JP2653639B2 - Superconducting magnet system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting magnet system using a superconducting coil.

[0002]

2. Description of the Related Art Recent advances in superconducting technology have been remarkable,
The superconducting coil also tends to gradually increase in capacity. As a system to which the superconducting coil is applied, there are nuclear fusion, electric power storage, accelerator, MRI, etc., but in practical use, optimum protection of the system including the superconducting coil is an important point.

FIG. 9 shows an example of the main circuit configuration of a conventional superconducting magnet system. In FIG. 9, reference numeral 1 is a DC power source composed of a static AC / DC converter for converting AC power input via an AC circuit breaker 2 into DC power, and 3 is connected to this DC power source 1 via a DC break switch 4. This is a superconducting coil.
DC is excited with the power turned on.

A protection resistor 5 protects the superconducting coil 3 when an abnormality occurs in the system.
Is connected in parallel to the superconducting coil 3 through a protective resistance input switch 6 in series.

In the superconducting magnet system having such a structure, during normal operation, the DC cutoff switch 4 is turned on, the protection resistance turning-on switch 6 is opened, and the superconducting coil 3 is DC-excited.

In this state, if any abnormality occurs in the system, the DC cutoff switch 4 is opened to disconnect the DC power supply 1 from the superconducting coil 3, and the protection resistor input switch 6 is turned on. The protective resistance 5 is connected in parallel to the superconducting coil 3 to absorb the energy accumulated in the superconducting coil 3 to protect the constituent devices including the superconducting coil 3.

[0007]

However, in the superconducting magnet system having such a structure, there is a problem of protection when the DC circuit is accidentally opened. For example, when the DC cutoff switch 4 malfunctions (erroneously opens),
Since there is no path circuit for the current due to the energy stored in the superconducting coil 3, an abnormal voltage is generated in the component equipment such as the superconducting coil 3 and the equipment may be damaged in some cases.

Further, even if the protective resistance input switch 6 malfunctions (does not close) when a system abnormality occurs, it takes a long time for the energy of the superconducting coil 3 to be attenuated. It may be damaged.

Regarding the malfunction of these switches, measures such as duplication of the switches can be considered, but in a large capacity system, the switches themselves become large in scale.
It is not desirable from the viewpoint of installation space and economy.

The present invention has been made in view of the above circumstances, and its purpose is to protect the components by preventing the DC circuit from being opened even if the switch malfunctions. To provide a high superconducting magnet system.

[0011]

According to the present invention, a superconducting magnet system is constituted by the following means in order to achieve the above object. The invention corresponding to claim 1 is a DC power source, a superconducting coil excited by the DC power source, a DC cutoff switch provided in an electric path connecting the DC power source and the superconducting coil, and opened during system protection, and the superconducting coil. In a superconducting magnet system comprising a protective resistance connected in parallel to the superconducting coil for absorbing energy accumulated in the superconducting coil, and a protective resistance closing switch provided in series with the protective resistance and being turned on at the time of system protection, A short circuit is formed to short-circuit between the circuit connecting the protection resistance switch and the circuit on the power supply side of the DC cutoff switch, and the protection resistance switch is closed during normal protection operation. In addition, a short-circuit switch that opens when the DC cutoff switch opens is provided.

According to a second aspect of the present invention, a short circuit that short-circuits a circuit connecting the protective resistor and the switch for turning on the protective resistor and a circuit on the power source side of the DC cutoff switch is formed. Provide a resistor.

According to a third aspect of the present invention, a short circuit is formed which short-circuits a circuit connecting the protective resistance and the switch for turning on the protective resistance and a circuit on the power source side of the DC cutoff switch. A short-circuit switch and a resistor are provided, which are closed when the protection resistor input switch is closed and the DC cutoff switch is opened during normal protection operation. The invention corresponding to claim 4 also uses the resistance value of the bus bar itself of the short circuit as the resistance of the invention according to claim 2 or claim 3.

[0014]

According to the superconducting magnet system of the inventions corresponding to claims 1 to 3, the DC main circuit is not opened, and the DC cutoff switch or the protection resistor closing switch malfunctions or malfunctions. Since the energy of the superconducting coil is attenuated by the time constant determined by the product of the L component of the superconducting coil and the R component of the protective resistance, the system can be surely protected and the reliability can be further improved. .

Further, according to the superconducting magnet system of the inventions corresponding to claims 2 and 4, a resistance is provided in the short circuit or the resistance value of the bus bar itself of the short circuit is shared. It is possible to obtain the same operation as described above without complicating the circuit.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration example of a superconducting magnet system according to the present invention. The same parts as those in FIG.

