JPH01283906A - Superconductive energy storing system - Google Patents

Abstract

PURPOSE:To prevent the breakdown of a coil which is a superconductive magnet even if a cooling device fails, by controlling an AC/DC converter with the abnormality detecting device of a superconductive magnet cooling device, and outputting energy that is stored in the superconductive magnet. CONSTITUTION:An abnormality detecting means 10 for a cooling device 9 is provided. When the cooling device 9 becomes abnormal, an AC/DC power converter 4 which controls the input and the output of energy of a superconductive magnet 7 is controlled with the detecting means 10. The energy stored in the superconductive magnet 7 is outputted to loads 12-2N. In this way, the stored energy is supplied to the loads of power when the cooling device 9 itself (cooling mechanism) fails and the superconductive magnet 7 cannot be cooled continuously. Thus, the breakdown of the superconductive magnet 7 and a permanent current switch 6 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an energy storage system applying superconducting phenomena, and particularly to protection of a superconducting energy storage system.

[Conventional technology]

There are various methods for storing energy, and pumped storage power generation is a typical example. However, this power generation method does not have very high storage efficiency, and recently energy storage that applies superconductivity phenomena is being considered. In this system, a current is passed through a superconducting magnet, and electrical energy is stored as a persistent current. By the way, superconducting magnets (coils made of superconductors) can be realized by cooling them to extremely low temperatures. Although the superconducting energy storage system depends on its scale, large-capacity systems having a capacity of several hundred MWh to several tens of GWh are being considered. In such a large-scale superconducting energy storage system, a cooling device that maintains the superconducting magnet in a superconducting state plays an important role. In the unlikely event that this cooling device does not work.

If cooling becomes impossible and the superconducting magnet changes from a superconducting state to a normal conducting state and electrical resistance occurs, the energy (electromagnetic energy) stored in the superconducting magnet will generate heat as Joule heat in the coil, which may burn out and cause a major accident. There is sex.

As one means for solving such problems, there is a "superconducting power storage device" disclosed in Japanese Patent Application Laid-Open No. 62-286209.

In this means, when the power source for driving the cooling device is lost due to a power outage, the power source for driving the cooling device is supplied using the energy stored in the superconducting magnet. This prevents the cooling device from stopping due to loss of power for driving the cooling device.

[Problem to be solved by the invention]

The above-mentioned conventional technology can sufficiently cope with a loss of power to the cooling device, but consideration must be given to the case where the cooling device itself (cooling mechanism) breaks down and cannot continue to cool the superconducting magnet. If this happens, the coil, which is a superconducting magnet, may burn out and cause a major accident.

The present invention has been made in view of the above points, and its purpose is to prevent the coil, which is a superconducting magnet, from being damaged even if the cooling device fails.

[Means to solve the problem]

The above objective can be achieved by outputting the energy stored in the superconducting magnet to the load side when the cooling device that cools the superconducting magnet fails in a system that stores energy using a superconducting magnet. can.

[Effect]

The present invention provides an abnormality detection means for detecting whether or not the cooling device is operating normally, and when the cooling device becomes abnormal, the detection means controls the input and output of energy of the superconducting magnet. - Since the DC power converter can be controlled to output the energy stored in the superconducting magnet to the load side, the coil, which is the superconducting magnet, will not be damaged.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. Portions with equal numbers each time indicate corresponding portions.

In FIG. 1, AC voltage from a power plant 1 is supplied to various loads 21 to 2N, and at the same time, it is also supplied to an energy storage system 3. The energy storage system 3 includes a transformer 11. Convert AC voltage to DC voltage,
Alternatively, in order to extract the electromagnetic energy stored in the superconducting magnet 7, an AC/DC power converter 4. converts DC voltage into AC voltage. Charge/discharge switch5. A persistent current switch 6, a cooling device 9 that cools the superconducting magnet 7, and the persistent current switch 6, and the cooling device 9
It consists of an abnormality detection device 10 that checks the health of the device.

AC/DC power converter 4. The operations of the charging/discharging switch 5, the persistent current switch 6, and the superconducting magnet 7 are well known. When storing energy in the superconducting magnet, first open the persistent current switch 6,
The charging/discharging switch 5 is closed, and the AC/DC power converter 4 applies input power to the superconducting magnet.

Thereafter, by closing the persistent current switch 6 and opening the charge/discharge switch 5, a persistent current flows through a closed loop circuit formed by the persistent current switch 6 and the superconducting magnet 7, and energy is stored.

When extracting the energy stored in the superconducting magnet, the charge/discharge switch 5 is closed, the persistent current switch 6 is opened, and the AC/DC power converter 4 operates to output energy to the load side. .

Here, the cooling device 9 is for maintaining the superconducting magnet 7 and the persistent current switch 6 in a superconducting state.

Now, if this cooling device 9 becomes abnormal and cannot cool the superconducting magnet 7 and the persistent current switch 6, they will not be able to maintain their superconducting state, and there is a possibility that they will be damaged and cause a major accident.

The abnormality detection device 10 is provided to prevent this.
It is.

The abnormality detection device 10 determines whether or not the cooling device 9 is abnormal, and if abnormal, closes the charging/discharging switch 5,
The persistent current switch 6 is opened.

It also controls the AC/DC power converter 4 to output the energy stored in the superconducting magnet to the load side.

Thereby, it is possible to prevent the superconducting magnet 7 and the persistent current switch 6 from being damaged when the cooling device 9 is abnormal. Further, it is economical because there is no need to make the entire large-scale cooling system redundant.

