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JP3911119B2 - Current limiter - Google Patents

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JP3911119B2
JP3911119B2 JP2000299929A JP2000299929A JP3911119B2 JP 3911119 B2 JP3911119 B2 JP 3911119B2 JP 2000299929 A JP2000299929 A JP 2000299929A JP 2000299929 A JP2000299929 A JP 2000299929A JP 3911119 B2 JP3911119 B2 JP 3911119B2
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current
current limiting
magnetic field
limiting element
parallel
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JP2002112454A (en
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充 森田
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Nippon Steel Corp
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Nippon Steel Corp
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02E40/60Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment

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Description

【0001】
【発明の属する技術分野】
本発明は、超伝導−常伝導転移型限流器に関するものである。
【0002】
【従来の技術】
電力回路で短絡事故が発生すると、極めて大きな短絡電流が流れる。短絡電流は遮断機によって遮断されるが、数十msは短絡電流が流れてしまうため、大きな電磁力と多量のジュール熱が発生し、電力機器や電路が大きな機械的・熱的損傷を受ける。このような事故発生時の短絡電流を抑えて遮断機の責務を軽減する事故時限流器(限流器)の開発が望まれている。また、このような限流器は各種送配電系統の安定化に寄与するところは極めて大きく、系統の複雑化が進む今日、限流器の早期実現が期待されている。
【0003】
限流器には多くの方式のものが提案されているが、本発明者等も、ミアンダ形状を有する超伝導バルク材料を用いた超伝導−常伝導転移型で抵抗型の限流器を提案している。例えば、Y系のバルク酸化物超伝導材料をミアンダ形状に加工し、これに限流動作時のバイパス回路としてNiCrの板を接続すると同時に、異常電流が流れた瞬間に超伝導材料に磁場を印加するための小型マグネットを取付け限流器を提案し、性能評価を行っている(第61回1999年度秋期低温工学・超伝導学会講演概要集P181および第62回2000年度春期低温工学・超伝導学会講演概要集P233)。また、特開平2000-32654号公報には、REBa2Cu3O7-x(ここでREはY、Pr、Nd、Sm、Eu、Gd、Dy、Ho、Er、Tm、Yb,Luから選ばれる1種類以上の元素を示す)相中にRE2BaCuO5が微細分散した酸化物超伝導体を用いた超伝導−常伝導転移型限流素子のc軸方向に、異常電流検出時に外部磁場を印加し、クエンチを助長することで、均等にかつ高速の限流動作が得られる限流器も提案している。
このように限流素子である超伝導材料に磁場を印加することで、異常電流検出時に良好な限流特性が得られることが知られている。
【0004】
【発明が解決しようとする課題】
異常電流検出後の酸化物超伝導材料への磁場印加は、より均一な常伝導転移をもたらし、素子の損傷を防止する他、より高速の限流動作を導き、超伝導限流器には極めて有効であるが、さらに有効性を増すために、より強い磁場を高速に印加する必要がある。強い磁場を印加するには、大電流を通電するとともにコイルの巻き数を増やす必要がある。しかしながら、巻き数を増やすとインダクタンスが増大し、磁場が立ち上がるまでの時間が長くなってしまう。そこで、より効率のよい磁場の印加方法やより均一な常伝導転移をもたらすバイパス回路の付与が重要な技術課題となる。
本発明は、このような課題を解決し、電流容量の大きい超伝導体を用いた応答が早い限流器を提供するものである。
【0005】
【課題を解決するための手段】
(1) 板状又は膜状の超伝導−常伝導転移型限流素子と、該限流素子の板面又は膜面に対して、平行磁場を印加する磁場印加機構と、異常電流検出機構と、を有し、前記磁場印加機構は、正常電流通電時に、前記限流素子の通電方向に対し、平行な磁場(縦磁場)を印加し、前記異常電流検出機構が異常電流を検出した場合に、前記限流素子の通電方向に対し、垂直方向の磁場(横磁場)を印加することを特徴とする限流器。
(2) 前記磁場印加機構は、前記縦磁場を印加する永久磁石を有することを特徴とする(1)に記載の限流器。
(3) 前記異常電流検出機構が異常電流を検出した場合に、前記磁場印加機構が、正常電流通電時に印加する縦磁場を打消す方向に、新たに縦磁場を印加する機構を備えることを特徴とする(1)又は(2)に記載の限流器。
【0006】
(4) 板状又は膜状の超伝導−常伝導転移型限流素子と、超伝導−常伝導転移検出機構と、前記限流素子に並列に接続した少なくとも1つのバイパス回路と、誘導電流発生用トランスと、前記転移検出機構の検出信号により前記トランスの一次コイルに通電する機構と、を有し、前記バイパス回路が、前記トランスの二次コイルを形成し、前記限流素子に通電方向に対して垂直方向の磁場(横磁場)を印加する誘導電流を流すことを特徴とする限流器。
(5) 前記限流素子が、単結晶状のREBa2Cu37-x(ここで、REは、Y、La、Pr、Nd、Sm、Eu、Gd、Dy、Ho、Er、Tm、Yb及びLuから選ばれる1種類以上の元素を示す)相中にRE2BaCuO5が分散してなる超伝導バルク材料であることを特徴とする(1)〜(4)の何れか1つに記載の限流器。
(6) 前記超伝導バルク材料中のREBa2Cu37-x相のc軸が、前記限流素子の板面又は膜面の法線に対して、平行であることを特徴とする(5)に記載の限流器。
(7) 板状又は膜状の超伝導−常伝導転移型限流素子と、該限流素子に並列に接続したバイパス回路と、該バイパス回路にバイパス電流が流れた場合に、該限流素子の通電方向に対し、垂直方向の磁場(横磁場)を印加する磁場印加機構と、を有し、前記限流素子が、単結晶状のREBa2Cu37-x(ここで、REは、Y、La、Pr、Nd、Sm、Eu、Gd、Dy、Ho、Er、Tm、Yb及びLuから選ばれる1種類以上の元素を示す)相中にRE2BaCuO5が分散してなる超伝導バルク材料であり、REBa2Cu37-x相のc軸が、前記限流素子の板面又は膜面の法線に対して、平行であることを特徴とする限流器。
(8) 前記横磁場が、前記限流素子の板面又は膜面の法線と平行であることを特徴とする(7)に記載の限流器。
(9) 前記限流素子が、実質的にミアンダ形状を有してなることを特徴とする(1)〜(8)の何れか1つに記載の限流器。
(10) 前記ミアンダ形状を有する限流素子内の折り返し部間に並列に接続した少なくとも1つのバイパス回路と、少なくとも該バイパス回路がバイパスする限流素子部位以外の限流素子部位にバイパス電流よる磁場を印加する機構と、を有することを特徴とする(9)に記載の限流器。
(11) 前記ミアンダ形状を有する限流素子内の折り返し部間に並列に接続した少なくとも1つのバイパス回路に誘導電流を流す機構を有することを特徴とする(9)に記載の限流器。
【0007】
【発明の実施の形態】
磁場印加用コイルを板および膜状の超伝導−常伝導限流素子に対し配置する場合、狭い領域に磁場を集中できることから、図1(a)のように、コイルを板および膜面に平行に磁場を印加する方が、図1(b)のように、コイルを板および膜面に垂直に磁場を印加するより、強い磁場が得られやすく、かつインダクタンスを小さくできるため、立ち上がりの速い磁場印加が可能となる。図1(a)に示すような配置の場合、発生磁界と垂直なコイル断面内の磁場空間のアスペクト比(図中の幅(a)/高さ(b))がより大きい方が良いが、コイルの内部に膜または板状の限流素子を挿入することから4以上であることが望ましい。
【0008】
通電方向に対し垂直でかつ、板および膜面に平行な磁場を印加することにより、限流素子の臨界電流密度は低下する。したがって、異常電流検出時にこのような磁場を印加することにより、限流素子の常伝導転移を助長し、素早い限流動作が可能となる。ここで、異常電流検出の基準としては、次の三つがある。
