This study aims to compare the spectral characteristics of electrical discharges in mineral oil (MO) with those in air. The results demonstrate that electrical discharge channels in MO exhibit a resistive nature, as evidenced by the phase difference, and that discharges in this medium are associated with higher energy levels due to their superior dielectric strength. This necessitates higher voltages for discharge initiation compared to electrical discharges in air, which involve lower energy levels due to air’s lower dielectric properties. Temporal domain analysis shows that electrical discharges in air propagate faster than those in MO. In addition, fast Fourier transform (FFT) analysis reveals that air discharges exhibit a broader spectrum with more high-frequency components, indicating faster propagation than MO discharges. The differences in dielectric properties—such as dielectric strength, breakdown voltage, density, and viscosity—are lower in the air than in MO, significantly influencing discharge characteristics, including current, voltage, power, and energy. These findings offer crucial insights into the nature of discharge channels, energy levels, propagation speeds, and discharge dynamics in air and MO. This contributes to developing more effective insulation monitoring and predictive maintenance strategies in electrical power systems.
{"title":"Spectral Analysis of Electrical Discharge in Mineral Oil—Comparison With Air Discharge","authors":"Salma Nait Bachir;Azzeddine Nacer;Hocine Moulai;Issouf Fofana","doi":"10.1109/TDEI.2025.3541615","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3541615","url":null,"abstract":"This study aims to compare the spectral characteristics of electrical discharges in mineral oil (MO) with those in air. The results demonstrate that electrical discharge channels in MO exhibit a resistive nature, as evidenced by the phase difference, and that discharges in this medium are associated with higher energy levels due to their superior dielectric strength. This necessitates higher voltages for discharge initiation compared to electrical discharges in air, which involve lower energy levels due to air’s lower dielectric properties. Temporal domain analysis shows that electrical discharges in air propagate faster than those in MO. In addition, fast Fourier transform (FFT) analysis reveals that air discharges exhibit a broader spectrum with more high-frequency components, indicating faster propagation than MO discharges. The differences in dielectric properties—such as dielectric strength, breakdown voltage, density, and viscosity—are lower in the air than in MO, significantly influencing discharge characteristics, including current, voltage, power, and energy. These findings offer crucial insights into the nature of discharge channels, energy levels, propagation speeds, and discharge dynamics in air and MO. This contributes to developing more effective insulation monitoring and predictive maintenance strategies in electrical power systems.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"32 5","pages":"2788-2796"},"PeriodicalIF":3.1,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145190285","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}
Pub Date : 2025-02-11DOI: 10.1109/TDEI.2025.3540786
Ali Abdali;Akbar Bayat;Payam Javadi;Kazem Mazlumi;Abbas Rabiee
Since the insulation state and hotspot temperature (HST) are closely linked, monitoring the thermal condition of distribution transformers (DTs)—critical and costly power grid components—can help prevent failures. This study focuses on accurately predicting the HST in DTs. During the temperature rise test, optical fiber sensors (OFSs) are used to evaluate proposed nonuniform 3-D computational fluid dynamic (CFD)-based models. In contrast to the OFS measurements, the new 3-D CFD-based thermal study displays an error percentage of 0.11% ($0.1~^{circ }$ C), indicating the high accuracy and efficiency of the model. Furthermore, the results of nonuniform 3-D CFD-based thermal assessments are validated using thermography for both top-oil temperature and bottom-oil temperature. With an error percentage of <0.65%,> $3.3~^{circ }$ C, $7.1~^{circ }$ C, and $10.3~^{circ }$ C more than the previous model without harmonics.
