Faculty Profiles - KOJIMA Hiroki

The progressive development of HVDC transmission system has urged us to develop a novel technique in supporting the performance of DC power apparatus. Functionally Graded Materials (FGM) are one of the techniques that allow us to control the electric field distribution within the DC insulation system. Our previous works have analytically revealed that FGM with spatial permittivity ε and conductivity σ distributions applied to a 320 kV DC-GIS spacer could reduce the maximum electric field under all DC operating conditions. In this paper, we fabricated a cone-type ε/σ-FGM spacer for DC-GIS and experimentally verified its flashover voltage improvement effect.

DOI： 10.23919/ISEIM60444.2023.10329009

Scopus

放電・プラズマ・パルスパワー分野における研究・技術開発の歩み今後の展望 Invited

小島寛樹，佐々木徹，高橋克幸，稲田優貴，中川雄介，中野裕介

令和5年電気学会基礎・材料・共通部門大会 2023.9.8 電気学会基礎・材料・共通部門

真空中沿面放電の初期進展過程における電子軌道追跡による過渡帯電・発光特性

杉浦拓真，小島寛樹，早川直樹，中野裕介

令和5年電気学会基礎・材料・共通部門大会 2023.9.7 電気学会基礎・材料・共通部門

回転機絶縁システムへの適用を目指したセルロースナノファイバー複合体の基礎特性

岩永拓実，山下優，岡本徹志，小島寛樹，早川直樹，古田尚，奥村浩史，安食厚志，山中雄太，梅本貴弘

令和5年電気学会基礎・材料・共通部門大会 2023.9.9 電気学会基礎・材料・共通部門

DC-GIS用ε/σ-FGMスペーサの作製および直流耐圧向上効果

杉本遼次，加藤拓夢，小島寛樹，早川直樹

令和5年電気学会電力・エネルギー部門大会 2023.9.6 電気学会電力・エネルギー部門

高融点陰極表面への低融点陽極材料の付着による真空中コンディショニング効果の抑制

北直樹，小島寛樹，福田英昭，山村健太，早川直樹

令和5年電気学会電力・エネルギー部門大会 2023.9.6 電気学会電力・エネルギー部門

真空中高周波交流コンディショニングにおける耐圧向上効果の周波数および印加電圧依存性

小名木良太，小島寛樹，飯塚伸介，小林将人，早川直樹

令和5年電気学会電力・エネルギー部門大会 2023.9.6 電気学会電力・エネルギー部門

Temperature Rise in Conductivity Graded Materials (σ-FGM) Spacer for HVDC GIS/GIL International conference

Rachmawati, H. Kojima, N. Hayakawa, H. Okubo

23rd International Symposium on High Voltage Engineering 2023.8.29 The Department of Electronic and Electrical Engineering of the University of Strathclyde

Event date： 2023.8 - 2023.9

Language：English Presentation type：Oral presentation (general)

Venue：Glasgow Country：United Kingdom

Functionally graded permittivity and conductivity materials (ε/σ-FGM) application is a novel method to improve electric field distribution around HVDC GIS/GIL spacer. Since there is interdependency between temperature and conductivity, in this paper, the relationship between conductivity and the semi-conductive SiC filler concentrations in epoxy-based ε/σ-FGM spacer is clarified, and the effect of SiC filler concentrations to the leakage current (ILC), maximum temperature (Tmax), as well as maximum conductivity (σmax) are investigated through electric field and thermal simulation. The simulation results revealed that Tmax started to exceed the temperature of HV conductor when σmax exceeds 4×10-9 S/m and ILC is of a few hundreds of nA. Since this criterion corresponds to 21 vol% SiC-filled epoxy composite in σ-FGM, 5–10 vol% SiC-filled epoxy composite in the specified U-type σ-FGM spacer has low enough conductivity not to cause temperature rise.

DOI： 10.1049/icp.2024.0516

Scopus

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