(1)ある一定値以上の電流値の検出
(2)ある一定値以上の電流の上昇率の検出
(3)素子内の超伝導−常伝導転移の検出
【0009】
一方、通電方向に対し平行でかつ、板および膜面に平行な磁場(縦磁場)を印加することにより、限流素子の臨界電流密度は増大する(縦磁場効果)。したがって、通常通電時にこのような磁場を印加することにより、限流素子の交流損失を低減し、高効率の限流器が可能となる。また、縦磁場の印加方法として、磁束トラップ式のバルクマグネットを含む永久磁石等を用いることにより、さらに高効率化することができる。
【0010】
さらに、通常通電時に縦磁場を印加する機構を有し、かつ異常電流検出時に通電方向に対し垂直で、板および膜面に平行な磁場を印加すると同時に通常通電時の縦磁場を打ち消す縦磁場を印加することにより、さらに優れた限流特性を有する。また、このような限流器は、両機構の特長を兼ね備えると同時に限流器の設計に融通性を持たせることが可能となる。
【0011】
ミアンダ形状を有する限流素子は、二次元的な構造を有することから、板および膜状の素子に包含される。また、通電方向は一次元的(一軸方向)であるために、ミアンダ形状の限流素子全体に同一方向の磁場を印加することで、素子の大部分に縦磁場効果を発生させることができる。このようなことは渦巻き状等の形状では不可能である。
【0012】
素子の限流動作を素早く行うには、素子の超伝導転移が伝播する機構を設けれることが有用である。図2のように、各限流素子と並列にかつ、離散的に接続されたバイパス回路にバイパス電流が流れることによって他の限流素子に磁場が印加される機構を設けることにより、ある一本の素子(または、素子の一部分)が常伝導転移し、バイパス回路であるコイルに大きな電流が流れることにより、他の素子または、常伝導転移していない素子の一部分)に常伝導転移を助長する方向で磁場(横磁場)が印加されると、他の素子(または、素子の一部分)の常伝導転移が起こりやすくなる。これにより、次々に常伝導転移が伝播しやすくなり、より高速の限流動作が実現する。
【0013】
異常電流検出時に板および膜状限流素子と平行な横磁場(クエンチアシスト用磁場)を印加する場合で、かつバイパス回路であるコイルによる発生磁場(クエンチ伝播用磁場)が板および膜状限流素子と平行な横磁場の場合、通電電流の極性を検出し、それぞれの横磁場が強め合う方向となるようにコイルに通電しなければならない。これに対し、異常電流検出時に板および膜状限流素子と平行な横磁場を印加する場合で、かつクエンチ伝播用磁場が板および膜状限流素子と垂直な横磁場の場合、それぞれの横磁場が直交するために、通電電流の極性とは無関係に強め合う方向に働く、そのため極性を検出し、コイル電流の極性を切り替える機構が不要になる。
【0014】
図2中には右隣の素子に対して磁場が印加される機構を示したが、両隣または、クエンチした素子自身も含め他の複数の素子にクエンチ伝播用磁場が印加される機構でも良い。
ミアンダ形状等を有する限流素子では、ミアンダ状限流素子内で発生した超伝導−常伝導転移にともなうバイパス電流を、各限流素子(折り返し間の素子部)の長手方向と垂直にアスペクト比の大きなコイルを設け、各折り返し間の一部に横磁場を集中的に印加することが容易にできる。これにより、素子内の多数の箇所を一度に常伝導転移させ、そこを起点に各折り返し間内で常伝導転移させることにより、より均一な限流動作が可能となる。
【0015】
また、図3のように、各限流素子と並列にかつ、離散的に接続されたバイパス回路にトランスを介して外部電源から通電することによって、誘導電流が他の限流素子に通電される機構を設け常伝導転移を均一化することができる。すなわち、ある一本の素子(または素子の一部分)が常伝導転移すると、これにともなう電圧を検知し、外部電源から誘導電流発生用のトランスに通電すことにより、バイパス回路である誘導コイルに大きな電流が流れ、常伝導転移していない素子(または常伝導転移していない素子の一部分)にはインピーダンスが小さいため、優先的に常伝導転移を助長する方向で多くの誘導電流が流れる。この機構により、他の素子(または素子の一部分)の常伝導転移が起こりやすくなり、より高速の限流動作が実現する。
【0016】
外部電源を用いずに、局部的な超伝導−常伝導転移にともなうバイパス電流により、誘導電流を発生させ均一な電流動作させる方法は、特開2000-37034号に開示されている。しかしながら、この方法では、誘導電流発生用トランスにバイパス回路の電流を供給しており、外部電源から電流を供給していないため、各限流素子に供給される誘導電流は不十分であり、クエンチの均一化にほとんど寄与しない。また、限流動作は、商用周波数において、半サイクル以内、望ましくは1msで動作する必要があるため、外部電源を用い立ち上がりの早い十分な誘導電流を各素子に供給する必要がある。
これらのバイパス電流による磁場アシストおよび誘導電流通電機構は、それぞれ並列および直列で組み合わせてもクエンチの均一化に寄与できる。
【0017】
単結晶状のREBa2Cu3O7-x(ここでREはY、La、Pr、Nd、Sm、Eu、Gd、Dy、Ho、Er、Tm、Yb、Luから選ばれる1種類以上の元素を示す)相中にRE2BaCuO5が分散したバルク材料や高度に配向したREBa2Cu3O7-x膜などのREBa2Cu3O7-x相からなる超伝導−常伝導転移型限流素子においては、REBa2Cu3O7-xの二次元的な結晶構造から、a-b軸方向 が通電方向として適している。したがってREBa2Cu3O7-xのc軸が板および膜面の法線に対し平行であることをが必要である。
【0018】
また、c軸が板および膜面の法線に対し平行で、かつ、板および膜面の法線に対し平行に磁場を印加する場合、磁場はc軸に対し垂直に印加されることになる。従来は、c軸に平行な磁場に対し、超伝導は最も弱いとされていたが、我々の検討結果では、c軸と垂直方向の磁場印加も同程度の効果があることが確認された。
【0019】
【実施例】
(実施例1)
YBa2Cu3O7-x中にY2BaCuO5が微細分散したバルク材料(Y系QMG)を用い、電流路断面積が2mm2の有効長さが約300mmで、表面に厚さ約5μmのAg-Au合金の薄膜を有するミアンダ形状の限流素子を作製した。この時、YBa2Cu3O7-xのc軸は 板面の法線に対し平行であった。図4に限流素子の形状を示す。限流素子の折り返し部分に電極を取付け繊維強化プラスチック(FRP)と樹脂により補強した。 つぎに、折り返し部分の電極間に銅線からなる2.5回巻きのコイルを取付けそれ ぞれ右隣の素子にミアンダ材の板面に対し平行でかつ、通電電流に対して垂直な磁場(クエンチ伝播用磁場)が印加されるようにした。図5に補強されかつコイル状のバイパス回路を取り付けられた限流素子の形状を示す。
【0020】
補強された限流素子に対して板面に対し平行でかつ、通電電流に対して、ほぼ垂直な磁場(クエンチアシスト用磁場)を印加するために、図6のように銅線を300回巻いた試料1を作製した。また、同様に銅線をY系QMGに置き換えた10回巻 きのコイルを有する試料2を作製した。この時折り返し部分は銅を使用し、半田により接続した。さらに、銅線および磁場印加用Y系QMGに樹脂を含浸し固定した。これら二つの試料のコイル内の磁場空間のアスペクト比は25であった。
【0021】
限流素子(試料1、試料2)は通電実験用電源に取り付けられるとともに、ある一定値以上の電流(異常電流)を検知すると同時に、その極性を判断して、限流素子が常伝導転移したときに流れるバイパス電流による磁界(クエンチ伝播用磁場)とクエンチアシスト用磁場とが強め合う方向に通電するように限流器を構成した。試料1に対してはコイル銅線に50Aを、試料2に対してはQMGコイルに1500Aを通電し、それぞれの試料にほぼ同じ強度の磁場を印加できるように構成し た。
【0022】
試料1は77Kに冷却され、以下の通電実験を行った。事故時を想定して、限流素子がない場合の異常電流を模擬した図7に示す電流を通電した(符号19)。位相が30度のところで電流が急増している。次に限流素子を挿入し、同様の通電を行い限流特性を試験した。そのときの各位置での電流および印加磁場の時間変化を図7に示す(符号20)。電流が2100Aに達してから、0.1msec以内に0.8Tが印加され、約2.5msec以内に限流動作がほぼ完了していることを確認した。また、試料2についても同様の結果が得られたが、コイルが超伝導体で構成されているため、磁場印加時の液体窒素の蒸発量は、試料1に比べ小さくすることができた。これらの実験から、限流素子の板面に対し平行な磁場を印加することにより、高速でかつ大きな限流効果を達成できることが分かった。
【0023】
(実施例2)
