIF":3.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149124498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of Forced Convection Heat Transfer for Bipolar MVDC Power Cable Envisaged for Wide-Body All-Electric Aircraft","authors":"Md Asifur Rahman;Mona Ghassemi","doi":"10.1109/TDEI.2026.3676013","DOIUrl":"https://doi.org/10.1109/TDEI.2026.3676013","url":null,"abstract":"The future wide-body all-electric aircraft (AEA) requires low-mass, high-power, dense electric power systems (EPSs) to deliver sufficient thrust power equivalent to that supplied by propulsion systems of conventional aircraft. To fulfill this requirement, the design of power cables is crucial since, due to their length, they occupy a substantial mass of the EPS and also ensure failsafe operation in harsh aviation environmental conditions. Thermal management of the cable is a major concern due to decreased heat transfer at lower air pressure at aviation altitudes compared to atmospheric pressure conditions at ground level. For this purpose, bipolar 5 kV medium voltage direct current (MVDC) cable for EPS architectures for a wide body AEA is proposed, designed, and fabricated with micro-multilayer multifunctional electrical insulation (MMEI) systems in our previous studies. Analysis of thermal performance of different shapes of the cable, such as cylindrical, cuboid, and coaxial configurations, is presented as a measure to increase radiative heat transfer to compensate for reduced convective heat transfer in our earlier work. Moreover, a performance analysis of several proposed MMEI designs is presented. In those studies, for convective heat transfer, only natural convection is considered, and for comparison, a parameter <inline-formula> <tex-math>$J$ </tex-math></inline-formula> is introduced, defined as the product of the total mass per unit length and the cross-sectional area of these cables. In this article, the impact of forced convection heat transfer on bipolar MVDC cable designed for wide-body AEA is analyzed with a comparison to natural convection in terms of <inline-formula> <tex-math>$J$ </tex-math></inline-formula>.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"33 5","pages":"3801-3810"},"PeriodicalIF":3.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149124500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Study on CO2 Methanation by Dielectric Barrier Discharge Plasma Over γ-Al2O3 Supported Co Catalyst","authors":"Yalong Li;Lei Yu;Huiyu Tan;Xiaoxing Zhang;Nnditshedzeni Eric Maluta;Zhaodi Yang;Zhe Huang;Zhongfeng Wang","doi":"10.1109/TDEI.2026.3697166","DOIUrl":"https://doi.org/10.1109/TDEI.2026.3697166","url":null,"abstract":"Global climate change driven by greenhouse gas emissions, especially CO₂, has become a serious challenge, and the issue of CO₂ emission reduction has attracted much attention. In this study, based on the dielectric barrier discharge (DBD) plasma experimental platform, the effect of a self-made <inline-formula> <tex-math>$gamma $ </tex-math></inline-formula>-Al₂O₃-supported Co (<inline-formula> <tex-math>$gamma $ </tex-math></inline-formula>-Al₂O₃@Co) catalyst on CO₂ methanation was investigated, and the variation of CO₂ conversion and product selectivity under different input power conditions was analyzed. The experimental results show that with the increase of input power, the CO₂ conversion and CH₄ selectivity of the three reaction systems—without filling, with <inline-formula> <tex-math>$gamma $ </tex-math></inline-formula>-Al₂O₃ filling, and with <inline-formula> <tex-math>$gamma $ </tex-math></inline-formula>-Al₂O₃@Co catalyst filling—progressively increase. At normal temperature and pressure, when the input power is 100 W, the CO₂ conversion in the reaction system filled with <inline-formula> <tex-math>$gamma $ </tex-math></inline-formula>-Al₂O₃@Co catalyst reaches 72.3%, with a CH₄ selectivity as high as 98.5%. Catalyst characterization indicates that the Co species in the <inline-formula> <tex-math>$gamma $ </tex-math></inline-formula>-Al₂O₃@Co catalyst mainly exist in the forms of Co⁰, CoO, and CoAl₂O₄, and exhibit good structural stability and catalytic activity before and after the reaction. The excited species generated in the DBD plasma, including CO<inline-formula> <tex-math>${}^{ast }$ </tex-math></inline-formula>, CH<inline-formula> <tex-math>${}^{ast }$ </tex-math></inline-formula>, and H<inline-formula> <tex-math>${}^{ast }$ </tex-math></inline-formula>, synergistically interact with Co⁰ active sites on the catalyst surface, thereby promoting efficient CO₂ conversion. This study provides a novel catalytic system and experimental evidence for CO₂ methanation.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"33 5","pages":"3501-3509"},"PeriodicalIF":3.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149124519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}