JP5060064B2 - Superconducting fault current limiter - Google Patents

Description

  The present invention relates to a resistance type superconducting fault current limiter installed at a connection point between power systems, and more particularly to a superconducting fault current limiter that reduces equipment loss and improves maintenance workability.

  In recent years, the introduction of regular private power generation facilities has been gradually increasing at customer sites where received power has been liberalized. When operating this private power generation facility, in order to ensure stable power supply even when trouble occurs in the private power generation facility itself, the site is not operated as an independent system by separating the site from the commercial power system. It is common to use private power generation while continuing to receive power from the grid.

  When commercial power and private power generation are used together, if a short circuit or ground fault occurs in the commercial power system, an excessive short circuit current flows from the private power generation facility installed on the customer side to the point of the accident. there is a possibility. Therefore, a superconducting fault current limiter is applied as a means for suppressing an excessive current passing through the connection point at the time of a system failure, a voltage drop in a healthy system caused by the excessive current, and the like.

  As a superconducting current limiting device, a resistance type, an inductance type, or the like is adopted according to the type of impedance to be generated. Among these, the resistance type superconducting fault current limiter utilizes the phenomenon of resistance increase based on the transition of the superconducting current limiting coil from the superconducting state to the normal conducting state, and a refrigerant such as liquid nitrogen is installed in the cryostat installed in the cubicle. In this refrigerant, a plurality of superconducting current limiting elements and a required number of cryogenic refrigerators are arranged, and current is supplied to the superconducting current limiting elements via current leads.

  In this way, the resistance type superconducting fault current limiter is a stationary device that can instantaneously limit the excessive fault current at the time of a short-circuit accident. In normal times, the system current flows through the superconducting wire without resistance. In the case of a system failure, the superconducting wire is quenched (normalized) by the excessive short-circuit current at the time of the accident, and the short-circuit current is instantaneously below the specified value by the generated resistance. It has the function to suppress to.

  In other words, the superconducting fault current limiter uses quenching of the superconducting wire (normal conduction), so in principle there is no malfunction or failure, and the protection operation can be started without any detection means. It is possible to suppress the current from the first wave and suppress it to about several times the normal operating current.

Conventionally, as a proposal of such a superconducting current limiting device, for example, liquid nitrogen or the like in which a current lead and a superconducting current limiting device composed of a superconducting coil are immersed on the top surface of a cryostat refrigerant container containing the superconducting current limiting device. There is a superconducting fault current limiter equipped with a cryogenic refrigerator that uses a refrigerant and liquefies and recondenses the evaporated gas of the refrigerant and suppresses deterioration due to current-limiting energy generated during current limiting (see, for example, Patent Document 1). .
JP 2001-298858 A

  A superconducting fault current limiter contains a refrigerant such as liquid nitrogen in a cryostat refrigerant container, and a plurality of superconducting current limiting elements and a required number of cryogenic refrigerators are arranged in the refrigerant to provide current leads to the superconducting current limiting element. In a conventional superconducting current limiter, for example, a plurality of current leads and superconducting current limiting elements are arranged in a ring shape at regular intervals in a plan view at the peripheral position in the cryostat, The refrigerator head is arranged at the center position in the cryostat or arranged so as to overlap vertically in a plan view.

  In such a conventional arrangement, a superconducting current limiting element such as a superconducting coil and a current lead always generate heat inside the cryostat, but the current lead and the cryogenic refrigerator head are arranged as described above. In the cryostat refrigerant vessel, the temperature of the refrigerant liquid such as liquid nitrogen increases in the portion near the normal temperature part of the current lead with large heat generation, and the gas temperature increases in the upper gas space part as it goes higher. A gradient may occur.

  The phenomenon of temperature gradient in the liquid or gas of the refrigerant appears more prominently in a cryogenic cryostat in which the specific resistance of copper or a copper alloy, which is the material of the current lead, becomes significantly higher as the temperature rises.

  That is, when a superconducting current limiting element composed of a superconducting coil or the like together with a current lead causes an AC loss, a liquid that conducts heat, such as liquid nitrogen having a wider temperature range than helium, is applied as the refrigerant, etc. This phenomenon is particularly prominent. In the case of liquid nitrogen, the temperature difference between the upper and lower parts of the refrigerant liquid may be 1K or more, and when a temperature gradient occurs in the refrigerant, the critical current of the superconducting current limiting element composed of a superconducting coil or the like is The lower part in the refrigerant becomes larger.

  As a result, conventionally, the superconducting current limiting element disposed at the top starts the current limiting operation first during the current limiting operation, and the current limiting resistance becomes smaller than the initial set resistance, so that a sufficient current limiting effect is obtained. Disappear. Also, in the upper gas space in the cryostat refrigerant container, the temperature becomes higher toward the upper side of the space, so the pressure of the refrigerant gas also increases with the temperature, and the gas pressure during normal operation may be higher than the design value. .

  Furthermore, if hot gas stays in the upper gas space in the refrigerant container, the temperature of the current lead will rise excessively, and depending on the energization current, it may cause damage to the lead due to overheating of the conductive part. is there.