DyBa2Cu3O7-x中にDy2BaCuO5が微細分散したバルク材料(Dy系QMG)を用い、電流路断面積が2mm2の有効長さが約300mmで、表面に厚さ約5μmのAg合金の薄膜を有する実施例1と同様のミアンダ形状限流素子を作製した。この時、DyBa2Cu3O7-xのc軸は板面の法線に対し平行であった。限流素子の折り返し部分に電極を取付けFRPと樹脂により補強した。つぎに、折り返し部分の電極間に銅線からなる3.5回巻きのコイルを各右隣の素子にミアンダ材の板面に対し垂直でかつ、通電電流に対して垂直な磁場(クエンチ伝播用磁場)が印加されるように素子の両面から取付けた。図8に補強されかつコイル状のバイパス回路を取り付けられた限流素子の形状を示す。
【0024】
補強された限流素子に対して板面に対し平行でかつ、通電電流に対して垂直な磁場を印加するために、実施例1と同様に、図6のように銅線を300回巻いた。さらに、試料ホルダーに取付け、限流素子に対して板面に対し平行でかつ、通電電流に対して平行な磁場(縦磁場)を打ち消すための磁場(縦磁場キャンセル用磁場)を印加するために、銅線を100回巻いた試料3を作製した。
【0025】
試料3は、Sm-Co系の永久磁石間に配置され、限流素子の通電方向と平行に磁 場(縦磁場)が印加できるように構成した。また、試料3は、通電実験用電源に取り付けられるとともに、ある一定値以上の電流(異常電流)を検知し、限流素子が常伝導転移したときに流れるバイパス電流による磁場(クエンチ伝播用磁場)とクエンチアシスト用磁場とが直交するように限流器を構成されている。
【0026】
試料3は77Kに冷却され、以下の通電実験を行った。事故時を想定して、限流素子がない場合の異常電流を模擬した図9に示す電流を通電した(符号22)。位相が45度のところで電流が急増している。次に限流素子を挿入し、同様の通電を行い限流特性を試験した。そのときの各位置での電流および印加磁場の時間変化を図9に示す(符号23)。電流が2300Aに達してから、0.1msec以内に1.2Tが印加され、約2.5msec以内に限流動作がほぼ完了していることを確認した。
これらの実験から限流素子の板面に対し平行な磁場を印加することにより、高速でかつ大きな限流効果を達成できることが分かった。
【0027】
(実施例3)
(Y0.5Er0.5)Ba2Cu3O7-x中に(Y0.5Er0.5)2BaCuO5が微細分散したバルク材料(Y・Er系QMG)を用い、電流路断面積が2mm2の有効長さが約300mmで、表面に厚さ約5μmのAg-Pt合金の薄膜を有する実施例1と同様のミアンダ形状を有する限流素子を作製した。この時、(Y0.5Er0.5)Ba2Cu3O7-xのc軸は板面の法線に対し平行であった。限流素子の折り返し部分に電極を取付けFRPと樹脂により補強した。つぎに、折り返し部分の電極間に銅線からなる3.5回巻きのコイルを各右隣の素子にミアンダ材の板面に対し垂直でかつ、通電電流に対して垂直な磁場(クエンチ伝播用磁場)が印加されるように素子の両面から取付けた。
【0028】
補強された限流素子の板面に対し平行でかつ、通電電流に対して垂直な磁場を印加するために、実施例1と同様に図6のように銅線を250回巻いた。さらに、 ホルダーに取付け、限流素子の板面に対し平行でかつ、通電電流に対して平行な磁場(縦磁場)を打ち消すための磁場(縦磁場キャンセル用磁場)を印加するために、銅線を用い80回巻いた。このコイル断面の磁場空間のアスペクト比は4であった。これを一旦、FRPと樹脂により再度補強した。さらに図11に示すように 、各電極にトランスを接続し限流素子を構成した。この限流素子は、図10に示すような等価回路を構成するように、2個のトランスの1次側入力端子を外部電源に対し並列に接続した。このトランス回路により、ある一本の素子が常伝導転移し、外部電源から電流が供給され、他の素子に常伝導転移を助長する方向で誘導電流が流れると、他の素子の常伝導転移がさらに起こりやすくなり、次々に常伝導転移が伝播し、より高速の限流動作が実現する。
【0029】
試料4は、Pr系の永久磁石間に配置され、限流素子の通電方向と平行に磁場(縦磁場)が印加できるように構成した。また、試料4は、通電実験用電源に取り付けられるとともに、ある一定値以上の電流(異常電流)を検知し、限流素子が常伝導転移したときに流れるバイパス電流による磁界(クエンチ伝播用磁場)とクエンチアシスト用磁場とが直交するように限流器を構成した。
【0030】
試料4は77Kに冷却され、以下の通電実験を行った。事故時を想定して、限流素子がない場合の異常電流を模擬した図12に示す電流を通電した(符号33)。位相が45度のところで電流が急増している。次に限流素子を挿入し、同様の通電を行い限流特性を試験した。そのときの各位置での電流および印加磁場の時間変化を図12に示す(符号34)。電流が2300Aに達してから、0.1msec以内に1.0Tが印加され、約2.0msec以内に限流動作がほぼ完了していることを確認した。
これらの実験から限流素子の板面に対し平行な磁場を印加することにより、高速でかつ大きな限流効果を達成できることが分かった。
【0031】
【発明の効果】
以上で述べたように、本発明は、限流素子の迅速な限流動作を行うようことを特徴とする限流器を提供するものであり、その工業的効果は甚大である。
【図面の簡単な説明】
【図1】 (a) 素子の板面に対して平行に磁場を印加する場合の模式図。
(b) 従来の磁場印加方法。素子の板面に対して垂直に磁場を印加する場合の 模式図。
【図2】ある素子または素子の一部分の常伝導転移にともなうバイパス電流により他 の素子または素子の一部分に磁場を印加し、常伝導転移を伝播する機構。
【図3】ある素子または素子の一部分の常伝導転移にともなうバイパス電流により他 の素子または素子の一部分に誘導電流を流し常伝導転移を伝播する機構。
【図4】実施例で用いたミアンダ形状を限流素子の形状(単位はmm)。
【図5】 FRPと樹脂補強され、かつ板面に平行な磁場印加するためのクエンチ伝播用の コイルが巻かれた限流素子。
【図6】クエンチアシスト用の銅線または超伝導バルクからなるコイルが巻かれた限流素子。
【図7】実施例1における限流特性を示した図。
【図8】 FRPと樹脂補強され、かつ板面に垂直な磁場印加するためのクエンチ伝播用の コイルが巻かれた限流素子。
【図9】実施例2における限流特性を示した図。
【図10】ある素子または素子の一部分の常伝導転移にともなうバイパス電流により他の素子または素子の一部分に磁場を印加し、さらに誘導電流を流すことにより、常伝導転移を伝播する機構。
【図11】トランスを用いて、素子または素子の一部の常伝導転移にともなうバイパス電流により他の素子または素子の一部分に磁場を印加し、さらに誘導電流を流すことにより、常伝導転移を伝播するために、トランスと限流素子との接続の様子。
【図12】実施例3における限流特性を示した図。
【符号の説明】
1 板状の超伝導限流素子
2 板面に平行な磁場を印加するためのコイル
3 板状の超伝導限流素子
4 板面に垂直な磁場を印加するためのコイル
5 超伝導限流素子
6 バイパス電流によって、磁場を印加するためのコイル
7 限流素子中の常伝導転移した部分
8 隣接した超伝導限流素子に印加される磁場
9 超伝導限流素子
10 誘導電流を印加するためのトランス
11 限流素子中の常伝導転移した部分
12 バイパス電流により素子に通電される誘導電流
13 クエンチ検出器
14 誘導電流発生用外部電源
15 バイパス電流により板面に平行な磁場を印加するコイル(クエンチ伝播用コイル)
16 FRP
17 電極
18 板面に平行な磁場を印加するためのコイル(クエンチアシスト用コイル)
19 実施例1における限流素子がない場合の電流の変化
20 実施例1における限流素子(試料1)を取り付けた場合の電流の変化
21 バイパス電流により板面に垂直な磁場を印加するコイル(クエンチ伝播用コイル)
22 実施例2における限流素子がない場合の電流の変化
23 実施例2における限流素子(試料3)を取り付けた場合の電流の変化
24 1次コイル
25 外部電源
26 2次コイルおよびバイパス回路
27 限流素子中の常伝導転移した部分
28 隣接した超伝導限流素子に印加される磁場
29 超伝導限流素子
30 誘導電流を印加するためのトランス
31 実施例3記載のトランス
32 1次側入力端子
33 実施例3における限流素子がない場合の電流の変化
34 実施例3における限流素子(試料4)を取り付けた場合の電流の変化
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a superconducting-normal conducting transition type current limiting device.
[0002]
[Prior art]
