論文 - 迫田 達也
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油入変圧器内の部分放電による弾性波の効果的な測定方法の提案 査読あり
森 航, 迫田 達也, 佐藤 正春, 武井 勝俊
電気学会論文誌． Ａ 142 ( 3 ) 124 - 125 2022年3月
担当区分：責任著者 記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：一般社団法人 電気学会
Based on numerical and experimental analyses of sound pressure distributions owing to partial discharges in oil-immersed transformer, we propose an effective arrangement of acoustic emission sensors. The sensor arrangement at the surface edge of the transformer housing allows us to minimize the required time for diagnosing.
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On-line PD Monitoring System (PDLOOK) for XLPE Cables 査読あり
Akaiwa S., Miyagawa K., Nakashima T., Sakoda T., Miyake T., Takayama A.
2022 9th International Conference on Condition Monitoring and Diagnosis, CMD 2022 703 - 706 2022年
掲載種別：研究論文（学術雑誌） 出版者・発行元：2022 9th International Conference on Condition Monitoring and Diagnosis, CMD 2022
We have developed a continuous remote monitoring system that can monitor partial discharge (PD) trends for a long period of time, which greatly saves the labor in operating. An Edge terminal uploads a signal obtained from the high frequency CT attached to the power cable to a cloud system. In this process, a PD-like signal is effectively discriminated from a large amount of acquired data by using a noise filtering function. The signal data uploaded on the cloud system is PD-judged by AI, and a learning cycle function improves the AI judgment accuracy.
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Degradation Monitoring of Silicone Rubber Used for Insulators 査読あり
Khaing M.T., Yoshimura K., Sakoda T., Oasa J., Higashiyama S., Inaoka Y.
2022 9th International Conference on Condition Monitoring and Diagnosis, CMD 2022 382 - 386 2022年
掲載種別：研究論文（学術雑誌） 出版者・発行元：2022 9th International Conference on Condition Monitoring and Diagnosis, CMD 2022
Electrical insulation equipment such as insulators contributes to reduction of electrical fault owing to overvoltage. Polymeric material such as silicone rubber (SiR) is gradually replacing porcelain. However, in Japan the application of polymeric material is limited because there are concerns about the hydrophobicity degradation and the decrease of insulation performance. Therefore, it is important to investigate not only pollution effect on the insulation performance but also the long-term reliability of polymeric material. Additionally, it is desired to establish an easy diagnostic technique which can grasp the degree of degradation of polymeric material. To evaluate the degradation degree of SiR of insulators arranged for a long period of time in the coastal area, we first characterized the surface of aged SiR specimen cut out from a line post insulator arrange for 20 years in the coastal area by using the attenuated total internal reflection Fourier transform infrared spectroscopy (ATR-FTIR). Next, we repeatedly performed a salt fog aging test against SiR specimens. Then, the surface hydrophobicity and the leakage current were evaluated. From the ATR-FTIR analysis, it was found that the reflectance peaks due to Si-CH3 symmetric bending of aged specimen decreases in comparison with those of unused specimen. The continuous salt fog aging test investigated that a required time for recovering hydrophobicity is a good index for degradation diagnosis because the required times for recovering hydrophobicity of SiR used for 20 years are much longer than that of unused SiR.
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Nakakoga Y., Tada Y., Sakoda T., Tazawa K., Ichikawa H.
Electronics and Communications in Japan 104 ( 4 ) 2021年12月
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） 出版者・発行元：Electronics and Communications in Japan
To develop a sterilization method for controlling post-harvest stem-end rot of mango, we examined to sterilize fungi on peduncle by using the dielectric barrier discharge (DBD). Additionally, to investigate the sterilization factors, we performed sterilization against stem-end rot on agar medium by using the DBD generated in air, argon gas, or oxygen gas. It was found that the DBD can sterilize fungi with high probability. Ultra-violet ray and O3 do not contribute to the sterilization. High energy electrons, and radicals such as O and OH play an essential role for the sterilization.
DOI： 10.1002/ecj.12325
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Evaluation of surface degradation of silicone rubber by continuous salt-fog aging test 査読あり
Adachi K., Miyake T., Sakoda T.
IEEJ Transactions on Fundamentals and Materials 141 ( 10 ) 590 - 596 2021年10月
担当区分：責任著者 記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：IEEJ Transactions on Fundamentals and Materials
To evaluate the long-term reliability of polymeric material used for housing material of electric power apparatus, we continuously performed a salt-fog aging test against silicone rubber (SiR) specimens cut out from line post insulators arranged for 10 and 20 years in the coastal area. Then, the surface hydrophobicity and the leakage current were evaluated. The results showed that a required time for recovering hydrophobicity and a discharge ignition time until the leakage current is detectable are good indexes for degradation diagnosis. Especially, the required time for recovering hydrophobicity is useful. The required times for recovering hydrophobicity of SiR used for 10 and 20 years were much longer than that of unused SiR.
