JP2011083128A - Transmission line protection device - Google Patents

Transmission line protection device Download PDF

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JP2011083128A
JP2011083128A JP2009233737A JP2009233737A JP2011083128A JP 2011083128 A JP2011083128 A JP 2011083128A JP 2009233737 A JP2009233737 A JP 2009233737A JP 2009233737 A JP2009233737 A JP 2009233737A JP 2011083128 A JP2011083128 A JP 2011083128A
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squid
transmission line
current
circuit
power transmission
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JP5100734B2 (en
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Kiyoshi Hata
潔 畑
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Chugoku Electric Power Co Inc
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission line protection device which can protect a superconductive cable with a small scale facility. <P>SOLUTION: The transmission line protection device includes an SQUID provided in refrigerant in order to detect a magnetic field according to the current of a transmission line which is in superconductive state, a bias current circuit which supplies a bias current to the SQUID so that a voltage is induced across the SQUID when the SQUID detects the magnetic field, a coil which generates a magnetic field that cancels the magnetic field detected by the SQUID when a current is supplied, and a control circuit which controls the operation so that the coil is supplied with such a current as bringing the magnetic field detected by the SQUID to zero based on the voltage induced across the SQUID, and a circuit breaker connected in series with the transmission line is interrupted. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、送電線保護装置に関する。   The present invention relates to a power transmission line protection device.

電気所に設けられている送電線保護装置は、例えば送電線に過電流が生じた場合に、送電線に流れる電流を遮断すべく遮断器を制御する。このような送電線保護装置は、送電線に流れる電流を測定する変流器等からの出力に基づいて動作する（例えば、特許文献１参照）。   For example, when an overcurrent occurs in the power transmission line, the power transmission line protection device provided in the electric station controls the circuit breaker to cut off the current flowing through the power transmission line. Such a power transmission line protection device operates based on an output from a current transformer or the like that measures a current flowing through the power transmission line (see, for example, Patent Document 1).

ところで、近年、送電線の一部に超伝導ケーブルが用いられることがある。このような場合であっても、超伝導ケーブルに接続される一般的な送電線を遮断器により遮断することにより、例えば過電流から超伝導ケーブルを保護することができる。   By the way, in recent years, a superconducting cable may be used as a part of the transmission line. Even in such a case, it is possible to protect the superconducting cable from, for example, overcurrent, by interrupting a general power transmission line connected to the superconducting cable with a circuit breaker.

特開平１０−２３６５２号公報JP-A-10-233652

一般に、送電線の一部に超伝導ケーブルを用いた際には、一般的な送電線のみを用いる場合と比較すると設備規模が大きくなる。したがって、送電線の一部に超伝導ケーブルを用いた際には、超伝導ケーブル以外の設備規模を小さくすることが重要となる。   In general, when a superconducting cable is used for a part of a transmission line, the facility scale is larger than when only a general transmission line is used. Therefore, when a superconducting cable is used as a part of the transmission line, it is important to reduce the scale of equipment other than the superconducting cable.

本発明は上記課題を鑑みてなされたものであり、設備規模が小さく、超伝導ケーブルを保護することが可能な送電線保護装置を提供することを目的とする。   The present invention has been made in view of the above problems, and an object of the present invention is to provide a power transmission line protection device having a small equipment scale and capable of protecting a superconducting cable.

上記目的を達成するため、本発明の一つの側面に係る送電線保護装置は、冷媒の中に設けられて超伝導状態となる送電線の電流に応じた磁場を検出すべく、前記冷媒の中に設けられたＳＱＵＩＤと、前記ＳＱＵＩＤが磁場を検出すると前記ＳＱＵＩＤの両端に電圧が発生するよう、前記ＳＱＵＩＤにバイアス電流を供給するバイアス電流回路と、電流が供給されると、前記ＳＱＵＩＤが検出する磁場を打ち消すような磁場を発生するコイルと、前記ＳＱＵＩＤの両端に生じる電圧に基づいて、前記ＳＱＵＩＤが検出する磁場がゼロとなるような電流を前記コイルに供給するとともに前記送電線に直列接続された遮断器を遮断するための制御を行う制御回路と、を備える。   In order to achieve the above object, a power transmission line protection device according to one aspect of the present invention provides a medium in the refrigerant to detect a magnetic field according to a current of a power transmission line that is provided in the refrigerant and is in a superconducting state. The SQUID provided in the SQUID, a bias current circuit for supplying a bias current to the SQUID so that a voltage is generated at both ends of the SQUID when the SQUID detects a magnetic field, and the SQUID detects when a current is supplied. A coil that generates a magnetic field that cancels the magnetic field, and a current that causes the magnetic field detected by the SQUID to be zero based on the voltage generated at both ends of the SQUID are supplied to the coil and are connected in series to the transmission line. And a control circuit for performing control for breaking the circuit breaker.

設備規模が小さく、超伝導ケーブルを保護することが可能な送電線保護装置を提供することができる。   It is possible to provide a power transmission line protection device having a small equipment scale and capable of protecting a superconducting cable.

本発明の一実施形態である送電線保護システム１０の構成を示した図である。It is the figure which showed the structure of the power transmission line protection system 10 which is one Embodiment of this invention. 送電線保護装置４０の一実施形態を示す図である。1 is a diagram illustrating an embodiment of a power transmission line protection device 40. FIG. ＳＱＵＩＤ６０の電流と電圧との関係を示す図である。It is a figure which shows the relationship between the electric current and voltage of SQUID60.