  In addition, the cryostat of the superconducting coil for the current limiter housed in the cubicle and the compressor for the cryogenic refrigerator have a cryogenic sliding part, etc., so that the refrigerator is, for example, about once a year or more. It is necessary to carry out maintenance while stopping the operation and releasing part of the evaporated gas to the outside of the cryostat.

  In this case, when the refrigerant temperature is operated at a temperature lower than the normal boiling point temperature (77K) (for example, lowered to 65K), the temperature rises to the boiling point is also used for a relatively long time. It is possible to perform maintenance while preventing evaporation of the refrigerant gas.

  On the other hand, when a system fault occurs, that is, when the current limiter is maintained in a current-carrying state with the normal boiling point temperature (77K), maintenance is performed in a standby state where a protective operation is possible. It was difficult to do.

  On the other hand, for the refrigerator compressor, for example, it is necessary to perform maintenance by replacing the adsorber (adsorber) about once every three years. As described above, the refrigerator head is placed in the center of the cryostat. In the case of the conventional configuration as described above, the refrigerator compressor and other equipment interfere with each other, and it is difficult to perform maintenance by pulling the compressor inside or outside the cubicle. .

  The present invention has been made in view of such circumstances, and an object thereof is to provide a superconducting fault current limiter capable of preventing and reducing device losses such as current leads and improving maintenance workability. .

In order to achieve the above object, in the present invention, a superconducting current limiting element and a cryogenic refrigerator are arranged in a cryostat containing a refrigerant, and the superconducting current limiting element is connected between a plurality of power systems through current leads. In the resistance type superconducting fault current limiter, the superconducting current limiting element and the cryogenic refrigerator are locally arranged in different regions occupied by each other in plan view in the cryostat, and the power system and the superconducting current limiting element are A breaker is provided between the cryostat and the cryostat, and the cryostat is disposed at different positions in a plan view in the cubicle. The cryostat refrigerator is provided outside the cryostat. The compressor and the cryostat are separated from the cubicle. The cryogenic refrigerator of the cryogenic refrigerator is arranged at different positions in a plan view of the inside of the cubicle with respect to the breaker Providing superconducting current limiting device head and the compressor are spaced.
In order to achieve the above object, according to the present invention, a superconducting current limiting element and a cryogenic refrigerator are disposed in a cryostat containing a refrigerant, and the superconducting current limiting element is connected to a plurality of power systems via current leads. In the resistance type superconducting fault current limiter connected to each other, the superconducting current limiting element and the cryogenic refrigerator are arranged in different one side regions with respect to the center in a plan view in the cryostat, and the power system and the superconducting current limiter A circuit breaker is provided between the current limiting element, the circuit breaker and the cryostat are arranged at different positions in plan view in the cubicle, and the compressor of the cryogenic refrigerator is provided outside the cryostat. The cryostat is disposed at a different position in plan view in the cubicle, and the pole is located with respect to the breaker in the cubicle space. To provide a superconducting current limiting device and said refrigerating machine head and compressor temperature refrigerator are spaced.
Furthermore, in order to achieve the above object, according to the present invention, a superconducting current limiting element and a cryogenic refrigerator are arranged in a cryostat that accommodates the refrigerant, and the superconducting current limiting element is connected to a plurality of power systems via current leads. And connecting the superconducting current limiting element and the cryogenic refrigerator in a region of the cryostat divided in two in plan view, and the power system and the superconducting current limiter. A circuit breaker is provided between the flow element, the circuit breaker and the cryostat are arranged at different positions in plan view in a cubicle, and a compressor of the cryogenic refrigerator is provided outside the cryostat. The cryostat is disposed at a different position in a plan view in the cubicle, and the cryogenic refrigeration is performed with respect to the breaker in the cubicle space. To provide a superconducting current limiting device and said refrigerating machine head and compressor are spaced.
Furthermore, in order to achieve the above object, according to the present invention, a superconducting current limiting element and a cryogenic refrigerator are arranged in a cryostat that accommodates the refrigerant, and the superconducting current limiting element is provided with current leads between a plurality of power systems. In a resistance type superconducting fault current limiter connected via a plane, the center point in plan view of the superconducting current limiting element and the center point in plan view of the cryogenic refrigerator are divided into two equal parts in plan view in the cryostat. The circuit breaker is disposed in an opposite region, and includes a circuit breaker between the power system and the superconducting current limiting element. The circuit breaker and the cryostat are disposed at different positions in a cubical view, and are external to the cryostat. Provided with a compressor for the cryogenic refrigerator, and the compressor and the cryostat are disposed at different positions in a plan view in the cubicle, In the space, with respect to the circuit breaker, to provide a superconducting current limiting device and said refrigerating machine head and the compressor of the cryogenic refrigerator is spaced.

  According to the present invention, the superconducting current limiting element and the cryogenic refrigerator are locally disposed in differently occupied areas in plan view in the cryostat, so that heat is generated on the superconducting current limiting element side inside the cryostat. Cooling is dominant on the cryogenic refrigerator side. Therefore, there is a flow in which the refrigerant circulates greatly inside the cryostat. This large circulation flow promotes heat removal of the refrigerant, and the resistance of the superconducting current limiting element and the current lead is lowered to reduce the resistance. Equipment loss can be prevented and reduced.

