JPH06333739A - Superconducting coil system - Google Patents

Abstract

PURPOSE:To provide a superconducting coil system capable of avoiding a DC breaking operation impossible region near a zero current point accompanied with the switching operation of a polarity transfer switch without applying a voltage higher than necessary to a superconducting coil when interrupting a direct current. CONSTITUTION:A main circuit consisting of a power supply equipment 6 is provided, which excites a superconducting coil 2 through a superconducting coil 2 having a quenching detector 1, a current detector 3 of the superconducting coil 2, and a parallel circuit of a DC circuit breaker 4 and a resistor 5. Moreover, a commutating circuit 13 which connects in parallel a commutating capacitor 10 having a polarity transfer switch 7 connected in parallel to a DC circuit breaker 4, a charging equipment 8 and a voltage detector 9 as well as a series configuration of a first switch 11 and a commutating reactor 12 to the polarity transfer switch 7, and a controller 14 for performing overall operation, control, protection and monitoring are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting coil system, and more particularly to a superconducting device having a direct current interruption device capable of performing appropriate direct current interruption at an arbitrary current value when the current flowing through the superconducting coil changes with time. The present invention relates to a superconducting coil system that protects a coil quench.

[0002]

2. Description of the Related Art The general features of a direct current interruption device which has been conventionally used in the fields of a fusion device and a superconducting energy storage device are shown below.

In the normal conduction nuclear fusion device, it is necessary to operate the direct current interruption device every time for the purpose of igniting plasma. Therefore, it is possible to preset the charging voltage of the commutation capacitor and the cutoff time in accordance with the operating conditions. Further, since the normal conducting coil is used, there is no quench phenomenon.

Although the track record of the superconducting nuclear fusion device is still small, since the DC interrupting device is operated every time when the coil for igniting the plasma is of the normal conducting type, the charging voltage of the commutation capacitor and the It is possible to preset the cutoff time. On the other hand, in the case of the superconducting type, there are many cases in which plasma ignition is performed at a high frequency, and there are almost no examples of installing a DC interrupting device for the above purpose, but a DC interrupting device for quench protection is newly required. When the current value of the superconducting coil is small, it is possible to forcibly cut off the direct current with an electromagnetic contactor or a fuse, but in order to cut off a large DC current of several tens of kA, a current zero point is created. The commutation circuit of is needed.

As described above, in the fields of nuclear fusion, superconducting energy storage, etc., where large-capacity superconducting coils are often used, it is understood that a DC interrupting device having a commutation circuit for quench protection is required. .

However, the quench phenomenon does not always occur at a specific coil current value, and it is impossible to preset the breaking current, operating time, etc. of the DC breaking device.

Generally, in order to cut off the current I flowing through the DC circuit breaker, the reverse current discharged from the commutation circuits connected in parallel is often set to about 1.2I. In this case, the magnitude of the reverse current can be determined by the charging voltage of the commutation capacitor forming the commutation circuit as in the following equation.

V = I _C √L / C (1) where V is the charging voltage of the commutation capacitor, C is the capacity of the commutation capacitor, L is the inductance of the commutation reactor,
And I _C are the magnitudes of the reverse currents.

[0009]

[Problems to be Solved by the Invention]
This is a method that is usually adopted when installing a DC interrupting device for the above purpose, but it is necessary to always detect the current I when aiming at quench protection of the superconducting coil. That is, since the current value at which quenching occurs in the superconducting coil is uncertain, the commutation capacitor must always be fully charged to a value corresponding to the rated current value of the superconducting coil. Therefore, if a quench occurs when the current flowing through the superconducting coil is small, a reverse current of a large value sufficient to interrupt the rated current of the superconducting coil flows into the DC circuit breaker and is interrupted. It will flow into the vessel and generate more voltage than necessary between the terminals of the superconducting coil, which will accelerate the deterioration of the insulation of the superconducting coil.

In addition, when the current flowing through the DC circuit breaker changes its polarity, it is necessary to open and close each of the switching devices constituting the polarity switching device each time. In the vicinity of the current zero point, that is, before and after the polarity change, a region in which the DC cutoff operation is impossible occurs.