本明細書および添付図面の記載により、少なくとも以下の事項が明らかとなる。   At least the following matters will become apparent from the description of this specification and the accompanying drawings.

図１は、本発明の一実施形態である送電線保護システム１０の構成を示した図である。
送電線保護システム１０は、変電所Ａと、変電所Ｂとの間に設けられた超伝導ケーブル３５に異常が発生した際に、変電所Ａと変電所Ｂとの間に設けられた遮断器２０、または遮断器２１を遮断するシステムである。送電線保護システム１０は、遮断器２０，２１、接続機器２５，２６、送電線３０〜３３、超伝導ケーブル３５、及び送電線保護装置４０，４１を含んで構成される。なお、本実施形態では、送電線３０〜３３は、電気を配電するための一般的な送電線である。 FIG. 1 is a diagram showing a configuration of a power transmission line protection system 10 according to an embodiment of the present invention.
The power transmission line protection system 10 includes a circuit breaker provided between the substation A and the substation B when an abnormality occurs in the superconducting cable 35 provided between the substation A and the substation B. 20 or a circuit breaker 21. The power transmission line protection system 10 includes circuit breakers 20 and 21, connection devices 25 and 26, power transmission lines 30 to 33, a superconducting cable 35, and power transmission line protection devices 40 and 41. In the present embodiment, the power transmission lines 30 to 33 are general power transmission lines for distributing electricity.

遮断器２０は、送電線保護装置４０の制御に基づいて、変電所Ａからの送電線３０と送電線３１との間を遮断する。   The circuit breaker 20 blocks between the power transmission line 30 and the power transmission line 31 from the substation A based on the control of the power transmission line protection device 40.

遮断器２１は、送電線保護装置４１の制御に基づいて、送電線３２と変電所Ｂへの送電線３３との間を遮断する。   The circuit breaker 21 blocks between the power transmission line 32 and the power transmission line 33 to the substation B based on the control of the power transmission line protection device 41.

接続機器２５は、送電線３１と超伝導ケーブル３５とを接続し、接続機器２６は、超伝導ケーブル３５と送電線３２とを接続する。   The connection device 25 connects the power transmission line 31 and the superconducting cable 35, and the connection device 26 connects the superconducting cable 35 and the power transmission line 32.

超伝導ケーブル３５は、液体窒素（冷媒）が充填されるチューブ５０と、チューブ５０の内部に挿通される送電線５１と、を含んで構成される。送電線５１の材質は、例えば９０Ｋ（ケルビン）で超伝導状態となるイットリウム系超伝導体である。本実施形態では、送電線５１は、およそ７７Ｋの液体窒素の中に設けられているため、送電線５１は超伝導状態となる。   The superconducting cable 35 includes a tube 50 filled with liquid nitrogen (refrigerant) and a power transmission line 51 inserted through the tube 50. The material of the power transmission line 51 is, for example, an yttrium-based superconductor that enters a superconducting state at 90 K (Kelvin). In the present embodiment, since the power transmission line 51 is provided in approximately 77K of liquid nitrogen, the power transmission line 51 is in a superconducting state.

送電線保護装置４０は、例えば、超伝導ケーブル３５に過電流が流れる場合やチューブ５０から液体窒素が漏れた場合等の異常を検出すると、遮断器２０を遮断する。送電線保護装置４０は、超電導量子干渉素子（Superconducting Quantum Interference Device：ＳＱＵＩＤ）６０、コイル６１、及び遮断器制御回路６２を含んで構成される。ＳＱＵＩＤ６０及びコイル６１は、チューブ５０の内部に設けられ、遮断器制御回路６２はチューブ５０の外部に設けられている。このため、チューブ５０には、ＳＱＵＩＤ６０及びコイル６１と、遮断器制御回路６２とを接続できるようなポート（不図示）が設けられている。送電線保護装置４０の詳細に関しては後述する。   The power transmission line protection device 40 shuts off the circuit breaker 20 when an abnormality is detected, for example, when an overcurrent flows through the superconducting cable 35 or when liquid nitrogen leaks from the tube 50. The power transmission line protection device 40 includes a superconducting quantum interference device (SQUID) 60, a coil 61, and a circuit breaker control circuit 62. The SQUID 60 and the coil 61 are provided inside the tube 50, and the circuit breaker control circuit 62 is provided outside the tube 50. For this reason, the tube 50 is provided with a port (not shown) through which the SQUID 60, the coil 61, and the circuit breaker control circuit 62 can be connected. Details of the power transmission line protection device 40 will be described later.

送電線保護装置４１は、送電線保護装置４０と同様に、超伝導ケーブル３５の異常を検出すると、遮断器２１を遮断する。送電線保護装置４１は、ＳＱＵＩＤ６５、コイル６６、及び遮断器制御回路６７を含んで構成される。送電線保護装置４０と送電線保護装置４１とは同様の構成であるため、以下送電線保護装置４０の詳細について図２を参照しつつ説明する。   Similarly to the power transmission line protection device 40, the power transmission line protection device 41 interrupts the circuit breaker 21 when detecting an abnormality in the superconducting cable 35. The power transmission line protection device 41 includes a SQUID 65, a coil 66, and a circuit breaker control circuit 67. Since the power transmission line protection device 40 and the power transmission line protection device 41 have the same configuration, the details of the power transmission line protection device 40 will be described below with reference to FIG.

