論文 - 小迫　雅裕

Data analysis for Imploving Diagnostic Accuracy in Partial Discharge Monitoring Systems using Power Line Communication 査読有り 国際誌

Ryota Kimoto, Lunnetta Safura Lumba, Akito Hodai, Masayuki Hikita, Masahiro Kozako

2025 Electrical Insulation Conference (EIC)   39 - 42   2025年06月

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

USA   Texas   2025年06月08日  -  2025年06月10日

Investigation of Optimal Electrical Insulation Systems of Stator Windings for Inverter-Fed Motors 査読有り 国際誌

T.Iwanaga, K.Zaizen, T.Okamoto, Y.Yamanaka, K.Miyazaki, T.Kuno, M.Hikita, M.Kozako

2025 Electrical Insulation Conference (EIC)   277 - 280   2025年06月

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

USA   Texas   2025年06月08日  -  2025年06月10日

Experimental Investigation on Detection and Localization of AC Partial Discharge in Form Wound Stator Windings in Rotating Machines using HFCT Sensors 査読有り 国際誌

T.Kajiyama, Y.Nagatani, K.Miyazaki, M.Hikita, T.Kuno, T.Iwanaga, M.Kozako, K.Zaizen, T.Yamada, Y.Inoue, T.Okamoto

2025 Electrical Insulation Conference (EIC)   188 - 191   2025年06月

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

USA   Texas   2025年06月08日  -  2025年06月10日

Morphological effect on high-voltage insulation properties in polypropylene/elastomer binary blends: An experimental and simulation study 査読有り 国際誌

Lee O.U., Kwon T., Normansah N.M.b., Kim D.K., Kwon Y.J., Kim M.J., Lee D.H., Kwon I.S., Eom Y., Kim H., Kozako M., Kim M., Yu S.

Polymer Degradation and Stability   234   2025年04月

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Polypropylene (PP)/elastomer blends have been widely studied as promising insulation materials for high-voltage (HV) power cables. Among various factors, the size of elastomer domains critically influences their electrical insulation performance, such as resistivity and breakdown strength (BDS). However, this relationship remains poorly understood. This study investigates the effect of the polyolefin elastomer (POE) domain size on the high-voltage insulation properties of the PP/POE blend. The binary blends were prepared through melt-blending of the PP and POE at the different mixing temperature from 185 to 235 °C. As an increase of the mixing temperature, the size of dispersed POE domain was linearly increased due to the viscosity differences between the PP and POE. In addition, the tensile strength, elongation, volume resistivity, and DC breakdown strength were decreased with mixing temperature, which were thus correlated with the POE domain size. The BDS values derived from simulations were consistent with those calculated via the Power law equation, showing a decline in BDS with increasing mixing temperature. Analysis of electric field distribution and space charge accumulation indicated that smaller POE domains more effectively mitigate electric field imbalances, delaying BD compared to larger domains. This study highlights the significant role of morphology in determining the insulation performance of polymer blends, providing valuable insights for the design of HV insulation materials.

DOI： 10.1016/j.polymdegradstab.2025.111223

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Improving the high-voltage insulation properties of polypropylene by introducing trace addition of polyvinylidene fluoride: An experimental and simulation study 査読有り 国際誌

Lee O., Kim D.K., Kim H., Lee S.H., Kwon T., Kwon I.S., Shinozaki K., Hikita M., Lee J.H., Lee D.H., Kim M.H., Kozako M., Yu S.

Composites Science and Technology   259   2025年01月

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Various additives ranging from inorganic nanoparticles to organic additives have been suggested to improve the insulation performance of polymeric materials for high-voltage engineering applications. Herein, a simple method for doping fluorine into a polypropylene (PP) matrix was presented by melt-blending of isotactic PP (iPP) with a small amount of polyvinylidene fluoride (PVDF) as a thermoplastic voltage stabilizer (TVS). During melt-mixing, the PVDF TVS, which is immiscible with PP, is gradually split into smaller domains within the iPP matrix and finely distributed, especially at a low PVDF content. The direct current (DC) breakdown strength (BDS) values of the PVDF-doped iPP increased by 110 % and 149 % at 25 and 110 °C, respectively, compared to those of the pristine PP, while its dielectric permittivity and loss tangent values remained nearly similar to those of iPP at wide temperature between 25 and 140 °C and frequency range between 1 Hz and 10 MHz. Quantum chemical simulation results reveal that a small amount of PVDF with high dipole moment introduces deep trap sites within the polymer matrix, which contribute for increasing BDS of iPP. Also, the PP with a small amount of PVDF dopants below 1.0 phr exhibited no any decrease in the tensile strength and elongation at break values. Therefore, the PVDF-doped iPP is anticipated as a potential candidate as high-performance high-voltage insulation materials for next-generation insulation applications.

