JPS61142937A - Method and apparatus for storing and discharging superconductive energy - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Application of the Invention) The present invention relates to a superconducting energy storage system that stores energy in a superconducting coil or releases energy from it.
The present invention relates to a superconducting energy storage/release method and a device thereof, which are suitable for efficiently charging, storing, and discharging energy.

(Background of the Invention) A superconducting coil (hereinafter simply referred to as a coil) has an electrical resistance of zero, and has the characteristic that once a current flows, it does not decay permanently. Superconducting energy storage devices take advantage of this property.

A superconducting energy storage device is an excitation power supply that supplies current to the coil.When charging (current increases), a positive voltage is applied to the coil to store energy, and when reversed or discharged (current decreases), a negative voltage is applied to the coil. It is controlled so that the energy stored in the coil is returned to the power grid by applying

In this case, if a positive voltage is still applied to the coil, the current will continue to increase and theoretically reach an infinite current value. Therefore, when a predetermined current value is reached.

It is necessary to set the excitation power supply voltage to zero voltage and maintain a constant current.

In this operation, a superconducting switch installed in parallel with the fill is turned on, both ends of the coil are short-circuited, the excitation power source is disconnected, and the current continues to flow. This is called persistent current mode.

The switches for operation and control described above are called persistent current switches, and include coil-shaped thermal water-filled current switches made of superconducting wire and heater wire wound together, and mechanical or magnetic field type persistent current switches. It has been known.

When transitioning to persistent current mode, for example, in the case of a thermal persistent current switch, the heater heating is stopped, the superconducting wire is returned to the superconducting state, and the switch is turned on, so that the switch is turned on after the command. There will be a time delay before this happens.

Similarly, in the case of mechanical and magnetic field type persistent current switches, there is a time delay from the command to the ON state.

As described above, there is a time delay in achieving a complete short-circuit state with the persistent current switch, which complicates the control of driving the excitation power supply from positive voltage to zero voltage.

Also, during this transition, the coil current changes to coil 1.

Because it flows through the excitation power supply which is in a zero voltage output state,
The coil current, that is, the stored energy, decreases due to the resistance of the excitation power source.

On the other hand, if we consider the time delay of the superconducting switch and try to extend the positive voltage output and period by a certain amount of time, now [42
The coil 1lfi capacity increases by ΔI = (dI/dt) x (g long time), which causes problems such as not being able to store energy according to the set value or complicating the control of the excitation power source.

These problems also appear when transitioning from persistent current mode to discharge mode.

The circuit configuration of conventional superconducting energy storage devices, etc. are discussed in 153jj of ``1 Secret of Power Storage Technology'' by Masami Masuda (Nikkan Kogyo Shimbun).

(Object of the Invention) The object of the present invention is to provide a superconducting energy storage/release method and device that stores energy in a superconducting coil or releases energy from the superconducting coil. It is an object of the present invention to provide a superconducting energy storage/release method and device that can smoothly transition to a discharge mode and improve energy storage efficiency.

(Summary of the Invention) In order to achieve the above-mentioned object, the present invention provides a bypass current that short-circuits the persistent current switch, in addition to a persistent current switch that is set to persistent current mode after charging a coil with energy using an excitation power source. It is distinctive in that it forms a road.

That is, for example, if a semiconductor switch that can short-circuit the persistent current switch is provided in parallel with the persistent current switch, the persistent current switch and the semiconductor switch can be controlled to be in the ON state at the time of transition to the persistent current mode, thereby turning the persistent current switch ON.
Even if there is a transient time delay in transitioning to this state, the semiconductor switch allows the coil to be instantaneously shorted at both ends.

After that, when the persistent current switch is turned on, the coil and the persistent current switch.

A complete superconducting closed loop is formed and becomes persistent current mode, allowing stable energy storage.

In this way, the present invention uses a semiconductor switch to smoothly perform energy charging to storage, that is, transition to persistent current mode.

Furthermore, when transitioning from the persistent current mode force S to the discharge mode, the bypass current path is formed at the same time as the operation of turning the persistent current switch OFF. By moving the current to a bypass current path (semiconductor switch) and then cutting off this bypass current path (semiconductor switch), the transition from persistent current mode to discharge mode can be smoothly performed.

(Example of the invention) An embodiment of the present invention will be described below with reference to FIG.

In Fig. 1, 1 is a coil and 2 is an excitation power source.