ＳＱＵＩＤ６０は、送電線５１に流れる電流に応じた磁場を検出する磁気センサであり、２つのジョセフソン結合を超伝導ループで結合した構成からなる。ＳＱＵＩＤ６０は、例えばイットリウム系の材質で製造されており、液体窒素中に設けられることにより超伝導状態となる。また、ＳＱＵＩＤ６０に加えられる磁場が無い場合におけるＳＱＵＩＤ６０に流れる電流Ｉ１と、ＳＱＵＩＤ６０の両端に発生する電圧Ｖ１との関係は、図３の実線に示すような波形となる。ここで、ジョセフソン接続が流すことのできる超伝導電流の大きさをＩＡ（絶対値）とすると、ＳＱＵＩＤ６０は、電流Ｉ１が電流値ＩＡよりも小さい場合には超伝導状態となる。このため、電流Ｉ１が電流値ＩＡよりも小さい場合には、電流Ｉ１が増加しても電圧Ｖ１は発生しない。一方、電流Ｉ１が電流値ＩＡよりも大きくなると超伝導状態が壊れ常伝導状態となる。このため、電圧Ｖ１は電流Ｉ１に応じて上昇する。また、ＳＱＵＩＤ６０に磁場が加えられると、ＳＱＵＩＤ６０には磁場を排除するような遮断電流が発生する。この結果、磁場が加えられた際の超伝導電流の大きさは、前述の電流値ＩＡよりも小さくなり、電流Ｉ１と電圧Ｖ１との関係は、図３の点線のようになる。したがって、ＳＱＵＩＤ６０に対し、例えば電流値ＩＡのバイアス電流が供給される場合、ＳＱＵＩＤ６０が磁場を検出すると電圧Ｖ１はゼロから増加することになる。   The SQUID 60 is a magnetic sensor that detects a magnetic field corresponding to a current flowing through the power transmission line 51, and has a configuration in which two Josephson couplings are coupled by a superconducting loop. The SQUID 60 is made of, for example, an yttrium-based material, and enters a superconducting state when provided in liquid nitrogen. Further, the relationship between the current I1 flowing through the SQUID 60 when there is no magnetic field applied to the SQUID 60 and the voltage V1 generated at both ends of the SQUID 60 is a waveform as shown by the solid line in FIG. Here, when the magnitude of the superconducting current that can flow through the Josephson connection is IA (absolute value), the SQUID 60 is in a superconducting state when the current I1 is smaller than the current value IA. For this reason, when the current I1 is smaller than the current value IA, the voltage V1 is not generated even if the current I1 increases. On the other hand, when the current I1 becomes larger than the current value IA, the superconducting state is broken and becomes a normal conducting state. For this reason, the voltage V1 rises according to the current I1. Further, when a magnetic field is applied to the SQUID 60, a blocking current that excludes the magnetic field is generated in the SQUID 60. As a result, the magnitude of the superconducting current when a magnetic field is applied becomes smaller than the above-described current value IA, and the relationship between the current I1 and the voltage V1 is as shown by the dotted line in FIG. Therefore, for example, when a bias current having a current value IA is supplied to the SQUID 60, the voltage V1 increases from zero when the SQUID 60 detects a magnetic field.

コイル６１は、遮断器制御回路６２から電流が供給されると、ＳＱＵＩＤ６０が検出する磁場を打ち消すような磁場を発生する。なお、本実施形態のコイル６１は、後述するＦＬＬ（Flux Locked Loop：磁束ロックループ)回路の一部である。   The coil 61 generates a magnetic field that cancels the magnetic field detected by the SQUID 60 when current is supplied from the circuit breaker control circuit 62. The coil 61 of this embodiment is a part of an FLL (Flux Locked Loop) circuit described later.

遮断器制御回路６２は、ＳＱＵＩＤ６０から出力される磁場の検出結果に基づいて、ＳＱＵＩＤ６０が検出する磁場がゼロとなるような電流をコイル６１に供給する。また、遮断器制御回路６２は、ＳＱＵＩＤ６０から出力される磁場の検出結果に基づいて、送電線５１に異常が生じていることを検出すると、遮断器２０を遮断する。遮断器制御回路６２は、バイアス電流回路７０、電流供給回路７１、電流検出回路７２、比較回路７３、及びタイマ回路７４を含んで構成される。また、電流供給回路７１、電流検出回路７２、比較回路７３、及びタイマ回路７４は制御回路に相当する。   The circuit breaker control circuit 62 supplies a current to the coil 61 such that the magnetic field detected by the SQUID 60 becomes zero based on the detection result of the magnetic field output from the SQUID 60. Moreover, the circuit breaker control circuit 62 will interrupt | block the circuit breaker 20, if it detects that abnormality has arisen in the power transmission line 51 based on the detection result of the magnetic field output from SQUID60. The circuit breaker control circuit 62 includes a bias current circuit 70, a current supply circuit 71, a current detection circuit 72, a comparison circuit 73, and a timer circuit 74. The current supply circuit 71, the current detection circuit 72, the comparison circuit 73, and the timer circuit 74 correspond to a control circuit.

バイアス電流回路７０は、ＳＱＵＩＤ６０が磁場を検出すると電圧Ｖ１がゼロから増加するようなバイアス電流Ｉｂを供給する。本実施形態のバイアス電流Ｉｂは、例えば電流値ＩＡよりも若干小さい電流であることとする。   The bias current circuit 70 supplies a bias current Ib such that the voltage V1 increases from zero when the SQUID 60 detects a magnetic field. The bias current Ib of the present embodiment is a current that is slightly smaller than the current value IA, for example.