The present invention has been made in view of the above points,
The purpose of this is to cut the direct current at an arbitrary current value flowing through the superconducting coil, operating time, etc., without applying an unnecessarily high voltage to the superconducting coil, and to prevent the current associated with the opening / closing operation of the polarity switching device. It is an object of the present invention to provide a superconducting coil system having a quench protection device capable of avoiding a DC cutoff inoperable region near the zero point.

[0012]

In order to achieve the above object, the present invention provides a superconducting coil having a quench detector, a current detector for the superconducting coil, and a superconducting circuit through a parallel circuit of a DC breaker and a resistor. A main circuit including a power supply device for exciting a coil, a polarity switching device connected in parallel to the DC circuit breaker, a commutation capacitor having a charging device and a voltage detector, a first switch and a commutation reactor are connected in series. In a superconducting coil system including a commutation circuit connected in parallel to a polarity switcher and a control device for performing overall operation, control, protection, and monitoring, a current detector for the superconducting coil is a magnetizing current value for the superconducting coil. Is sequentially sent to the control device to perform a predetermined calculation, and as a result, a charging method capable of sequentially controlling the charging voltage of the commutation capacitor forming the commutation circuit is set up. The Rukoto, those occupying become possible proper DC blocking even if the current of the superconducting coil is varied sequentially.

Further, in the structure in which the polarity switching device is omitted, the first switch is an anti-parallel circuit of directional switches, so that the direct current cutoff corresponding to the current polarity of the superconducting coil becomes possible. .

[0014]

The power supply device is used to excite the superconducting coil through the parallel circuit of the DC breaker and the resistor. The current flowing through the superconducting coil is sequentially taken into the control device by the current detector, and an appropriate calculation is performed to determine the charging voltage value of the commutation capacitor. When the quench detector provided in the superconducting coil detects the occurrence of the quench, the DC circuit breaker is opened via the control device, but at the same time, the first switch of the commutation circuit is closed, and the DC circuit breaker is closed. A zero current is created in the DC current flowing through. Further, the polarity switcher is appropriately switched so that when the polarity of the DC current flowing through the DC circuit breaker changes, the discharge current of the commutation capacitor tends to create a current zero point in the DC current. Further, the second switch is closed in synchronization with the breaking operation of the DC breaker to protect the power supply device from overvoltage. Further, the first switch in the configuration in which the polarity switch is omitted is used to discharge the commutation capacitor of the commutation circuit.

[0015]

The present invention will be described in detail below with reference to the illustrated embodiments.

FIG. 1 shows an embodiment of the present invention.

As shown in the figure, in this embodiment, a superconducting coil having a quench detector 1, a current detector 3 for the superconducting coil 2, a DC circuit breaker 4 and a resistor 5 are connected in parallel through a superconducting coil. 2, a main circuit consisting of a power supply device 6 for exciting 2, a polarity switching device 7 connected in parallel to the DC breaker 4, a charging device 8 and a commutation capacitor 10 having a voltage detector 9, a first switch 11 and a commutation. The reactor 12 comprises a commutation circuit 13 in which a series configuration of the reactor 12 is connected in parallel to the polarity switching device 7, and a control device 14 for operating, controlling, protecting, and monitoring the whole.

The superconducting coil 2 is excited by the power supply device 6. However, if a quench occurs during excitation or the like, the energy stored in the superconducting coil 2 should be transferred to the outside as quickly as possible in order to prevent damage to the superconducting coil 2. It is necessary to consume it in the resistor 5 of. For this purpose, it is necessary to open the DC circuit breaker 4 connected in series to the superconducting coil 2,
Since the current flowing through the DC breaker 4 is DC, it is necessary to operate the commutation circuit 13 to create a current zero point and cut off the DC. At this current zero point, if the value of the current flowing in the DC circuit breaker 4 at the time of DC interruption is I, the reverse current discharged from the commutation circuit 13 connected in parallel is 1.2I.
Generally, it is set to a degree. In this case, the magnitude of the reverse current can be determined by the charging voltage V of the commutation capacitor 10 forming the commutation circuit 13 as shown in the equation (1).

