JPH11299088A - Alternating current suppressing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized, economical short circuit current suppressing device, which suppresses current in the short circuit with reliability as well as ensures low-reactance characteristic and system stability during steady state, and allows for the adoption of high-speed re-closing system required for high- voltage systems. SOLUTION: This alternating current suppressing device is provided with a first coil 3 and a second coil 4, series-connected with each other and wounded in such a direction that magnetic fluxes produced by passage of alternating current cancel out each other, a nonlinear resistor 5 parallel-connected with the second coil 4, and a short-circuit switch 6 parallel-connected with the non- linear resistor 5. When a short circuit current is passed, the nonlinear resistor 5 is actuated to let the current through it, and the device is provided with a reactance of a large value close to the self reactance of the first coil 3 and suppresses short circuit currents.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alternating current suppressing device used in the field of power receiving and transforming and distribution of a power system.

[0002]

2. Description of the Related Art FIG. 12 shows, for example, 1988 issued by the Institute of Electrical Engineers of Japan.
FIG. 10 is a circuit diagram including a short-circuit current suppressing device, which is a conventional AC current suppressing device to which the reactor described in page 691 of the Annual Electrical Engineering Handbook is applied. In the figure, reference numeral 80 denotes a reactor which is a short-circuit current suppressing device inserted into a transmission line 81, 83 denotes transmission lines 81 and 82 and main buses 84 and 85.
The circuit breaker 86 inserted in between is an electric station such as a power station, a substation, a switchyard, etc., composed of the above components.

[0003] In the electric station 86 shown in FIG. 12, for example, when a failure 87 occurs, or when a failure occurs in a transformer circuit or a transmission line circuit (neither is shown) connected to the main bus 84, the reactor Since 80 is inserted into the end of the transmission line 81, the fault current is suppressed by the reactance of the reactor 80, which has a great effect in terms of miniaturization of the equipment or improvement in economic efficiency. Here, the reactor 80 is formed of, for example, an air-core reactor so that even if a large current such as a short-circuit current flows, its reactance does not change due to magnetic saturation or the like. However, since there is always a voltage drop due to the reactance of the reactor 80, it is limited in terms of application, is not preferable in terms of power system stability, and is not applied very much.

[0004] The short-circuit current suppressing device shown in FIG. 13 solves the above-mentioned drawbacks.
No. 5 (Japanese Utility Model Laid-Open No. 57-6334). In the figure, reference numeral 88 denotes a current limiting reactor composed of a main winding 90 and a secondary winding 91 wound via an iron core 89.
The main winding 90 is inserted and connected to the transmission line 81 together with the circuit breaker 83, and the secondary winding 91 is connected to a fuse 92.

Next, the operation of the short-circuit current suppressing device shown in FIG. 12 will be described. First, in a steady current state, the main magnetic flux due to the current flowing through the main winding 90 of the current limiting reactor 88 is in the opposite direction due to the current of the secondary winding 91 which is magnetically tightly coupled to the main winding 90. The current limiting reactor 88 is canceled by the magnetic flux and operates as an impedance element having a small reactance corresponding to the leakage magnetic flux. Therefore, there are no problems related to voltage drop or system stability in the power system.

Next, when a large current such as a short-circuit current flows, the fuse 92 connected to the secondary winding 91 of the current limiting reactor 88 operates earlier than the shut-off operation of the circuit breaker 83, and the current limiting reactor 88 The current in the secondary circuit is interrupted. as a result,
The magnetic flux in the opposite direction due to the current in the secondary winding 91 disappears, and the current limiting reactor 88 functions as an impedance element having a large reactance based on the main magnetic flux. Thus, the function as a short-circuit current suppressing device is exhibited.