電流供給回路７１は、増幅回路８０、積分回路８１、及び抵抗８２を含んで構成される。増幅回路８０は電圧Ｖ１を増幅し、積分回路８１は増幅された電圧Ｖ１を積分する。そして、抵抗８２は、積分回路８１の出力のレベルに応じた電流をコイル６１へと供給する。この結果、コイル６１は、ＳＱＵＩＤ６０が検出する磁場を打ち消すような磁場を発生する。このように、増幅回路８０、積分回路８１、抵抗８２及びコイル６１からなる回路は、ＦＬＬ回路を構成する。したがって、例えば、送電線５１に流れる電流が増加し、ＳＱＵＩＤ６０が検出する磁場が増加すると、電流供給回路７１は増加した磁場に応じて大きくなる電流をコイル６１に供給する。なお、電流供給回路７１が動作し、ＳＱＵＩＤ６０が検出する磁場がゼロとなるような電流がコイル６１に供給されている際には、電圧Ｖ１はゼロとなる。   The current supply circuit 71 includes an amplifier circuit 80, an integration circuit 81, and a resistor 82. The amplifier circuit 80 amplifies the voltage V1, and the integrator circuit 81 integrates the amplified voltage V1. The resistor 82 supplies a current corresponding to the output level of the integrating circuit 81 to the coil 61. As a result, the coil 61 generates a magnetic field that cancels the magnetic field detected by the SQUID 60. As described above, the circuit including the amplification circuit 80, the integration circuit 81, the resistor 82, and the coil 61 constitutes an FLL circuit. Therefore, for example, when the current flowing through the power transmission line 51 increases and the magnetic field detected by the SQUID 60 increases, the current supply circuit 71 supplies the coil 61 with a current that increases according to the increased magnetic field. Note that when the current supply circuit 71 operates and a current is supplied to the coil 61 such that the magnetic field detected by the SQUID 60 is zero, the voltage V1 is zero.

電流検出回路７２（制御信号出力回路）は、例えば、積分回路８１の出力が所定のレベル以上となると、すなわち、コイル６１の電流が所定の電流値Ｉｘ以上となると、遮断器２０を遮断するための制御信号を出力する。なお、所定の電流値Ｉｘは、送電線５１に流れる電流が過電流の際に、電流供給回路７１がコイル６１に供給する電流の値より若干小さくなるよう設定されている。また、所定のレベルは、電流値Ｉｘと抵抗８２の抵抗値との積である。このため、電流検出回路７２は、コイル６１に流れる電流に基づいて送電線５１に流れる電流が過電流であるか否かを確実に検出することができる。   The current detection circuit 72 (control signal output circuit) shuts off the circuit breaker 20 when, for example, the output of the integration circuit 81 becomes a predetermined level or more, that is, when the current of the coil 61 becomes a predetermined current value Ix or more. The control signal is output. The predetermined current value Ix is set to be slightly smaller than the value of the current supplied from the current supply circuit 71 to the coil 61 when the current flowing through the transmission line 51 is an overcurrent. The predetermined level is a product of the current value Ix and the resistance value of the resistor 82. For this reason, the current detection circuit 72 can reliably detect whether the current flowing through the power transmission line 51 is an overcurrent based on the current flowing through the coil 61.

比較回路７３は、電圧Ｖ１を所定レベルの電圧Ｖｘと比較する。ここで、所定レベルの電圧Ｖｘは、常伝導状態のＳＱＵＩＤ６０に対して前述のバイアス電流Ｉｂが供給された際の電圧Ｖ１より若干低い電圧である。このため、ＳＱＵＩＤ６０が検出する磁場がゼロであっても、何らかの影響でＳＱＵＩＤ６０が常伝導状態となると、電圧Ｖ１は電圧Ｖｘより高くなる。一方、ＳＱＵＩＤ６０が検出する磁場がゼロであり、ＳＱＵＩＤ６０が超伝導状態である場合には、電圧Ｖ１は電圧Ｖｘより低くなる。このため、比較回路７３は、電圧Ｖ１に基づいてＳＱＵＩＤ６０が超伝導状態であるか否かを確実に検出することができる。本実施形態の比較回路７３は、電圧Ｖ１が電圧Ｖｘより高い場合、すなわちＳＱＵＩＤ６０が常伝導状態である場合には、例えばＨレベル（ハイレベル）の比較信号を出力する。一方、比較回路７３は、電圧Ｖ１が電圧Ｖｘより低い場合、すなわちＳＱＵＩＤ６０が超伝導状態である場合には、例えばＬレベル（ローレベル）の比較信号を出力する。   The comparison circuit 73 compares the voltage V1 with the voltage Vx at a predetermined level. Here, the predetermined level voltage Vx is slightly lower than the voltage V1 when the aforementioned bias current Ib is supplied to the SQUID 60 in the normal conduction state. For this reason, even if the magnetic field detected by the SQUID 60 is zero, the voltage V1 becomes higher than the voltage Vx when the SQUID 60 is in a normal conduction state due to some influence. On the other hand, when the magnetic field detected by the SQUID 60 is zero and the SQUID 60 is in a superconducting state, the voltage V1 is lower than the voltage Vx. Therefore, the comparison circuit 73 can reliably detect whether or not the SQUID 60 is in the superconducting state based on the voltage V1. The comparison circuit 73 of the present embodiment outputs, for example, an H level (high level) comparison signal when the voltage V1 is higher than the voltage Vx, that is, when the SQUID 60 is in a normal conduction state. On the other hand, when the voltage V1 is lower than the voltage Vx, that is, when the SQUID 60 is in the superconducting state, the comparison circuit 73 outputs an L level (low level) comparison signal, for example.