However, it is difficult to predict the timing at which the quench occurs in the superconducting coil 2. Therefore, the DC current value flowing in the superconducting coil 2 is sequentially detected, and the charging voltage of the commutation capacitor 10 corresponding to this value is sequentially controlled in the same manner, whereby the DC cutoff under the optimum condition becomes possible. The power supply device 6 is normally in a short-circuit mode so that an overvoltage is not applied when the direct current is cut off.

FIG. 2 shows another embodiment of the present invention. That is,
In the figure, a second switch 15 is provided in parallel with the power supply device 6 so that an overvoltage is not applied to the power supply device 6 when the direct current is cut off. In this case, the short circuit mode by the power supply device 6 in FIG. 1 may not be performed.

FIG. 3 shows still another embodiment of the present invention. That is, in the figure, among the various constituent elements of FIG. 1, the first switch 11 is an antiparallel circuit 16 of a directional switch, and the polarity switch 7 is further omitted.
Not only the charging voltage of the superconducting coil 2
The charging method that can be controlled according to the current value and its polarity is provided. For example, in FIG.
In the current flowing through the DC circuit breaker 4 as shown in (1), when the current polarity changes from positive to negative, the polarity switch 7 needs to be opened and closed, but a delay time occurs in this switching operation, so that The DC cutoff inoperable region 17 is generated. That is, by providing the anti-parallel circuit 16 of the directional switch, it is possible to successively control the polarity of the charging voltage of the commutation capacitor 10 forming the commutation circuit 13.

[0022]

According to the superconducting coil system of the present invention described above, the commutation capacitor charging voltage of the DC circuit breaker that operates when a quench occurs can be optimally controlled successively, so that an excessive voltage is applied to the superconducting coil. It is not necessary to do so, and it is possible to significantly suppress the insulation deterioration of the superconducting coil. Also, by using the directional switch in anti-parallel connection, the polarity switch can be omitted, not only the charging voltage of the commutation capacitor but also the charging polarity can be controlled and the switching time of the polarity can be shortened. It becomes possible to avoid the area where direct current cannot be cut off, and the effect is great.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a superconducting coil system of the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the superconducting coil system of the present invention.

FIG. 3 is a circuit diagram showing still another embodiment of the superconducting coil system of the present invention.

FIG. 4 is a diagram showing an example of a waveform of a current flowing through a DC circuit breaker constituting the superconducting coil system of the present invention.

[Explanation of symbols]

1 ... Quench detector, 2 ... Superconducting coil, 3 ... Current detector, 4 ... DC circuit breaker, 5 ... Resistor, 6 ... Power supply device, 7 ...
Polarity changer, 8 ... Charging device, 9 ... Voltage detector, 10 ... Commutation capacitor, 11 ... Thyristor switch, 12 ... Commutation reactor, 13 ... Commutation circuit, 14 ... Control device, 15 ...
Inserter, 16 ... Anti-parallel circuit of thyristor switch, 17
... DC cutoff operation impossible area.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hojin Saigo Inventor 3-1, 1-1 Saiwaicho, Hitachi City, Ibaraki Prefecture Hitachi Ltd. Hitachi Factory (72) Inventor Keigo Fukaura 3-chome, Saiwaicho, Hitachi City, Ibaraki Prefecture No. 2-2 Hitachi Engineering Service Co., Ltd.

Claims (3)

[Claims] 1. A superconducting coil having a quench detector, a current detector for the superconducting coil, a main circuit comprising a power supply device for exciting the superconducting coil via a parallel circuit of a DC breaker and a resistor, and the DC breaker. Commutation capacitor having a polarity switcher, a charging device, and a voltage detector connected in parallel to the first switch, and a commutation circuit in which a series configuration of a commutation reactor is connected in parallel to the polarity switcher, and the whole. Driving,
In a superconducting coil system including a control device for controlling, protecting and monitoring, the superconducting coil system has a charging method capable of controlling the charging voltage of the commutation capacitor according to the current value of the superconducting coil. Is a superconducting coil system. 2. The superconducting coil system according to claim 1, wherein a second switch which is closed in synchronization with the opening of the DC circuit breaker is arranged in parallel with the power supply device. 3. The direct commutation circuit according to claim 1, wherein the first switch is an antiparallel circuit of directional switches such as ignitron and thyristor, and the polarity switch is omitted. Is connected in parallel with the DC circuit breaker, a superconducting coil system.