{"title":"Impact of Combined Current and Voltage Harmonics on the Thermal Behavior of Distribution Transformers: A Coupled Nonuniform Magnetic–Thermal Approach","authors":"Ali Abdali;Akbar Bayat;Payam Javadi;Kazem Mazlumi;Abbas Rabiee","doi":"10.1109/TDEI.2025.3540786","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3540786","url":null,"abstract":"Since the insulation state and hotspot temperature (HST) are closely linked, monitoring the thermal condition of distribution transformers (DTs)—critical and costly power grid components—can help prevent failures. This study focuses on accurately predicting the HST in DTs. During the temperature rise test, optical fiber sensors (OFSs) are used to evaluate proposed nonuniform 3-D computational fluid dynamic (CFD)-based models. In contrast to the OFS measurements, the new 3-D CFD-based thermal study displays an error percentage of 0.11% (<inline-formula> <tex-math>$0.1~^{circ }$ </tex-math></inline-formula>C), indicating the high accuracy and efficiency of the model. Furthermore, the results of nonuniform 3-D CFD-based thermal assessments are validated using thermography for both top-oil temperature and bottom-oil temperature. With an error percentage of <0.65%,> <tex-math>$3.3~^{circ }$ </tex-math></inline-formula>C, <inline-formula> <tex-math>$7.1~^{circ }$ </tex-math></inline-formula>C, and <inline-formula> <tex-math>$10.3~^{circ }$ </tex-math></inline-formula>C more than the previous model without harmonics.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"32 4","pages":"2413-2423"},"PeriodicalIF":3.1,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144739798","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}
Pub Date : 2025-02-11DOI: 10.1109/TDEI.2025.3540773
Zhibin Qiu;Yu Song;Wenhao Chen;Zijian Wu
To evaluate the dielectric strength of a long air gap under a positive 250/$2500~mu $ s impulse waveform, various parameters should be taken into account, among which the electric field (EF) is the most important. This article proposes a random forest (RF) model to construct the dependence mapping from the static EF distribution characteristics of long air gaps to their dielectric strengths. Forty interelectrode features were adopted to describe the EF distribution of an air gap and their correlation degrees with the 50% discharge voltages were analyzed. A high-quality feature subset was input to train the RF model with some limited discharge test data. The dielectric strengths of large-size sphere-plane long air gaps, which are used in valve hall, were forecast by the RF model, and the results show a mean absolute percentage error (MAPE) of only 2.0% for 17 samples. The model was also extrapolated to the grading ring and cap to ground gaps, and the predicted dielectric strengths have similar variation trend with the experimental values. This study can provide references for insulation distance selection of shield fittings in converter station or substations.
{"title":"Dependence Mapping of the Static Electric Field Distribution Characteristics to Dielectric Strength of Long Air Gap Based on Random Forest","authors":"Zhibin Qiu;Yu Song;Wenhao Chen;Zijian Wu","doi":"10.1109/TDEI.2025.3540773","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3540773","url":null,"abstract":"To evaluate the dielectric strength of a long air gap under a positive 250/<inline-formula> <tex-math>$2500~mu $ </tex-math></inline-formula>s impulse waveform, various parameters should be taken into account, among which the electric field (EF) is the most important. This article proposes a random forest (RF) model to construct the dependence mapping from the static EF distribution characteristics of long air gaps to their dielectric strengths. Forty interelectrode features were adopted to describe the EF distribution of an air gap and their correlation degrees with the 50% discharge voltages were analyzed. A high-quality feature subset was input to train the RF model with some limited discharge test data. The dielectric strengths of large-size sphere-plane long air gaps, which are used in valve hall, were forecast by the RF model, and the results show a mean absolute percentage error (MAPE) of only 2.0% for 17 samples. The model was also extrapolated to the grading ring and cap to ground gaps, and the predicted dielectric strengths have similar variation trend with the experimental values. This study can provide references for insulation distance selection of shield fittings in converter station or substations.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"32 3","pages":"1271-1278"},"PeriodicalIF":2.9,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144213509","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}
Pub Date : 2025-02-11DOI: 10.1109/TDEI.2025.3541005
Xiaolong Chen;Lu Liu;Xuejing Li;Yanhui Wei;Yuanwei Zhu;Shengtao Li;Yongjie Nie;Guochang Li
The cable accessory structure involves a double-layer composite insulation interface and exists the problem of interface matching between the main insulation and the accessory insulation. In this article, the electrical-thermal-mechanical properties of two combined interfaces, crosslinked polyethylene (XLPE)/silicone rubber (SiR) and polypropylene (PP)/SiR, are tested. Also, the interface matching properties of the two combined interfaces are compared and analyzed. For electrical properties matching, the results show that the interface of PP/SiR accumulates more space charge than that of XLPE/SiR. The maximum interfacial charge accumulation is $- 4.35times 10^{-{4}}$ C/m2 for XLPE/SiR and $- 6.01times 10^{-{4}}$ C/m2 for PP/SiR. In terms of thermal properties matching, the thermal expansion coefficient of XLPE is the highest. As for mechanical properties matching, the interfacial pressure of XLPE/SiR and PP/SiR dropped below 0.1 MPa at 23 and 96 h. The molecular simulation results show that the molecular chains of PP have strong dynamic ability, and the free volume change and trap depth are largest for SiR. The experimental results show that XLPE/SiR is better matched in electrical properties, while PP/SiR is better matched in thermal and mechanical properties. This work is an important reference for improving the safety of cable accessories and promoting the development of environmentally friendly PP cables.