タイマ回路７４は、比較回路７３からＨレベルの比較信号が出力される期間を計測する。そして、タイマ回路７４は、比較信号がＨレベルとなる期間が所定期間となると遮断器２０を遮断するための制御信号を出力する。つまり、タイマ回路７４は、ＳＱＵＩＤ６０が所定期間だけ常伝導状態である場合に遮断器２０を遮断する。なお、前述の所定期間は、ＦＬＬ回路が電圧Ｖ１に基づいて、ＳＱＵＩＤ６０が検出する磁場をゼロとするまでの期間より十分長くなるよう設定されている。このため、例えば、過渡的に送電線５１に流れる電流が変化して電圧Ｖ１が電圧Ｖｘより高くなることがあっても、タイマ回路７４は遮断器２０を遮断するための制御信号を出力することは無い。   The timer circuit 74 measures a period during which an H level comparison signal is output from the comparison circuit 73. And the timer circuit 74 outputs the control signal for interrupting | blocking the circuit breaker 20 if the period when a comparison signal becomes H level becomes a predetermined period. That is, the timer circuit 74 shuts off the circuit breaker 20 when the SQUID 60 is in a normal conduction state for a predetermined period. The predetermined period is set to be sufficiently longer than the period until the FLL circuit sets the magnetic field detected by the SQUID 60 to zero based on the voltage V1. Therefore, for example, even if the current flowing through the transmission line 51 changes transiently and the voltage V1 becomes higher than the voltage Vx, the timer circuit 74 outputs a control signal for shutting off the circuit breaker 20. There is no.

＝＝送電線５１に過電流が流れた際の動作例＝＝
送電線５１に過電流が流れた際の送電線保護装置４０の動作について説明する。なお、ここでは、超伝導ケーブル３５には過電流以外の異常は発生していないこととする。 == Example of operation when overcurrent flows through the transmission line 51 ==
The operation of the power transmission line protection device 40 when an overcurrent flows through the power transmission line 51 will be described. Here, it is assumed that no abnormality other than overcurrent has occurred in the superconducting cable 35.

まず、送電線５１に過電流が流れると、ＳＵＱＩＤ６０が検出する磁場も増加する。そして電流供給回路７１は、電圧Ｖ１の変化に応じてＳＵＱＩＤ６０が検出する磁場がゼロとなるような電流を、コイル６１へと供給する。この際に、コイル６１へ供給される電流は、前述の電流値Ｉｘより大きくなる。このため、電流検出回路７２は、遮断器２０を遮断するための制御信号を出力する。この結果、遮断器２０は遮断され、送電線５１は過電流から保護される。   First, when an overcurrent flows through the transmission line 51, the magnetic field detected by the SUQID 60 also increases. Then, the current supply circuit 71 supplies a current to the coil 61 such that the magnetic field detected by the SUQID 60 becomes zero according to the change in the voltage V1. At this time, the current supplied to the coil 61 becomes larger than the aforementioned current value Ix. For this reason, the current detection circuit 72 outputs a control signal for breaking the circuit breaker 20. As a result, the circuit breaker 20 is interrupted and the power transmission line 51 is protected from overcurrent.

＝＝チューブ５０から液体窒素が漏れた際の動作例＝＝
例えば、事故が発生して超伝導ケーブル３５のチューブ５０から液体窒素が漏れた際の送電線保護装置４０の動作について説明する。なお、ここでは、超伝導ケーブル３５には液体窒素の漏れ以外の異常は発生していないこととする。 == Example of operation when liquid nitrogen leaks from the tube 50 ==
For example, an operation of the power transmission line protection device 40 when an accident occurs and liquid nitrogen leaks from the tube 50 of the superconducting cable 35 will be described. Here, it is assumed that no abnormality other than leakage of liquid nitrogen has occurred in the superconducting cable 35.

チューブ５０から液体窒素が漏れると、ＳＱＵＩＤ６０の温度が上昇するため、ＳＱＵＩＤ６０は常伝導状態となる。ＳＱＵＩＤ６０が常伝導状態となると、電圧Ｖ１は前述の所定レベルの電圧Ｖｘより高くなるため、比較回路７３からはＨレベルの比較信号が出力される。この結果、タイマ回路７４はＨレベルの比較信号の期間の計測を開始する。また、ＳＱＵＩＤ６０が常伝導状態の場合、比較信号はＨレベルのままである。そして、比較信号がＨレベルとなる期間が所定期間となると、タイマ回路７４は、遮断器２０を遮断するための制御信号を出力する。この結果、遮断器２０は遮断され、液体窒素が漏れた状態で送電線５１に電流を流し続けることを防ぐことができる。   When liquid nitrogen leaks from the tube 50, the temperature of the SQUID 60 rises, so that the SQUID 60 enters a normal conduction state. When the SQUID 60 is in a normal conduction state, the voltage V1 becomes higher than the above-mentioned predetermined level voltage Vx, so that the comparison circuit 73 outputs an H level comparison signal. As a result, the timer circuit 74 starts measuring the period of the H level comparison signal. Further, when the SQUID 60 is in a normal conduction state, the comparison signal remains at the H level. When the period during which the comparison signal is at the H level is a predetermined period, the timer circuit 74 outputs a control signal for breaking the circuit breaker 20. As a result, the circuit breaker 20 is interrupted, and it is possible to prevent the current from continuing to flow through the transmission line 51 in a state where liquid nitrogen leaks.