When a short circuit accident occurs in the power circuit, a very large short circuit current flows. Although the short-circuit current is interrupted by the circuit breaker, since the short-circuit current flows for several tens of milliseconds, a large electromagnetic force and a large amount of Joule heat are generated, and the power equipment and the electric circuit are seriously damaged mechanically and thermally. Development of an accident time limiter (current limiter) that reduces the duty of the breaker by suppressing the short-circuit current at the time of such an accident is desired. In addition, such a current limiter contributes greatly to the stabilization of various power transmission and distribution systems, and today, with the increasing complexity of the system, early realization of the current limiter is expected.
[0003]
Many types of current limiters have been proposed, but the present inventors also proposed a superconducting-normality transition type resistance type current limiting device using a superconducting bulk material having a meander shape. is doing. For example, a Y-based bulk oxide superconducting material is processed into a meander shape, and a NiCr plate is connected to this as a bypass circuit during current limiting operation, and at the same time an abnormal current flows, a magnetic field is applied to the superconducting material. Proposal of a current limiter with a small magnet attached to it (see 61st 1999 Fall Cryogenics / Superconductivity Society P181 and 62nd 2000 Spring Cryogenics / Superconductivity Society) Lecture Summary Collection P233). JP 2000-32654 discloses REBa 2 Cu 3 O 7-x (where RE is selected from Y, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu) In the c-axis direction of a superconducting-normal conduction transition type current limiting device using an oxide superconductor in which RE 2 BaCuO 5 is finely dispersed in the phase), an external magnetic field is detected when an abnormal current is detected. We have also proposed a current limiter that applies uniform current and promotes quenching to achieve uniform and high-speed current limiting operation.
It is known that by applying a magnetic field to a superconducting material that is a current limiting element in this way, good current limiting characteristics can be obtained when detecting an abnormal current.
[0004]
[Problems to be solved by the invention]
Applying a magnetic field to the oxide superconducting material after detecting an abnormal current leads to a more uniform normal-conducting transition and prevents damage to the device. Although effective, it is necessary to apply a stronger magnetic field at high speed in order to further increase the effectiveness. In order to apply a strong magnetic field, it is necessary to energize a large current and increase the number of turns of the coil. However, when the number of turns is increased, the inductance increases and the time until the magnetic field rises becomes longer. Therefore, it is important to provide a more efficient magnetic field application method and a bypass circuit that provides a more uniform normal conduction transition.
The present invention solves such problems and provides a current limiter using a superconductor having a large current capacity and quick response.
[0005]
[Means for Solving the Problems]
(1) A plate-like or film-like superconducting-normal conduction transition type current limiting element, a magnetic field applying mechanism for applying a parallel magnetic field to the plate surface or film surface of the current limiting element, an abnormal current detecting mechanism, The magnetic field application mechanism applies a magnetic field (longitudinal magnetic field) parallel to the energization direction of the current limiting element during normal current energization, and the abnormal current detection mechanism detects an abnormal current. A current limiting device, wherein a magnetic field (transverse magnetic field) in a vertical direction is applied to the energizing direction of the current limiting element.