{"title":"Electrical–Thermal–Mechanical Matching Properties of the Interface Between Main Insulation of High-Voltage Cables and Accessory Silicone Rubber Insulation","authors":"Xiaolong Chen;Lu Liu;Xuejing Li;Yanhui Wei;Yuanwei Zhu;Shengtao Li;Yongjie Nie;Guochang Li","doi":"10.1109/TDEI.2025.3541005","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3541005","url":null,"abstract":"The cable accessory structure involves a double-layer composite insulation interface and exists the problem of interface matching between the main insulation and the accessory insulation. In this article, the electrical-thermal-mechanical properties of two combined interfaces, crosslinked polyethylene (XLPE)/silicone rubber (SiR) and polypropylene (PP)/SiR, are tested. Also, the interface matching properties of the two combined interfaces are compared and analyzed. For electrical properties matching, the results show that the interface of PP/SiR accumulates more space charge than that of XLPE/SiR. The maximum interfacial charge accumulation is <inline-formula> <tex-math>$- 4.35times 10^{-{4}}$ </tex-math></inline-formula> C/m2 for XLPE/SiR and <inline-formula> <tex-math>$- 6.01times 10^{-{4}}$ </tex-math></inline-formula>C/m2 for PP/SiR. In terms of thermal properties matching, the thermal expansion coefficient of XLPE is the highest. As for mechanical properties matching, the interfacial pressure of XLPE/SiR and PP/SiR dropped below 0.1 MPa at 23 and 96 h. The molecular simulation results show that the molecular chains of PP have strong dynamic ability, and the free volume change and trap depth are largest for SiR. The experimental results show that XLPE/SiR is better matched in electrical properties, while PP/SiR is better matched in thermal and mechanical properties. This work is an important reference for improving the safety of cable accessories and promoting the development of environmentally friendly PP cables.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"32 4","pages":"2355-2365"},"PeriodicalIF":3.1,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144739800","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}
The ultrahigh-frequency (UHF) maps are often used as an important basis to evaluate the insulation status. However, the current research is mostly driven by pure data, making it difficult to judge the actual status of defects through UHF maps. Multiscale simulation technologies are adopted to simulate the UHF maps of surface defects from physical mechanisms. The microprocess of surface discharge is simulated using the plasma model, and the electromagnetic (EM) signal amplitudes are calculated based on the finite-difference time-domain (FDTD) method, using the current in the microsimulation as an excitation. Then, the segmented equivalent parameters of the circuit model are solved using the microsimulation results. The phases of the UHF pulses are simulated in the circuit model, and the UHF maps are obtained combined with the signal amplitude. It is found that the undischarged segment resistance determines the voltage recovery time, which is a key parameter that affects the UHF maps. The random settings of the simulation are important factors making the simulation results more reasonable. The relationship between the microprocess of surface discharge and the UHF maps is established theoretically, providing a basis for the accurate assessment of the insulation defect status of power equipment.