3 is a converter transformer, 4 is a superconducting switch as a thermal persistent current switch, 5 is a low temperature tank, 6 is a helium liquefier,
7 is a heater, 8 is a heater power supply, 9 is a switch, and 10 is a thyristor switch which is a semiconductor switch.

As shown in the figure, a superconducting switch 4 which is a persistent current switch
A thyristor switch 10 is connected in parallel with. 1
1 is a control circuit, and the excitation power supply 2 is controlled by the control signal from here.
．． Switch 9. Controls the thyrisk switch 10 and the like. 12.13 is a current shunt for current measurement.

In Fig. 2, (a) is the average value Kpm of the output voltage of the excitation power supply 2, (b) is the voltage of the coil 1, (cl is the state of the switch 9 of the heater power supply circuit, and (d) is the state of the thyristor switch lO. The gate signal, (e) shows the current of the thyristor switch 10, and (f) shows the current of the superconducting switch 4, respectively.

Next, the operation of this embodiment will be explained in detail with reference to the right side of FIG. 1 and FIG. 2.

First, the helium liquefier 6 supplies liquid helium to the cryostat 5 . Thereby, the coil 1 in the cryostat 5 is kept at an extremely low temperature and is kept in a superconducting state with zero electrical resistance.

Time t. Then, the excitation power supply 2 is set to the rectifier operation mode by the control signal from the control circuit 11, and as shown in FIG. 2 (&),
Output the expected positive voltage. Due to this positive voltage, the coil current increases linearly as shown in FIG. 2(b).

At this time, the circuit switch 9 of the heater power source 8 is turned on, and the superconducting switch 4 is heated by the heater 7. As a result, the superconducting wire constituting the persistent current switch has a finite resistance, and therefore the superconducting switch 4 is turned off.
It is in a state.

Next, time 1. when the current I flowing through the coil l reaches a predetermined value (set value). Then, the switch 9 of the heater power supply circuit is turned off by a signal from the control circuit 11, and at the same time, a gate signal is applied to the thyristor switch 10.

These control signals compare the current value detected by the current shunt 12 with the set value of the coil current I, and when the two match, 1ζ is output.

At this time, the thyristor switch 10 is instantaneously turned on by the control signal, but the superconducting switch 4 is turned on at time l, which is delayed by a time t' from the application of the control signal.

This is because the switch 9 is generally mechanical, and there is a time delay until it is completely opened even when a signal is applied, and the superconducting switch has thermal inertia.

However, in this embodiment, even if there is a time delay in switching the superconducting switch 4 to the ON state, the thyristor switch 10
is immediately turned ON, so the electrician of coil 1 is
The current continues to flow through the coil 1-thyristor switch 10-coil 1 loop with almost no damping.

Thereafter, when the superconducting switch 4 is turned on, the superconducting switch 4 has zero electrical resistance, whereas the thyristor switch 10 has a resistance that causes a forward voltage drop (CFVD).

Therefore, the coil current I flowing through the thyristor switch 10 transfers to the superconducting switch 4 and increases by ℃.Finally, all of the coil current I transfers to the superconducting switch 4, and the coil 1-superconducting switch 4- The coil 1 continues to flow loosely and becomes a complete persistent current mode.

When the coil current I moves to the electromotive conduction switch 4 and the current of the thyristor switch 10 falls below the latching current, the thyristor switch 10+2 naturally turns OFF.

Then, the closed loop between the coil 1 and the superconducting switch 4 is
The persistent current mode in which the current I continues to flow continues until the superconducting switch 4 is turned off.

In order to operate as described above, the current waveform of the thyrisk switch 10 and the current shape of the superconducting switch 4 become as shown in FIG. ) becomes flat.

As the excitation power source 2, as shown in FIG. 11ζ, a thyristor converter is generally used. Therefore, at time t1 when transitioning to persistent current mode, for example, FIG.
In the case of the three-phase bridge shown, operation is performed such that all thyristors are blocked, and the output voltage of the excitation power source 2 is set to zero voltage. The above control can be performed by the control circuit 11.

Next, at time 1, switch 9 of the heater power supply circuit is turned on, and at the same time, a gate signal is applied to the thyrisk switch 10 to turn it on. This causes the superconducting wire to reach heater 7.
As a result, the superconducting switch 4 is turned off.

Since the above-mentioned process does not occur instantaneously, the coil current I is transferred to the thyristor switch 10 that is in the ON state,
At time t8 when the superconducting switch 4 is turned off and all the coil current I is transferred to the thyristor switch 10, the thyristor switch 10 is cut off.