以上、本実施形態における送電線保護システム１０について説明した。例えば、一般的な送電線３０等に流れる電流が過電流か否かを検出する際には変流器等が用いられる。過電流を検出可能な変流器は、通常大きなトランスを含むため設備規模は大きくなる。本実施形態では、超伝導ケーブル３５の送電線５１の電流を検出するためにＳＱＵＩＤ６０及びコイル６１を用いているが、一般にＳＱＵＩＤ６０及びコイル６１のサイズは前述の変流器より小さい。このため、本実施形態では、設備規模が小さい送電線保護装置４０で、超伝導ケーブル３５を保護することが可能である。   The power transmission line protection system 10 according to the present embodiment has been described above. For example, a current transformer or the like is used when detecting whether or not the current flowing through a general power transmission line 30 or the like is an overcurrent. A current transformer capable of detecting an overcurrent usually includes a large transformer, so that the scale of equipment increases. In the present embodiment, the SQUID 60 and the coil 61 are used to detect the current of the power transmission line 51 of the superconducting cable 35, but generally the size of the SQUID 60 and the coil 61 is smaller than that of the above-described current transformer. For this reason, in this embodiment, it is possible to protect the superconducting cable 35 with the power transmission line protection device 40 having a small facility scale.

また、電流供給回路７１は、電圧Ｖ１に基づいて、ＳＱＵＩＤ６０が検出する磁場がゼロとなるような電流をコイル６１に供給する。したがって、送電線５１に流れる電流が増加し、ＳＱＵＩＤ６０が検出する磁場が増加すると、コイル６１に供給される電流も増加する。電流検出回路７２は、コイル６１の電流が所定の電流値Ｉｘ以上となると、遮断器２０を遮断するための制御信号を出力する。このため、送電線５１に過電流が生じた場合、送電線５１を過電流から保護することができる。   Further, the current supply circuit 71 supplies a current to the coil 61 such that the magnetic field detected by the SQUID 60 becomes zero based on the voltage V1. Therefore, when the current flowing through the power transmission line 51 increases and the magnetic field detected by the SQUID 60 increases, the current supplied to the coil 61 also increases. The current detection circuit 72 outputs a control signal for breaking the circuit breaker 20 when the current of the coil 61 becomes equal to or greater than a predetermined current value Ix. For this reason, when an overcurrent occurs in the power transmission line 51, the power transmission line 51 can be protected from the overcurrent.

また、例えば、コイル６１の電流が所定の電流値Ｉｘ以上となるか否かは、例えば電流センサ等を用いても判定可能である。しかしながら、本実施形態の電流検出回路７２は、ＦＬＬ回路における積分回路８１の出力が所定レベル以上となるか否かに基づいて遮断器２０を制御する。このため、電流センサ等の部品を用いることなく簡単な構成でコイル６１の電流を検出することができる。   Further, for example, whether or not the current of the coil 61 is equal to or greater than a predetermined current value Ix can be determined using, for example, a current sensor. However, the current detection circuit 72 of this embodiment controls the circuit breaker 20 based on whether or not the output of the integration circuit 81 in the FLL circuit is equal to or higher than a predetermined level. For this reason, the current of the coil 61 can be detected with a simple configuration without using components such as a current sensor.

また、チューブ５０から液体窒素が漏れると、ＳＱＵＩＤ６０は常伝導状態となる。ＳＱＵＩＤ６０が常伝導状態となると、ＳＱＵＩＤ６０の電圧Ｖ１はゼロから増加する。比較回路７３は、電圧Ｖ１を所定レベルの電圧Ｖｘと比較することにより、ＳＱＵＩＤ６０が超伝導状態であるか否か検出する。そして、タイマ回路７４は、電圧Ｖ１が電圧Ｖｘより高ことを示すＨレベルの比較信号が所定期間出力されると、すなわち、ＳＱＵＩＤ６０が所定期間だけ常伝導状態であることを検出すると、遮断器２０を遮断する。この結果、本実施形態では、液体窒素が漏れた状態で送電線５１に電流を流し続けることを防ぐことができる。   Further, when liquid nitrogen leaks from the tube 50, the SQUID 60 becomes a normal state. When the SQUID 60 becomes a normal conduction state, the voltage V1 of the SQUID 60 increases from zero. The comparison circuit 73 detects whether or not the SQUID 60 is in the superconducting state by comparing the voltage V1 with the voltage Vx of a predetermined level. When the timer circuit 74 detects that the H level comparison signal indicating that the voltage V1 is higher than the voltage Vx is output for a predetermined period, that is, detects that the SQUID 60 is in the normal conduction state for a predetermined period, the circuit breaker 20 Shut off. As a result, in the present embodiment, it is possible to prevent the current from continuing to flow through the power transmission line 51 in a state where liquid nitrogen has leaked.