(2) The current limiter according to (1), wherein the magnetic field application mechanism includes a permanent magnet that applies the longitudinal magnetic field.
(3) When the abnormal current detection mechanism detects an abnormal current, the magnetic field application mechanism includes a mechanism that newly applies a longitudinal magnetic field in a direction that cancels the longitudinal magnetic field applied when normal current is applied. The current limiting device according to (1) or (2).
[0006]
(4) A plate-like or film-like superconducting-normal conduction transition type current limiting element, a superconducting-normal conduction transition detecting mechanism, at least one bypass circuit connected in parallel to the current limiting element, and induction current generation And a mechanism for energizing the primary coil of the transformer according to a detection signal of the transition detection mechanism, and the bypass circuit forms a secondary coil of the transformer, and in the energization direction of the current limiting element On the other hand, a current limiter is characterized in that an induced current is applied to apply a vertical magnetic field (transverse magnetic field).
(5) The current limiting element is a single-crystal REBa 2 Cu 3 O 7-x (where RE is Y, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Any one of (1) to (4), characterized in that it is a superconducting bulk material in which RE 2 BaCuO 5 is dispersed in a phase (showing one or more elements selected from Yb and Lu). The current limiter described.
(6) The c-axis of the REBa 2 Cu 3 O 7-x phase in the superconducting bulk material is parallel to the normal of the plate surface or film surface of the current limiting element ( The current limiting device according to 5).
(7) A plate-like or film-like superconducting-normal conduction transition type current limiting element, a bypass circuit connected in parallel to the current limiting element, and when a bypass current flows through the bypass circuit, the current limiting element A magnetic field application mechanism that applies a vertical magnetic field (transverse magnetic field) with respect to the energization direction, and the current limiting element is a single crystal REBa 2 Cu 3 O 7-x (where RE is , Y, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Lu) (represented by RE 2 BaCuO 5 dispersed in the phase) A current limiter, which is a conductive bulk material, wherein the c-axis of the REBa 2 Cu 3 O 7-x phase is parallel to the normal of the plate surface or film surface of the current limiting element.
(8) The current limiter according to (7), wherein the transverse magnetic field is parallel to a normal line of a plate surface or a film surface of the current limiting element.
(9) The current limiting device according to any one of (1) to (8), wherein the current limiting element substantially has a meander shape.
(10) At least one bypass circuit connected in parallel between the folded portions in the current limiting element having the meander shape, and a magnetic field due to a bypass current in at least a current limiting element part other than the current limiting element part bypassed by the bypass circuit The current limiting device according to (9), further comprising:
(11) The current limiter according to (9), further including a mechanism for causing an induced current to flow through at least one bypass circuit connected in parallel between the folded portions in the current limiting element having the meander shape.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
When the magnetic field application coil is arranged on a plate and a film-like superconducting-normal current limiting element, the magnetic field can be concentrated in a narrow region, so that the coil is parallel to the plate and the film surface as shown in FIG. As shown in Fig. 1 (b), a strong magnetic field can be easily obtained and the inductance can be reduced by applying a magnetic field to the coil and the plate and the film surface as shown in Fig. 1 (b). Application is possible. In the case of the arrangement shown in FIG. 1 (a), the aspect ratio (width (a) / height (b) in the figure) of the magnetic field space in the coil cross section perpendicular to the generated magnetic field is better. Since a film or plate-like current limiting element is inserted into the coil, the number is preferably 4 or more.
[0008]
By applying a magnetic field perpendicular to the energizing direction and parallel to the plate and the film surface, the critical current density of the current limiting element is lowered. Therefore, by applying such a magnetic field at the time of detecting an abnormal current, the normal conduction transition of the current limiting element is promoted, and a quick current limiting operation becomes possible. Here, there are the following three standards for detecting abnormal current.
(1) Detection of current value above a certain value (2) Detection of current increase rate above a certain value (3) Detection of superconducting-normal conduction transition in the device
On the other hand, by applying a magnetic field (longitudinal magnetic field) parallel to the energization direction and parallel to the plate and the film surface, the critical current density of the current limiting element increases (longitudinal magnetic field effect). Therefore, by applying such a magnetic field during normal energization, the AC loss of the current limiting element is reduced, and a highly efficient current limiting device is possible. Further, by using a permanent magnet including a magnetic flux trap type bulk magnet as a method of applying a longitudinal magnetic field, the efficiency can be further increased.
[0010]
Furthermore, it has a mechanism that applies a longitudinal magnetic field during normal energization, and a vertical magnetic field that cancels the longitudinal magnetic field during normal energization at the same time as applying a magnetic field that is perpendicular to the energizing direction and that is parallel to the plate and film surface when an abnormal current is detected. By applying, it has further excellent current limiting characteristics. In addition, such a current limiter combines the features of both mechanisms and at the same time allows flexibility in the design of the current limiter.
[0011]
Since the current limiting element having a meander shape has a two-dimensional structure, it is included in a plate and a film-like element. In addition, since the energization direction is one-dimensional (uniaxial direction), a longitudinal magnetic field effect can be generated in most of the elements by applying a magnetic field in the same direction to the entire meander-shaped current limiting element. Such a thing is impossible with a spiral shape.
[0012]
In order to quickly perform the current limiting operation of the element, it is useful to provide a mechanism for propagating the superconducting transition of the element. As shown in FIG. 2, by providing a mechanism in which a magnetic field is applied to other current limiting elements when a bypass current flows in a bypass circuit discretely connected in parallel with each current limiting element, The element (or a part of the element) undergoes a normal conduction transition, and a large current flows through the coil that is the bypass circuit, thereby promoting the normal conduction transition to another element or a part of the element that has not undergone the normal conduction transition. When a magnetic field (transverse magnetic field) is applied in the direction, normal transition of other elements (or part of the elements) is likely to occur. As a result, the normal transition is easily propagated one after another, and a faster current limiting operation is realized.
[0013]
When an abnormal current is detected, a transverse magnetic field (quenching assist magnetic field) parallel to the plate and film current limiting element is applied, and the magnetic field generated by the bypass circuit coil (quenching propagation magnetic field) is the plate and film current limiting. In the case of a transverse magnetic field parallel to the element, the polarity of the energization current must be detected, and the coil must be energized so that the transverse magnetic fields are in a direction in which each other strengthens. On the other hand, when a transverse magnetic field parallel to the plate and the film current limiting element is applied at the time of detecting an abnormal current, and the quench propagation magnetic field is a transverse magnetic field perpendicular to the plate and the film current limiting element, Since the magnetic fields are orthogonal to each other, they work in directions that reinforce each other regardless of the polarity of the energized current, and therefore a mechanism for detecting the polarity and switching the polarity of the coil current is not necessary.
[0014]
Although FIG. 2 shows a mechanism in which a magnetic field is applied to the adjacent element on the right, a mechanism in which a quench propagation magnetic field is applied to both adjacent elements or a plurality of other elements including the quenched element itself may be used.