This time t may be a time when the current of the thyrisk switch 1o is detected by the current shunt 13 and matches the set value.

On the other hand, the shutoff of the thyrisk switch 10 is shown in FIG. 2(a).
As shown in 1 time t! This can be achieved by using a control signal from the control circuit 11 to put the excitation power supply 2 into a rectifier operating state that instantaneously outputs a positive voltage, and applying a reverse voltage to the thyrisk switch 10.

Thereafter, the excitation power supply 2 is operated as an inverter by a control signal from the control circuit 11, and a negative voltage is output from the excitation power supply 2 as shown in FIG. 2 (&).

This negative voltage causes the coil current I to decrease linearly as shown in Figure 2 (bl), allowing the energy stored in the coil to be returned to the power grid.

Thereafter, the excitation power source 2 is stopped at time t when the coil current I becomes zero.

In this way, even when transitioning from persistent current mode to discharge mode, it takes time for the superconducting switch 4 to completely turn off, so the transition cannot be made instantaneously, but as in this embodiment, a thyristor By using the switch 10 in combination to form a current bypass path, it is possible to smoothly transition from the persistent current mode to the discharge mode at the same time as a control command is issued.

By performing the operations described above, the superconducting coil can charge, store, and discharge energy.

Therefore, the superconducting energy storage device of this embodiment can be applied to fields such as power systems for the purpose of power storage and system stabilization, or pulse power sources for nuclear fusion devices.

As described above, according to this embodiment, when the coil 1 is charged with energy by the excitation power source 2 and then transferred to the persistent current mode in which the energy is stored in the coil 1, the superconducting switch 4 is turned on. Even if there is a time delay, the coil 1 can be short-circuited at the same time as the command control signal is applied using the thyrisk switch 10. (1) The excitation power source 2 can smoothly shift to zero-voltage operation. (2) It is possible to reduce the decrease in stored energy due to the activation time delay of the superconducting switch 4, and (3) it is possible to reduce the undesired increase in coil current when the excitation power source 2 is operated with the activation time delay of the superconducting switch 4 taken into consideration. (4) It is easy to control the excitation power supply, and (5)
Since the transition from persistent current mode to discharge mode can be performed extremely smoothly, excellent effects such as improved energy storage efficiency can be achieved.

FIG. 3 shows another embodiment of the invention. In Figure 3,
Components having the same functions and operations as the circuit configuration shown in FIG. 1 are given the same reference numerals.

In Fig. 3, the difference from Fig. 1 is that instead of the thyristor switch 10, there is a gate turn-off switch (hereinafter referred to as
This is because a switch 14 (abbreviated as GTO) is used.

Since the circuit operation in FIG. 3 is almost the same as that in FIG. 1, it will be briefly explained using the waveform diagram in FIG. 4.

In Fig. 4, the difference from Fig. 2 is that (dl is GTO
(e) shows the gate signal, and (e) shows the GTO current.

Time t. Then, the excitation power supply 2 is operated as a rectifier as shown in Fig. 4(a).
As shown in the figure, a positive voltage is output, and a coil current I is caused to flow to charge energy.

At time t1 when the coil current reaches a predetermined value, the switch 9 of the heater power supply circuit is turned off, and at the same time, as shown in FIG.
An ON gate signal is applied to the GTO switch 14 as shown in FIG.

As a result, the GTO switch 14 is instantly turned on, but the superconducting switch 4 is turned on with a delay of time t' due to the above-mentioned reason.

However, since the GTO switch 14 is in the ON state, the above-mentioned problem that occurs when only the superconducting switch 4 is used does not occur.

At this time, the current of the GTO switch 14 is detected by the current shunt 13. Then, the superconducting switch 4 is turned on (
Before the moment when the coil current flowing through the GTO switch 14 begins to decrease, the GTO switch 14 is in the superconducting state as shown in Fig. 4 (dl).
Apply the OFF gate signal and turn it off.

This instantly removes the coil current flowing through the GTO switch 14. It becomes possible to move to 4 switch 4.

By the above operation, a complete persistent current mode is established by the coil 1-superconducting switch 4-coil 1 loop.

The current waveforms of the GTO switch 14 and the superconducting switch 4 at this time are shown in FIG. 4, (f), respectively.

Next, to switch to discharge mode, press the time, /.

At the same time as turning on the switch 9 of the heater power supply circuit, an ON gate signal is applied to the GTO switch 14.