[0007]

Since the conventional short-circuit current suppressing device is configured as described above, there are the following problems. That is, after a large current rises, SF
₆ Normally, 10 to 4 until the gas 62 starts the current limiting operation.
Since a large current without a current limiting effect flows for about 0 ms, the equipment in which these currents flow must endure it. Further, once the fuse 92 performs the shut-off operation, the secondary winding 91 maintains the open state, so that the current limiting reactor 88 cannot return to the low reactance state, and the high-speed reclosing method required in the high-voltage system. However, there was also a problem that it could not be adopted. Further, when the current is cut off by the fuse 92, a high voltage may be generated between the terminals of the main winding 90, and accordingly, the insulation of the main winding 90 needs to be strengthened and the cost increases. Had.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has a low reactance characteristic in a steady state.
Provide a small and economical short-circuit current suppression device that not only ensures system stability, but also reliably suppresses current during a short circuit and can adopt the high-speed reclosing method required for high-voltage systems. The purpose is to:

[0009]

According to a first aspect of the present invention, there is provided an AC current suppressing device which is inserted into an AC current passage.
First and second coils connected in series with each other and wound in such a direction that magnetic fluxes generated by the passage of the alternating current cancel each other, and flows through the second coil when the alternating current exceeds a predetermined value. It has a current reducing means for reducing the current.

According to a second aspect of the present invention, in the first aspect, the first and second coils are coupled to each other when the number of turns is substantially equal to each other and the alternating current is equal to or less than a predetermined value. The intersecting magnetic flux is configured to be substantially zero.

According to a third aspect of the present invention, there is provided an alternating current suppressing device according to the first or second aspect, wherein:
A non-linear resistor connected in parallel with the second coil, and the current increases rapidly when the voltage exceeds a predetermined value.

According to a fourth aspect of the present invention, there is provided an AC current suppressing device according to the third aspect, wherein the AC current suppressing device is connected in parallel with the non-linear resistance, and closes after a sharp increase in the current of the non-linear resistance, so that the current in the current path is equal to or less than a predetermined value. It is equipped with a switch that opens when it becomes.

According to a fifth aspect of the present invention, there is provided an AC current suppressing device according to the first or second aspect, wherein:
Means for detecting current in the current path, and a switch connected in parallel with the second coil and closing when the detected current exceeds a predetermined value.

According to a sixth aspect of the present invention, there is provided an alternating current suppressing device according to the first or second aspect, wherein:
This gap is connected in parallel with the second coil and discharges when the voltage exceeds a predetermined value.

According to a seventh aspect of the present invention, there is provided the AC current suppressing device according to the sixth aspect, wherein the AC current suppressing device is connected in series with the gap, and is closed after the gap has been discharged and the current in the current path becomes equal to or less than a predetermined value. The switch is provided with a switch.

An AC current suppressing device according to an eighth aspect of the present invention is characterized in that, in any one of the first to seventh aspects, there is provided means for disconnecting at least one of the first and second coils from the current path.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a circuit configuration diagram showing a gas-insulated switchgear provided with a short-circuit current suppressing device according to Embodiment 1 of the present invention, and FIG. 2 is a side view showing its outer shape. Each shows a single phase component. In the figure, reference numeral 1 denotes a short-circuit current suppressing device. First, components of the short-circuit current suppressing device 1 are listed in order as follows. 2 is inserted into a transmission line 81, which is an AC current passage,
Reactors 5 and 6 which are composed of a first coil 3 and a second coil 4 connected in series and wound in a direction in which magnetic fluxes generated by energization cancel each other are branched buses 7,
8 is a non-linear resistor and a short-circuit switch, which are current reducing means connected in parallel with the second coil 4 via 8. 9, 1
Reference numeral 0 denotes a current transformer that detects the current of the branch buses 11 and 12 connected to the reactor 2.

Reference numerals 13 to 17 denote branch buses 11, 1 respectively.
Disconnectors provided at 8, 20, 12, 21;
Is a circuit breaker, and 24 and 25 are current transformers. Each of the above-described devices is housed in a grounded container together with an insulating medium such as insulating oil or SF ₆ gas to constitute a gas insulated switchgear 26.

