研究者詳細 - 兒玉　直人

論文 - 兒玉　直人

分割表示 85 件中 1 - 20 件目／全件表示 >>

A Proposal for a Detection Method of Short-Gap Arcs Generated in Low Voltage DC Facilities

Mikimasa Iwata, Naoki Nishiyama, Yasunobu Yokomizu, Naoto Kodama, Ayaka Nakamura, Tomoyasu Sakai, Masahiro Tsukahara, Atsushi Miyamoto

Proceeding of IEEJ P&ES – IEEE PES Thailand Joint Symposium 2025 – Advanced Technology in Power Systems – 2025年3月

Interpretation of Transient Arc Resistance Rise Process Using Silicone Resin Based on Arc Diameter Reduction and Thermal Diffusivity of Electric Fuse Arc 国際誌

Waku Takenaka, Naoto Kodama, Yasunobu Yokomizu, Kanata Nakamura, Koki Kameshima, Mikimasa Iwata, Ayaka

Proceedings of ISPlasma2025/IC-PLANTS2025 2025年3月

Proposal of Emergency Operation and Active Power Dispatch Control Scheme for Bipolar VSC-MTDC System 査読有り国際誌 Open Access

Nakamura A., Iwata M., Yokomizu Y., Kodama N.

IEEE Access 13 巻頁： 31590 - 31602 2025年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE Access

In a bipolar voltage source converter-based multi-terminal DC (VSC-MTDC) system, the power flow of the positive and negative pole networks can be controlled independently. This advantage allows bipolar systems to maintain operation with only the healthy pole even in the event of DC faults. However, existing power flow control methods for bipolar systems do not include the optimal mode-switching of each converter’s operation and may not be sufficiently reliable during fault conditions. Thus, this paper proposes a new control scheme considering coordination between the poles and flexibility in power shifting. The proposed method consists of two steps: (a) a mode-switching method of converters to maintain DC voltage stability during converter trips and (b) an active power dispatch control method to enable power shifting from the faulty pole to the healthy pole, mitigating the risk of power surplus and ensuring a robust response to AC grid stability issues. The power assurance coefficient ω mass,i is defined as critical factor for determining the interpolar power dispatch. The simulation results show that an average transmission power outage of approximately 220 MW can be prevented during a single-pole trip while maintaining the operation within the rated VSC capacity when ω mass,i is set to 0.5. This highlights the effectiveness of the proposed method in maintaining the system reliability and stability. Overall, the proposed method enhances the transmission capability by maintaining the operation within the rated capacity, enabling interpolar power shifting, and mitigating the AC grid instability during fault conditions regardless of the bipolar configuration.

DOI： 10.1109/ACCESS.2025.3542740

Open Access

Scopus

Transient Quenching Properties of Vapor Arc Formed in Silica Sand: Contribution of Vaporized SiO2 Mixture to DC Arc Extinction Performance 査読有り国際誌

Kodama, N; Yokomizu, Y; Takenaka, W; Nakamura, K

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING 19 巻 ( 12 ) 頁： 1965 - 1975 2024年12月

担当区分：筆頭著者,　最終著者,　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：IEEJ Transactions on Electrical and Electronic Engineering

The current-limiting fuse uses silica (SiO2)-sand as arc quenching medium to increase a current-limiting performance during the DC arc quenching process. In order to increase the current-limiting performance of the fuse, a detailed understanding of an arc resistance (Formula presented.) rise process is necessary. This paper first carried out a 1000 A DC Cu arc quenching experiment using the silica-sand to obtain transient change in (Formula presented.), morphology of the arc, and arc temperature (Formula presented.) during the arc quenching process. As a result, a current decaying increased (Formula presented.). The arc was maintained in the cavity surrounded by the fulgurite during the current decaying process. The temperature of Cu/SiO2 arc was 25–8 kK at a current region of 950–400 A during the arc quenching process. Second, we theoretically calculated an electrical resistivity (Formula presented.), and a thermal diffusivity (Formula presented.) as vapor properties for the Cu/SiO2 vapor mixture. As typical results, the admixing of the SiO2 vapor into the Cu arc less increased (Formula presented.) of the Cu/SiO2 vapor mixture at (Formula presented.) between 25 and 5 kK. The (Formula presented.) of the Cu/SiO2 vapor mixture drastically increased due to only decay in (Formula presented.). In contrast, the admixing of the SiO2 vapor into the Cu arc significantly increased (Formula presented.) at (Formula presented.) between 15 and 8 kK. The present results indicate that an increase in (Formula presented.) and consequent rise in thermal energy dissipation from the arc is the main role of the silica-sand vapor mixed with Cu arc in the DC fuse during the arc quenching process. The increased thermal energy dissipation due to the SiO2 vapor admixing further decreases (Formula presented.) to rapidly rise (Formula presented.) and (Formula presented.) during the arc quenching process. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

DOI： 10.1002/tee.24156

Web of Science

Scopus

電力ケーブル終端接続部でアークが発生した場合の内部圧力上昇推定手法の開発

富田雄大, 横水康伸, 兒玉直人, 三木栄治, 八木正史

Proceedings of the 14th International Workshop on High Voltage Engineering 2024年11月