DOI： 10.1016/j.compscitech.2024.110939

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Acoustic Partial Discharge Localization in Refined, Bleached and Deodorized Palm Oil (RBDPO) Based on the Savitzky-Golay and Moving Average Denoising Methods 査読有り

Ahmad N.D., Azis N., Jasni J., Rezali K.A.M., Talib M.A., Ali N.H.N., Kozako M.

Pertanika Journal of Science and Technology   33 ( Special Issue 4 )   115 - 128   2025年01月

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This research describes an investigation on the localization of partial discharge (PD) in Refined, Bleached and Deodorized Palm Oil (RBDPO) with the applications of 2 denoising methods, namely Savitzky-Golay (SG) and Moving Average (MA). A needle-plane electrode setup was used to initiate the PD. The electrical PD signal measurement was carried out through the impedance matching circuit (IMC), and the acoustic PD signal was obtained by acoustic emission (AE) sensors. The AE sensors were attached to the tank’s surface, and pre-amplifiers were used to boost the acquired acoustic PD signal. A high-voltage AC supply initiated the PD within the test tank filled with RBDPO. Both electrical and acoustic PD signals were denoised by SG and MA methods. The 2 denoising methods were evaluated based on the signal-to-noise ratio (SNR), root mean squared error (RMSE) and correlation coefficient (CC) metrics. The denoised acoustic PD signals were then utilized in the time difference of arrival (TDOA) technique to perform PD localization. The SG was found to be more effective than the MA in denoising both the electrical and acoustic PD signals based on its low RMSE and high CC. The estimated PD source locations based on the SG-denoised acoustic PD signals are closer to the actual PD source than those derived from the MA-denoised signals.

DOI： 10.47836/pjst.33.S4.07

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Effect of Electrical Field on Conductivity of Synthetic Ester Induced by Space Charge Accumulation 査読有り 国際誌

Yu R., Matharage S., Shen S., Wang Z., Tsuchie M., Kozako M., Hikita M.

IEEE Transactions on Dielectrics and Electrical Insulation   32 ( 3 )   1279 - 1288   2025年01月

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Synthetic ester has emerged as an alternative in applications where mineral oil has traditionally been used. Furthermore, their new applications in areas such as converter transformers and battery energy storage systems are currently being investigated. Conductivity of insulating materials is a crucial parameter for such new applications. This article investigates the impact of electrical field on the conductivity of synthetic ester through a combination of experimental and simulation studies. The experimental results indicate that short-term conductivity increases while long-term conductivity exhibits a nonlinear trend with applied electrical field. The simulation results show that the increase in the measured short-term conductivity is due to field-enhanced charge dissociation while the nonlinear trend in the measured long-term conductivity is a combined effect of space charge accumulation and field distortion. Furthermore, the simulation model incorporating space charge accumulation and charge injection is used to explain electrical field dependent conductivity phenomena, and key parameters and formulae describing field enhanced intrinsic and injected charge density are identified for synthetic ester and compared with those of mineral oil.

DOI： 10.1109/TDEI.2025.3527414

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Investigation of Liquid Insulating Material for Power Module Encapsulation: Effects on Partial Discharge and Electric Field Characteristics 査読有り 国際誌

Tomaiwa R., Suenaga S., Okamoto T., Tsuchie M., Hikita M., Kozako M.

Proceedings IEEE International Conference on Dielectric Liquids   2025年01月

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Next-generation power modules require rigorous evaluation of insulating substrates due to increasing voltage levels and the associated risk of partial discharge (PD). PD typically occurs in regions of high electric field intensity, particularly at encapsulant–metal interfaces, and leads to dielectric degradation. Conventional encapsulants, such as epoxy resins and silicone gels, suffer from poor thermal conductivity and lack self-healing properties. This study investigates liquid dielectric materials as alternative encapsulants, specifically Novec 7100, Vertrel XF, FC-3283, and Pastel NEO. These liquids, each exhibiting distinct dielectric and thermal properties, were applied to ceramic substrates. Partial discharge inception voltage (PDIV) measurements were conducted under a 60 Hz AC voltage, in conjunction with electric field analysis. The results indicate that high-permittivity insulating liquids can effectively modulate electric field distribution, thereby influencing PDIV. These findings suggest that appropriate selection of liquid encapsulants, based on dielectric strength and field relaxation characteristics, can enhance the insulation reliability of power modules.

