JPS60249307A - Quenching protection circuit of superconductive coil system - Google Patents

Abstract

PURPOSE:To avoid the excessive overload state of a coil or an excitation power source enabling to maintain other normal coil group under a rated current in the case that one coil is quenched and discharged during a superconductive coil system operation only by adding a simple circuit based upon a conventional coil protection circuit. CONSTITUTION:When a coil 1-1 is quenched in a circuit unit B-1, coil energy is discharged through a discharge resistance 2-1 cutting a DC breaker 3-1 and an auxiliary DC breaker 5-1 off simultaneously. At the same time, DC breakers 3-1-3-n are cut off in circuit units B-2-B-n. In this case, the coil energy of each normal coil 1-2-1-n is discharged by each discharge resistance 2-2-2-n and each control resistance 6-2-6-n. [Refer to Drawings (b) and (c)]. After each coil 1-2-1-n is discharged for a definite time t2-tn respectively, each DC breaker 3-2-3-n is closed again. The value of each control resistance is extremely smaller than the value of each discharge resistance.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for producing a large number of magnetically coupled superstructures. It is well known that devices are beginning to emit 13F4. Now, the superconducting coil C, which is an important element of this fusion reactor (hereinafter simply referred to as the coil), is quenched.

Needless to say, in such a case, it is necessary to turn off the DC breaker and discharge the coil energy to an external discharge resistor to protect the coil. Conventionally, a method using a discharge resistor as described above has been established as a protection method for this purpose. It can be considered that However, this method has only been established for cases where there is only one coil or no coil, and if the conventional method is directly applied to a quench protection method for a coil system consisting of many coils, the following problems will occur. occurs.

First, the configuration of a conventional quench protection circuit for one coil is as shown in Figure 2, as is well known.
, a discharge resistor 2-2, a sink or IJi device 3-1, and an excitation power source 4-1. If this protection circuit is directly applied to a coil system, as shown in FIG. 2, circuit units A-s to A-n having exactly the same configuration will be arranged. In Figure 2, the coils are arranged in a torus shape, assuming a toroidal coil system for a fusion reactor.
The present invention is not limited to this, and the target circuit is an array of coils that are magnetically coupled.

In this case, when one coil quenches and discharges, the current flowing through the other normal coils is exhausted due to magnetic induction. This increase in power L5 is larger in coils closer to the quenched coil in the coil group, and in particular for adjacent coils, it generally reaches 20 to 25% of the rated current L5, causing a very excessive overload for the coil itself and the power supply. It is dangerous. Conventionally, to solve such problems, the following (
Methods 1) to (3) have been devised, but each has its own problems.

(1) Both the coil and power supply should be designed to withstand 120 to 125% overload. However, it goes without saying that increasing costs and increasing the size of the equipment cannot be avoided, which is a disadvantage.

(2) Other normal coils also discharge simultaneously due to magnetic induction. However, in this case, the discharge rate generally decreases to about 10%, quenches, and the safety of the coil is likely to be compromised, and the evaporation of liquid helium from all the coils results in enormous consumption and thermal damage. This is a major change and is unfavorable in terms of the design of the equipment.

On the other hand, in the case of a toroidal coil system for a nuclear fusion reactor, from the perspective of plasma generation, it is said that there is a U6 possibility that plasma generation can still be maintained even if one coil out of all the coils is discharged. ing. Therefore, if the 1r (other normal coils are also discharged to zero ampere) at the same time, the operation rate of the fusion reactor will be reduced.

(3) It is also possible to maintain the current below the rated current by providing sufficient inverter voltage to the excitation power supplies 4-1 to 4-n and inverting the increased current to the system side (power pack).

However, since the coil is generally a superconducting coil and is not operated statically, the output voltage of the power supply required during steady state is 10~10~10 to compensate for the cable or bus drop.
30 V is also sufficient. Contrary to this small fact, if you try to use the inverter voltage as described above, you will need 10 to 9100 times more voltage capacity.

[Purpose of the invention]

The present invention aims to solve the problems of the conventional method described above, and uses a simple equipment configuration to suppress the increase in current in the other normal coils, keep the current below the rated current, and increase the current of the coil and excitation power source. Overload [Summary of the Invention] When one superconducting coil in a superconducting coil system consisting of a large number of superconducting coils is quenched, the other normal coils are overloaded to suppress the increase in current generated due to magnetic induction. A small-capacity control resistor is set in parallel with the discharging resistor, and discharge is caused to the control resistor for a predetermined period of time so that the coil current of other normal coils is maintained below the rated value.

[Embodiments of the invention]

The present invention connects a series circuit consisting of an appropriately small capacity control resistor and an auxiliary DC breaker in parallel with a conventional discharge resistor, and when a coil is discharged due to quenching, other normal coils mainly use the coil energy. The magnet shall be demagnetized at a speed determined by the resistance value of the control resistor for a pre-calculated period of time to maintain the current below the rated current. On the other hand, if the own coil quenches, discharge is performed by the discharge resistor as in the conventional method.