{"title":"A Generating Method for UHF Maps of Epoxy Surface Discharge Based on the Multiscale Simulation System","authors":"Zhaoqi Zhang;Hui Song;Jiejie Dai;Lingen Luo;Gehao Sheng;Xiuchen Jiang","doi":"10.1109/TDEI.2025.3540000","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3540000","url":null,"abstract":"The ultrahigh-frequency (UHF) maps are often used as an important basis to evaluate the insulation status. However, the current research is mostly driven by pure data, making it difficult to judge the actual status of defects through UHF maps. Multiscale simulation technologies are adopted to simulate the UHF maps of surface defects from physical mechanisms. The microprocess of surface discharge is simulated using the plasma model, and the electromagnetic (EM) signal amplitudes are calculated based on the finite-difference time-domain (FDTD) method, using the current in the microsimulation as an excitation. Then, the segmented equivalent parameters of the circuit model are solved using the microsimulation results. The phases of the UHF pulses are simulated in the circuit model, and the UHF maps are obtained combined with the signal amplitude. It is found that the undischarged segment resistance determines the voltage recovery time, which is a key parameter that affects the UHF maps. The random settings of the simulation are important factors making the simulation results more reasonable. The relationship between the microprocess of surface discharge and the UHF maps is established theoretically, providing a basis for the accurate assessment of the insulation defect status of power equipment.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"32 2","pages":"859-868"},"PeriodicalIF":2.9,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143761394","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}
Recyclable thermoplastic polypropylene (PP) cable insulation with excellent performances is expected to represent traditional thermoset cross-linked polyethylene (XLPE) insulation. However, the poor resistance to thermal aging of PP-based cable insulation is generally considered as an obstacle limiting their practical applications. In this article, trace self-grown $gamma $ -crystals of PP were accidentally found in impact PP copolymer (IPC) cable insulation during thermal aging, which evidently retarded degradation in breakdown strength caused by decline in crystallinity. The unexpected growth of $gamma $ -crystals is further proven to be facilitated by crystalline ethylene segments from rubber phases and those blocked in PP chains. As a result, more deep traps are introduced by $gamma $ -crystals that are presented as crystalline structure defects. It makes carriers in IPC more difficult to migrate and detrap under external electric field. Therefore, although the crystallinity, which determines the breakdown strength of semi-crystalline polymers, decreases at day 12 of thermal aging, the degradation in breakdown strength is delayed until day 24. The self-grown $gamma $ -crystals in IPC insulation thus achieve the self-protective resistance against thermal aging. This work provides a new understanding to the effect of elastomers on thermal-aging stability in PP-based eco-friendly power cable insulation.
{"title":"Evidently Retarded Degradation in Breakdown Strength of Polypropylene Eco-Friendly Cable Insulation From Trace Self-Grown γ-Crystals During Thermal Aging","authors":"Kangning Wu;Haoran Sui;Yongruo Ren;Kai Yang;Peng Zhao;Benhong Ouyang;Huan Li;Xu Zhang;Li Ran;Jianying Li","doi":"10.1109/TDEI.2025.3540004","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3540004","url":null,"abstract":"Recyclable thermoplastic polypropylene (PP) cable insulation with excellent performances is expected to represent traditional thermoset cross-linked polyethylene (XLPE) insulation. However, the poor resistance to thermal aging of PP-based cable insulation is generally considered as an obstacle limiting their practical applications. In this article, trace self-grown <inline-formula> <tex-math>$gamma $ </tex-math></inline-formula>-crystals of PP were accidentally found in impact PP copolymer (IPC) cable insulation during thermal aging, which evidently retarded degradation in breakdown strength caused by decline in crystallinity. The unexpected growth of <inline-formula> <tex-math>$gamma $ </tex-math></inline-formula>-crystals is further proven to be facilitated by crystalline ethylene segments from rubber phases and those blocked in PP chains. As a result, more deep traps are introduced by <inline-formula> <tex-math>$gamma $ </tex-math></inline-formula>-crystals that are presented as crystalline structure defects. It makes carriers in IPC more difficult to migrate and detrap under external electric field. Therefore, although the crystallinity, which determines the breakdown strength of semi-crystalline polymers, decreases at day 12 of thermal aging, the degradation in breakdown strength is delayed until day 24. The self-grown <inline-formula> <tex-math>$gamma $ </tex-math></inline-formula>-crystals in IPC insulation thus achieve the self-protective resistance against thermal aging. This work provides a new understanding to the effect of elastomers on thermal-aging stability in PP-based eco-friendly power cable insulation.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"32 2","pages":"815-822"},"PeriodicalIF":2.9,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143761462","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}
Free metal particles within HVdc gas-insulated transmission line (GIL) pose a significant threat to insulation integrity. This article presents a multiscale dynamic simulation method for micrometer-sized metal particles in HVdc GIL systems. It establishes an adhesion simulation model for these metal particles and captures their macroscopic movement in conjunction with microscopic properties. Based on this model, the collision characteristics of particles of algorithms, sizes, and shapes are analyzed. The simulation results indicate that the critical adsorption velocity of ellipsoidal particles with an eccentricity of 5 is six times greater than that of particles of the same size. The belly of the tri-post insulator is identified as a high-risk area for the adsorption of metal particles. While increasing the particle trap length enhances capture efficiency, a saturation phenomenon occurs, which varies with the electric field of the GIL insulator. Following simulation analysis, the optimal trap length is determined to be 550 mm. These studies provide methodologies for the accurate simulation of metal particles and contribute to particle pollution control and the reliability enhancement of HVdc GIL equipment.