DOI： 10.1109/ICDL63868.2025.11068273

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Evaluation of Dielectric and Insulation Properties of Various Fluorinated Liquids and Analysis Using Molecular Descriptors 査読有り 国際誌

Suenaga S., Tomaiwa R., Okamoto T., Tsuchie M., Kawano S., Hikita M., Kozako M.

Proceedings IEEE International Conference on Dielectric Liquids   2025年01月

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

The objective of this study is to investigate the electrical properties of various fluorinated liquids, analyze them from multiple perspectives, and elucidate the impact of three-dimensional molecular structural differences on their electrical characteristics. The electrical properties of nine fluorinated liquids were compared. Additionally, the Pearson correlation coefficients were calculated between molecular descriptors - derived from SMILES representations - and breakdown voltage were determined. The results indicate that hexafluorobenzene and SS-110, which exhibited low relative permittivity and low DC conductivity, tended to have higher breakdown voltages. Furthermore, the molecular descriptors EState_VSA1, HallKierAlpha, and FpDensityMorgan2 demonstrated a strong correlation with breakdown voltage. These findings suggest that molecular descriptor calculations based on SMILES representations can serve as a useful tool for predicting the breakdown voltage (BDV) of fluorinated liquids. Moreover, this approach holds potential for estimating BDV values for unknown samples and contributing to the design of molecular structures with high dielectric strength.

DOI： 10.1109/ICDL63868.2025.11068220

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Power Line Communication Application for Enhanced Partial Discharge Monitoring: From Theory to Application 査読有り 国際誌

Safura Lumba L., Kozako M., Hikita M., Sato H., Soeda M.

IEEE Transactions on Dielectrics and Electrical Insulation   31 ( 6 )   2915 - 2921   2024年12月

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Partial discharge (PD) activity is an important indicator of insulation health in high-voltage power apparatuses. Ensuring optimal functioning and timely equipment maintenance is crucial for operational efficiency and safety. This article introduces an innovative approach to equipment monitoring by utilizing power line communication (PLC) technology for detecting PD data. The novelty of this approach lies in the PLC receiver's dual capability to detect PD occurrences while simultaneously demodulating the PLC signal. This research analyzes the proposed low-cost, online PD monitoring system against traditional PD measurement techniques. Signals detectable by PLC were shown to propagate in PLC, allowing PLC to recognize PD from defect-simulated electrodes. To validate this, a simulated electrical substation circuit was constructed to facilitate the measurement of PD through the PLC system. The findings of this study indicate a good outcome for improving equipment monitoring procedures through the integration of PLC technology, providing a cost-effective alternative for continuous health assessment of electrical power equipment.

DOI： 10.1109/TDEI.2024.3425810

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Partial Discharge and Degradation Characteristics of Cast Resin Transformers Due to Bipolar Impulse Application 査読有り 国際誌

Yao Y., Miyagawa M., Hikita M., Kozako M., Harada Y., Takei K., Ikeda M., Miyazaki K., Futakawa K.

IEEE Transactions on Dielectrics and Electrical Insulation   31 ( 6 )   3489 - 3496   2024年12月

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

The objective of our work is to investigate partial discharge (PD) behaviors and degradation characteristics in winding insulation of an actual 22 kV cast resin transformer (CRTr) when subjected to bipolar impulse voltages. A differential high-frequency current transformer (HFCT) was employed on the high-voltage coils to measure PD pulses induced by impulse voltages. Additionally, PD measurement at ac voltage was carried out to characterize the aging process resulting from the application of bipolar impulses. Experimental findings indicated that higher-level bipolar impulses could cause large-amplitude PDs in the windings, occurring at the peak value of the applied impulse voltages and increasing with the number of applied impulses. PD inception voltage (PDIV) at ac voltage decreased to the operating voltage, and the discharge amplitude and phasewidth in phase-resolved PD (PRPD) patterns increased due to impulse PD occurrences. Considering these results, it is evident that the bipolar lightning impulses could cause large-amplitude PDs, intensify impulse PD activity, and ultimately lead to dielectric breakdown in the CRTr windings. Space charge accumulation and residual charge deposition resulting from impulse PD play a significant role in the generation and the process of development for impulse PDs in the winding insulation, contributing to an acceleration effect in the degradation process and eventual insulation failure.

