JPH07105531B2 - Operation control method for superconducting device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting device, and more particularly to the operation of a superconducting device having a superconducting coil used in a nuclear fusion device or a superconducting energy storage device, and a controller for operating the superconducting coil. Regarding control method.

[Background of the Invention]

One application field of superconductors is a superconducting coil for generating a strong magnetic field in a nuclear fusion device. The biggest problem in applying this super-electric coil is how to prevent the normal conducting dislocation (hereinafter referred to as quench) of the coil caused by insufficient cooling or the like. As a conventional publicly known example of this quench prevention method, there is disclosed in JP-A-48-52491, 49-91788,
49-96691, 50-115995, 53-17292, etc., in which, for example, the coil terminal voltage is monitored, and when a quench occurrence is detected from an abnormal rise in voltage, it is accumulated in the coil. The energy was released to an external resistor. However, such a conventional method has a drawback that the operation of the superconducting device must be stopped during the quench preventing operation. Further, when forced circulation cooling is performed, quenching can be prevented by always increasing the circulation amount of the refrigerant, but this leads to an increase in the size of the cooling system equipment and an increase in wasteful energy consumption.

[Object of the Invention]

An object of the present invention is to provide an operation control method for a superconducting device having a plurality of pancake (layered) superconducting coils for forced circulation cooling, which can prevent quenching without stopping the operation, and which wastes little energy consumption. To provide.

[Outline of Invention]

If a quench occurs in the superconducting coil of the superconducting device,
In general, the entire quench of the coil does not occur suddenly, but first the normal conduction region occurs in one pancake coil of the coil, and if the heat removal capacity is insufficient due to insufficient cooling, this normal conduction region will be generated. The process gradually expands to other pancake coils, leading to a full quench. Therefore, in the present invention, a temperature detector and a forced cooling means are provided for each pancake coil, and when the temperature detection value of a certain pancake coil exceeds a predetermined value, the refrigerant amount of the pancake coil is set to be smaller than that in a normal time. The present invention is characterized in that the quenching of the pancake coil is eliminated and the expansion thereof is prevented.

Example of Invention

An embodiment of the present invention will be described below. FIG. 1 is a block diagram showing an embodiment of the superconducting device according to the present invention. The superconducting coil 6 is housed in a vacuum container 7, cooled by liquid helium, and excited by an external power source (not shown). In this example, the coil 6 is nine pancake coils.
Each of the pancake coils 61 to 69 has a refrigerant passage for forced cooling therein (two coils 6 are shown, but only one of them is shown below). Liquid helium, which is a refrigerant, is frozen by the refrigerator 5, and pumped by the pumps 41 to 49 to the pancake coils 61 to 69 via the pipe 91. After cooling the coil, the liquid helium whose temperature has risen returns to the refrigerator 5 via the pipe 92, and the temperature can be lowered as much as necessary for cooling again. The controller 100 outputs a command to each of the pumps 41 to 49 to control the circulating amount of liquid helium in each of the pancake coils 61 to 69. That is, this control device
100 is a feature of the present invention, which receives signals from the temperature detectors 81 to 89 installed on the pancake coils 61 to 69, and the temperature thereof exceeds a predetermined value by the detection device 1. The rising pancake coil is detected by temperature comparison, and this detection signal is given to the corresponding pump control devices 31 to 39 to increase the refrigerant flow rate to the corresponding pancake coil.

FIG. 2 shows an embodiment of the detection device 1, and converters 101 to 109 for receiving temperature signals from the respective sensors 81 to 89 of the superconducting coil 6 and converting them into appropriate electric signals, and the electric signals Comprising comparators 111 to 119 which output signals to the pump control devices 31 to 39 when reaching a preset predetermined value T ₀ + ΔT.

FIG. 3 shows a reference temperature T ₀ + Δ for comparison in the comparators 111 to 119.
It is an explanatory view of the determination method of T, simulating the process in which the normal conduction transition occurs in the pancake coil 61 and the transition expands to other coils. That is, first, pancake coil 61
Heat is applied in order to experimentally generate a normal conduction region.
The method of inputting heat is by using a heater installed in the coil or by reducing the flow rate of the refrigerant. Test heat input from t = 0
until t = t _a (shown in solid line in the drawing) KoTsuta cases, showing the temperature change of each pancake coil 61-69 in solid lines. As is clear from the figure, the closer the heat is applied to the pancake coil 61, the sooner the temperature rises, and the lower the temperature after the end of heat input (when the quench is not reached). That is, in this case, since the cooling amount is sufficient as compared with the heat input amount, the normal conduction region gradually recovers to the superconducting state (returns to the original temperature) after the heat input is stopped.