  Further, according to the present invention, since the current lead group is disposed in a spatial relationship with the cryogenic refrigerator in the cryostat, the lead group is made of an insulating material such as rubber or an acrylic plate. By isolating, it is possible to easily and reliably isolate from the worker, and the worker can safely access the refrigerator group. Therefore, the maintenance of the refrigerator head can be performed while maintaining the energized state of the current limiter, and the maintenance workability can be improved.

  Embodiments of a superconducting fault current limiter according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing the overall configuration (planar configuration) of a superconducting fault current limiter and a power supply circuit to which the superconducting fault current limiter is applied, and FIG. It is a block diagram (the AA line cross section of FIG. 1). FIG. 3 is an explanatory diagram showing an enlarged arrangement of the superconducting current limiting element and the refrigerator in the cryostat in the superconducting current limiting device.

As shown in FIG. 1, a normal load 104, an important load 105, and the like are connected to a common power supply system 103 from a commercial power supply 101 and a self-generated power supply 102 via a load circuit breaker (not shown). In addition, a superconducting fault current limiter 1 and a circuit 107 having a switch 106 that bypasses the superconducting current limiter 1 are connected to this system.

  The superconducting fault current limiter 1 of the present embodiment accommodates a refrigerant 4 such as liquid nitrogen in a cryostat 3 installed in a cubicle 2, and a plurality of superconducting current limiting elements 5 and a required number of cryogenic refrigeration units in the refrigerant 4. The machine 6 is arranged to supply current to the superconducting current limiting element via a plurality of current leads 7.

  The cubicle 2 is divided into, for example, two chambers. A cryostat 3 and a refrigerator compressor (compressor) 8 are installed in one room 2a, and a circuit breaker 9, a control system 10, and a detector 11 are installed in the other room 2b. Etc. are installed. The cubicle 2 is provided with opening / closing doors 12 and 13 and the like for performing inspections and the like.

  In this way, the superconducting current limiting element 5 and the cryogenic refrigerator 6 are arranged in the cryostat 3 that accommodates the refrigerant 4, and the superconducting current limiting element is provided with a plurality of current leads (current lead groups) 7 between a plurality of power systems. Connected through.

  Next, as shown in FIGS. 2 and 3, in this superconducting current limiter, the superconducting current limiting element 5 and the current lead group 7 and the cryogenic refrigerator 6 are different from each other in plan view in the cryostat 3. Locally arranged in regions A and B.

  That is, in this embodiment, the superconducting current suppresses an excessive accident current by using the normal conducting transition of the superconducting current limiting element 5 made of a superconducting wire, a superconducting film, or the like, and the normal conducting transition at the time of current rising and the generation of resistance. In the current limiter, three pairs of current leads 7 connected to the superconducting current limiting element 5 for AC three-phase are provided on the upper surface flange of the substantially cylindrical cryostat 3 accommodating the superconducting current limiting element 5, and the superconducting current limiting element 1 or a plurality of cryogenic refrigerators 6 for liquefying and re-condensing the evaporative gas of the refrigerant 4 such as liquid nitrogen in which 5 is immersed, and these three pairs of current leads and the cryogenic refrigerator 6 are For example, they are locally arranged on the upper surface flange 14 of the cryostat 3 so as not to overlap with other occupied portions.

  As shown in FIG. 3, the superconducting current limiting element 5 and the cryogenic refrigerator 6 are arranged in one-side regions A and B that are different from the center in plan view in the cryostat 3.

  Specifically, the three pairs of current leads 7 and the cryogenic refrigerator 6 are both housed and disposed in a positional relationship that does not fit within the semicircular position on one side of the top flange 14.

  Further, in the present embodiment, the superconducting current limiting element 5 and the cryogenic refrigerator 6 are arranged in a region that is divided into two equal parts in the cryostat 3 in plan view.

  Specifically, each of the three pairs of current leads and the cryogenic refrigerator 6 is arranged in different semicircles on the upper surface flange 14 of the cryostat 3 that is divided into two equal parts.

  Further, in the present embodiment, the regions A, opposite to each other, which are divided into two equal parts in the plan view in the cryostat 3 between the center point in plan view of the superconducting current limiting element 5 and the center point in plan view of the cryogenic refrigerator 6. The configuration is arranged in B.

  Specifically, the geometric center point on the top flange 14 at the position of the three pairs of current leads 7 and the geometric center point at the position of the cryogenic refrigerator 6 are each divided into two equal parts by a semicircle. The upper surface flange 14 of the cryostat 3 is disposed in a semicircle opposite to each other.

  As described above, the current lead group composed of a total of six current leads 7 each including two three phases corresponding to the system power cable wiring is concentrated on one side of the upper surface flange 14 (disk) of the cryostat 3. One or a plurality of refrigerator head parts are arranged in a portion of the upper surface flange where no current lead group is arranged. In other words, the current lead group and the cryogenic refrigerator 6 forming one or a plurality of groups are not uniformly distributed in a uniform spatial ratio, but are spatially separated from other groups. Localized at the position.