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迫田 達也
宮崎大学工学部紀要 50 105 - 112 2021年9月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：宮崎大学工学部
The purpose of this study is to assist the operation and maintenance of PV systems by studying the resistive conditions of bypass diode used in PV modules and to develop the diagnosis and on-line monitoring system for small and medium scale PV systems. This paper analyzes the breakdown and non-breakdown
characteristics of Schottky diodes and PN Junction diodes by application of various ranges of voltages by Lightning surge simulator (LSS). In this study, we compare and discuss the numerical data of experimental results obtained under variable voltage applications of LSS are compared for both diodes on the resistive
characteristics after breakdown, waveforms of voltage and current and the behaviors of dynamic curves.
An applied voltage, on which the breakdown of diode takes place and dramatic change in I-V characteristics occurs, is called “critical voltage (Vc)”. From the study, it was observed that the magnitude of critical voltage (Vc) of PN junction diodes is higher than that of Schottky diodes in reverse direction although
there is almost the same in forward direction. The authors are also probing that the possibility of more sensitive monitoring and diagnosis system for the resistive bypass diode in PV system based on numerical simulation results. The great difference of Vc is reflected for the dynamic relationship between voltage and current in reverse biasing for both diodes. -
Voltage Profi les on HV Distribution Lines with Various Network Confi gurations and Customers 査読あり
迫田 達也
宮崎大学工学部紀要 50 95 - 103 2021年9月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：宮崎大学工学部
Electrical power system reliability is a critical issue for utilities and power loss occurred in transmission and distribution network is a must consideration. Electrical distribution system is the largest portion of network in the electrical power system. There is voltage drop on long HV distribution line (D/L) due to heavy load consumption, absent of voltage regulation, as well as poor power factor collection on long HV D/L. Therefore, phase advancing capacitors (Shunt Capacitor, SCs) are installed in parallel with customer loads for voltage improvement and power factor correction. However, these SCs, sometimes, lead to Ferranti effect, especially at the very lightly loaded condition. Moreover, in recent years, the introduction of photovoltaic power generation systems (PV systems) into HV D/L has developed rapidly and may cause the unacceptable voltage variation on HV D/L.
In this study, a virtual 6.6 kV long distance (20 km) HV D/L without PV system supported from Kyushu Electric Power Company (Qden) in Miyazaki branch, is introduced. In this long distance HV D/L, a 20 MVA transformer, three static voltage regulators (SVRs), and 50 customer loads are included. For very lightly loaded condition, the effects of SCs detachment area on the voltage profiles of HV D/L are numerically investigated and discussed. Moreover, the optimal location is proposed to change the suitable SVR for the purpose of upgrading voltage drop in heavy loaded condition.
Then, voltage profiles of different lengths (20.3 km for long and 8.70 km for short) HV D/Ls with PV system installing SCs at customer’s side and different load capacity are discussed. Furthermore, the conditions of flowing line current on HV D/L with PV system for different load locations are explained with phasor diagram. A program based on the Newton Raphson method was coded for the power flow calculation. -
Dynamic I-V Characteristics of Schottky Diodes and PN Junction Diodes When Lightning Impulse Voltage Is Applied on Them
May Oo KHIN, Ryo TORIHARA , Tatsuya SAKODA, Noriyuki HAYASHI
Memoirs of faculty of engineering university of miyazaki 50 105 - 112 2021年9月
記述言語：英語 掲載種別：研究論文（大学，研究機関等紀要）
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Voltage Profiles on HV Distribution Lines with Various Network Configurations and Customers
May Thin KHAING, Tatsuya SAKODA, Noriyuki HAYASHI
Memoirs of faculty of engineering university of miyazaki 50 95 - 104 2021年9月
記述言語：英語 掲載種別：研究論文（大学，研究機関等紀要）
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誘電体バリア放電によるマンゴーの軸腐病殺菌と殺菌要因の解明に関する研究 査読あり
中古賀雄太 多田陽一朗 迫田達也 田澤和俊 市川博章
電気学会論文誌A 141 ( 6 ) 385 - 390 2021年6月
担当区分：責任著者 記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：IEEJ Transactions on Fundamentals and Materials
To develop a sterilization method for controlling post-harvest stem-end rot of mango, we examined to sterilize fungi on peduncle by using the dielectric barrier discharge (DBD). Additionally, to investigate the sterilization factors, we performed sterilization against stem-end rot on agar medium by using the DBD generated in air, argon gas or oxygen gas. It was found that the DBD can sterilize fungi with high probability. Ultra-violet ray and O3 don't contribute to the sterilization. High energy electrons, and radicals such as O and OH play an essential role for the sterilization.