On the other hand, when the test heat input is carried out from t = 0 to t = t _b (shown by broken lines in the figure), temperature changes of the pancake coils 61 to 69 are shown by broken lines. In this case, the amount of heat input exceeds the amount of cooling, so the normal conduction region does not return to the superconducting state even if the heat input is stopped. Due to heat conduction to the cake coil, the temperature rise of the entire superconducting coil,
In other words, it reaches the quench. Therefore, it is necessary to increase the refrigerant flow rate of each pancake coil before the temperature of each pancake coil rises so much. Therefore, according to the experiment shown in Fig. 3, the heat input that can restore the superconducting state without changing the refrigerant flow rate as in the case of the solid line in Fig. 3 is investigated, and the maximum temperature T _{1 at} that time is calculated. Lower eye temperature than
Let T ₀ + ΔT be the reference temperature of the comparators 111-119. However
T ₀ is the temperature during normal operation. For simplicity, the reference temperatures of the comparators 111 to 119 are all equal to T ₀ + Δ.
Although it is assumed to be T, it is actually the third due to the structural variations of the pancake coils 61 to 69 and the positions where they are arranged.
There may be cases where the characteristics described in the figure differ, but in this case, an appropriate T ₀ + ΔT may be experimentally determined and set for pancake correspondence.

FIG. 4 shows an example of the operation time chart of the present embodiment, in which the temperature rise in the pancake coil 61 due to some cause is t = 0.
Let's start from Therefore, at time t ₁ , the temperature of the pancake coil 61 reaches T ₀ + ΔT as shown in FIG. 3, the output of the comparator 111 is turned on, and the refrigerant flow rate by the pump 41 is increased. Then, from the setting method of the reference value T ₀ + ΔT, even if the heat input to the pancake coil continues, the temperature rise due to the heat input can be prevented by increasing the refrigerant flow rate, and eventually the temperature returns to the superconducting state and the temperature becomes T ₀ + ΔT or less. The refrigerant flow rate also returns to the normal state. At this time, other pancake coils 62-69
Temperature rises due to the temperature rise of the pancake coil 61, which is the cause of these temperature rises.
Since the heat input to 61 is blocked early due to the increase in the refrigerant flow rate by the pump 41 described above, the temperature rise is smaller than in the case of FIG. 3 in which the refrigerant flow rate does not change. However, when the temperature rise still exceeds ΔT at times t ₂ , t ₃ , ... Etc., the pumps 42 to 49 also increase the flow rate of the refrigerant and have an effect of accelerating the cooling of the pancake coil 61.

As described above, according to the present embodiment, quenching can be prevented by increasing the refrigerant flow rate without stopping the operation of the device,
Moreover, since the flow rate of the refrigerant increases only when the temperature rises, the cooling system can be operated efficiently.

In this embodiment, the detection device is composed of the converter and the comparator as hardware, but the comparator can be composed of software on the computer. Further, the refrigerant flow rate control can be performed proportionally by the deviation from the temperature T ₀ of the normal operation of each pancake coil. In this case, the comparators 111 to 119 are used to detect the difference between the detected temperature and the normal operation temperature T ₀ . Should be calculated and replaced with a controller that performs a control device such as proportional-plus-integral. This controller can also be realized by either an analog circuit or computer software.

〔The invention's effect〕

According to the present invention, in a superconducting device having a plurality of pancake coils for performing forced circulation cooling, quenching can be prevented without stopping the operation of the device, and energy consumption for preventing quenching is unnecessary. There is an effect that can be eliminated.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing details of the detection device of FIG. 1, FIG. 3 is a diagram showing test heat input and coil temperature changes, and FIG. The figure shows an example of the operation time chart of the embodiment shown in FIG. 1 ... Detection device, 31-39 ... Pump control device, 41-49 ...
… Pump, 5 …… Refrigerator, 6 …… Superconducting coil, 7 ……
Vacuum vessel, 61-69 …… Pancake coil, 81-89 …… Temperature detector, 111-119 …… Comparator.

Claims (1)

[Claims] 1. A plurality of superconducting coils provided adjacent to each other, each having a refrigerant passage therein,
A pump provided corresponding to the superconducting coil that flows the refrigerant in the refrigerant passage of each superconducting coil, a temperature detecting means provided for the superconducting coil that detects the temperature of each superconducting coil, and a refrigerant circulation amount by each pump by controlling each pump. In the operation control method of the superconducting device provided with a pump control device provided for each pump to control the, each superconducting coil is pre-test heat input to each of the superconducting coils operating at the normal operating temperature T0. A temperature increase ΔT corresponding to the maximum heat input that enables recovery to the superconducting state without increasing the refrigerant flow rate is obtained for the superconducting coils, and the corresponding temperature detecting means can be used during the operation of each superconducting coil. The detected temperature rise of the superconducting coil is compared with the ΔT obtained corresponding to the superconducting coil, and when the temperature rise exceeds the ΔT, the superconducting coil is detected. Operation control method of a superconducting device characterized by increasing to the refrigerant flow.