  Next, the operation will be described.

  The superconducting fault current limiter quickly generates resistance in the event of a system fault, and makes it possible to limit the fault current from the first wave. Since the superconducting current limiting element 5 composed of a superconducting coil or the like generates resistance at the time of current limiting, the refrigerant 4 such as liquid nitrogen that cools the superconducting current limiting element 5 evaporates due to heat generation. In normal operation, the two power systems are connected to each other, so that a predetermined alternating current always continues to flow through the superconducting current limiter. For this reason, unlike other superconducting devices, the superconducting current limiting element 5 composed of a superconducting coil or the like constantly generates an AC loss while maintaining a superconducting state, and heat based on this is transferred to the refrigerant 4, The temperature rise and evaporation will continue constantly.

  Thus, the superconducting current limiting element 5 such as a superconducting coil used in the superconducting current limiter is operated while generating heat constantly and transiently, and heat is applied to the refrigerant 4 such as liquid nitrogen. It is operated while being conveyed or while the refrigerant 4 is evaporated.

The current lead 7 has a role of conducting a large current of several hundreds of A to several thousand A from the system of the commercial power supply 101 connected to the superconducting current limiting element 5 composed of a superconducting coil or the like. The current lead 7 is made of a material having good conductivity such as copper in order to pass a large current as little as possible in resistance and joule heat generation. The current lead 7 has a certain thickness and a current density of several A / mm ² or more. It is made not to become.

  On the other hand, since the current lead 7 connects the current terminal of the power system at room temperature and the superconducting current limiting element 5 placed in the cryogenic environment, heat is continuously transmitted from the room temperature side to the cryogenic stage by thermal conduction. The current lead 7 constantly generates heat due to thermal conduction from the superconducting current limiting element 5 side, and Joule heat generation due to energization is added to form a large heat source.

  As described above, in the superconducting current limiter, heat is always generated by the current lead 7 and the superconducting current limiting element 5 due to constant energization. Further, in the event of an accident, a larger amount of heat is generated mainly by the superconducting current limiting element 5. The heat is transferred to a liquid such as liquid nitrogen that is the refrigerant 4. The cryogenic refrigerator 6 is used to cool the refrigeration 4 by suppressing heat input to the refrigerant 4 with normal heat generation, and to liquefy and recondense. The refrigerator used is a Gifford McMahon (GM type) refrigerator, a pulse tube refrigerator or the like, but the refrigerator head is usually directly attached to the cryostat 3 for the current limiter that houses the superconducting current limiting element 5. .

  The cryostat 3 has a structure in which a disk-like flange is usually provided on the upper part of a cylindrical container in consideration of the pressure increase due to the evaporative gas when the current is limited and taking into account the ease of manufacture. . The current lead 7 is installed on the disk-shaped upper surface flange so as to penetrate from the normal temperature portion to the cryogenic temperature portion. Further, the head of the cryogenic refrigerator 6 is also installed so as to penetrate from the normal temperature part to the cryogenic part on the disk-like flange on the upper part of the cylindrical container.

  Conventionally, when the flange of the cryostat 3 has a disk shape, the current leads 7 are rotationally symmetrical on the circumference in the flange, that is, on the circumference centered on the central axis of the disk. It is arranged with. This is because by making the insulation distance between the leads as large as possible, it is not necessary to conduct detailed insulation design examination and electrolytic analysis, and it is possible to configure a device that is safe in insulation.

  Further, when the head portion 6 a of the cryogenic refrigerator 6 is used in combination with the current lead 7, the head portion 6 a is installed at the center position of the upper surface flange 14 which is a neutral position with respect to the above-described current lead 7. This is because the distance from the current lead 7 is made uniform and the merit that the piping can be drawn from any position is taken into consideration.

  As described above, inside the cryostat 3, the superconducting current limiting element 5 such as a superconducting coil and the current lead 7 always generate heat, but the current lead 7 and the refrigerator head of the cryogenic refrigerator 6 are as described above. In the arrangement configuration, in the cryostat 3, the temperature of the refrigerant 4 such as liquid nitrogen is higher in the portion near the normal temperature portion of the current lead 7 that generates a large amount of heat, and the gas temperature is higher in the upper gas space 16 portion. A temperature gradient occurs that increases the.

  The phenomenon that a temperature gradient is generated in the liquid 4 or the gas above the refrigerant 4 is more noticeable in the cryostat 3 where the specific resistance of the copper or copper alloy that is the material of the current lead 7 is significantly higher as the temperature is higher. When the refrigerant 4 that transmits heat when the superconducting current limiting element 5 composed of a superconducting coil or the like together with the current lead 7 causes an AC loss is liquid nitrogen having a wider temperature range than helium or the like. It is a phenomenon that appears particularly prominently.