また、所定レベルの電圧Ｖｘは、常伝導状態のＳＱＵＩＤ６０に対してバイアス電流Ｉｂが供給された際の電圧Ｖ１に基づいて定められている。具体的には、電圧Ｖｘは、常伝導状態のＳＱＵＩＤ６０に対してバイアス電流Ｉｂが供給された際の電圧Ｖ１より若干低い電圧である。このため、比較回路７３は、確実にＳＱＵＩＤ６０が超伝導状態であるか否か検出することができる。   The voltage Vx at a predetermined level is determined based on the voltage V1 when the bias current Ib is supplied to the SQUID 60 in the normal conduction state. Specifically, the voltage Vx is slightly lower than the voltage V1 when the bias current Ib is supplied to the SQUID 60 in the normal conduction state. Therefore, the comparison circuit 73 can reliably detect whether or not the SQUID 60 is in the superconducting state.

また、タイマ回路７４が計測する所定期間は、ＦＬＬ回路が電圧Ｖ１に基づいて、ＳＱＵＩＤ６０が検出する磁場をゼロとするまでの期間より長くなるよう設定されている。このため、例えば、過渡的に送電線５１に流れる電流が変化して電圧Ｖ１が電圧Ｖｘより高くなることがあっても、タイマ回路７４が誤って遮断器２０を遮断することは無い。   The predetermined period measured by the timer circuit 74 is set to be longer than the period until the FLL circuit sets the magnetic field detected by the SQUID 60 to zero based on the voltage V1. For this reason, for example, even if the current flowing through the power transmission line 51 changes transiently and the voltage V1 becomes higher than the voltage Vx, the timer circuit 74 will not accidentally shut off the circuit breaker 20.

また、送電線５１は、液体窒素が充填されるチューブ５０の内部に挿通され、ＳＱＵＩＤ６０もチューブ５０の内部に設けられている。このため、ＳＱＵＩＤ６０は精度良く送電線５１の電流を検出することができる。   The power transmission line 51 is inserted into the tube 50 filled with liquid nitrogen, and the SQUID 60 is also provided inside the tube 50. For this reason, the SQUID 60 can detect the current of the power transmission line 51 with high accuracy.

なお、上記実施例は本発明の理解を容易にするためのものであり、本発明を限定して解釈するためのものではない。本発明は、その趣旨を逸脱することなく、変更、改良され得ると共に、本発明にはその等価物も含まれる。
例えば、チューブ５０に充填される冷媒は液体ヘリウム等であっても良い。 In addition, the said Example is for making an understanding of this invention easy, and is not for limiting and interpreting this invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.
For example, the refrigerant filled in the tube 50 may be liquid helium or the like.

１０ 送電線保護システム
２０，２１ 遮断器
２５，２６ 接続機器
３０〜３３，５１ 送電線
３５ 超伝導ケーブル
４０，４１ 送電線保護装置
５０ チューブ
６０，６５ ＳＱＵＩＤ
６１，６６ コイル
６２，６７ 遮断器制御回路
７０ バイアス電流回路
７１ 電流供給回路
７２ 電流検出回路
７３ 比較回路
７４ タイマ回路
８０ 増幅回路
８１ 積分回路
８２ 抵抗 DESCRIPTION OF SYMBOLS 10 Transmission line protection system 20, 21 Circuit breaker 25, 26 Connection apparatus 30-33, 51 Transmission line 35 Superconducting cable 40, 41 Transmission line protection apparatus 50 Tube 60, 65 SQUID
61, 66 Coils 62, 67 Circuit breaker control circuit 70 Bias current circuit 71 Current supply circuit 72 Current detection circuit 73 Comparison circuit 74 Timer circuit 80 Amplifier circuit 81 Integration circuit 82 Resistance

Claims (7)

