JPH0251315A - Protection of superconducting energy storing system - Google Patents

Abstract

PURPOSE:To utilize energy effectively by providing a switch being fired by the overvoltage occurring across a converter to shortcircuit the converter, thereby stopping the converter corresponding to a shortcircuited switch and performing bypass operation through a sound converter. CONSTITUTION:Power is fed from an AC bus 1 through transformers 2A, 2B and converters 3A, 3B and stored in a superconducting coil 4. Overvoltage is produced across the element of the converter 3A upon erroneous extinction thereof and an overvoltage firing circuit 5A operates to turn a shortcircuit switch 6A ON. Consequently, a current detector 9A detects current flowing through the shortcircuit switch 6A and a faulty group judging circuit 10 provides a gate block signal 55 to the converter 3A thus stopping the converter 3A. Bypass pair commands 52 are fed to the sound converter 3B, and the shortcircuit switch 6A is turned OFF by the voltage produced from the converter 3B upon elapse of a predetermined time, thus carrying out operation only at the converter 3B side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a superconducting energy storage system, and relates to a protection method when a failure occurs in a system in which a plurality of converters are connected to each other.

(Prior art) Since the resistance valve of a superconducting coil is almost zero, the time constant of the coil is very large. For this reason, research is underway on a superconducting energy storage system (hereinafter abbreviated as SMES) that stores energy by circulating current through superconducting coils and is used as a countermeasure for T4 lus loads such as nuclear fusion and peak loads of 1 wt force. . In addition to long-term power regulation, SMES uses self-extinguishing elements (such as dirt turn-off thyristors, hereinafter referred to as GTOs) to convert converters connected to the power grid.
It is abbreviated as ), it is possible to have functions such as system stabilization and system invalidity compensation. However, in order to effectively perform such a function, the current flowing through the superconducting coil must have a capacity of several tens of kilowatts to several hundred KA. Therefore,
The conversion device is also configured by connecting several to several hundred GTOs in parallel.

Figure 4 shows a conventional system. In Figure 4, 1 is an AC bus, 2 is a transformer, 3 is a self-excited converter configured with a GTO, 4 is a superconducting coil, and 5 is an overvoltage generated. An overvoltage ignition circuit ignites the short-circuit switch 6 when a failure occurs, and 7 is a resistor for consuming coil energy in the event of a failure.

In an SMES as shown in Fig. 4, a self-excited converter 3
is a current type converter due to the nature of SMES, which stores energy by the current flowing through the coil. In current star converters, overvoltage occurs when the circuit is open. During normal operation, the circuit is controlled to prevent it from becoming open, but if the GTO is accidentally extinguished or misfired, or if the wire is cut, the Ni conductive coil 4
Due to the energy of the current flowing through the circuit, an overvoltage with a steep rise is generated. At that time, in the circuit shown in FIG. 4, the overvoltage ignition circuit 5 operates, and the short switch 6 closes.
The coil energy is consumed and maintained by resistor 7.

(Problems to be Solved by the Invention) However, in a practical scale SMES, coil energy ranges from several megawatt hours to several gigawatt hours, and it is uneconomical to consume all the energy in resistance when a failure occurs.

An object of the present invention is to provide a method for protecting a superconducting energy storage system that can effectively utilize the energy of a coil even when a failure occurs.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a superconducting energy storage system consisting of several OL converters composed of self-extinguishing elements and a superconducting coil, in which the energy generated at both ends of the converter is The device is equipped with a switch that is ignited by an overvoltage generated to short-circuit both ends of the converter, and a means for determining a faulty converter based on the operating signal of the switch, and gives a stop signal to the faulty converter to determine if it is healthy. Give a bypass pair signal to the converter, then perform forward conversion operation, and after detecting that the current flowing through the short-circuit switch of the failed converter is zero, restart the system with only the healthy converter. This makes it possible to provide a superconducting energy storage system that can effectively utilize the energy stored in the coil.

(Function) According to the present invention, even if one of the plurality of converters breaks down and an overvoltage occurs, the overvoltage generated at both ends of the converter ignites the short circuit switch and protects the converter. Further, by providing means for determining a faulty converter, a stop signal is given to the faulty converter, and a bypass pair signal is given to a healthy converter.

After that, operate the healthy converter in forward conversion mode, make the short-circuit switch of the failed converter sufficiently small to '4 IL', disconnect the failed converter, and restart operation with only the healthy converter. This allows for efficient use of the energy of the coil.

(Example) An example of the present invention is shown in FIG. In FIG. 1, the same elements as those in FIG. 4 already described are given the same reference numerals, and their explanation will be omitted. 8, 8B is a friend reactor that balances the current between multiple converters, 9m, 9B is an "IjL flow detector that detects the tg of the short circuit switch, 10 is 9,
9B is a failure group discriminating circuit for determining a failed converter from the output; 1 is a delay circuit for delaying the failure occurrence signal 51ft outputted from the failure group discriminating circuit 10 to the healthy group; 12k;

JJB is an AND circuit, 13 is an inversion circuit, and J4A.

14B is a pi/mother spare command 52, forward conversion operation command 53
, a restart command 54, a dirt block command 55, etc., and a firing control circuit that controls the on/off of 3B in the self-excited converter 3 based on commands from a power supply control circuit (not shown).