  In the case of liquid nitrogen, the temperature difference between the upper part and the lower part of the liquid that is the refrigerant 4 may be 1K or more. However, if a temperature gradient is created in the refrigerant 4, a superconducting current limiting element constituted by a superconducting coil or the like. The critical current of 5 increases as it goes down. As a result, at the time of the current limiting operation, the element located at the top starts the current limiting operation first, so that the current limiting resistance is initially smaller than the predetermined resistance, and a sufficient current limiting effect may not be obtained. There is sex.

  Moreover, in the gas space 16, since the temperature increases toward the upper part, the pressure of the refrigerant gas also increases with the temperature, and the gas pressure during normal operation may be higher than the design value. Furthermore, if the high temperature gas stays in the upper gas space 16 in the refrigerant container, the temperature of the current lead 7 excessively rises, and depending on the energization current, it may cause damage to the lead due to energization overheating of the conductive portion. There is also sex.

  In addition, according to the present embodiment, the current lead group constituted by the total of six current leads 7 of each of the three phases corresponding to the system power cable wiring is concentrated on one side on the upper surface flange 14 of the cryostat 3. The one or more refrigerator head units 6 are arranged in a portion of the upper surface flange 14 where no current lead group is arranged.

  On the other hand, according to this embodiment, as shown in FIG. 2, the current lead group and the cryogenic refrigerators 6 forming one or a plurality of groups are not evenly distributed and arranged separately. Locally located at a position spatially separated from the group. Thus, heat generation is dominant on the current lead group side inside the cryostat 3, and cooling is dominant in the cryostat 3 on the cryogenic refrigerator 6 side of one or a plurality of groups.

  As a result, in the cryostat 3, the liquid and gas of the refrigerant 4 heated by heat generation on the lead group side in the refrigerant 4 such as liquid nitrogen and in the gas space 16, as shown by arrows c 1 and d 1 in FIG. As shown in FIG. 2 by arrows c2 and d2 due to the volume reduction of the gas or refrigerant 4 cooled by the refrigerator head 6 on the cryogenic refrigerator 6 side. , Flowing from top to bottom. In the vicinity of the gas space 16 at the top of the cryostat 3 and the liquid level of the refrigerant 4, the gas and the refrigerant 4 move from the lead group whose pressure and volume have increased due to the temperature rise to the refrigerator side where the pressure and volume have decreased due to condensation and cooling. In the same manner, at the bottom of the cryostat 3, the refrigerant flows from the refrigerator group side toward the lead group side so as to correspond to these flows.

  As a result, a flow in which the refrigerant 4 circulates greatly is generated inside the cryostat 3. Due to this large circulation flow, the low-temperature refrigerant 4, which is continuously cooled from the lower part, is supplied and removed from the heat at the current lead 7 side, and the heated refrigerant 4 separates and moves from the lead surface, so that the cooling is accelerated. In addition, since the temperature of the current lead 7 is lowered and the resistance is reduced, the effect of reducing the device loss also appears.

  Since the temperature of the refrigerant layer and gas layer in the vicinity of the liquid level of the refrigerant 4 above the current lead 7 does not stay due to the flow to the cryogenic refrigerator 6 side, the temperature rise and pressure rise are suppressed. . Thereby, damage due to overheating of the current lead 7 at the top can be prevented, and the temperature uniformity of the refrigerant 4 and gas of the cryostat 3 can be improved.

  On the cryogenic refrigerator 6 side of the cryostat 3, the refrigerant 4 and evaporative gas that are constantly warmed are sent from the current lead 7 group side toward the refrigerator head 6 a whose temperature has decreased due to cooling condensation and pressure has decreased. In the low temperature part of the refrigerator head 6a, the cooled and condensed refrigerant gas is always released from the surface, heat exchange in the refrigerator head 6a is promoted, and the refrigerating efficiency is improved. The effect of promoting the flow and further promoting the heat exchange can be obtained.

  The superconducting current limiting element 5 composed of a non-inductive superconducting coil or the like is usually installed near the bottom of the cryostat 3 that houses the refrigerant 4. When the element is a superconducting coil, the superconducting coils for three phases are often arranged symmetrically with respect to the central axis of the cylinder of the cryostat 3. In this case, the heat generated by the non-inductive superconducting coil is generated by the cryostat 3. Although it is generated symmetrically on the central axis, the refrigerant 4 and bubbles to which heat has been transmitted are guided to the current lead 7 side by the above-described flow, and the flow is partially offset but does not block the flow. .

  In particular, when the heat generation of the current lead 7 and the superconducting current limiting element 5 is compared, the heat penetration from the current lead 7 and the heat generation are nearly one digit larger, so the flow of heat in the cryostat 3 does not change greatly. .

  While this tendency is accompanied by an increase in the current of the superconducting current limiting element 5 and a reduction in the AC loss of the superconducting conductor that has been developed, the heat generation at the current lead 7 is almost determined by the physical shape and the energizing current, Since this will not be significantly reduced in the future, the flow according to the invention in the cryostat 3 will not be significantly disturbed.

  If the center position of the current limiting coil as a whole can be decentered due to the relationship between the inner diameter of the cryostat 3 container and the outer diameter of the superconducting current limiting element 5, the coil center position should be positioned below the current lead group side. By arranging them closer and away from the refrigerator side, the current-limiting coil can also form an inherently large convection, and can contribute to soaking and improving cooling characteristics.