According to the present invention, there is also an effect that energy can be released in a short time by supplying energy stored in a load that consumes a large amount of power when the cooling device is abnormal.

By the way, the AC/DC power converter 4 is basically the second
The rectifier circuit shown in the figure is capable of switching between charging mode and discharging mode by controlling the firing angle of its switching element (silis in this figure). When the three-phase AC voltage is Es and the DC voltage is E6, the following relational expression is obtained.

Ed=1.35Es-cosα-(1)
However, if the firing angle α of the α switching element is controlled at 0 to 90″, the charging mode will be set as shown in Fig. 3, and if the firing angle α is controlled at 90 to 180 m, it will be in the discharging mode. Therefore, when releasing the energy stored in the superconducting magnet in a short time, the firing angle α
It may be controlled so that the angle becomes 180°.

Furthermore, when energy is output from the superconducting magnet 7 to the loads 21 to 2N of the power system, the power plant 1 adjusts the power according to the power adjustment command 12 from the abnormality detection device 10. In FIG. 1, the power adjustment command 12 is sent to the power plant 1, but instead of sending this command, the power plant 1 automatically monitors the power consumption state of the power system.
When energy is output from the superconducting magnet 7 to the power system, it is also possible to provide a regulator that lowers the output power from the power plant 1 itself using the monitoring function described above.

Now, to detect an abnormality in the cooling system, the flow rate of the coolant,
This can be achieved by detecting changes in conditions such as pressure and temperature and determining whether or not these exceed specified values. In general, changes in these state quantities do not occur suddenly, but are caused by slight cracks mechanically occurring in the structural material (for example, piping).
By detecting such an initial abnormal condition that often changes gradually, the AC/DC power converter 4 is activated as described above.
If the energy stored in the superconducting magnet 7 is released by controlling the superconducting magnet 7, the superconducting magnet 7 will not be damaged. That is, in this way, signs of mechanical failure of the cooling device 7 can be detected, and as a result of this, the stored energy of the superconducting magnet can be released. By the way, at this time, the relationship between the energy release time and the time when the temperature of the superconducting magnet exceeds the critical temperature due to an abnormality in the cooling device becomes important. As mentioned above, when signs of cooling system abnormality can be detected, the cooling temperature rises quite slowly, so the energy release of the superconducting magnet can be controlled slowly accordingly, and as a result, the load 21 It is possible to reduce fluctuations in power supply to ~2N. However, in the case of a major accident such as a major break in the piping of the cooling device 9, the cooling temperature rises quickly. In this case, in addition to the above-mentioned abnormality detection, means for detecting the current detection of the superconducting magnet 7 can also be applied. The abnormality detection device 10 outputs a command signal to the power plant 1 to lower the power to a certain value. Here, the amount of reduction in power supply is a value corresponding to the energy stored in the superconducting magnet. After outputting the above command to the power plant 1, the abnormality detection device 10 controls the AC/DC power converter 4 to transfer the stored energy to the load 2 before the superconducting magnet rises to a critical temperature.
Can output 1 to 2N.

In addition, in Fig. 1, when the cooling system is abnormal, the power plant 1
Although the command signal 12 is output directly to the central power supply control center, it is also possible to output the command signal 12 to a central power supply control center to control the power supply.

Next, as an abnormality in the cooling device, AC power for driving may be lost. This can be handled by providing emergency power sources (generators, batteries, etc.) and configuring them so that they can be driven automatically. In addition, in the event that the cooling device cannot be driven due to a failure in the electrical circuit of the cooling device, the electrical circuit section of the cooling device can be configured to have a redundant configuration, and this section can be switched and driven. , as described above, the AC/DC power converter 4
This can be done by controlling the energy stored in the superconducting magnet and releasing the energy stored in the superconducting magnet. Here, detection of an electrical abnormality in the cooling device can be achieved by detecting a drop in voltage or current, or a drop in the rotational speed of a pump for driving the cooling mechanism.

〔Effect of the invention〕

The present invention provides a means for detecting whether or not a device for cooling a superconducting magnet is operating normally, and when the cooling device becomes abnormal, this detecting means controls charging and discharging of energy in the superconducting magnet. By controlling the AC/DC power converter and outputting the energy stored in the superconducting magnet to the load side, it has the effect of preventing damage to the superconducting magnet in the event of an abnormality in the cooling system, and its industrial value is extremely large. It is.

[Brief explanation of the drawing]

Figure 1 shows an embodiment of the present invention, Figure 2 shows an example of the configuration of an AC/DC power converter, and Figure 3 shows the relationship between charging mode and discharging mode of a superconducting magnet and the control amount of the AC/DC power converter. This is a diagram shown in . 4... AC/DC power converter, 7... Superconducting magnet, 9... Cooling device, 10... Abnormality detection device. Figure 1

Claims (1)

[Claims] 1. In a system that stores energy using a superconducting magnet, an abnormality detection device is provided to detect an abnormality in a cooling device that cools the superconducting magnet, and the abnormality detection device detects an abnormality in the cooling device. A superconducting energy storage system that outputs the energy stored in the superconducting magnet by controlling an AC/DC power converter that controls charging and discharging of energy in the superconducting magnet. 2. The superconducting energy storage system according to claim 1, further comprising a control device that reduces the amount of electric power being supplied to the load and supplies the stored energy of the storage conductive magnet to the load when the cooling device is abnormal.