  [研究内容] 超電導応用電力技術の実現のためには，変圧器，限流器，ケーブルなどといった機器単体としてのコンポーネント開発に留まらず，実運用を考慮して，電力システムとの協調を考慮した機器･システム開発の必要がある．特に，超電導電力システム全体としての効率向上を目指すためには，冷却条件なども含めた機器の複合化や機器の統合などの技術開発が重要となる. このような観点から，筆者らは，超電導変圧器に限流機能を複合化した「超電導限流変圧器」(Superconducting Fault Current Limiting Transformer: SFCLT) を提案している． SFCLTは通常運転時に超電導変圧器として動作し，故障時に過電流が通電された場合には超電導限流器として動作する．SFCLTのコンセプトは，変圧器自身の漏れインピーダンスが電力システムにおいて既に故障電流の抑制機能を果たしているという点に着目して発想された．すなわち，変圧器に限流機能を付加させることにより，故障電流の抑制とともに，定常時における漏れインピーダンスを低減することができる．これにより，電力システムにおける定態安定度の向上(変圧器としての漏れインピーダンス低減効果)および過渡安定度の向上(限流器としての故障電流抑制効果)の両立が可能となる．SFCLTの開発により，機器単体としての効率化・小型化という従来のメリットに加え，電力システムの保護・機器の複合化，運用の合理化・高信頼度化という新しいメリットの創成が期待できる． 現在，SFCLT開発プロジェクトのStep-5としYBCOテープ導体を用いた2MVA級SFCLT(3相，22kV/6.6kV)を設計・製作し，無負荷試験，短絡試験および部分負荷試験を行い，設計パラメータの検証および超電導変圧器としての機能を有していることを確認した．今後は，限流試験および超電導復帰試験を行い，超電導限流器として機能を検証していく予定である． [学術論文] (10) K.Omura, H.Kojima, N.Hayakawa, F.Endo, M.Noe and H.Okubo: "Current Limiting Characteristics of Parallel-Connected Coated Conductors for High-Tc Superconducting Fault Current Limiting Transformer (HTc-SFCLT)", IEEE Trans. on Applied Superconductivity, Vol.19, No.3, pp.1880-1883 (2009) (9) H.Kojima, S.Ito, N.Hayakawa, F.Endo, M.Noe and H.Okubo: "Self-recovery Characteristics of High-Tc Superconducting Fault Current Limiting Transformer (HTc-SFCLT) with 2G Coated Conductors", Journal of Physics: Conference Series, No.12154 (2006) (8) H.Okubo, C.Kurupakorn, S.Ito, H.Kojima, N.Hayakawa, F.Endo and M.Noe: "High-Tc Superconducting Fault Current Limiting Transformer (HTc-SFCLT) with 2G Coated Conductor s", IEEE Trans. on Applied Superconductivity, Vol.17, No.2, pp.1768-1771 (2007) (7) C.Kurupakorn, H.Kojima, N.Hayakawa, F.Endo, N.Kashima, S.Nagaya, M.Noe and H.Okubo: "Simulation of electrical and thermal behavior of high temperature superconducting fault current limiting transformer (HTc-SFCLT) ", Journal of Physics: Conference Series 43 pp.950-953 (2006) (6) C.Kurupakorn, H.Kojima, N.Hayakawa, M.Goto, N.Kashima, S.Nagaya, M.Noe, K-P.Juengst and H.Okubo: "Recovery Characteristics after Current Limitation of High Temperature Superconducting Fault Current Limiting Transformer (HTc-SFCLT)", IEEE Trans. on Applied Superconductivity, Vol.15, No.2, pp.1859-1862 (2005) (5) C.Kurupakorn, N.Hayakawa, N.Kashima, S.Nagaya and H.Okubo: "Development of High Temperature Superconducting Fault Current Limiting Transformer (HTc-SFCLT)" Trans. IEEJ-B,, Vol.124, No.10, pp.1193-1199 (2004) (4) C.Kurupakorn, N.Hayakawa, N.Kashima, S.Nagaya, M.Noe, K-P.Juengst and H.Okubo: "Development of High Temperature Superconducting Fault Current Limiting Transformer (HTc-SFCLT) with Bi2212 Bulk Coil", IEEE Transactions on Applied Superconductivity, Vol.14, No.2, pp.900-903 (2004) (3) H.Kagawa, et al: “Experimental Study on Superconducting Fault Current Limiting Transformer (SFCLT) for Fault Current Suppression and System Stability