JPH0993800A - Superconducting coil electric power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress insulation withstanding voltage low for a superconducting coil by decreasing cut-off voltage at the time of quench protecting action. SOLUTION: In a superconducting coil electric power unit connecting a plurality of superconducting coils 1a to 1f in series to an excitation power supply 2, DC circuit breakers 3a to 3f breaking a circuit at quench time are alternately connected in series to the superconducting coils 1a to 1f, also protection resistors 4a to 4f consuming accumulated energy of the coil are connected in parallel to the DC circuit breakers 3a to 3f, and all the DC circuit breakers are simultaneously actuated at a quench time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toroidal magnetic field coil power source for a nuclear fusion experimental apparatus, in which a plurality of superconducting coils serving as loads are connected in series to an exciting power source, by quenching the superconducting coil. The present invention relates to a superconducting coil power supply device that employs a quench protection system that protects from damage.

[0002]

2. Description of the Related Art In recent years, superconducting coils have been applied in various fields such as nuclear fusion experimental equipment, accelerators, and superconducting power storage equipment. The superconducting coil normally has an electric resistance of zero, but an abnormal phenomenon in which the superconducting property is lost due to a sudden change in magnetic field or temperature (hereinafter referred to as "quenching") may occur.

When a quench occurs in the superconducting coil, the coil is damaged due to the pressure rise due to the abnormal occurrence of liquid helium, and the energy stored in the coil is consumed by the quenched coil, resulting in a failure of the coil. Therefore, a protective device is required to quickly demagnetize the coil when a quench occurs.

FIG. 6 shows an example of the structure of a general superconducting coil power supply device equipped with this type of protection device. In FIG. 6, 1 is a superconducting coil that serves as a load, 2 is an exciting power source for exciting the superconducting coil 1 (the thyristor converter is shown as an example in the figure), and 3 is an exciting power source 2 on the output side of the exciting power source 2. The DC breakers 4 connected in series are connected in parallel with the superconducting coil 1, and are protective resistors for absorbing the energy stored in the superconducting coil 1 when a quench occurs.

In a superconducting coil power supply device equipped with such a protection device, when a quench occurs in the superconducting coil 1, a DC circuit breaker 3 is cut off to form a closed loop circuit between the superconducting coil 1 and the protective resistor 4. The energy formed and stored in the superconducting coil 1 is the protective resistance 4
The superconducting coil 1 can be rapidly demagnetized.

Further, for example, in the case of a toroidal magnetic field coil power source for a nuclear fusion experimental apparatus, it is conceivable that a plurality of superconducting coils are connected in series to one exciting power source.
FIG. 7 shows a configuration example of a conventional power supply device in such a case.

In FIG. 7, reference numerals 1a to 1f show a plurality of superconducting coils installed in a toroidal shape. In the example shown in the figure, six superconducting coils are used. Often composed. In the case of the power supply device having such a configuration, when any one of the superconducting coils 1a to 1f is quenched, the DC breaker 3 is cut off and all the energy is collectively absorbed by the protective resistance 4. It was done.

[0008]

As described above, in the conventional superconducting coil power supply device in which a plurality of superconducting coils are connected in series to the exciting power supply, the energy of all the coils is absorbed by one protection resistor. Therefore, the cutoff voltage applied to the coil becomes considerably large.

In particular, as the size of the nuclear fusion experimental apparatus has increased in recent years, the size of the superconducting coil has also increased, the current flowing through the coil and the inductance have increased, and the problem that the cut-off voltage has increased becomes prominent.

That is, when the inductance of all the coils is L and the protection resistance value is R, a certain short time (for example, a few seconds to
Since it needs to be performed for about ten and several seconds), R is set to a large value so that the time constant of attenuation given by L / R becomes small.

Therefore, the breaking voltage given by the coil energizing current I × R becomes large, which causes a problem that the insulation withstand voltage allowed by the current superconducting coil is greatly exceeded.

The present invention has been made to solve the above problems, and provides a superconducting coil power supply device capable of reducing the cut-off voltage during the quench protection operation and suppressing the withstand voltage of the superconducting coil. With the goal.

[0013]

In order to achieve the above object, the present invention constitutes a superconducting coil power supply device by the following means. The invention corresponding to claim 1 is:
In a superconducting coil power supply device in which a plurality of superconducting coils are connected in series to an excitation power source, a DC circuit breaker that interrupts a circuit during quenching is connected in series with the superconducting coils alternately, and a protective resistance that consumes energy stored in the coil is described above. Connected in parallel with the DC breakers, all DC breakers are operated at the same time at the time of quench.