DOI： 10.1109/TDEI.2024.3468249

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Long-Term AC Partial Discharge Characteristics Till Dielectric Breakdown in an Aged 22 kV Cast Resin Transformer 査読有り 国際誌

Miyagawa M., Yao Y., Kawano H., Hikita M., Kozako M., Harada Y., Takei K., Ikeda M., Miyazaki K., Futakawa K.

IEEE Transactions on Dielectrics and Electrical Insulation   31 ( 6 )   3462 - 3468   2024年12月

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This article presents a trend analysis of long-term ac partial discharge (PD) characteristics till dielectric breakdown by accelerated degradation test in an aged 22 kV cast resin transformer (CRTr). The long-term ac PD characteristics till dielectric breakdown showed that the maximum PD charge Q<inf>max</inf> and the average PD charge Q<inf>mean</inf> increased sharply during the cumulative charging time t<inf>c</inf>, which was between 100 and 200 h before dielectric breakdown. These results suggest that defects could expand and propagate due to PD degradation and penetrate the insulating paper, resulting in large PD as a precursor to dielectric breakdown. With a voltage acceleration factor AF<inf>v</inf> and a frequency acceleration factor AF<inf>f</inf> in the accelerated degradation test considered, the time at which this sign was observed was well before dielectric breakdown. Therefore, this sign can be expected as one of the indicators of equipment replacement. The time sequence of ac PD characteristics just before dielectric breakdown was successfully measured. The result indicates the possibility that a fatal dielectric breakdown can be prevented owing to a fast interruption utilizing a circuit breaker. Furthermore, a breakdown site in the winding of the aged 22 kV CRTr could be located by the thermography, i.e., high electric field sections between the top block layers of the high-voltage side winding.

DOI： 10.1109/TDEI.2024.3425312

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Partial Discharge Initiation Voltage Mechanism Improvement of Polyimide Film by Adding Boehmite Alumina Nanofiller under Impulse Voltage 査読有り 国際誌

Arif A.I., Kozako M., Hikita M., Suwarno , Khayam U., Bando S., Hayashisaka N.

6th International Conference on Power Engineering and Renewable Energy Icpere 2024 Proceedings   2024年11月

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Indonesia   Bandung   2024年11月05日  -  2024年11月06日

One of the methods to assess the insulation's condition is measuring the partial discharge initiation voltage (PDIV). Researchers have examined the dielectric and insulating properties of polyimides (PI) and polyimides that have had boehmite alumina (BA) added. When the films are tested under impulse voltage, it is found that a PI film has a greater PDIV but a lower lifespan than a BA film. Using a finite element technique simulation on the atmospheric air wedge gap between the HV electrode and the polyimide film samples above the grounded electrode, the PDIV estimate in a computational model of the IEC (b) electrode system determines the electric field strength. At the intersection of the curve with Paschen's curve, the PDIV is found. The Dakin equation is used to validate the PDIV estimate process. Based on the additional nanofiller content, measurement and estimation findings verify that PI films have a greater PDIV than BA films and that they adhere to the Dakin's equation line. On the other hand, the BA films exhibit a greater PDIV at unipolar positive impulse voltage, indicating that the nanocomposite-added PI films are not the source of the initial electron emission.

DOI： 10.1109/ICPERE63447.2024.10845701

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Application of Multipurpose Intelligent Pulse Signal Generator in Cable PD Detection Technology Training 査読有り 国際誌

Min C., Hikita M., Kozako M., Zhipeng Z., Yingying L.

2024 10th International Conference on Condition Monitoring and Diagnosis Cmd 2024   ( 241 )   41 - 44   2024年10月

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Korea   Gangwon-do,   2024年10月20日  -  2024年10月24日

A multipurpose intelligent pulse signal generator that can simulate and generate various PD signal patterns and common interference noise has been developed to improve the partial discharge (PD) detection and localization skills of the professional team of operation and maintenance of power cable lines. It can simulate and generate various types of PD and noise signals similar to the measured signal spectrum in the test site and laboratory, including PD signal level, repetition rate, time interval, waveform, polarity, and PRPD pattern. It can not only provide some kinds of typical reference signals for verification of the signal identification functions and the calibration of PD detection devices, but also can be used with a simulated cable line model to form a training platform for developing PD detection and PD localization technology, which can also be applied to some technique competition of inspection and maintenance for cable line as well. Using this training and evaluation platform, it can simulate various signal patterns like the on-site signals of PD combined with noise under the safety environment without high voltage, such as background noise covering PD or multiple PD signals at the same time, to meet the training needs of testers to cope with various complex PD test problems on site, and it is also suitable for the learning and training of PD localization or cable fault localization based on traveling wave detection technology.