An embodiment of the present invention is shown in FIG. 1 below. circuit units) 1
Taking 3-s as an example, the 4th η component of the coil l-+, the discharge resistor 2-1, the DC disconnector 3-1, and the excitation power source 41 is the second
It is the same as the conventional insurance circuit configuration explained in the figure. The present invention further provides circuit units B-1 to B-n in which a series circuit consisting of an auxiliary DC breaker 5-Ll and a control resistor 6-1 is connected in parallel with the discharge resistor 2-s.
and the control panel 7 that controls the cut-off timing in a predetermined manner, and the people of these DC cutoff g = 3-t to 3-n and the auxiliary DC breakers 5-1 to 5-n, and the control panel 7 that instructs the timing. Signal line 8-! This will be explained below. During steady operation, DC breaker 3-1 to 3-n and auxiliary DC breaker 5
−+ to 5-n are in the closed state. For example, circuit unit B-
1, when the coil]-1 is quenched, the DC breaker 3-1 and the auxiliary DC breaker 5-1 are turned off at the same time, and the coil energy is discharged to the discharge resistor 2-1 (Fig. 3a).
reference). At the same time, the circuit units B and 2 to B-n are configured to cut off (open) direct current and %53-2 to 3-n.

In this case, the normal coil energy of each coil 1-2 to 1-n is
~6-n (see Figure 3, c).

After each coil 1-2 to 1-n is discharged for a predetermined period of time t2 to tn, each DC breaker 3-2 to 3-n is turned on again.

Here, the resistance value of each control resistor is much smaller than the resistance value of the discharge resistor. The values of the control resistor insertion times t2 to tn are calculated in advance so that the current flowing through the coils 1-2 to 1-n is kept constant around the rated value. Assuming that a quench occurs in coil 1-+, control is applied to each other (remaining) coil.
Prepare the insertion time for the I resistor in advance. Similarly, coil J
, -2, and the other (:
For the coils (A), the insertion time of each control resistor is determined in advance. In this way, the auxiliary DC current is connected in series with the control resistor according to the position (magnetic coupling situation) of the coil where quenching has occurred for all the coils, and the time is preset in the control panel 7. The importance of circuit breaker is controlled. On the other hand, the timing commands from t2 to tn are set in the control panel 7 and transmitted based on an output signal from a known quench detection circuit (not shown). Normal coil l as shown in Figure 3
-2, l-3... are somewhat smaller than the rated current, but the rated current must not be exceeded, so both the coil and the excitation power supply should be in an auto-<0-to LC range. On the other hand, since the rated currents of the coils l-2 to 1-n are kept substantially constant, the discharge time constant of the coil 1-1 can be kept substantially equal to the self-inductance/discharge resistance value. Therefore, it is safe to protect the quenched coil l-1.

In the present invention, the DC circuit breakers 3-1 to 3-n are required to perform a closing operation as a closing device in addition to their original purpose of breaker operation, but if a closing error occurs, a fail occurs as follows. It is designed to perform a safety function. In other words, if the coils 1-2 to 1-n cannot be turned on, each of the coils 1-2 to 1-n will be discharged to zero current at a slow discharge rate determined by the resistance values of the control resistors 6-1 to 6-n, resulting in a superconducting coil system. safety will be maintained. However, in the present invention, it is assumed that the DC circuit breakers 3-1 to 3-n are highly reliable in their closing operation, or are modified in such a manner.

In the present invention, as shown in FIG.
It can also be applied to a conventional protection circuit in which DC breaker 3-1 is connected in parallel, while DC breaker 3-+ is connected in series. That is, by connecting a series circuit of the control resistor 6-1 and the auxiliary direct current or disconnector 5-1 in parallel to the discharge resistor 2-1, the same operation and effect as described above can be achieved.

In the above-described embodiment of the present invention, a coil/stem in which one excitation power source is connected to one coil was explained, but the present invention is applicable to a coil/stem in which several coil groups are connected in series as shown in FIG. Exactly the same action and effect can be obtained for a coil/stem that is associated with one excitation power source.

Here, m means the number of coils connected in series with one excitation power supply V, and n is an integral multiple of m. The structural positional relationship of the 1η coils can be completely arbitrary, regardless of whether the coils are 9 comrades or different devices. Furthermore, n′,? It's Yu.

〔Effect of the invention〕

As described above, according to the present invention, by adding a simple circuit based on the conventional coil protection circuit by just 1", if one of the superconducting coils 7 stems quenches and discharges while the superconducting coil 7 stem is in operation, the other The normal coil group can be kept below the rated current, and if the excessive overload condition of the coil or excitation power source can be amplified, plasma generation can still be maintained at a constant level. has.

[Description of drawings]

A block diagram showing the Lucuente protection circuit, and FIG. 3 is a graph showing time changes in the current flowing through each coil during a protection operation based on the quench generated in the coil 1-1 according to the present invention.
FIGS. 4 and 5 are block diagrams showing circuit configurations of circuit units according to other embodiments of the present invention.

1, -1~1-n...Coil 2-1~2-n...Discharge resistance 3-1~3-n...DC or IDI visit 4-1~
4. -n... Excitation source A-1 to A-n ・Circuit unit l-5-1 to 5-n ・・Auxiliary DC breaker 6 to 1 to 6
-n... Control resistor 7... Control panel 8-1 to 8-n ・
・Signal line 13-, +~B-n...Circuit unit agent Patent attorney Noriyuki Chika (and 1 other person) Figure 2

Claims (1)

[Claims] (1) In a superconducting magnet system that includes multiple superconducting coils that are magnetically coupled to each other and a protection circuit consisting of an excitation power source, a discharge resistor, and a DC or 1Ifl device provided independently for each coil. A series circuit consisting of a small-capacity control resistor and an auxiliary DC breaker is connected in parallel with the discharge resistor, and when one coil quenches and discharges to the discharge resistor, other normal residuals are connected. Each of the above coils operates the auxiliary DC breaker for a predetermined period of time.