JP2003500985A - Overcurrent protection method for superconducting cables. - Google Patents

Abstract

(57) [Summary] With a method for overcurrent protection and a superconducting cable, a current detector consisting of a circuit breaker or a current limiter is inserted in series with the superconducting cable. Can be made of a superconducting material that suppresses with a lower current than the cable conductor of the above. If the current in the superconducting material becomes too large, it is supplied to the cold shunt for a short period of time, which is coupled in parallel with the cable conductors of the superconducting cable. After this short period, this current is supplied to a hot shunt that is coupled in parallel outside the cable conductors of the cable, resulting in heat dissipation to take place at room temperature. The use of the method and the cable according to the invention prevents the breakage of the cable even if the superconducting cable loses its superconductivity, for example due to a cooling failure, without the need to repair the damage. Normal operation can be started soon.

Description

Detailed Description of the Invention

[0001]   The present invention relates to a method of overcurrent protection in superconducting cables.

[0002]   The invention further relates to a superconducting cable.

When using a superconducting cable in a high voltage system, it is important that the cable is protected from overcurrent because the result of the overcurrent in the cable conductor of the superconducting cable is its superconductivity. It is because of the loss of sex. This means that the cable will soon be subject to breakage, because the superconducting tape that conducts electric current is not adapted to conducting large currents at all when it is not superconducting.

A typical requirement for superconducting cables is that they should be protected from overcurrent. This protection requirement is that, for example, the cable should be able to withstand about 40 KA for 1 second.

It is an object of the present invention to provide a method of protecting the superconducting cable that meets the above requirements.

This object of the invention is achieved by a method of the type defined in the preamble of claim 1.
This method is characterized in that a current detector, which can consist of part or all of the cable, is inserted in series in the cable conductor of the superconducting cable.

[0007] Thus, a constant monitoring of the current in the superconducting cable during operation is ensured, so that if the current exceeds a certain predetermined limit, the current will be interrupted or interrupted prior to the destructive, massive overheating of the cable. Limited.

By inserting at least one superconducting piece as a current detector as described in claim 2, reliable overcurrent detection is obtained, because the superconducting piece has a current which is too large. This is because when exposed to heat, it leaves the superconducting state and intensely generates heat in the superconducting piece.

This generation of heat can be used there and, if a fuse is inserted as a circuit breaker, as in claim 3, interrupts the current to the cable conductor of the superconducting cable.

For the purpose of accommodating the time delay in the circuit breaker, in particular for accommodating the essential time delay defined by the time period required for interrupting the current by means of the circuit breaker. As shown, it is advantageous to insert a cold shunt in parallel with the superconducting cable, which cold shunt is designed to be capable of carrying 40 KA for, for example, 0.1 seconds.

In order to divert the current to the superconducting cable after the lapse of 0.1 seconds described above, an electrical conductor is inserted in parallel with the cable conductor of this cable and the current detector as shown in claim 5. Preferably, the electrical conductor has a higher impedance when the superconducting cable is in the superconducting state. Thus, when the superconducting state ceases, the current is allowed to switch to the hot shunt.

[0012]   Additional suitable embodiments of this method are described in claims 6 to 8.

As already mentioned, the invention also relates to a superconducting cable. This cable is of the type defined in the preamble of claim 9, in which the cable conductor of the cable is connected in series with a current detector and a circuit breaker or current limiter for detecting overcurrent. Is characterized by.

[0014]   Suitable embodiments of this cable are described in claims 8-14.

In FIG. 1, a superconducting cable is designated by 1, the superconducting cable 1 is probably composed of a core, as known in the art, around which one or more superconducting tapes are placed. It is rolled.

The current detectors 3, 4 are coupled to both ends of the cable, which current detector has a built-in circuit breaker or current limiter. These current detectors are, for example, YBCO or Bi22 with built-in circuit breakers.
A superconducting strip such as 12 can be included and can be dimensioned to suppress at a lower current than the actual cable superconductor, which means that if the current in the superconducting strip is constant. Above that value, the current to the superconducting cable is cut off after a short period of time. Due to the use of current limiters, the current is naturally limited. The hot shunt is coupled in parallel to the series connection of the superconducting strip and the cable conductor of the superconducting cable, and this shunt is short-term if the current detector interrupts the current or the current limiter limits the current. It is possible to switch the current supplied over time.

FIG. 2 shows a more detailed embodiment of the superconducting cable according to the invention. In this figure, 13 indicates a current detector corresponding to that shown by 3 and 4 in FIG. Reference numeral 7 indicates a superconducting cable corresponding to the cable 1 of FIG. A cold shunt is provided in parallel with the cable conductor of the cable, this shunt being designated by the reference numeral 11. This shunt is cooled to the temperature of the superconductor. The crystal 8 is located outside the cold / hot shunt, and the electrical insulator 9 is located outside the crystal 8. Inside the electrical insulator 9 is provided an electrical conductor 10, which is made of, for example, copper and serves as a hot shunt at ambient temperature, referenced below.