As a result, the superconducting switch 4 is turned off, but
As mentioned above, it takes a certain amount of time to turn off completely. Therefore, the coil current ■ gradually moves from the superconducting switch 4 to the GTO switch 14.

At time t2 when all of the current I in the coil 1 has been transferred to the GTO switch 14, an OFF gate signal is applied to the GTO switch 14 to shut off the GTO switch 14, and at the same time, the excitation power source 2 is operated by an inverter to output a negative voltage.

As a result, the coil current I decreases linearly as shown in FIG. Stop the excitation power supply 2.

As is clear from comparing FIG. 4fa) with FIG. 2(a), when the GTO switch 14 is used as a bypass means for the superconducting switch 4, when the thyristor switch 10 is used (FIG. 1) Since there is no need to output a positive voltage from the excitation power supply 2 at time t2, the control circuit is simplified.

This is because the GTO switch 14 can be controlled to turn on and turn off by the gate signal as described above. Through the above operations, energy can be charged, stored, and discharged.

As described above, according to this embodiment, not only the same effects as the embodiment shown in FIG. 1 can be achieved, but also the GT
This is because the O switch 14 can be turned off by the OFF gate signal.

(1) The fill current can be instantly transferred from the GTO switch 14 to the superconducting switch 4, and (2) therefore,
The time required to shift to full persistent current mode is shortened, and it is possible to reduce the decrease in energy during the transition process to full persistent current mode.
There is a unique effect that turning off the 31GTO switch 14 does not require complex operation control of the excitation power source 2 such as a single thyristor switch.

The unique effect of the other examples of the present invention described above is that the GTO switch 14 shown in FIG. 3 is replaced by a transistor that is turned ON only when the base current is energized, or by a gate signal.

Can be turned off f! MOS FET f! It is clear that the same result can be achieved no matter which method is used.

FIG. 5 shows still another embodiment of the present invention. In FIG. 5, components having the same functions and operations as the circuit configuration shown in FIG. 1 are given the same reference numerals.

5 differs from FIGS. 1 and 3 in that semiconductor switches such as the thyristor switch 10 and the GTO switch 14 are not provided.

The operation of the embodiment shown in FIG. 5 will be explained below.

First, the excitation power supply 2 is operated as a rectifier to output a positive voltage,
The operation of charging the coil 1 with energy and the operation of operating the excitation power supply 2 as an inverter to output a negative voltage and release energy to the power grid in the discharge mode are shown in FIG.
This is the same as the embodiment shown in FIG.

The difference in operation from the embodiments shown in FIGS. 1 and 3 is that in FIGS. 1 and 3, the superconducting switch 4 is turned on when transitioning to persistent current mode after charging energy. Simultaneously with the operation of Cζ, the semiconductor switch connected in parallel with Cζ was turned on to form a bypass current path for the coil current ■.In contrast, in Fig. 5,
Instead of semiconductor switches, thyristors (21 to 26) constituting the excitation power source 2 are controlled.

That is, in the embodiment shown in FIG. 5, the coil current value I detected by the current shunt 12 matches the set value (time 1).
．． ), a bypass operation is performed in which the arm of the excitation power source 2 is short-circuited.

The above-mentioned bypass operation means, for example, that the thyristors 21 and 26 which were in the Cζ conducting state just before the moment t
Then, at time t1, the excitation power source 2 performs a gate shift from rectifier operation to inverter operation, applies forward voltage to the other thyristor 24 connected in series with thyristor 21, and then applies a forward voltage to only these thyristors 21 and 24. The operation is such that a gate signal is applied and the gate signals of other thyristors are blocked.

This causes an arm short circuit in which only the thyristors 21 and 24 are in a conductive state, and the load is brought into a short circuit state.

Therefore, at the time tl of transition to the persistent current mode, the control signal from the control circuit 11 turns the switch 9 of the heater power supply circuit 0FFIζ, and at the same time, the excitation power supply 2 is operated by bypass (this causes an arm short-circuit, and the coil 1 is instantaneously turned off). The coil current I flows in a loop of, for example, coil 1 - thyristor 24 - thyristor 21 - coil 1.

Thereafter, the superconducting switch 4 is turned on, so that the coil current I is completely transferred to the superconducting switch 4, resulting in a complete persistent current mode.

Furthermore, when transitioning to the discharge mode, at the same time as the superconducting switch 4 is turned off, the excitation power source 2 is operated in bypass to form a bypass current path for the coil current, and then the excitation electrode 2 is transitioned to inverter operation. Bye.