DOI： 10.23919/CMD62064.2024.10766232

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Propagation Characteristics of Surface Currents Induced by Partial Discharges in an Oil-filled Bushing on Transformer Tank 査読有り 国際誌

Toyoda S., Miyagawa M., Hikita M., Kozako M., Kitoh Y., Sasaki M., Maekawa T., Aoki K.

2024 10th International Conference on Condition Monitoring and Diagnosis Cmd 2024   ( 722 )   665 - 668   2024年10月

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Korea   Gangwon-do   2024年10月20日  -  2024年10月24日

The objective of this study is to determine the optimal placement of surface current sensors for detecting partial discharge (PD) in oil-filled bushings. To achieve this, the propagation characteristics of surface currents induced by PD events were investigated through both experimental and numerical approaches. The findings suggest that electromagnetic waves generated by PD escape from the bushing mounting flange to the outer wall surface of the tank and propagate at the speed of light along this surface. Additionally, the propagation of surface currents along the tank's outer wall appears to be influenced by the superposition of reflected waves from the tank's corners and bushing mounting flanges. By analyzing the difference in the arrival time of detection signals from multiple surface current sensors and the amplitude of the V0-<inf>p</inf> component, it was determined that the location of the PD can potentially be identified.

DOI： 10.23919/CMD62064.2024.10766300

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Polarity Effects of Residual Charge on Impulse PD of Three-Layer Polyester Films with a Void 査読有り 国際誌

Yao Y., Miyagawa M., Nagatani Y., Hikita M., Kozako M.

2024 10th International Conference on Condition Monitoring and Diagnosis Cmd 2024   ( 252 )   727 - 730   2024年10月

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Korea   Gangwon-do   2024年10月20日  -  2024年10月24日

Partial discharge (PD) is a well-known characteristic associated with the presence of defects and electrical damage to the winding insulation of cast resin transformers. Previous studies have showed that the repetitive bipolar impulse voltage applications have a polarity effect on impulse PD generation and subsequent AC PD test. This paper aims to investigate the polarity effect of residual charge on impulse PD in three-layer polyethylene terephthalate (PET) film specimens with one void, subjected to multiple bipolar impulses. The results are discussed in terms of the residual surface charge on the specimens. Experimental results revealed that the impulse PD magnitude was higher under bipolar impulse applications compared to single polarity impulses. Surface charge mapping, which quantitatively characterizes the residual charge deposition on the sample, indicated that residual charges generated by an impulse PD occupied only a portion of the cavity surface, possibly due to the presence of discharge channels and the surface condition inside the cavity. Residual charge has a significant memory effect on subsequent PD behavior, influencing the distribution and magnitude of the next discharge channels in the defect walls. Based on these findings, it is suggested that repetitive bipolar impulses, due to the polarity effect of residual charge, are more likely to promote the aging of the transformer's insulation layer.

DOI： 10.23919/CMD62064.2024.10766280

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Investigation of the Relationship between Impulse Pre-stress and Subsequent AC Partial Discharge 査読有り 国際誌

Nagatani Y., Miyazaki K., Kozako M., Hikita M., Miyake H., Tanaka Y., Fujii Y., Nakamura Y., Ito D., Nakamae T., Oyama K., Ozaki T.

2024 10th International Conference on Condition Monitoring and Diagnosis Cmd 2024   ( 815 )   744 - 747   2024年10月

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Korea   Gangwon-do,   2024年10月20日  -  2024年10月24日

The primary objective of this study is to elucidate the mechanism of insulation degradation in cast resin transformers subjected to surge stress. To achieve this, it is essential to quantitatively assess the relationships among impulse pre-stress, subsequent AC partial discharge (PD) characteristics, and the degree of material degradation. In this paper, impulse pre-stress and subsequent AC PD characteristics were measured on void specimens. The results quantitatively demonstrate the relationship between the impulse PD charge and the total subsequent AC PD charge.

DOI： 10.23919/CMD62064.2024.10766165

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Investigation of Breakdown Strength and Dielectric Properties of Polypropylene/Polyolefin Elastomer Blends with Mixing Temperature 査読有り 国際誌

Kim H., Shinozaki K., Hikita M., Kozako M., Lee O., Yu S.