  Next, the current lead group located locally on the upper surface flange 14 of the cryostat 3 and the refrigerator heads of one or more cryogenic refrigerators 6 are arranged in the arrangement of the components of the current limiter system, Demonstrates unique effects in terms of maintainability and maintenance of responsibility during maintenance. With respect to this configuration and effect, the present embodiment will be described with reference to FIGS. 1 and 2.

  As shown in FIG. 1 and FIG. 2, in the superconducting fault current limiter 1 used by consumers and the like, a standard panel in which equipment including superconducting related equipment such as a cryostat 3 and a compressor 8 for a refrigerator is a cubicle 2. It is necessary to be installed inside. The cryostat 3 of the superconducting coil housed in the cubicle 2 and the cryogenic refrigerator compressor 8 have a cryogenic sliding part and the like, so that the refrigerator is operated at a frequency of about once a year or more. It is necessary to stop and carry out maintenance.

  When the operation of the refrigerator is stopped for several hours, the normally used refrigerant 4 such as liquid nitrogen is maintained while releasing a part of the evaporated gas outside the cryostat 3 when the normal operation is cooling at the boiling point (77 K). However, when operating at a temperature lower than the normal boiling point temperature (for example, down to 65K), the temperature rise to the boiling point is also used for a relatively long time. Maintenance can be performed while preventing evaporation of the refrigerant gas.

  In such a case, by applying this embodiment, maintenance can be performed while the current limiter is kept in the energization maintenance state, that is, in a standby state in which a protective operation can be performed when a system fault occurs. Is possible. That is, in the present embodiment, the cryostat 3 includes a cryostat main body 3a having an upper surface opened and an upper surface flange 14 as a lid for closing the opening, and the superconducting current limiting element 5 and the cryogenic refrigerator 6 are provided on the upper surface flange 14. The cryostat body 3a and the upper surface flange 14 are detachably connected by a fastener such as a bolt 17 or the like.

  Thereby, the upper surface flange 14 of the substantially cylindrical cryostat 3 is hermetically fixed to the cryostat body 3a by the bolts 17 and the like, and can be easily separated from the cryostat body 3a.

  Further, in the present embodiment, a circuit breaker 9 is provided between the system of the commercial power source 101 and the superconducting current limiting element 5, and the circuit breaker 9 and the cryostat 3 are arranged at different positions in plan view in the cubicle 2, The circuit breaker 9 is arranged closer to the arrangement region side of the superconducting current limiting element 5 than the arrangement region of the cryogenic refrigerator 6 in the cryostat 3. That is, the cryostat 3 is housed in the cubicle 2, and is connected to a commercial power supply system that is a current limit protection target in the cubicle 2 and a bolt nut for connecting a current-carrying portion of the cryostat 3 of the superconducting fault current limiter. The connector that can be easily attached and removed regardless of the arrangement area of the cryogenic refrigerator 6 is set closer to the arrangement area side of the three pairs of current leads 7 of the cryostat 3.

  Further, a compressor 8 of a cryogenic refrigerator 6 is provided outside the cryostat 3, and the compressor 8 and the cryostat 3 are arranged at different positions in a plan view in the cubicle 2, and the compressor 8 is a cryogenic refrigerator in the cryostat 3. The arrangement is closer to the arrangement region side of the superconducting current limiting element 5 than the arrangement region of the machine 6. That is, the cryostat 3 is housed in the cubicle 2 and is connected to a power system that is a current limit protection target in the cubicle 2 and a current-carrying portion of the cryostat 3 of the superconducting current limiter by a bolt nut or the like. In addition, the compressor 8 for the refrigerator is arranged closer to the arrangement region of the cryogenic refrigerator 6 than the arrangement region side of the three pairs of current leads 7 of the cryostat 3. is set up.

  Further, the disconnector 18 of the current lead 7 is provided outside the cryostat 3, and the disconnector 18 is structured to be able to switch connection / disconnection by shifting the position of the cryostat 3 on the rail 19 installed below the cryostat 3. ing. That is, the disconnector 18 as a connector that can be easily attached and detached without using bolts and nuts is mechanically coupled to the current limiter cryostat 3, and the position of the current limiter cryostat 3 is shifted to disconnect the connector. It has a structure that can switch contact.

  In addition, a current conducting conductor such as a current lead 7 that connects the power system and the superconducting fault current limiter, and a pipe 20 that connects the cryogenic refrigerator 6 and the compressor 8 of the cryogenic refrigerator 6 are respectively provided in the cubicle 2. The current-carrying conductor and the pipe 20 are arranged in a non-crossing manner in the space in the cubicle 2.

  That is, the cryostat 3 is housed in the cubicle 2 and is connected to a power system that is a current limit protection target in the cubicle 2 and a current-carrying portion of the cryostat 3 of the superconducting current limiter by a bolt nut or the like. Equipped with a connector that can be easily attached and detached, and connecting piping and wiring from the refrigerator head 6 a to the compressor 8 for the refrigerator are easily attached to and detached from the three pairs of current leads 7 of the cryostat 3. A current-carrying conductor to be connected is not spatially intersected.