The operation of the current detector in the superconducting cable will be described in more detail with reference to the current plot of FIG. If it is determined that too much current is flowing in the superconductor strip 3, 4 or 13, this current will flow in the cold shunt 11 for a short period of time. This current is supplied to the hot shunt 10 and increases sharply at time 0.1 seconds as shown by the dashed line in FIG. At the same time, the current in the cold temperature shunt 11 decreases sharply.

Damage to the superconducting cable when superconductivity ceases can thus be avoided, which makes it resistive and thus unable to carry the usual electric currents that can conduct in the superconducting state. Means that.

FIG. 4 shows the superconducting cable that occurs in a practical implementation in perspective and partial cross section, which can be used for the current protection described with respect to the preceding figures.

In this figure, 12 indicates a shield, and a jacket 14 is provided on the outer side thereof. Inside the jacket is a dielectric insulator 15 which surrounds an outer steel tube 16. Spacers 17 are arranged inside the steel pipe 16, and these are supported by an aluminum foil 18 that abuts the inner steel pipe 19. Inside the inner steel tube 19, several superconducting tapes 20 are wrapped around a hollow core 21. Cooling of the superconducting tape can be performed by supplying a coolant to the groove 22 of the hollow core.

The reference numeral 23 indicates the position in which the cold and hot shunts can be placed, as described above, whereas the reference numeral 24 indicates the position in the dielectric insulator in which the hot and cold shunts can be placed.

[Brief description of drawings]

[Figure 1]   1 shows the basic structure of a superconducting cable with overcurrent protection according to the present invention.

[Fig. 2]   3 shows a more detailed structure of an embodiment of a cable with overcurrent protection according to the present invention.

FIG. 3 shows the time relationship between the respective currents flowing in the cable according to FIG. 2 in an overcurrent situation.

[Figure 4]   1 shows a superconducting cable with overcurrent protection according to the invention in perspective and partial section.

[Procedure for Amendment] Submission for translation of Article 34 Amendment of Patent Cooperation Treaty

[Submission date] July 6, 2001 (2001.7.6)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Contents of correction]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Contents of correction]

The present invention relates to a method of overcurrent protection in a superconducting cable, including a current detector inserted in series in the cable conductor of the superconducting cable.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Contents of correction]

[0002] The present invention relates to a superconducting cable, the cable conductor of the cable is connected to the current detector in series for overcurrent detection.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Contents of correction]

A typical requirement for superconducting cables is that they should be protected from overcurrent. The protection requirement is that the cable should be able to withstand, for example, about 40 KA for 1 second. JP 01 039230 discloses a method for protecting a superconducting cable from the overcurrent by the child inserting a current detector to the cable conductor series.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Contents of correction]

This object of the invention is achieved by a method of the type defined in the preamble of claim 1.
This method is characterized in that the electrical conductor is inserted in parallel with the cable conductor of the superconducting cable and the current detector .

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Contents of correction]

[0007] Thus, a constant monitoring of the current in the superconducting cable during operation is ensured, so that if the current exceeds a certain limit, the current may be interrupted or interrupted prior to the destructive, massive overheating of the cable. Limited. Therefore, when the superconducting state ceases, current, Ru allowed to convert into the hot shunt.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Contents of correction]

According to a fourth aspect , the current detector comprises at least one superconducting piece ,
Reliable overcurrent detection is obtained , because if this superconducting piece is exposed to too much current, it will exit its superconducting state and generate intense heat in the superconducting piece. .

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Contents of correction]

This generation of heat can be used to cut off the electric current to the cable conductor of the superconducting cable if a fuse is inserted as a circuit breaker as described in claim 6 .

[Procedure Amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Contents of correction]

[0010] In order to accommodate the circuit breaker in the time delay, to accommodate the integral time delay defined by the time period necessary to particularly interrupting a current by means of the circuit breaker, to claim 8 As shown, it is advantageous to insert the cold / hot shunt in parallel with the cable conductor of the superconducting cable. This cold temperature can be designed to be able to carry 40 KA for 0.1 second, for example.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

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[0011] After 0.1 seconds above has passed, to convert the current to the superconducting cable, where the electrical conductors that are the most may be preferable to insert.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Contents of correction]

Additional suitable embodiments of this method are described in claims 2, 3, 5 and 7 .

[Procedure Amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Contents of correction]

[0013] As already mentioned, the present invention also relates to a superconducting cable, cable conductors of this cable is connected to the current detector in series for overcurrent detection. This cable is of the type defined in the preamble of claim 9 and is characterized in that the electrical conductor is connected in parallel with the cable conductor of the superconducting cable and the current detector.

[Procedure Amendment 13]

[Document name to be amended] Statement

[Correction target item name] 0014

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[Contents of correction]

Suitable embodiments of this cable are described in claims 10 to 14.