In a current limiting element having a meander shape, etc., the aspect ratio perpendicular to the longitudinal direction of each current limiting element (element part between folds) can be reduced by bypassing the superconducting-normal conducting transition generated in the meandering current limiting element. It is possible to easily apply a transverse magnetic field intensively to a part between the turns. As a result, a more uniform current limiting operation can be performed by causing a normal conduction transition at a large number of locations in the element at a time, and a normal conduction transition between each turn from that point.
[0015]
In addition, as shown in FIG. 3, by passing current from an external power source through a transformer to a bypass circuit that is discretely connected in parallel with each current limiting element, the induced current is supplied to other current limiting elements. A mechanism can be provided to make the normal conduction transition uniform. That is, when a certain element (or a part of the element) transitions to normal conduction, a voltage associated with this element is detected, and an induction current generation transformer is energized from an external power supply, thereby causing a large induction coil as a bypass circuit. Since the current flows and the impedance of the element that is not in the normal conduction transition (or a part of the element that is not in the normal conduction transition) is small, a large amount of induced current flows preferentially in the direction that promotes the normal conduction transition. By this mechanism, normal conduction transition of other elements (or a part of the elements) is likely to occur, and higher speed current limiting operation is realized.
[0016]
Japanese Unexamined Patent Publication No. 2000-37034 discloses a method for generating an induced current by a bypass current associated with a local superconducting-normal conducting transition without using an external power source, and performing a uniform current operation. However, in this method, since the current of the bypass circuit is supplied to the transformer for generating the induced current and no current is supplied from the external power source, the induced current supplied to each current limiting element is insufficient, and the quenching is performed. Hardly contributes to the homogenization. Further, the current limiting operation needs to operate within half a cycle, preferably 1 ms, at the commercial frequency, and therefore, it is necessary to supply a sufficient induced current with a fast rise to each element using an external power supply.
These magnetic field assist and induced current conduction mechanisms by bypass current can contribute to uniform quenching even when combined in parallel and in series.
[0017]
Single crystalline REBa 2 Cu 3 O 7-x (where RE is one or more elements selected from Y, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu) Superconducting-normal conduction transition type limit consisting of REBa 2 Cu 3 O 7-x phase such as bulk material in which RE 2 BaCuO 5 is dispersed in the phase and highly oriented REBa 2 Cu 3 O 7-x film In the flow element, the ab axis direction is suitable as the energization direction because of the two-dimensional crystal structure of REBa 2 Cu 3 O 7-x . Therefore, it is necessary that the c-axis of REBa 2 Cu 3 O 7-x is parallel to the normal of the plate and the film surface.
[0018]
When the c-axis is parallel to the normal of the plate and the film surface and the magnetic field is applied parallel to the normal of the plate and the film surface, the magnetic field is applied perpendicular to the c-axis. . Conventionally, superconductivity was considered to be the weakest against a magnetic field parallel to the c-axis, but our examination results confirmed that the application of a magnetic field in the direction perpendicular to the c-axis has the same effect.
[0019]
【Example】
(Example 1)
Using a bulk material (Y-based QMG) in which Y 2 BaCuO 5 is finely dispersed in YBa 2 Cu 3 O 7-x , the effective length of the current path cross-sectional area is 2 mm 2 is about 300 mm, and the thickness is about 5 μm on the surface. A meander-shaped current limiting element having a thin film of Ag-Au alloy was fabricated. At this time, the c-axis of YBa 2 Cu 3 O 7-x was parallel to the normal of the plate surface. FIG. 4 shows the shape of the current limiting element. An electrode was attached to the folded part of the current limiting element and reinforced with fiber reinforced plastic (FRP) and resin. Next, a 2.5-turn coil made of copper wire is attached between the electrodes at the folded part, and a magnetic field (quenching propagation) parallel to the meandering plate surface and perpendicular to the energizing current is applied to each element on the right. Magnetic field) was applied. FIG. 5 shows the shape of a current limiting element reinforced and provided with a coiled bypass circuit.
[0020]
In order to apply a magnetic field (quenching assist magnetic field) that is parallel to the plate surface and substantially perpendicular to the energized current to the reinforced current limiting element, a copper wire is wound 300 times as shown in FIG. Sample 1 was prepared. Similarly, Sample 2 having a 10-turn coil in which the copper wire was replaced with Y-based QMG was produced. At this time, the folded portion was made of copper and connected by solder. Further, a copper wire and a magnetic field applying Y-based QMG were impregnated with resin and fixed. The aspect ratio of the magnetic field space in the coil of these two samples was 25.
[0021]
The current limiting elements (sample 1 and sample 2) are attached to the power supply for the energization experiment, and at the same time as detecting a current (abnormal current) above a certain value, the polarity is judged and the current limiting element is changed to the normal conduction state. The current limiter was configured to energize in the direction in which the magnetic field (quenching propagation magnetic field) due to the bypass current flowing occasionally and the quench assisting magnetic field strengthen each other. For sample 1, 50A was applied to the coiled copper wire, and for sample 2, 1500A was applied to the QMG coil, and a magnetic field having substantially the same strength was applied to each sample.
[0022]
Sample 1 was cooled to 77K and the following energization experiment was conducted. In the event of an accident, the current shown in FIG. 7 simulating an abnormal current in the absence of a current limiting element was applied (reference numeral 19). The current increases rapidly when the phase is 30 degrees. Next, a current limiting element was inserted and the same current was applied to test the current limiting characteristics. FIG. 7 shows the time change of the current and the applied magnetic field at each position (reference numeral 20). After the current reached 2100A, 0.8T was applied within 0.1msec, and it was confirmed that the current limiting operation was almost completed within about 2.5msec. Similar results were obtained for sample 2, but the amount of liquid nitrogen evaporated when a magnetic field was applied was smaller than that of sample 1 because the coil was made of superconductor. From these experiments, it was found that a large current limiting effect can be achieved at high speed by applying a magnetic field parallel to the plate surface of the current limiting element.
[0023]
(Example 2)
Using a bulk material (Dy-based QMG) in which Dy 2 BaCuO 5 is finely dispersed in DyBa 2 Cu 3 O 7-x , the effective length of the current path cross-sectional area is 2 mm 2 is about 300 mm, and the thickness is about 5 μm on the surface. A meander-type current limiting element similar to Example 1 having a thin film of an Ag alloy was prepared. At this time, the c-axis of DyBa 2 Cu 3 O 7-x was parallel to the normal of the plate surface. An electrode was attached to the folded part of the current limiting element and reinforced with FRP and resin. Next, a 3.5-turn coil made of copper wire is placed between the electrodes at the folded part, and the magnetic field perpendicular to the energizing current (magnetic field for quench propagation) is perpendicular to the plate surface of the meander material on each right adjacent element. It was attached from both sides of the element so that was applied. FIG. 8 shows the shape of a current limiting element reinforced and provided with a coiled bypass circuit.
[0024]
In order to apply a magnetic field parallel to the plate surface and perpendicular to the energizing current to the reinforced current limiting element, a copper wire was wound 300 times as in FIG. . In order to apply a magnetic field (vertical magnetic field canceling magnetic field) for canceling the magnetic field (longitudinal magnetic field) that is attached to the sample holder and is parallel to the plate surface and parallel to the energizing current with respect to the current limiting element. The sample 3 which wound the copper wire 100 times was produced.