Reaction products and withstanding electric field properties of arc quenching air mixed with CH2O vapor decomposition -Comparison with other polymer vapors-

山本伊織, 横水康伸, 兒玉直人, 大野拓也, 江戸貴広

Proceedings of the 14th International Workshop on High Voltage Engineering 2024年11月

Simultaneous Estimation of Transient Arc Diameter, Electrical Resistivity and Temperature based on High-Speed Camera Observation for High-Temperature Cu/SiO2 Mixture Arc Generated inside Modeled DC Fuse

2024年11月

Numerical Calculation of High-Temperature Properties of Hot-Gases and Arc Discharges Formed in Electric Fuse 招待有り査読有り

Naoto Kodama

Proceedings of The 8th Annual Conference of the Division of Plasma Physics of the Association of Asia Pacific Physics Society 2024年11月

Optimized sequence control of a fuse-semiconductor hybrid circuit breaker through real-time fuse state estimation 査読有り国際誌

SONGAH SHIN, Reon Sasaki, Yusuke Nakano, Shungo Zen, Naoto Kodama, Yasushi Yamano, Yuki Inada, Wataru Ohnishi

Proceedings of the 50th Annual Conference of the IEEE Industrial Electronics Society 2024年11月

故障発生時における正極負極間電力配分を考慮した双極多端子直流送電システム制御手法の基礎検討

中村綾花, 岩田幹正, 横水康伸, 兒玉直人

電気学会研究会資料電力技術/電力系統技術合同研究会 2024年9月

Additive effect of silicone resin on direct current arc quenching performance of a model electric fuse: electrical resistivity and thermal diffusivity of high-temperature Cu/SiO2 vapor mixed with C2H6SiO vapor decomposition 招待有り査読有り国際誌 Open Access

Takenaka, W; Kodama, N; Yokomizu, Y; Hasegawa, K; Nakamura, K; Iwata, M

JAPANESE JOURNAL OF APPLIED PHYSICS 63 巻 ( 9 ) 2024年9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：Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers

Concerning DC fuses equipped with silica sand (SiO2) as an arc quenching material, the authors have proposed an additive installation of silicone resin (C2H6SiO) on a fuse-element surface to improve the limitation and interruption ability of high DC. This paper describes the additive effect of the silicone resin on the transient resistance of the arc that has formed during the DC interrupting process in a model fuse, based on the measurement result that the arc resistance markedly rises with the silicone mass coated on the fuse element. This phenomenon is subsequently explained as resulting from a thermal diffusivity of high-temperature C2H6SiO/SiO2/Cu vapor. In other words, the mixing of C2H6SiO decomposition vapor into the arc can promote vapor temperature decay through the higher thermal diffusivity, resulting in a rapid increase in the electrical resistivity of the vapor during the DC interrupting process.

DOI： 10.35848/1347-4065/ad7432

Open Access

Web of Science

Scopus

Power Flow Control and Mode-Switching Method Considering Single-Pole Trip for Bipolar MTDC System 査読有り国際誌

Nakamura A., Iwata M., Yokomizu Y., Kodama N.

Proceedings of the 2024 International Conference on Sustainable Energy: Energy Transition and Net-Zero Climate Future, ICUE 2024 2024年9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）出版者・発行元：Proceedings of the 2024 International Conference on Sustainable Energy: Energy Transition and Net-Zero Climate Future, ICUE 2024

Due to the advantage of the system operation reliability and flexibility, the bipolar multi-terminal high voltage dc (MTDC) transmission has attracted worldwide attention for the integration of offshore windfarms. However, majority of existing operation methods and dc power flow algorithms are designed to control the monopolar MTDC system. It is difficult to implement the conventional control method for the monopolar system into the bipolar system due to the difference in the characteristics of dc power flow control scheme between the two configurations. Therefore, this paper proposes an operation method of the bipolar MTDC system composed of the dc power flow control scheme and mode-switching method. As a simulation result, the proposed method can realize the power sharing between each VSC and reduce the impact of the active power fluctuation on the AC grid connected to the system even when the single-pole trip occurs in the bipolar MTDC system.

DOI： 10.1109/ICUE63019.2024.10795532

Scopus

直流限流遮断における高分子材配置による効果の出現とアーク抵抗急増域

清水翔太，横水康伸，兒玉直人，岩田幹正，中村綾花，酒井智康，塚原正浩，宮本淳史

電気学会研究会資料放電・プラズマ・パルスパワー/静止器/開閉保護合同研究会 2024年8月

高温ドライエアへの高分子分解蒸気CH2O混入による反応生成物および耐電界特性 --他種高分子分解蒸気との比較--

山本伊織, 横水康伸, 兒玉直人, 大野拓也, 江戸貴広

電気学会研究会資料放電・プラズマ・パルスパワー/静止器/開閉保護合同研究会 2024年8月

純水を消弧材とした限流ヒューズの遮断試験

小林泰平，兒玉直人，山田圭矢，山田雄大，野々山颯太，前山光明，山納康，稲田優貴

2024年8月

限流ヒューズ内で生じる直流アークの遮断に対するポリイミド樹脂と純水の試適用