{"title":"Multiscale Dynamic Simulation Study on the Adsorption of Micrometer-Sized Metal Particles on Insulator Surfaces for HVDC GIL","authors":"Yutong Zhang;Chenbin Jin;Luming Xin;Pengfei Zhang;Haoran Wang;Shengwu Tan;Peng Liu;Zongren Peng","doi":"10.1109/TDEI.2025.3539996","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3539996","url":null,"abstract":"Free metal particles within HVdc gas-insulated transmission line (GIL) pose a significant threat to insulation integrity. This article presents a multiscale dynamic simulation method for micrometer-sized metal particles in HVdc GIL systems. It establishes an adhesion simulation model for these metal particles and captures their macroscopic movement in conjunction with microscopic properties. Based on this model, the collision characteristics of particles of algorithms, sizes, and shapes are analyzed. The simulation results indicate that the critical adsorption velocity of ellipsoidal particles with an eccentricity of 5 is six times greater than that of particles of the same size. The belly of the tri-post insulator is identified as a high-risk area for the adsorption of metal particles. While increasing the particle trap length enhances capture efficiency, a saturation phenomenon occurs, which varies with the electric field of the GIL insulator. Following simulation analysis, the optimal trap length is determined to be 550 mm. These studies provide methodologies for the accurate simulation of metal particles and contribute to particle pollution control and the reliability enhancement of HVdc GIL equipment.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"32 5","pages":"3049-3058"},"PeriodicalIF":3.1,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145210136","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}
Pub Date : 2025-02-04DOI: 10.1109/TDEI.2025.3538816
Abdellatif K. Rashed;Abdelrahman M. Alshehawy;Diaa-Eldin A. Mansour;Rizwan A. Farade;M. Ghali;Tamer F. Megahed
Power transformers are critical components in power grids, whose main role is maintaining the required voltage levels throughout the grid; thus, continuous condition monitoring of their status is crucial. Otherwise, catastrophic repercussions would occur. Diagnosis and condition assessment of power transformers ensure that the power transformer operates safely without service interruption and allow to schedule preventive maintenance. Optical spectroscopy has gained considerable attention over conventional condition assessment techniques due to its simplicity, speed, accuracy, nondestructiveness, and cost-effectiveness. This article reviews various optical spectroscopy technologies applied to condition assessment and fault diagnosis of insulation systems inside power transformers to predict their quality. These techniques include ultraviolet–visible (UV–Vis) spectroscopy, photoluminescence (PL) spectroscopy, near-infrared (IR) spectroscopy, and IR spectroscopy. First, transformer insulation parameters correlated with aging are highlighted. Then, the technologies used in optical spectroscopy approach are discussed. After that, the detailed application of these technologies and the possible correlation between their characteristic parameters and insulation condition are discussed. Finally, further needs for future research, development, and standardization are identified.