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発電状態においてストリング電流の時間変動特性比較に基づいた不具合ストリングの可視化及び検出手法 査読あり
鳥原 亮, 小玉 昂史, 竹之内 修, 迫田 達也, 林 則行
太陽エネルギー 47 ( 3 ) 27 - 36 2021年5月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：一般社団法人 日本太陽エネルギー学会
In this paper, we propose a new method to detect defective string(s) in a photovoltaic (PV) array, in which the temporal variation of string current is employed since it is easily measured in generation mode, independently of the scale of photovoltaic systems. Based on the results of experimental works using both a newly-installed and 20-years-old PV systems, it is demonstrated that the amplitude of string current variation corresponds to the voltage-current characteristics of the target string at the operation voltage of power conditioning system. Numerical results using a simple PV array model quantitatively confirm the experimental results. Two parameters are newly proposed to visualize the measured data. It is illustrated that those two parameters are useful to this end, and consequently, make it possible to easily evaluate the conditions of target string such as power loss and cluster loss.
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Torihara R., Latt N.Z., Khin M.O., Lwin Y.M., Sakoda T., Hayashi N.
IEEE Region 10 Annual International Conference, Proceedings/TENCON 2020-November 1007 - 1012 2020年11月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：IEEE Region 10 Annual International Conference, Proceedings/TENCON
The intent of this paper is to analyze the power consumption or heat dissipation of defective bypass diode (BPD) at open circuit (OC) and maximum power point (MPP) load conditions when the BPD turns to have resistive behavior in a photovoltaic (PV) string and array. We also analyze the thermal impact of defective BPD in a PV string under different irradiances and cell temperatures. It was observed that the power consumption of defective BPD largely depends on load condition and the thermal impact is more severe in OC condition. It was also observed that the thermal impact of defective BPD is larger under either high irradiance level for the same cell temperature or lower cell temperature on the same irradiance. This study indicates that it is necessary to monitor the heat dissipation of BPDs and to evaluate the electrical properties of the BPDs to realize the reliable PV systems.
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On-line PD System and PD Locator for XLPE Cables
Sakoda T., Yamasaki Y., Nakanose S., Hayashi N., Miyake T., Miyagawa K., Kawano W.
Proceeding - 8th International Conference on Condition Monitoring and Diagnosis, CMD 2020 222 - 225 2020年10月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Proceeding - 8th International Conference on Condition Monitoring and Diagnosis, CMD 2020
We constructed an on-line partial discharge (PD) monitoring system (PDOM) with a CT sensor, an analogue-digital converter, and a tablet PC. A sampling frequency for data acquisition is 100 MHz, and we exchange on-site PD data through a cloud system. We successfully measured PDs in the early stage of insulation deterioration of a cross-linked polyethylene (XLPE) cable in a field site. Additionally, following PD detection by using a PDOM, we can locate a PD position by using a PD locator (PDL) system. By locating a PD, we can estimate the actual PD magnitude considering attenuation factor of a high frequency pulse. We show how the PDL system works on a XLPE cable network with time synchronization between two positions by using an injection current pulse. The locating accuracy of the PDL system is evaluated.
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On-line PD system and PD Locator for XLPE Cables 査読あり
Tatsuya Sakoda, Noriyuki Hayashi, Yuhei Yamasaki, Soichiro Nakanose, Takuma Miyake, Wataru Kawano, Koji Miyagawa
8th International Conference on Condition Monitoring and Diagnosis 1 - 4 2020年10月
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）
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小田 浩史, 間 壱誠, 迫田 達也, 久保 克隆, 水谷 学, 春日 靖宣, 深野 孝人
宮崎大学工学部紀要 49 111 - 114 2020年9月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：宮崎大学工学部
Surge arrester with a spark gap has been installed for reducing the electrical failures in distribution systems. The top and the bottom of a ceramic spacer for sustaining an electrode gap contact with electrodes, in which there are triple junction points among the ceramic spacer, the gap electrodes and the atmosphere. Corona discharges formed at around the triple junction points may influence discharge characteristics for a spark gap. Additionally, the charges on the inner surface of the ceramic spacer, which are electrified by corona dischaeges, may act on the discharge characteristics. We measured V-t characteristic and residual voltage after operating a surge arrester with a spark gap. Based on the results, we evaluate affecting factors to V-t characteristics of impulse discharge .
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Study on degradation diagnostic method for silicone rubber
Sakoda T., Minami E., Miyake T., Hayashi N., Goto S., Aka Y., Anjiki T., Kasuga Y., Fukano T.
