報告書番号

W97024

タイトル（和文）

超電導磁気遮へい型限流器の定常時の損失特性

タイトル（英文）

LOSS CHARACTERISTICS OF MAGNETIC SHIELDING TYPE SUPERCONDUCTING FAULT CURRENT LIMITERS UNDER STEADY STATE CONDITIONS

概要 （図表や脚注は「報告書全文」に掲載しております）

高温超電導体の電力機器への応用の一環として，現用送電系統の短絡電流の抑制，および，将来導入が期待されている超電導機器の保護を目指し，超電導磁気しゃへい型減流器の開発を進めている。これまで，限流器要素モデルを試作し基本的な限流動作などを明らかにするとともに，４００Ａ級減流器モデルの試設計を行ってきた。今回，定常運転状態における限流器の発生損失を明らかにし，以下の結果が得られた。（１）定常時に超電導円筒体で発生する損失は，超電導のヒステリシス損失と比べてかなり大きい。したがって超電導円筒体での損失はしゃへい電流による損失であると考えられる。（２）要素モデルで測定した損失を用いて，４００Ａ級限流器モデルの定常時の損失を計算した。その結果，限流器のインピーダンス電圧は一般的な変圧器に比べて十分小さいことが分かった。しかし，限流器は系統へ直列に挿入される機器であるから，一層の損失低減が必要である。

概要 （英文）

WE HAVE BEEN DEVELOPING SUPERCONDUCTING FAULT CURRENT LIMITERS AS AN APPLICATION OF HIGH-TC SUPERCONDUCTORS FOR ELECTRIC POWER APPARATUS TO SUPPRESS SHORT-CIRCUIT CURRENTS IN EXISTING TRANSMISSION SYSTEMS AND TO PROTECT SUPERCONDUCTING APPARATUS EXPECTED TOBE INTRODUCED IN THE FUTURE. SO FAR, ELEMENTS OF FAULT CURRENT LIMITERS MANUFACTURED EXPERIMENTALLY TO CLARIFY BASIC FAULT CURRENT LIMITING ACTIONS, ETC., AND A 400-A FAULT CURRENT LIMITER MODEL HAS BEEN DESIGNEDEXPERIMENTALLY. TO DEVELOP PRACTICAL FAULT CURRENT LIMITERS, IT IS IMPORTANT TO CLARIFY THE LOSSES GENERATED IN THE STEADY STATE, THE THERMALCHARACTERISTICS AT FAULT CURRENT LIMITING ACTIONS, ETC. WE MEASURED THE LOSSES GENERATED IN A MAGNETIC SHIELDING TYPE SUPERCONDUCTING FAULT CURRENT LIMITER AT STEADY OPERATION USING A FAULT CURRENT LIMITER ELEMENT MODEL CONSISTING OF A SMALL SUPERCONDUCTING CYLINDER AND A MAIN COIL WOUND AROUND IT. THE FOLLOWING RESULTS WERE OBTAINED: (1) THE LOSSES GENERATED IN THE SUPERCONDUCTING CYLINDER AT STEADY OPERATION ARE FAR LARGER THAN THE HYSTERESIS LOSS. THEREFORE, THE MAIN LOSS IS DUE TO THE SHIELDING CURRENT FLOWING IN THE CYLINDER. SINCE THE LOSS CORRELATES WITHTHE MAGNETIC SHIELDING CHARACTERISTICS, THE CRITICAL CURRENT DENSITY OF THE SUPERCONDUCTOR MUST BE ENHANCED TO IMPROVE THE MAGNETIC SHIELDINGPERFORMANCE AND DECREASIE THE LOSS. (2) TO CLARIFY HOW THE MAGNETIC FLUX PEREHRATES IN THE SUPERCONDUCTING CYLINDER, WE ANALYZED IT BY APPLYING A BEAM MODEL TO THE FINITE ELEMENT METHOD. AS A RESULT, THE PENETRATION OF THE MAGNETIC FLUX COULD BE SIMULATED, AND IT MAY BE POSSIBLE TO ESTIMATE THE LOSS GENERATED IN THE CYLINDER. (3) THE LOSSES MEASURED WITH THE ELEMENT MODEL WERE USED TO CALCULATE THE LOSSES OF THE EXPERIMENTAL 400-A FAULT CURRENT LIMITER IN THE STEADY STATE. AS A RESULT, IT WAS FOUND THAT LEAKAGE IMPEDANCE OF THE FAULT CURRENT LIMITER IS SUFFICIENTLY SMALL COMPARED TO THE IMPEDANCE VOLTAGE OF A GENERAL TRANSFORMER. HOWEVER, IT IS NECESSARY TO FURTHER THE

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