According to a second aspect of the present invention, in a superconducting coil power supply device in which a plurality of superconducting coils are connected in series to an exciting power source, one DC breaker is provided for each of two or more superconducting coils. With serial connection,
A protective resistor that consumes energy stored in the coil is connected in parallel with the DC breaker, and all the DC breakers are simultaneously operated at the time of quenching.

The invention corresponding to claim 3 is the above claim 1.
Alternatively, the midpoint of each superconducting coil or the midpoint of each protective resistor of the invention according to claim 2 is directly grounded. In the invention corresponding to claim 4, the midpoint of each superconducting coil or the midpoint of each protection resistor of the invention according to claim 1 or 2 is grounded by resistance.

[0016]

In the superconducting coil power supply device of the invention according to claim 1, since the resistance value of one protection resistor may correspond to one superconducting coil, the cutoff voltage applied to the coil is small. It becomes possible to suppress.

In the superconducting coil power supply device of the invention according to claim 2, since the resistance values of the plurality of protective resistors may correspond to one superconducting coil, the cutoff voltage applied to the coil is also set. It is possible to keep the size small, and further, since the number of current leads and the number of bus lines connected to the power source can be reduced, and the capacity of the refrigerant liquefier can be reduced, an economically advantageous system can be formed.

In the superconducting coil power supply device of the invention according to claim 3, the ground voltage of the circuit during the quench protection operation is halved by directly grounding the midpoint of each superconducting coil or the midpoint of each protection resistor. Can be

In the superconducting coil power supply device of the invention according to claim 4, one of a plurality of circuit breakers is provided by grounding the middle point of each superconducting coil or the middle point of each protective resistor. It is possible to suppress a large ground current that flows when a disconnection failure occurs, and it is possible to improve the current imbalance between the coils.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a circuit configuration diagram showing a first embodiment of a superconducting coil power supply device according to the present invention, and the same parts as those in FIG. 7 are designated by the same reference numerals.

In the first embodiment, as shown in FIG. 1, a plurality of superconducting coils 1a to 1 connected in series to the exciting power source 2 are connected.
f and a plurality of DC breakers 3a to 3f are alternately connected in series, and a protection resistor 4 is provided to each DC breaker 3a to 3f.
In this configuration, a to 4f are connected in parallel.

In the superconducting coil power supply device having such a circuit configuration, for example, when a quench occurs in the superconducting coil 1a, all the DC breakers 3a to 3f are simultaneously operated to cut off the circuit. In this case, if only the DC breaker 3a is cut off, all the energies of the superconducting coils 1a to 1f will flow into the protective resistance 4a, but each DC breaker 3a
3 to 3f are all operated simultaneously to cut off the circuit, and the energy of each superconducting coil 1a to 1f is absorbed by the protective resistances 4a to 4f in series with the coil.

As described above, according to the first embodiment, the protection resistors 4a to 4f can be manufactured by considering only the stored energy per corresponding superconducting coil. Therefore, in the case of FIG. 7, it is necessary to consider, for example, the insulation of the superconducting coil 1a from the ground with the voltage of V = IR which is the cutoff voltage. However, in the case of the embodiment shown in FIG. Is shown in FIG. 2, and the resistance value R ′ of one protection resistor may be, for example, about ⅙ of that in the case of FIG. 7. Therefore, the potential difference between the maximum voltage and the minimum voltage of the circuit given by V ′ = IR ′ is For example, it can be suppressed to about 1/6 of that in FIG.

As a result, the insulation of the coil from the ground can be reduced, and an economical coil can be manufactured. Further, since the resistance value of one protection resistor itself becomes small, there is an advantage that the design and manufacture of the resistor can be facilitated.

FIG. 3 is a circuit configuration diagram showing a second embodiment of the superconducting coil power supply device according to the present invention. The same parts as those in FIG. 7 are designated by the same reference numerals. In the second embodiment, as shown in FIG. 3, for example, one DC breaker 3a 'is connected in series to two superconducting coils 1a, 1b, and a protection resistor 4a is connected to this DC breaker 3a'. In this case, one DC breaker and the protective resistance connected in parallel to this are connected in series to the two superconducting coils in such a manner that ′ is connected in parallel.