[0025]
Sample 3 was arranged between Sm—Co permanent magnets and configured to apply a magnetic field (longitudinal magnetic field) parallel to the energization direction of the current limiting element. Sample 3 is attached to a power supply for energization experiment, detects a current (abnormal current) of a certain value or more, and a magnetic field due to a bypass current that flows when the current limiting element transitions to normal conduction (quenching propagation magnetic field) And the quench assist magnetic field are configured to be orthogonal to each other.
[0026]
Sample 3 was cooled to 77K, and the following energization experiment was conducted. Assuming an accident, the current shown in FIG. 9 simulating an abnormal current when there is no current limiting element was applied (reference numeral 22). The current increases rapidly when the phase is 45 degrees. Next, a current limiting element was inserted and the same current was applied to test the current limiting characteristics. The time change of the current and the applied magnetic field at each position at that time is shown in FIG. 9 (reference numeral 23). It was confirmed that 1.2T was applied within 0.1msec after the current reached 2300A, and the current limiting operation was almost completed within about 2.5msec.
From these experiments, it was found that a large current limiting effect can be achieved at high speed by applying a magnetic field parallel to the plate surface of the current limiting element.
[0027]
Example 3
(Y 0.5 Er 0.5 ) Ba 2 Cu 3 O 7-x (Y 0.5 Er 0.5 ) 2 BaCuO 5 bulk material (YEr-based QMG) finely dispersed, current path cross-sectional area 2 mm 2 effective A current limiting element having a meander shape similar to that of Example 1 having a thin film of Ag—Pt alloy having a length of about 300 mm and a thickness of about 5 μm was prepared. At this time, the c-axis of (Y 0.5 Er 0.5 ) Ba 2 Cu 3 O 7-x was parallel to the normal of the plate surface. An electrode was attached to the folded part of the current limiting element and reinforced with FRP and resin. Next, a 3.5-turn coil made of copper wire is placed between the electrodes at the folded part, and the magnetic field perpendicular to the energizing current (magnetic field for quench propagation) is perpendicular to the plate surface of the meander material on each right adjacent element. It was attached from both sides of the element so that was applied.
[0028]
In order to apply a magnetic field parallel to the plate surface of the reinforced current limiting element and perpendicular to the energization current, a copper wire was wound 250 times as in FIG. Furthermore, in order to apply a magnetic field (longitudinal magnetic field canceling magnetic field) for canceling the magnetic field (longitudinal magnetic field) that is attached to the holder and is parallel to the plate surface of the current limiting element and parallel to the energizing current, Wound 80 times. The aspect ratio of the magnetic field space of this coil cross section was 4. This was once reinforced again with FRP and resin. Further, as shown in FIG. 11, a current limiting element was constructed by connecting a transformer to each electrode. In this current limiting element, primary side input terminals of two transformers are connected in parallel to an external power source so as to form an equivalent circuit as shown in FIG. With this transformer circuit, when one element changes to normal conduction, current is supplied from an external power supply, and when an induced current flows in a direction that promotes normal conduction to another element, the normal conduction transition of the other element occurs. It becomes more likely to occur, and the normal conduction transition propagates one after another, realizing a faster current limiting operation.
[0029]
Sample 4 was arranged between Pr permanent magnets and configured to apply a magnetic field (longitudinal magnetic field) parallel to the energization direction of the current limiting element. Sample 4 is attached to a power supply for energization experiment, detects a current (abnormal current) of a certain value or more, and magnetic field due to a bypass current that flows when the current limiting element transitions to normal conduction (quenching propagation magnetic field). The current limiting device was constructed so that the quench assist magnetic field was orthogonal.
[0030]
Sample 4 was cooled to 77K, and the following energization experiment was conducted. In the event of an accident, the current shown in FIG. 12 simulating the abnormal current when there is no current limiting element was applied (reference numeral 33). The current increases rapidly when the phase is 45 degrees. Next, a current limiting element was inserted and the same current was applied to test the current limiting characteristics. FIG. 12 shows changes over time in the current and applied magnetic field at each position (reference numeral 34). It was confirmed that 1.0T was applied within 0.1msec after the current reached 2300A, and the current limiting operation was almost completed within about 2.0msec.
From these experiments, it was found that a large current limiting effect can be achieved at high speed by applying a magnetic field parallel to the plate surface of the current limiting element.
[0031]
【The invention's effect】
As described above, the present invention provides a current limiter characterized in that the current limiting device performs a rapid current limiting operation, and its industrial effect is enormous.
[Brief description of the drawings]
FIG. 1A is a schematic diagram when a magnetic field is applied parallel to the plate surface of an element.
(b) Conventional magnetic field application method. Schematic diagram when applying a magnetic field perpendicular to the plate surface of the element.
FIG. 2 is a mechanism for applying a magnetic field to another element or part of an element by a bypass current accompanying the normal conduction transition of an element or part of an element and propagating the normal transition.
FIG. 3 is a mechanism for propagating a normal transition by causing an induced current to flow through another element or a part of an element by a bypass current associated with the normal transition of an element or a part of an element.
FIG. 4 shows the meander shape used in the embodiment as the shape of the current limiting element (unit: mm).
FIG. 5 is a current limiting element in which a coil for quench propagation for applying a magnetic field parallel to the plate surface is reinforced with FRP and resin.
FIG. 6 shows a current limiting element in which a coil made of a copper wire or a superconducting bulk for quench assist is wound.
7 is a graph showing current limiting characteristics in Example 1. FIG.
FIG. 8 shows a current limiting element in which a coil for quench propagation is applied to apply a magnetic field perpendicular to the plate surface, which is reinforced with FRP and resin.
FIG. 9 is a diagram showing current limiting characteristics in Example 2.
FIG. 10 is a mechanism for propagating a normal transition by applying a magnetic field to another element or a part of the element by a bypass current accompanying a normal conduction transition of a certain element or a part of the element and flowing an induced current.
FIG. 11 Using a transformer, propagates a normal conduction transition by applying a magnetic field to another element or a part of the element by a bypass current accompanying a normal conduction transition of the element or a part of the element, and further causing an induced current to flow. To connect the transformer and the current limiting element.