2024 10th International Conference on Condition Monitoring and Diagnosis Cmd 2024   ( 579 )   738 - 740   2024年10月

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Korea   Gangwon-do,   2024年10月20日  -  2024年10月24日

This study investigates DC breakdown strength and dielectric properties of polypropylene (PP)/polyolefin elastomer (POE) binary blends were investigated as a function of the mixing temperature. Mixing temperatures of 185, 195, 205, 215, 225, and 235°C were employed to alter the dispersed domain size of the POE within the PP matrix. The DC breakdown strength E<inf>b</inf> and dielectric properties of the PP/POE blend samples were measured at room temperature, with the relative complex permittivity ϵ<inf>r</inf>∗ evaluated across frequencies ranging from 1 Hz to 10 kHz. The PP/POE blend prepared at 185°C exhibited the highest DC breakdown strength as well as smallest real part of permittivity ϵ<inf>r</inf>'. A similar trend was observed for the imaginary part of permittivity ϵ<inf>r</inf>' across all samples. These results indicate that the mixing temperature significantly influences E<inf>b</inf>and dielectric properties, with the blend prepared at 185°C being particularly advantageous for enhancing the dielectric properties.

DOI： 10.23919/CMD62064.2024.10766336

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Improvement of Partial Discharge Initiation Voltage of Polyimide Film by Adding Boehmite Alumina Nanofiller 査読有り 国際誌

Arif A.I., Kozako M., Hikita M., Suwarno , Khayam U., Bando S., Hayashisaka N.

2024 10th International Conference on Condition Monitoring and Diagnosis Cmd 2024   ( 767 )   222 - 225   2024年10月

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Korea   Gangwon-do,   2024年10月20日  -  2024年10月24日

Measuring the insulation's partial discharge initiation voltage (PDIV) is advised in order to determine the insulation condition. The dielectric and insulating characteristics of a polyimide (PI) and polyimide with boehmite alumina (BA) added have been studied. It is discovered that a PI film has a higher PDIV but a lower lifetime than a BA film when the films are tested under impulse voltage. In an IEC (b) electrode system computational model, the PDIV estimation involves obtaining the electric field strength using a finite element method simulation on atmospheric air wedge gap between the HV electrode and the polyimide film samples above the grounded electrode. The PDIV is obtained at the point where the curve meets the Paschen's curve. PDIV estimation is continued by confirming to the Dakin equation. Measurement and estimation results confirm PI films have a higher PDIV than of BA films based on the nanofiller content added and conforms the Dakin's equation line. However, the BA films have a higher PDIV under unipolar positive impulse voltage which suggest the first electron emission doesn't start from the nanocomposite added PI films.

DOI： 10.23919/CMD62064.2024.10766117

Scopus

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85214428409&origin=inward

Feature Extraction Using Kullback-Leibler Divergence for Long-Term Trend Analysis of PRPD Patterns of Cast Resin Transformer 査読有り 国際誌

Miyagawa M., Satake T., Kawano H., Hikita M., Kozako M., Harada Y., Takei K., Ikeda M., Miyazaki K., Futakawa K.

2024 10th International Conference on Condition Monitoring and Diagnosis Cmd 2024   ( 1043 )   785 - 788   2024年10月

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Korea   Gangwon-do,   2024年10月20日  -  2024年10月24日

In the previous report, the partial discharge (PD) data of the aged 22 kV cast resin transformer (CRTr) till breakdown were obtained and the long-term PD trends were evaluated in general PD quantities such as PD repetition rate, but it was difficult to extract the changes to estimate the degradation state. Therefore, the purpose of this paper is to propose an optimal method of applying the Kullback-Leibler divergence (KL-D), which is a relatively easy method for quantifying changes in phase-resolved PD (PRPD) patterns, by focusing on several targets as reference values for KL-D and comparing the results. In this paper, KL-D was applied to the PRPD pattern of the long-term PD data of the aged 22 kV CRTr till breakdown to extract the amount of change. The results show that the PRPD pattern till dielectric breakdown of the aged 22 kV CRTr gradually changes as the accumulated time increased. This suggests on going degradation caused by PD within the insulation system. By leveraging KL-D for quantitative analysis, our study offers insights into the progression of degradation in CRTrs, paving the way for more precise monitoring and diagnosis of faults in these crucial power equipment systems.

DOI： 10.23919/CMD62064.2024.10766176

Scopus

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85214402346&origin=inward