[Procedure Amendment 14]

[Document name to be amended] Statement

[Correction target item name] 0017

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[Contents of correction]

FIG. 2 shows a more detailed embodiment of the superconducting cable according to the invention. In this figure, 3 and 4 again indicate current and reference numeral 7 indicates a superconducting cable. A cold shunt is provided in parallel with the cable conductor of the cable, this shunt being designated by the reference numeral 11. This shunt is cooled to the temperature of the superconductor. The crystal 8 is located outside the cold / hot shunt, and the electrical insulator 9 is located outside the crystal 8. Inside the electrical insulator 9 is provided an electrical conductor 10, which is made of, for example, copper and serves as a hot shunt at ambient temperature, referenced below.

[Procedure Amendment 15]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Contents of correction]

The operation of the current detector in the superconducting cable will be described in more detail with reference to the current plot of FIG. If it is confirmed that an excessively large electric current is flowing through the superconductor pieces 3 and 4 , this electric current flows through the cold temperature shunt 11 for a short period of time. This current is then supplied to the hot shunt 10, which rapidly increases at time 0.1 seconds as shown by the dashed line in FIG. At the same time, the current in the cold temperature shunt 11 decreases sharply.

[Procedure Amendment 16]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Contents of correction]

In this figure, 12 indicates a shield, and a jacket 14 is provided on the outside thereof. Inside the jacket is a dielectric insulator 15 surrounding an outer steel tube 16. Spacers 17 are arranged inside the steel pipe 16, and these are supported by an aluminum foil 18 that abuts the inner steel pipe 19. Inside the inner steel tube 19, several superconducting tapes 1 are wrapped around a hollow core 21. Cooling of the superconducting tape can be performed by supplying a coolant to the groove 22 of the hollow core.

[Procedure Amendment 17]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Contents of correction]

Reference numeral 11 indicates the position in which the cold shunt can be placed, as described above, while reference numeral 24 indicates the position in the dielectric insulator where the hot shunt can be placed.

[Procedure 18]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

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[Fig. 2]

[Procedure Amendment 19]

[Document name to be corrected] Drawing

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[Figure 4]

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE), OA (BF, BJ , CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, K E, LS, MW, SD, SL, SZ, TZ, UG, ZW ), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, C R, CU, CZ, DE, DK, DM, EE, ES, FI , GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, K Z, LC, LK, LR, LS, LT, LU, LV, MA , MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, S K, SL, TJ, TM, TR, TT, TZ, UA, UG , US, UZ, VN, YU, ZA, ZW (72) Inventor Ostergarde, Jens, Jacob             Frederiksberg, Denmark             ー 、 Tee 、 Balfod Vey 11,1 、             Tea F-term (reference) 5G004 BA03 BA04 DC01 DC10 DC12                 5G013 AA04 AA11 BA01 CA02

Claims (14)

[Claims] 1. A method for overcurrent protection in a superconducting cable, characterized in that a current detector which can be constituted by part or all of the cable is inserted in series in a cable conductor of the superconducting cable. How to protect. 2. The method according to claim 1, wherein at least one superconducting piece is inserted as the current detector. 3. Method according to claim 1 or 2, characterized in that the fuse is inserted as a circuit breaker. 4. The method of overcurrent protection according to claim 1, wherein the cold / hot shunt is inserted in parallel with the cable conductor of the superconducting cable. 5. The method according to claim 1, wherein the electric conductor is inserted in parallel with the cable conductor of the superconducting cable and the current detector or the current limiter, and the electric conductor is superconducting. A method of overcurrent protection, which has a higher impedance than a superconducting cable in the superconducting state of the cable. 6. The method according to claim 1, wherein a material made of a superconducting material that suppresses at a lower current than the superconducting cable is inserted as the current detector. Method of current protection. 7. The method according to claim 1, wherein the current detector comprises a relay, a fuse, a thyristor or similar power electronic component. 8. The overcurrent protection method according to claim 1, wherein the current detector comprises a current-dependent resistor. 9. In a superconducting cable, the cable conductor of the cable is
A superconducting cable, which is connected in series with a current detector for detecting an overcurrent and a circuit breaker or a current limiter. 10. The superconducting cable according to claim 9, wherein the circuit breaker comprises a fuse. 11. The superconducting cable according to claim 8 or 9, wherein the current detector is made of a superconducting material such as YBCO or Bi2212. 12. The superconducting cable according to claim 8, wherein the cold / hot shunt is connected in parallel to the cable conductor of the cable. The cold shunt is wound such that the current therein decreases to a minimum during normal operation. 13. The superconducting cable according to claim 10, wherein the shunt at ambient temperature is coupled in parallel with the superconducting material of the superconducting cable and the current detector. 14. The superconducting cable according to claim 9, wherein the circuit breaker comprises a high speed power electronic device.