In the space of the cubicle 2, the refrigerator head 6 a of the cryogenic refrigerator 6 and the compressor 8 are spaced from the circuit breaker 9. That is, the cryostat 3 is housed in the cubicle 2 and is connected to a power system that is a current limit protection target in the cubicle 2 and a current-carrying portion of the cryostat 3 of the superconducting current limiter by a bolt nut or the like. A connector that can be easily attached and detached is provided, and the cryogenic refrigerator head 6a and the compressor 8 for the cryogenic refrigerator 6 are not close to each other.

Moreover, the circuit breaker 9 is installed in the position higher than the upper surface of the cryostat 3, as shown in FIG. That is, the cryostat 3 is housed in the cubicle 2 and is connected to a power system that is a current limit protection target in the cubicle 2 and a current-carrying portion of the cryostat 3 of the superconducting current limiter by a bolt nut or the like. A connector that can be easily attached and detached is provided, and the connector is installed at a position higher than the upper surface flange 14 of the cryostat 3.

  The cryostat 3 has a sealed structure capable of preventing the refrigerant gas evaporated inside from being released into the atmosphere even when the internal pressure increases due to the current limiting operation and becomes higher than the atmospheric pressure. . That is, even if the pressure inside the cryostat 3 due to the current limiting operation becomes higher than the pressure on the rising atmosphere side, the refrigerant gas evaporated inside is not released into the atmosphere.

  Also, in the cubicle 2, the current conducted to the room temperature portion of the current lead 7 connected to the superconducting current limiting element 5 is smaller than a certain current value, or the temperature of the current lead 7 has dropped to a certain level. With either or both of these as criteria, the air flows and does not stay. That is, in the cubicle 2, the current passed through the room temperature portion of the three pairs of current leads 7 connected to the superconducting current limiting element 5 for AC three-phase is smaller than a certain current value, or the temperature of the leads Based on either or both of the fact that it has fallen below a certain level, air flows by a convection generating means (not shown) and does not stay there.

  Next, the operation will be described. As described above, in the present embodiment, the current lead group is arranged in a spatially spaced relationship with one or a plurality of refrigerators on the flange, so that the lead group is made of rubber or an acrylic plate or the like. By isolating it from the refrigerator group with the insulating material, it is possible to easily and reliably isolate it from the worker, and the worker can access the refrigerator group safely. This makes it possible to carry out maintenance of the refrigerator head while maintaining the energized state of the current limiter.

  The refrigerator compressor 8 also needs to be maintained by replacing an adsorber (adsorbent) about once every three years. However, because of the arrangement of the refrigerator head according to the present invention, the refrigerator compressor 8 is also a current lead group. Since the pipes are arranged so as to be drawn away from each other, maintenance can be performed by pulling out the compressor 8 inside the cubicle 2 or outside without interfering with other devices. Thus, the implementation of the present invention makes it possible for the first time to perform maintenance of the cryogenic refrigerator 6 while maintaining the basic function of the current limiter.

  When the cryostat 3 is slid out of the cubicle 2 due to a failure or the like and pulled out on the rail, the disconnector disposed on the opposite side to the pulling side automatically disconnects and mechanically disconnects the cryostat 3 from the power system. In some cases, the current lead group is arranged on the side close to the disconnector by implementing the present invention, so that the length of the conductor at normal temperature, which is high in material cost, is shortened. Then, it becomes possible to equip the disconnector with the safety device as a set.

  When maintaining the refrigerator head and the refrigerator compressor 8, depending on the operation method, in some cases, energization of the superconducting fault current limiter may be stopped in principle. In such a case, when the maintenance is performed, the current limiting standby state is canceled before the maintenance is performed. Therefore, by placing the disconnector on the side opposite to the drawing side as described above, the cryostat 3 is arranged. By pulling out, the disconnector is automatically disconnected, and the cryostat 3 is mechanically disconnected from the power system.

  Since the disconnector is provided on the side opposite to the pulling direction, the cryostat 3 can be safely peeled off from the system circuit, and the refrigerator head is disposed on the pulling side. Maintenance can be performed safely from the side where the door is opened with good workability.

  While there is a system that needs to perform maintenance by releasing the current-limiting standby state (the state when the cryostat 3 is energized) (switching to the bypass side) and supplying power to the system circuit, In the case of a climate where there is no concern about the occurrence of an accident current such as lightning, as a routine to disconnect the disconnector, after bypassing the system circuit with a bypass circuit before disconnecting the disconnector of the current limiting coil, It is possible to carry out maintenance of the refrigerator.