As is clear from the above explanation, according to the embodiment shown in FIG. no switch is required;
This has the effect of simplifying the structure.

(Effects of the Invention) According to the present invention, after the coil is charged with energy, a thyristor switch or a GT
By providing a semiconductor switch such as an O switch or by bypassing the excitation power supply, the bypass path for the coil current is set at the moment the coil current reaches a predetermined value when transitioning to the persistent current mode in which the coil is short-circuited. Since the coil can be short-circuited by forming a
This has the effect of improving energy storage efficiency.

Furthermore, when the persistent current mode is transferred to the discharge mode, the use of the superconducting switch and the bypass path for the coil current has the effect that the transition can be made smoothly.

[Brief Description of the Drawings] Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is a waveform diagram for explaining its operation, and Figure 3 is a circuit diagram showing another embodiment of the present invention. 4 are waveform diagrams for explaining the operation thereof, and FIG. 5 is a circuit diagram showing still another embodiment of the present invention. 1... Superconducting coil, 2... Excitation power supply, 3
...Converter transformer, 4...Superconducting switch,
5... Low temperature tank, 6... Helium liquefaction machine, 7
... Heater, 8... Heater power supply, 9... Switch, 10... Thyristor switch, 11.
...Control circuit, 12...Current shunt, 13
...Current shunt, 14...GTO switch,
21-26...Thyristor

Claims (11)

[Claims] (1) A superconducting switch consisting of a superconducting coil as energy storage means, a shorting superconducting wire connected to both ends of the superconducting coil, and a means for controlling the superconducting state thereof, and an excitation power source connected to both ends of the superconducting coil. A method for storing energy in a superconducting energy storage device comprising: (a) operating the excitation power source as a rectifier while maintaining the coil in a superconducting state and a superconducting switch in an OFF state; Apply positive voltage,
a step of increasing the coil current flowing through the coil; and (b) a step of bringing the excitation power source into a zero voltage output state, controlling the superconducting switch to an ON state, and simultaneously forming a bypass current path that short-circuits the coil. (c) A superconducting energy storage method comprising the steps of: (c) opening the bypass current path after the superconducting switch transitions to an ON state. (2) The superconducting energy storage method according to claim 1, wherein the bypass current path is formed by bypassing the excitation power source. (3) The superconducting energy storage method according to claim 1, wherein the bypass current path is formed by turning on a semiconductor switch connected in parallel with the superconducting switch. (4) A superconducting switch consisting of a superconducting coil as energy storage means, a shorting superconducting wire connected to both ends of the superconducting coil, and a means for controlling the superconducting state, and an excitation power source connected to both ends of the superconducting coil. A method for releasing energy from a superconducting energy storage device comprising: (a) controlling the superconducting switch to an OFF state in a state in which a superconducting coil current is stored in a loop consisting of the coil and the superconducting switch; At the same time, forming a bypass current path to short-circuit the coil; (b) after the superconducting switch transitions to an OFF state;
A superconducting energy release method comprising the steps of opening the bypass current path and operating the excitation power source as an inverter to generate a negative voltage at its terminal. (5) The superconducting energy release method according to claim 4, wherein the bypass current path is formed by bypassing the excitation power source. (6) The superconducting energy release method according to claim 4, wherein the bypass current path is formed by turning on a semiconductor switch connected in parallel with the superconducting switch. (7) A superconducting switch consisting of a superconducting coil as energy storage means, a shorting superconducting wire connected to both ends of the superconducting coil, and a means for controlling the superconducting state thereof, and an excitation power source connected to both ends of the superconducting coil. A superconducting energy storage device comprising: A semiconductor switch is provided in parallel with the superconducting coil, and the semiconductor switch is connected in a forward direction with respect to the current flowing through the superconducting coil. Device. (8) The superconducting energy storage device according to claim 7, wherein the means for controlling the superconducting state of the shorting superconducting wire is a heater that heats the shorting superconducting wire. (9) The superconducting energy storage device according to claim 7, wherein the means for controlling the superconducting state of the shorting superconducting wire is means for applying a magnetic field to the shorting superconducting wire. (10) The superconducting energy storage device according to claim 8 or 9, wherein the semiconductor switch is a thyristor switch. (11) The superconducting energy storage device according to any one of claims 8 to 10, wherein the semiconductor switch is a gate turn-off thyristor switch.