Journal of Electrostatics 107 2020年9月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Electrostatics
To evaluate the degradation degree of silicone rubber (SiR) of electric power apparatus arranged for a long period of time in the coastal area, we repeatedly performed a salt fog aging test against SiR specimens. Then, the surface hydrophobicity and the leakage current were evaluated. The results showed that a required time for recovering hydrophobicity and a discharge ignition time until the leakage current is detectable are good indexes for degradation diagnosis. Especially, the required time for recovering hydrophobicity is useful.
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XLPE ケーブルを用いた部分放電電流の長距離伝搬特性 査読あり
山下 勝也, 迫田 達也
宮崎大学工学部紀要 49 95 - 99 2020年9月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：宮崎大学工学部
The demand of reliable power systems and stability of electrical power supply are quite crucial for all of power companies. On the other hand, power systems installed during the period of high economic growth have been operating for over 30 years in Japan. For transmission and distribution lines, cross-linked polyethylene (XLPE) cable plays an important role in distributing the stable power to customers. Electric failure for the XLPE cable decreases year by year because of progress of manufacturing. However, at joint and terminal sections of the XLPE cable, partial discharges (PDs) occur in defects of insulating materials. The PD generation can occur at any points in the insulation system where electric field strength exceeds a PD inception electric field and can develop until breakdown occurs. That is, PDs which are owing to local electrical stress in the insulation or on the surface of the insulation reflect a kind of sign of insulation deterioration. Therefore, PD measurement is a useful technique of assessing the insulation deterioration of XLPE cables. In this study, the pulse propagation characteristics of a PD on actual 22kV XLPE cables were investigated.
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太田 靖之, 迫田 達也
宮崎大学工学部紀要 49 119 - 127 2020年9月
記述言語：英語 掲載種別：研究論文（大学，研究機関等紀要） 出版者・発行元：宮崎大学工学部
Generally, the performance of a PV system depends not only on its basic technical characteristics but also on the environmental conditions in which they will be set up. Therefore, studying the effects of climatic parameters such as solar irradiance on the plane of array (GPOA), ambient temperature (Ta), relative humidity (RH) and wind speed (νa) on the performance of PV is vital to be able to utilize efficiently solar energy.
The authors have studied the effects of various climatic parameters on the output performances of the two PV systems, 60 kW Copper Indium Gallium Selenide (CIGS) and 50 kW Multi-Crystalline Silicon (MC-Si), which were installed within the campus of University of Miyazaki, Japan. The main objectives of the research are to improve the prediction of the PV systems performance while knowing the climatic parameters of a particular area in which they stand, and also provide a useful dataset for the comparative studies.
The analyses were done by the multiple linear regression analysis (MLR) using the statistical software R. The performances of the two PV systems are in positive proportion to the GPOA and νa, however, as per the values of the slopes of the regression equations, the MC-Si PV system is smaller than the CIGS PV system, attributed to their different module tilt angles and elevations of the PV sites. The performances are in negative proportion to the Ta, but the more sensitivity can be observed in the MC-Si PV system. The RH negatively affected on the MC-Si PV system, although its positive effects can be observed in the CIGS PV system. -
電力ケーブルにおける部分放電発生位置標定技術の精度評価 査読あり
山下 勝也, 迫田 達也
宮崎大学工学部紀要 49 91 - 94 2020年9月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：宮崎大学工学部
For transmission and distribution lines, cross-linked polyethylene (XLPE) cable plays an important role in distributing the stable power to customers. Electric failure for the XLPE cable decreases year by year because of progress of manufacturing. However, at joint and terminal sections of the XLPE cable, partial discharges (PDs) occur in defects of insulating materials. The PD is a precursor to dielectric breakdown. Once PD occurs, it continuously erodes insulation material. The demand of reliable power systems is quite crucial for all of power companies, and then it is demanded to develop an on-line PD measurement technique and a monitoring system. In this study, we propose a PD locating system for XLPE cables in operation, in which the propagation velocity of PD current is not required for locating a PD. We first show how the locating system works on a XLPE cable network with time synchronization between two points. Additionally, the locating accuracy of the system is investigated.
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誘電体バリア放電を用いたマンゴー軸腐病の殺菌と 雰囲気ガスが殺菌に与える影響 査読あり
木之下 俊輔, 多田 陽一朗, 迫田 達也, 田澤 和俊, 市川 博章
宮崎大学工学部紀要 49 115 - 118 2020年9月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：宮崎大学工学部
Apple mango has been a representative product in Miyazaki. However, Stem–end rot of mango is likely to corrupt the fruit during transportation, which may lead to a decrease in the reliability of branded mangoes. Therefore, it is necessary to perform sterilization. So we made a sterilization device with a dielectric barrier discharge source. In order to confirm the usefulness of this device and the factor of stelirization, we performed sterilization against Lasiodiplodia theobromae and mango fruit inoculated with the fungus evaluated.