The plane block diagram which shows the superconducting fault current limiter by one Embodiment of this invention. AA sectional view taken on the line AA of FIG. Explanatory drawing which expands and shows the arrangement structure of the superconducting current limiting element in a cryostat and a refrigerator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Superconducting current limiter 2 Cubicle 3 Cryostat 4 Refrigerant 5 Superconducting current limiting element 6 Cryogenic refrigerator 7 Current lead 8 Compressor 9 Circuit breaker 14 Top flange 18 Disconnector

Claims (11)

A superconducting current limiter of a resistance type in which a superconducting current limiting element and a cryogenic refrigerator are disposed in a cryostat that contains a refrigerant, and the superconducting current limiting element is connected between a plurality of power systems through current leads. The current limiting element and the cryogenic refrigerator are locally arranged in areas where the occupied portions are different from each other in plan view in the cryostat ,
A breaker is provided between the power system and the superconducting current limiting element, and the breaker and the cryostat are arranged at different positions in a plan view in a cubicle,
The compressor of the cryogenic refrigerator is provided outside the cryostat, and the compressor and the cryostat are arranged at different positions in plan view in the cubicle,
A superconducting fault current limiter , wherein a refrigerator head and a compressor of the cryogenic refrigerator are spaced apart from the circuit breaker in the cubicle space . A superconducting current limiter of a resistance type in which a superconducting current limiting element and a cryogenic refrigerator are disposed in a cryostat that contains a refrigerant, and the superconducting current limiting element is connected between a plurality of power systems through current leads. The current limiting element and the cryogenic refrigerator are disposed in different one-side regions with respect to the center in plan view in the cryostat ,
A breaker is provided between the power system and the superconducting current limiting element, and the breaker and the cryostat are arranged at different positions in a plan view in a cubicle,
The compressor of the cryogenic refrigerator is provided outside the cryostat, and the compressor and the cryostat are arranged at different positions in plan view in the cubicle,
A superconducting fault current limiter , wherein a refrigerator head and a compressor of the cryogenic refrigerator are spaced apart from the circuit breaker in the cubicle space . A superconducting current limiter of a resistance type in which a superconducting current limiting element and a cryogenic refrigerator are disposed in a cryostat that contains a refrigerant, and the superconducting current limiting element is connected between a plurality of power systems through current leads. The current limiting element and the cryogenic refrigerator are arranged in a region divided into two equal parts in a plan view in the cryostat ,
A breaker is provided between the power system and the superconducting current limiting element, and the breaker and the cryostat are arranged at different positions in a plan view in a cubicle,
The compressor of the cryogenic refrigerator is provided outside the cryostat, and the compressor and the cryostat are arranged at different positions in plan view in the cubicle,
A superconducting fault current limiter , wherein a refrigerator head and a compressor of the cryogenic refrigerator are spaced apart from the circuit breaker in the cubicle space . A superconducting current limiter of a resistance type in which a superconducting current limiting element and a cryogenic refrigerator are disposed in a cryostat that contains a refrigerant, and the superconducting current limiting element is connected between a plurality of power systems through current leads. The plan view center point of the current limiting element and the plan view center point of the cryogenic refrigerator are arranged in regions opposite to each other that are equally divided into two in plan view in the cryostat ,
A breaker is provided between the power system and the superconducting current limiting element, and the breaker and the cryostat are arranged at different positions in a plan view in a cubicle,
The compressor of the cryogenic refrigerator is provided outside the cryostat, and the compressor and the cryostat are arranged at different positions in plan view in the cubicle,
A superconducting fault current limiter , wherein a refrigerator head and a compressor of the cryogenic refrigerator are spaced apart from the circuit breaker in the cubicle space . The cryostat includes a cryostat main body whose upper surface is open and a lid that closes the opening, and the superconducting current limiting element and the cryogenic refrigerator are suspended from the lid, and the cryostat main body and the lid The superconducting fault current limiter according to any one of claims 1 to 4, wherein the two are detachably connected by a fastener. 6. The circuit breaker according to any one of claims 1 to 5, wherein the circuit breaker is arranged closer to the arrangement region side of the superconducting current limiting element than the arrangement region of the cryogenic refrigerator in the cryostat. The superconducting fault current limiter according to claim 1. The said disconnector is arrange | positioned near the arrangement | positioning area | region side of the said superconducting current limiting element rather than the arrangement | positioning area | region of the said cryogenic refrigerator in the said cryostat, Any of Claim 1-6 The superconducting fault current limiter according to claim 1. The disconnector of the current lead is provided outside the cryostat, and the disconnector has a structure capable of switching connection / disconnection by shifting the position of the cryostat. The superconducting fault current limiter according to claim 1. An energizing conductor that connects the power system and the superconducting fault current limiter, and a pipe that connects the cryogenic refrigerator and the compressor of the refrigerator, are each disposed in a cubicle, and the energizing conductor and the pipe The superconducting fault current limiter according to claim 1, wherein the superconducting fault current limiters are arranged in a non-intersecting arrangement within a space in the cubicle. The superconducting fault current limiter according to any one of claims 6 to 9 , wherein the circuit breaker is installed at a position higher than an upper surface of the cryostat . The cryostat is characterized by having a sealed structure capable of preventing the refrigerant gas evaporated inside from being released into the atmosphere even when the internal pressure increases due to the current limiting operation and becomes higher than the pressure on the atmosphere side. The superconducting fault current limiter according to any one of claims 1 to 10.

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