Improvement”, Physica C, Vol.372-376, Part III, pp.1706-1710 (2002) (2) N.Hayakawa, et al: “A System Study on Superconducting Fault Current Limiting Transformer (SFCLT) with the Function of Fault Current Suppression and System Stability Improvement”, IEEE Trans. on Applied Superconductivity, Vol.11, No.1, pp.1936-1939 (2001) (1) N.Hayakawa, et al: “Feasibility Study on Superconducting Fault Current Limiting Transformer (SFCLT)”, Cryogenics, Vol.40, pp.325-331 (2000) [発表実績] (9) M.Kotari, H.Kojima, N.Hayakawa, F.Endo and H.Okubo: "Development of 2 MVA Class Superconducting Fault Current Limiting Transformer (SFCLT) with YBCO Coated Conductors", 9th European Conference on Applied Superconductivity, Dresden Germany (2009) (8) K.Omura, H.Kojima, N.Hayakawa, F.Endo, M.Noe and H.Okubo: "Current Limiting Characteristics of Parallel-Connected Coated Conductors for High-Tc Superconducting Fault Current Limiting Transformer (HTc-SFCLT)", Applied Superconductivity Conference 2008, Chicago USA (2008) (7) H.Kojima, S.Ito, N.Hayakawa, F.Endo, M.Noe and H.Okubo: "Self-recovery Characteristics of High-Tc Superconducting Fault Current Limiting Transformer (HTc-SFCLT) with 2G Coated Conductors", 8th European Conference on Applied Superconductivity, Brussels Belgium (2007) (6) H.Okubo,C. Kurupakorn, S. Ito, H. Kojima, N. Hayakawa, F. Endo, and M. Noe, “High-Tc Superconducting Fault Current Limiting Transformer (HTc-SFCLT) with 2G Coated Conductors”, Applied Superconductivity Conference 2006, Seattle USA (2006) (5) C.Kurupakorn, H.Kojima, N.Hayakawa, F.Endo, N.Kashima, S.Nagaya, M.Noe and H.Okubo, “Simulation of electrical and thermal behavior of High Temperature Superconducting Fault Current Limiting Transformer (HTc-SFCLT)”, 7th European Conference on Applied Superconductivity, Vienna Austria (2005) (4) C.Kurupakorn, H.Kojima, N.Hayakawa, M.Goto, N.Kashima, S.Nagaya, M.Noe, K-P.Juengst and H.Okubo, “Recovery Characteristics after Current Limitation of High Temperature Superconducting Fault Current Limiting Transformer (HTc-SFCLT)”, Applied Superconductivity Conference 2004, Florida USA (2004) (3) C.Kurupakorn, N.Hayakawa, N.Kashima, S.Nagaya, M.Noe, K-P.Juengst and H.Okubo, "Development of High Temperature Superconducting Fault Current Limiting Transformer (HTc-SFCLT) with Bi2212 Bulk Coil", 18th International Conference on Magnet Technology, Morioka Japan (2003) (2) H.Okubo et al: “Development of Superconducting Fault Current Limiting Transformer (SFCLT) with the Functions of Fault Current Suppression and System Stability Improvement”, IEEE PES T&D, Vol.1, pp.301-306 , Yokohama Japan (2002) (1) H.Kagawa, et al: “Experimental Study on Superconducting Fault Current Limiting Transformer (SFCLT) for Fault Current Suppression and System Stability Improvement”, 5th European Conference of Applied Superconductivity, Copenhegen Denmark (2001) |