Even with the circuit configuration according to the second embodiment, even if the number of coils to be borne by the DC circuit breaker and the protective resistance is increased within the range permitted by the design standard of the coil and the protective resistance, It is possible to obtain the same effect as that of the embodiment.

When actually manufacturing a power supply device, the number of current leads and the number of bus lines connected to the power supply can be reduced by optimally designing a certain number of coils together as described above. Since the capacity of the helium liquefier can be reduced, a more economical system can be realized.

FIG. 4 is a circuit configuration diagram showing a third embodiment of a superconducting coil power supply device according to the present invention. The same parts as those in FIG. 7 are designated by the same reference numerals. In the third embodiment, as shown in FIG. 4, a plurality of superconducting coils 1a to 1f and a plurality of DC breakers 3a to 3f connected in series to the excitation power source 2 are alternately connected in series, and each DC Breaker 3a-3f
The protection resistors 4a to 4f are connected in parallel with each other, and the middle point of each of the protection resistors 4a to 4f is directly grounded.

With such a configuration, the voltage to ground of the circuit during the quench protection operation can be halved compared to the case where one end is grounded, and a further effect can be obtained in terms of the coil insulation design. it can.

If it is technically possible, the same effect can be obtained even if the ground line is drawn from the midpoint of each superconducting coil. FIG. 5 is a circuit configuration diagram showing a fourth embodiment of a superconducting coil power supply device according to the present invention. In the circuit shown in FIG. 4, each ground is not grounded directly but is grounded via grounding resistances 5a to 5f. It was done.

In the direct grounding method, the ground current becomes large when a ground fault occurs in the circuit or when one of the plurality of circuit breakers has a breaking scale, and a current imbalance between the coils occurs. There is a problem that it becomes easier, but the fourth
By adopting the resistance grounding method as in the above embodiment, the problem of the direct grounding method can be solved.

[0032]

As described above, according to the present invention, it is possible to provide a superconducting coil power supply device capable of reducing the cutoff voltage during the quench protection operation and suppressing the withstand voltage of the superconducting coil.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing a first embodiment of a superconducting coil power supply device according to the present invention.

FIG. 2 is a diagram showing the potential of each part of the circuit during a quench protection operation in the circuit configuration of FIG.

FIG. 3 is a circuit configuration diagram showing a second embodiment of the present invention.

FIG. 4 is a circuit configuration diagram showing a third embodiment of the present invention.

FIG. 5 is a circuit configuration diagram showing a fourth embodiment of the present invention.

FIG. 6 is a circuit configuration diagram showing a conventional general superconducting coil power supply device.

FIG. 7 is a circuit configuration diagram showing a conventional superconducting coil power supply device in which a plurality of superconducting coils are connected in series to an exciting power supply.

[Explanation of symbols]

1a-1f ... Superconducting coil, 2 ... Excitation power supply, 3a-
3f, 3a ', 3c', 3e '... DC breaker, 4a
~ 4f, 4a ', 4c', 4e '... protective resistance, 5a ~
5f: Ground resistance.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H02J 15/00 ZAA H02M 9/00 A H02M 9/00 H05H 7/04 H05H 7/04 H01F 5 / 08 ZAAC (72) Inventor Toshiya Kai 1-1-1 Shibaura, Minato-ku, Tokyo Toshiba Head Office Office

Claims (4)

[Claims] 1. In a superconducting coil power supply device in which a plurality of superconducting coils are connected in series to an exciting power source, a DC circuit breaker for interrupting a circuit at the time of quenching is connected in series with the superconducting coils in series, and energy stored in the coils is consumed. A power supply device for a superconducting coil, characterized in that the protection resistors are connected in parallel with the DC breaker, and all the DC breakers are simultaneously operated at the time of quenching. 2. In a superconducting coil power supply device in which a plurality of superconducting coils are connected in series to an exciting power source, one DC breaker is connected in series to each of two or more superconducting coils and A superconducting coil power supply device, characterized in that a protection resistor for consuming stored energy is connected in parallel with the DC breaker, and all the DC breakers are simultaneously operated at the time of quenching. 3. The superconducting coil power supply device according to claim 1, wherein the midpoint of each superconducting coil or the midpoint of each protective resistor is directly grounded. 4. The superconducting coil power supply device according to claim 1, wherein the middle point of each superconducting coil or the middle point of each protection resistor is resistance grounded.