In FIG. 1, reference numeral 1 is a DC power source comprising a static AC / DC converter for converting AC power input via an AC circuit breaker 2 into DC power, and 3 is a DC power switch 1 connected to this DC power source 1 via a DC cutoff switch 4. The superconducting coil 3 is connected to the superconducting coil 3, and the superconducting coil 3 is DC-excited with the DC cutoff switch 4 turned on.

Reference numeral 5 is a protective resistance for protecting the superconducting coil 3 when an abnormality occurs in the system.
Are connected in parallel to the superconducting coil 3 via a protection resistor input switch 6 in series.

In the superconducting magnet system having such a structure, in the present embodiment, a short circuit is formed between the connection between the protective resistance 5 and the protective resistance input switch 6 and between the direct current cutoff switch 4 and the direct current power source 1. The short circuit switch 11 is provided in this short circuit.

Next, the operation of the superconducting magnet system configured as described above will be described. In FIG. 1, during normal operation, the DC cutoff switch 4 and the short-circuit switch 11 are closed, the protection resistance switch 6 is open, and the current is superconducting coil 3 → DC power supply 1 → DC cutoff switch 4 → superconducting. It flows through the current path of the coil 3.

Next, a case where an abnormality occurs in the system will be described. First, the normal protection interlocking operation will be described with reference to FIG. 2. When a system abnormality is detected, the DC power supply 1
Is a bypass pair (BPP), and the AC circuit and the DC circuit are electrically separated. After that, the protection resistance input switch 6 is closed, the DC cutoff switch 4 is opened, and then the short-circuit switch 11 is opened to transfer the energy of all the superconducting coils 3 to the protection resistance circuit. And the DC power supply 1 are disconnected.

By the above series of operations, the superconducting coil 3
Is stored in the protection resistor 5, so that the system can be protected. 3 to 6 show the flow of current in each stage of the protection operation example described above. That is, FIG. 3 shows the flow of current after the DC power supply BPP in the normal protection operation, FIG. 4 shows the flow of current after the closing of the protection resistor closing switch 6 in the normal protection operation, and FIG. 5 shows the direct current in the normal protection operation. FIG. 6 shows the current flow after opening of the short-circuit switch 11 during the normal protection operation.

Considering the case where the short-circuit switch 11 is opened, that is, the case where the state of FIG. 5 shifts to the state of FIG. 6, the impedance of the protective resistance switching switch 6 is higher than that of the DC power source 1. It can be made sufficiently small.

Therefore, the short-circuit switch 11 having a relatively small breaking capacity can be used. On the other hand, when the protection resistance input switch 6 malfunctions (does not close) during system protection, if the DC cutoff switch 4 is opened, the current is superconducting coil 3 → DC power supply 1 → short circuit switch 11 → protection resistance 5 → Since the current flows through the path of the superconducting coil 3, the energy stored in the superconducting coil 3 can be absorbed by the protection resistor 5.

The current flow at this time is shown in FIG. Also,
Even if the DC cutoff switch 4 malfunctions (erroneously opens) during normal operation, the current flows through the same path (superconducting coil 3 → DC power source 1 → short circuit switch 11 → protection resistor 5 → superconducting coil 3). The energy accumulated in the superconducting coil 3 can be absorbed by the protective resistor 5 without generating an abnormal voltage due to the opening of the main circuit.

Next, another embodiment of the superconducting magnet system according to the present invention will be described with reference to FIG. 8. In FIG. 8, the same parts as those in FIG. I will describe.

In this embodiment, as shown in FIG. 8, a short circuit is formed between the connection between the protective resistance 5 and the protective resistance input switch 6 and between the direct current cutoff switch 4 and the direct current power source 1.
Instead of the short-circuiting switch 11 of FIG.
1 is provided.

Next, the operation of the superconducting magnet system thus constructed will be described. In FIG. 8, during normal operation, the DC cutoff switch 4 is closed, the protective resistance input switch 6 is open, and the current is superconducting coil 3 → DC power supply 1
→ DC cut-off switch 4 → Superconducting coil 3 is flowing in the path.

Next, a case where an abnormality occurs in the system will be described. When a system abnormality is detected, the DC power supply 1 is set to a bypass pair (BPP), the AC circuit breaker 2 is opened, and the AC circuit and the DC circuit are separated. Thereafter, the protection resistor switch 6 is closed, and the DC cutoff switch 4 is opened.

At this time, the current is superconducting coil 3 → DC power source 1 → resistor 21 → protecting resistor 5 → pass of superconducting coil 3 (pass 1) and superconducting coil 3 → switch for turning on protective resistor 6 → protecting resistor 5 → superconducting The current flows through the path of the coil 3 (path 2), but the impedance of the path 1 is larger than that of the path 2, so most of the current is attenuated via the path 2.