12 is a graph showing current limiting characteristics in Example 3. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Plate-shaped superconducting current limiting element 2 Coil for applying a magnetic field parallel to the plate surface 3 Plate-shaped superconducting current limiting device 4 Coil for applying a magnetic field perpendicular to the plate surface 5 Superconducting current limiting device 6 Coil for applying magnetic field by bypass current 7 Normal conduction transition portion 8 in current limiting element 8 Magnetic field applied to adjacent superconducting current limiting element 9 Superconducting current limiting element
10 Transformer for applying induced current
11 Normal conduction transition in current limiting element
12 Inductive current that is passed through the element by bypass current
13 Quench detector
14 External power supply for inductive current generation
15 Coil that applies a magnetic field parallel to the plate surface by bypass current (coil for quench propagation)
16 FRP
17 electrodes
18 Coil for applying a magnetic field parallel to the plate surface (quenching assist coil)
19 Current change without current limiting element in Example 1
20 Changes in current when the current limiting element (sample 1) in Example 1 is attached
21 Coil that applies magnetic field perpendicular to the plate surface by bypass current (coil for quench propagation)
22 Current change without current limiting element in Example 2
23 Current change when the current limiting element (sample 3) in Example 2 is attached
24 Primary coil
25 External power supply
26 Secondary coil and bypass circuit
27 Normal conduction transition in current limiting element
28 Magnetic field applied to adjacent superconducting current limiting element
29 Superconducting current limiting element
30 Transformer for applying induced current
31 Transformer described in Example 3
32 Primary side input terminal
33 Current change without current limiting element in Example 3
34 Current change when the current limiting element (sample 4) in Example 3 is attached

Claims (11)

板状又は膜状の超伝導−常伝導転移型限流素子と、
該限流素子の板面又は膜面に対して、平行磁場を印加する磁場印加機構と、
異常電流検出機構と、
を有し、
前記磁場印加機構は、
正常電流通電時に、前記限流素子の通電方向に対し、平行な磁場(縦磁場)を印加し、
前記異常電流検出機構が異常電流を検出した場合に、前記限流素子の通電方向に対し、垂直方向の磁場(横磁場)を印加することを特徴とする限流器。
A plate-like or film-like superconducting-normal conducting transition type current limiting element;
A magnetic field application mechanism for applying a parallel magnetic field to the plate surface or film surface of the current limiting element;
An abnormal current detection mechanism;
Have
The magnetic field application mechanism is
Applying a magnetic field (longitudinal magnetic field) parallel to the current-carrying direction of the current limiting element during normal current application,
A current limiter, wherein when the abnormal current detection mechanism detects an abnormal current, a vertical magnetic field (transverse magnetic field) is applied to the energization direction of the current limiting element.
前記磁場印加機構は、前記縦磁場を印加する永久磁石を有することを特徴とする請求項1に記載の限流器。  The current limiting device according to claim 1, wherein the magnetic field application mechanism includes a permanent magnet that applies the longitudinal magnetic field. 前記異常電流検出機構が異常電流を検出した場合に、前記磁場印加機構が、正常電流通電時に印加する縦磁場を打消す方向に、新たに縦磁場を印加する機構を備えることを特徴とする請求項1又は2に記載の限流器。  When the abnormal current detection mechanism detects an abnormal current, the magnetic field application mechanism includes a mechanism that newly applies a longitudinal magnetic field in a direction that cancels the longitudinal magnetic field applied when normal current is applied. Item 5. A current limiting device according to item 1 or 2. 板状又は膜状の超伝導−常伝導転移型限流素子と、
超伝導−常伝導転移検出機構と、
前記限流素子に並列に接続した少なくとも1つのバイパス回路と、
誘導電流発生用トランスと、
前記転移検出機構の検出信号により前記トランスの一次コイルに通電する機構と、
を有し、
前記バイパス回路が、前記トランスの二次コイルを形成し、前記限流素子に通電方向に対して垂直方向の磁場(横磁場)を印加する誘導電流を流すことを特徴とする限流器。
A plate-like or film-like superconducting-normal conducting transition type current limiting element;
Superconducting to normal conducting transition detection mechanism,
At least one bypass circuit connected in parallel to the current limiting element;
An induction current generating transformer;
A mechanism for energizing the primary coil of the transformer by a detection signal of the transition detection mechanism;
Have
The current limiting device, wherein the bypass circuit forms a secondary coil of the transformer, and an induced current is applied to the current limiting element to apply a magnetic field (transverse magnetic field) perpendicular to the energizing direction.
前記限流素子が、単結晶状のREBa2Cu37-x(ここで、REは、Y、La、Pr、Nd、Sm、Eu、Gd、Dy、Ho、Er、Tm、Yb及びLuから選ばれる1種類以上の元素を示す)相中にRE2BaCuO5が分散してなる超伝導バルク材料であることを特徴とする請求項1〜4の何れか1項に記載の限流器。The current limiting element is a single crystal REBa 2 Cu 3 O 7-x (where RE is Y, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu. A current limiting device according to any one of claims 1 to 4, wherein the current limiting device is a superconducting bulk material in which RE 2 BaCuO 5 is dispersed in a phase. . 前記超伝導バルク材料中のREBa2Cu37-x相のc軸が、前記限流素子の板面又は膜面の法線に対して、平行であることを特徴とする請求項5に記載の限流器。6. The c-axis of the REBa 2 Cu 3 O 7-x phase in the superconducting bulk material is parallel to the normal line of the plate surface or film surface of the current limiting element. The current limiter described. 板状又は膜状の超伝導−常伝導転移型限流素子と、
該限流素子に並列に接続したバイパス回路と、
該バイパス回路にバイパス電流が流れた場合に、該限流素子の通電方向に対し、垂直方向の磁場(横磁場)を印加する磁場印加機構と、
を有し、
前記限流素子が、単結晶状のREBa2Cu37-x(ここで、REは、Y、La、Pr、Nd、Sm、Eu、Gd、Dy、Ho、Er、Tm、Yb及びLuから選ばれる1種類以上の元素を示す)相中にRE2BaCuO5が分散してなる超伝導バルク材料であり、REBa2Cu37-x相のc軸が、前記限流素子の板面又は膜面の法線に対して、平行であることを特徴とする限流器。
A plate-like or film-like superconducting-normal conducting transition type current limiting element;
A bypass circuit connected in parallel to the current limiting element;
A magnetic field application mechanism that applies a magnetic field in a vertical direction (transverse magnetic field) to the energizing direction of the current limiting element when a bypass current flows through the bypass circuit;
Have
The current limiting element is a single crystal REBa 2 Cu 3 O 7-x (where RE is Y, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu. A superconducting bulk material in which RE 2 BaCuO 5 is dispersed in a phase), and the c-axis of the REBa 2 Cu 3 O 7-x phase is the plate of the current limiting element. A current limiting device characterized by being parallel to a normal of a surface or a membrane surface.
前記横磁場が、前記限流素子の板面又は膜面の法線と平行であることを特徴とする請求項7に記載の限流器。  The current limiting device according to claim 7, wherein the transverse magnetic field is parallel to a normal line of a plate surface or a film surface of the current limiting element. 前記限流素子が、実質的にミアンダ形状を有してなることを特徴とする請求項1〜8の何れか1項に記載の限流器。  The current limiting device according to claim 1, wherein the current limiting element has a meander shape substantially. 前記ミアンダ形状を有する限流素子内の折り返し部間に並列に接続した少なくとも1つのバイパス回路と、
少なくとも該バイパス回路がバイパスする限流素子部位以外の限流素子部位にバイパス電流よる磁場を印加する機構と、
を有することを特徴とする請求項9に記載の限流器。
At least one bypass circuit connected in parallel between the folded portions in the current limiting element having the meander shape;
A mechanism for applying a magnetic field due to a bypass current to at least a current limiting element part other than the current limiting element part bypassed by the bypass circuit;
The current limiting device according to claim 9, comprising:
前記ミアンダ形状を有する限流素子内の折り返し部間に並列に接続した少なくとも1つのバイパス回路に誘導電流を流す機構を有することを特徴とする請求項9に記載の限流器。  The current limiter according to claim 9, further comprising a mechanism for causing an induced current to flow in at least one bypass circuit connected in parallel between the folded portions in the current limiting element having the meander shape.
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