56 is a failure group cutting blade release completion signal indicating that the current of the short circuit switch of the failure group is zero.

The present invention will be explained in detail using FIG. As mentioned above, in the R type converter, an overvoltage occurs when the circuit becomes open. For example, suppose that the element of the converter 3A in FIG. 1 is erroneously extinguished. Then, an overvoltage is generated across the three converters, the overvoltage ignition circuit 5A is activated, and the short circuit switch 6A is turned on. Then, the current detector 9A detects the current flowing through the six semiconductor switches. Fault group familiarization circuit 10
Then, a failure and a failure group are determined based on the signal from the '1 flow detector, and a dart block command 55f is outputted to the failure group to stop it, and a failure occurrence number 1g is outputted to the healthy group. Then, the bypass pair command 52 is output until the time set by the delay circuit 11 after the failure occurs.

At that time, the load '11c current flows through the healthy converter 3B and the six semiconductor switches. When the time determined by the delay circuit 11 has elapsed, a forward conversion operation command 53 is output to the healthy group, and the healthy group converter 3B outputs an appropriate current and voltage.Then, a reverse voltage is applied to the short circuit switch. When the current decreases and the current becomes zero, it is turned off.The fault group converter is now disconnected from the system.In the fault group discrimination circuit, the short circuit switch 1 of the fault group is turned off when the current becomes zero. When this is detected, a restart command 54 is output, and operation is resumed only in the healthy group.

Figure 2 is a flowchart showing the protective operation in the event of a failure. The failure group detection circuit IQ discriminates between failure and malfunction [-] based on the signal from the % current detector, and outputs a dirt block signal to the failure group and outputs a bypass pair signal to the healthy group. After a certain period of time has elapsed, the healthy group is operated for forward conversion. It is detected that the current in the short-circuit switch of the faulty group is zero, and the healthy group is restarted.

Although the case where three self-excited converters fail has been described above, the same applies to the case where converter 3B fails. The same applies to the case where the converter is composed of two or more converters.

As explained above, according to this embodiment, it is possible to provide a protection device that can effectively utilize all of the energy stored in the coil even in the event of a failure.

In addition, in one aspect of the present invention, as a self-extinguishing element, G
It goes without saying that the same effect can be obtained even if elements other than TO, such as transistors and electrostatic induction thyristors, are made of gold.

Another embodiment of the invention is shown in FIG. In FIG. 3, the same elements as those in FIGS. 1 and 2 already described are represented by the same reference numerals, and the explanation thereof will be omitted. 15 in Figure 3, 15B
is a circuit that detects the voltage across the short-circuit switch. FIG. 3 shows the operation of short-circuit switch 6 detected by photodetector 9A and 19B in FIG.
Detected with 5B. It goes without saying that the same effect can be obtained even if the operations of gA and 6B are detected by voltage. In addition, the operation of the short circuit switch 61.6B is changed to the overvoltage ignition circuit 5,
The same is true for detection using the 5B operating current.

[Effects of the Invention] As in the present invention, in the Mi'914 energy storage system consisting of a plurality of converters composed of self-extinguishing elements and a superconducting coil, the voltage at both ends of the converter ll'I: The switch is equipped with a switch that shorts both ends of the converter, and a means for determining a faulty converter based on the operating signal of the switch.The faulty converter is given stop No. 1g, and a healthy converter is given a bypass pair. If you apply a signal, then perform a forward conversion operation, and detect that the short-circuit switch of the faulty converter is zero, restart the system with only the healthy converter, and the coil The energy stored in d M can be used effectively.
, 4 Energy storage system protection method f: Can be provided.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing one embodiment of the present invention, Fig. 2 is a flowchart explaining the recycle maintenance operation of the present invention, Fig. 3 is a block diagram showing another embodiment of the present invention, and Fig. 4 is a block diagram showing an embodiment of the present invention. 1 is a diagram illustrating a conventional superconducting energy storage system. 1... AC bus, 2, 2B... rectifier transformer,
JA, :IB... Self-excited converter, 4... Superconducting coil, 51.58... Overvoltage detection circuit, 6, 6B.
... Short circuit switch, 7... Mining resistor, 8, 8B.
...Parant reactor, 9, 9B...% flow detector, 10...Failure group discrimination circuit, 11...Delay circuit, 1
2, 12B... Theory @Rin circuit%13... Inversion circuit,
J4A, 14B...Ignition control circuit, J5A, 15B...
...Overvoltage detection circuit, 51...Failure occurrence signal, 52.
... Bypass pair command, 53 ... Forward conversion operation command, 5
4...Restart command, 55...r-) block signal,
56...Failure group separation child Ryo No. 16. Figure Figure Figure Figure Figure

Claims (1)

[Claims] In a superconducting energy storage system that energizes a superconducting coil by connecting multiple converters consisting of self-extinguishing elements in parallel, each converter is ignited by the overvoltage generated across the converter to perform conversion. It has a short-circuit switch that shorts the converter, and upon receiving the operating signal of the switch, it determines which converter has overvoltage, gives a stop signal to the overvoltage converter, and sends a bypass pair signal to a healthy converter. The superconducting energy system is characterized in that the current flowing through the short-circuit switch of the overvoltage converter is detected to be zero, and then only the healthy conversion is restarted. How to protect storage systems.