On the other hand, when the protection resistance input switch 6 malfunctions during system protection (does not close), the DC cutoff switch 4 is opened, and the current is superconducting coil 3 → DC power supply 1 → resistor 21 → protection. Since the resistor 5 flows through the path of the superconducting coil 3, the energy stored in the superconducting coil 3 can be absorbed by the protective resistor 5 and the resistor 21.

Even if the DC cutoff switch 4 malfunctions (mis-opening) during normal operation, current flows through the same path (superconducting coil 3 → DC power supply 1 → resistor 21 → protective resistor 5 → superconducting coil 3). Therefore, no abnormal voltage is generated due to the opening of the main circuit, and the energy stored in the superconducting coil 3 can be absorbed by the protection resistor 5 and the resistor 21.

The resistor 21 described in the above embodiment can also serve as the resistor 21 by adjusting the cross-sectional area and distance of the bus bar constituting the main circuit and utilizing the resistance value of the bus bar itself. It is. Further, it goes without saying that the same effect can be expected even if the short-circuit switch 11 and the resistor 21 shown in FIG. 1 are provided in series in a short-circuit circuit.

[0034]

As described above, according to the present invention, there is no fear that the DC circuit is opened due to the malfunction of the switch, and even if the switch malfunctions or malfunctions, the energy of the superconducting coil can be absorbed by the protection resistor. Therefore, it is possible to provide a more reliable superconducting magnet system that can be configured with a minimum number of devices.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of a superconducting magnet system according to the present invention.

FIG. 2 is an explanatory diagram showing a normal protection operation example in the embodiment.

FIG. 3 is a diagram showing a current flow after a DC power supply BPP during a normal protection operation in the embodiment.

FIG. 4 is a diagram showing a current flow after closing a switch for turning on a protective resistance in a normal protective operation in the embodiment.

FIG. 5 is a diagram showing a current flow after opening of a DC cutoff switch during a normal protection operation in the embodiment.

FIG. 6 is a diagram showing a current flow after a short-circuit switch is opened during a normal protection operation in the embodiment.

FIG. 7 is a diagram showing a current flow when a switch is abnormal in the embodiment.

FIG. 8 is a circuit diagram showing another embodiment of the superconducting magnet system according to the present invention.

FIG. 9 is a circuit configuration diagram showing a conventional superconducting magnet system.

[Explanation of symbols]

1 ... DC power supply, 2 ... AC breaker, 3 ... Superconducting coil, 4 ... DC cutoff switch, 5 ... Protection resistance, 6 ...
Switch for turning on protective resistance, 11 ... Short-circuit switch, 21
……resistance.

Claims (4)

(57) [Claims] 1. A DC power supply, a superconducting coil excited by this DC power supply, a DC cutoff switch provided in an electric path connecting the DC power supply and the superconducting coil and opened at system protection, and connected in parallel to the superconducting coil. In a superconducting magnet system comprising a protective resistance for absorbing energy accumulated in the superconducting coil, and a protective resistance turning-on switch which is provided in series with the protective resistance and is turned on at the time of system protection, the protective resistance and the protective resistance turning on are provided. Forming a short circuit between the electric path connecting the power switch and the electric circuit on the power supply side of the DC cutoff switch, and the protection resistance closing switch is closed and the DC cutoff occurs during the normal protection operation. The superconducting magnet system is equipped with a short-circuit switch that opens when the switch opens. 2. A DC power source, a superconducting coil excited by the DC power source, a DC cutoff switch provided in an electric path connecting the DC power source and the superconducting coil and opened at system protection, and connected in parallel to the superconducting coil. A superconducting magnet system comprising: a protection resistor that absorbs energy stored in the superconducting coil; and a protection resistor input switch that is provided in series with the protection resistor and is turned on during system protection. A superconducting magnet system, characterized in that a short circuit is formed to short-circuit between an electric path connecting the power switch and a power supply side electric circuit of the DC cutoff switch, and a resistance is provided in the short circuit. 3. A DC power supply, a superconducting coil excited by the DC power supply, a DC cutoff switch provided in an electric path connecting the DC power supply and the superconducting coil and opened at system protection, and connected in parallel to the superconducting coil. In a superconducting magnet system comprising a protective resistance for absorbing energy accumulated in the superconducting coil, and a protective resistance turning-on switch which is provided in series with the protective resistance and is turned on at the time of system protection, the protective resistance and the protective resistance turning on are provided. Forming a short circuit between the electric path connecting the power switch and the electric circuit on the power supply side of the DC cutoff switch, and the protection resistance closing switch is closed and the DC cutoff occurs during the normal protection operation. A superconducting magnet system characterized by having a short-circuit switch that opens when the switch opens and a resistor. . 4. The superconducting magnet system according to claim 2, wherein the resistance also serves as a resistance value of the bus bar itself of the short circuit.