冷媒の中に設けられて超伝導状態となる送電線の電流に応じた磁場を検出すべく、前記冷媒の中に設けられたＳＱＵＩＤと、
前記ＳＱＵＩＤが磁場を検出すると前記ＳＱＵＩＤの両端に電圧が発生するよう、前記ＳＱＵＩＤにバイアス電流を供給するバイアス電流回路と、
電流が供給されると、前記ＳＱＵＩＤが検出する磁場を打ち消すような磁場を発生するコイルと、
前記ＳＱＵＩＤの両端に生じる電圧に基づいて、前記ＳＱＵＩＤが検出する磁場がゼロとなるような電流を前記コイルに供給するとともに前記送電線を保護すべく前記送電線に接続された遮断器を遮断するための制御を行う制御回路と、
を備えることを特徴とする送電線保護装置。 A SQUID provided in the refrigerant to detect a magnetic field corresponding to a current of a transmission line provided in the refrigerant and in a superconducting state;
A bias current circuit for supplying a bias current to the SQUID so that a voltage is generated across the SQUID when the SQUID detects a magnetic field;
A coil that generates a magnetic field that cancels the magnetic field detected by the SQUID when current is supplied;
Based on the voltage generated at both ends of the SQUID, a current that causes the magnetic field detected by the SQUID to be zero is supplied to the coil and the circuit breaker connected to the power transmission line is cut off to protect the power transmission line. A control circuit for performing control for,
A power transmission line protection device comprising: 請求項１に記載の送電線保護装置であって、
前記制御回路は、
前記ＳＱＵＩＤの両端に生じる電圧に基づいて、前記ＳＱＵＩＤが検出する磁場がゼロとなるような電流を前記コイルに供給する電流供給回路と、
前記コイルに供給される電流が所定の電流値以上となると、前記遮断器を遮断するための制御信号を出力する制御信号出力回路と、
を含むこと、
を特徴とする送電線保護装置。 The power transmission line protection apparatus according to claim 1,
The control circuit includes:
A current supply circuit for supplying a current to the coil such that a magnetic field detected by the SQUID becomes zero based on a voltage generated at both ends of the SQUID;
A control signal output circuit that outputs a control signal for breaking the breaker when a current supplied to the coil is equal to or greater than a predetermined current value;
Including,
A power line protection device. 請求項２に記載の送電線保護装置であって、
前記電流供給回路は、
前記ＳＱＵＩＤの両端に生じる電圧を増幅する増幅回路と、
前記増幅回路の出力を積分する積分回路と、
前記積分回路の出力の電圧レベルに応じた電流を前記コイルに供給する抵抗と、
を含み、
前記制御信号出力回路は、
前記積分回路の出力が所定の電圧レベル以上となると、前記遮断器を遮断するための制御信号を出力すること、
を特徴とする送電線保護装置。 The power transmission line protection device according to claim 2,
The current supply circuit includes:
An amplifying circuit for amplifying a voltage generated at both ends of the SQUID;
An integrating circuit for integrating the output of the amplifier circuit;
A resistor for supplying a current corresponding to the voltage level of the output of the integrating circuit to the coil;
Including
The control signal output circuit is
When the output of the integration circuit is equal to or higher than a predetermined voltage level, a control signal for breaking the breaker is output;
A power line protection device. 請求項１に記載の送電線保護装置であって、
前記制御回路は、
前記ＳＱＵＩＤの両端に生じる電圧に基づいて、前記ＳＱＵＩＤが検出する磁場がゼロとなるような電流を前記コイルに供給する電流供給回路と、
前記ＳＱＵＩＤの両端に生じる電圧が所定レベルより高いか否かを比較する比較回路と、
前記ＳＱＵＩＤの両端に生じる電圧が前記所定レベルより高いことを示す比較結果が所定期間出力されると、前記遮断器を遮断するための制御信号を出力する制御信号出力回路と、
を含むこと、
を特徴とする送電線保護装置。 The power transmission line protection apparatus according to claim 1,
The control circuit includes:
A current supply circuit for supplying a current to the coil such that a magnetic field detected by the SQUID becomes zero based on a voltage generated at both ends of the SQUID;
A comparison circuit for comparing whether or not the voltage generated across the SQUID is higher than a predetermined level;
A control signal output circuit that outputs a control signal for breaking the circuit breaker when a comparison result indicating that a voltage generated at both ends of the SQUID is higher than the predetermined level is output for a predetermined period;
Including,
A power line protection device. 請求項４に記載の送電線保護装置であって、
前記所定レベルは、
前記バイアス電流が常伝導状態の前記ＳＱＵＩＤに対して供給された際に、前記ＳＱＵＩＤの両端に生じる電圧値に基づいて定められること、
を特徴とする送電線保護装置。 The power transmission line protection device according to claim 4,
The predetermined level is:
When the bias current is supplied to the SQUID in a normal conduction state, the bias current is determined based on a voltage value generated at both ends of the SQUID.
A power line protection device. 請求項４または請求項５に記載の送電線保護装置であって、
前記所定期間は、
前記電流供給回路及び前記コイルが前記ＳＱＵＩＤの両端に生じる電圧に基づいて、前記ＳＱＵＩＤが検出する磁場をゼロとするまでの期間より長い期間であること、
を特徴とする送電線保護装置。 The power transmission line protection device according to claim 4 or 5,
The predetermined period is
The current supply circuit and the coil are longer than the period until the magnetic field detected by the SQUID is zero based on the voltage generated at both ends of the SQUID.
A power line protection device. 請求項１〜６の何れか一項に記載の送電線保護装置であって、
前記送電線は、
前記冷媒が充填される管の内部に挿通されること、
を特徴とする送電線保護装置。 The power transmission line protection device according to any one of claims 1 to 6,
The transmission line is
Being inserted into a pipe filled with the refrigerant,
A power line protection device.
JP2009233737A 2009-10-07 2009-10-07 Transmission line protection device Expired - Fee Related JP5100734B2 (en)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01178874A (en) * 1988-01-08 1989-07-17 Nec Corp Latch-type circuit for detecting overcurrent
JPH11264862A (en) * 1998-03-18 1999-09-28 Seiko Instruments Inc Superconductive quantum interference element flux meter
JP2001141799A (en) * 1999-11-12 2001-05-25 Sumitomo Electric Ind Ltd Squid magnetic field detection device
JP2002135917A (en) * 2000-10-20 2002-05-10 Toshiba Corp Transmission and transformation facility
JP2003500985A (en) * 1999-05-17 2003-01-07 エヌケイティ リサーチ アクティーゼルスカブ Overcurrent protection method for superconducting cables.
JP2009504120A (en) * 2005-07-29 2009-01-29 アメリカン スーパーコンダクター コーポレイション Failure management of HTS power cable

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01178874A (en) * 1988-01-08 1989-07-17 Nec Corp Latch-type circuit for detecting overcurrent
JPH11264862A (en) * 1998-03-18 1999-09-28 Seiko Instruments Inc Superconductive quantum interference element flux meter
JP2003500985A (en) * 1999-05-17 2003-01-07 エヌケイティ リサーチ アクティーゼルスカブ Overcurrent protection method for superconducting cables.
JP2001141799A (en) * 1999-11-12 2001-05-25 Sumitomo Electric Ind Ltd Squid magnetic field detection device
JP2002135917A (en) * 2000-10-20 2002-05-10 Toshiba Corp Transmission and transformation facility
JP2009504120A (en) * 2005-07-29 2009-01-29 アメリカン スーパーコンダクター コーポレイション Failure management of HTS power cable

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