{"title":"Optical Spectroscopy Techniques for Condition Assessment and Fault Diagnosis of Power Transformer Insulation: A Critical Review on Technologies, Methods, and Standards","authors":"Abdellatif K. Rashed;Abdelrahman M. Alshehawy;Diaa-Eldin A. Mansour;Rizwan A. Farade;M. Ghali;Tamer F. Megahed","doi":"10.1109/TDEI.2025.3538816","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3538816","url":null,"abstract":"Power transformers are critical components in power grids, whose main role is maintaining the required voltage levels throughout the grid; thus, continuous condition monitoring of their status is crucial. Otherwise, catastrophic repercussions would occur. Diagnosis and condition assessment of power transformers ensure that the power transformer operates safely without service interruption and allow to schedule preventive maintenance. Optical spectroscopy has gained considerable attention over conventional condition assessment techniques due to its simplicity, speed, accuracy, nondestructiveness, and cost-effectiveness. This article reviews various optical spectroscopy technologies applied to condition assessment and fault diagnosis of insulation systems inside power transformers to predict their quality. These techniques include ultraviolet–visible (UV–Vis) spectroscopy, photoluminescence (PL) spectroscopy, near-infrared (IR) spectroscopy, and IR spectroscopy. First, transformer insulation parameters correlated with aging are highlighted. Then, the technologies used in optical spectroscopy approach are discussed. After that, the detailed application of these technologies and the possible correlation between their characteristic parameters and insulation condition are discussed. Finally, further needs for future research, development, and standardization are identified.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"32 4","pages":"2162-2176"},"PeriodicalIF":3.1,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144739876","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}
Pub Date : 2025-02-04DOI: 10.1109/TDEI.2025.3539260
Sihang Gao;Yuqing Lei;Yongxi Liu;Cong Huang;Lijun Yang
The corrosive sulfides in the insulating oil have been confirmed to induce insulation faults; thereby, the corrosive sulfides can be removed during the refining process of oil to overcome the corrosion threat. Some inactive sulfides are retained to improve the oxidation stability of oil, mainly including thiophenic sulfides. However, the activation of thiophenic sulfides under the operating conditions and whether it causes corrosion of copper winding remain unclear. Therefore, this article focuses on the reaction mechanism of copper winding corrosion induced by the pyrolysis of thiophenic sulfides in oil from the perspective of microscopic reaction mechanism, mainly including the analysis of thermal decomposition products of thiophenic sulfides, the activation energy of thiophenic sulfides on varied heating rates, the molecular dynamics simulation of thiophenic sulfides degradation, and the thermal aging verification test. The results indicate that the pyrolysis products of thiophenic sulfides consist of sulfur-containing micromolecules and inorganic products, such as hydrogen sulfide and its ion (H2S, ${mathrm {HS}}^{-}$ ), elemental sulfur (S, S2), and hydrogen and its ion (H2, H+). Thiophene has the lowest activation energy; thereby, it is the most prone to pyrolysis, followed by benzothiophene and dibenzothiophene. The continuous energy accumulation results in the decomposition of thiophenic sulfides due to long-term thermal action and generates low molecular corrosive sulfides, further intensifying the oil corrosivity and leading to the corrosion of oil-paper insulation.
{"title":"The Corrosion and Activation Mechanism of Thiophenic Sulfides in the Oil-Paper Insulation","authors":"Sihang Gao;Yuqing Lei;Yongxi Liu;Cong Huang;Lijun Yang","doi":"10.1109/TDEI.2025.3539260","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3539260","url":null,"abstract":"The corrosive sulfides in the insulating oil have been confirmed to induce insulation faults; thereby, the corrosive sulfides can be removed during the refining process of oil to overcome the corrosion threat. Some inactive sulfides are retained to improve the oxidation stability of oil, mainly including thiophenic sulfides. However, the activation of thiophenic sulfides under the operating conditions and whether it causes corrosion of copper winding remain unclear. Therefore, this article focuses on the reaction mechanism of copper winding corrosion induced by the pyrolysis of thiophenic sulfides in oil from the perspective of microscopic reaction mechanism, mainly including the analysis of thermal decomposition products of thiophenic sulfides, the activation energy of thiophenic sulfides on varied heating rates, the molecular dynamics simulation of thiophenic sulfides degradation, and the thermal aging verification test. The results indicate that the pyrolysis products of thiophenic sulfides consist of sulfur-containing micromolecules and inorganic products, such as hydrogen sulfide and its ion (H2S, <inline-formula> <tex-math>${mathrm {HS}}^{-}$ </tex-math></inline-formula>), elemental sulfur (S, S2), and hydrogen and its ion (H2, H+). Thiophene has the lowest activation energy; thereby, it is the most prone to pyrolysis, followed by benzothiophene and dibenzothiophene. The continuous energy accumulation results in the decomposition of thiophenic sulfides due to long-term thermal action and generates low molecular corrosive sulfides, further intensifying the oil corrosivity and leading to the corrosion of oil-paper insulation.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"32 3","pages":"1353-1363"},"PeriodicalIF":2.9,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144213519","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}
Pub Date : 2025-01-30DOI: 10.1109/TDEI.2025.3530651
{"title":"IEEE Transactions on Dielectrics and Electrical Insulation Information for Authors","authors":"","doi":"10.1109/TDEI.2025.3530651","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3530651","url":null,"abstract":"","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"32 1","pages":"C4-C4"},"PeriodicalIF":2.9,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10858326","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143360944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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