FIG. 3 is a sectional view showing the internal structure of the reactor 2. In the figure, reference numeral 27 denotes a three-legged iron core having a plurality of iron core gaps 28 provided at its central leg to prevent magnetic saturation when a large current flows. A first coil 3 and a second coil 4 are wound around the center leg.
The coils 3 and 4 have the same number of turns, and are wound in directions that cancel each other out of magnetic flux. The iron core 27 is housed in the grounding container 30 together with the insulating oil 29. One ends of the two coils 3 and 4 and an intermediate connection point between the two coils are connected to a branch bus 12, a branch bus 7 and a branch bus 8, respectively, via a connection conductor 31 and an insulating oil-gas through bushing 32.
It is connected to the.

FIG. 4 is a sectional view showing the internal structure of the nonlinear resistor 5. In the figure, reference numeral 33 denotes a non-linear resistance element such as a zinc oxide element, which is accommodated in an insulating tube. 35 is a shield provided at the upper and lower ends of the non-linear resistance element 33;
Is a supporting insulator. As described above, the non-linear resistor 5 is formed by arranging a plurality of non-linear resistance elements 33 stacked in series and arranging a plurality of non-linear resistance elements 33 in parallel. . Then, the ground receptacle 40 of these non-linear resistance element 33 and the like together with SF ₆ gas 39
Housed within. Both poles of the nonlinear resistor 5 are
And an insulating spacer 38 connected to the branch bus 7 and the branch bus 8.

FIG. 5 is a sectional view showing the internal structure of the short-circuit switch 6. In the figure, 41a is a fixed contact, 41b is a fixed arc contact, 42a is a movable contact, 42b is a movable arc contact, 43 is a nozzle, 44 is an arc extinguishing chamber, 45 is a cylinder, 46 is a piston, and 47 is a connection. Reference numeral 48 denotes an insulating rod, 49 denotes a supporting insulator, 50 denotes an operating device, and 51 denotes a shield conductor. The short-circuit switch 6 described above is housed in the grounding container 53 together with the SF ₆ gas 52. Both poles of the short-circuit switch 6 are connected to a branch bus 7 and a branch bus 8 via a conductor 54 and an insulating spacer 55, respectively.

Next, the operation will be described. For the sake of simplicity, the description will be made with reference to FIG. 6 which shows a portion of the short-circuit current suppressing device 1 extracted from FIG. First, when a steady current flows through the reactor 2 in FIG.
Are a first coil 3 and a second coil 4 connected in series and wound so that magnetic fluxes cancel each other.
, The magnetic flux inside the iron core 27 (FIG. 3) is substantially zero, that is, the magnetic flux linked to both coils 3 and 4 is substantially zero, and the apparent reactance of the reactor 2 is 4, which is an extremely small value only for the leakage reactance. Therefore, in this state, even if the reactor 2 is inserted into the transmission line, its reactance is extremely small, so that the stability of the power system is not affected.

Next, when a large current that greatly exceeds a steady current such as a short-circuit current flows through the reactor 2 in FIG. 6, the voltage across the first coil 3 and the second coil 4 respectively increases, but the second voltage increases. Since the non-linear resistor 5 is connected to the coil 4 in parallel, when this voltage reaches the limit voltage of the non-linear resistor 5, most of the current flows to the non-linear resistor 5 and the second coil 4
Is also limited to the above-mentioned limit voltage. As a result, the apparent reactance of the reactor 2 is a value close to the self-reactance of the first coil 3, and therefore, compared to the reactance in a state where both coils 3 and 4 cancel each other's magnetic flux at the time of steady current. This is a sufficiently large value to suppress the short circuit current of the circuit. That is, the function as the short-circuit current suppressing device is exhibited.

In this case, since the current suppressing effect occurs simultaneously with the rapid increase of the current of the non-linear resistance 5, the function as the short-circuit current suppressing device 1 becomes effective from the moment of the short-circuit, and the short-circuit current flowing to the related equipment is surely suppressed. be able to. Also,
As a result of the operation of the non-linear resistor 5, the voltage between the terminals of the second coil 4 is suppressed to the limit voltage of the non-linear resistor 5, and as a result, the voltage between the terminals of both the coils 3 and 4 is limited to a certain value or less. Does not occur and can be constructed economically.

In order to prevent the non-linear resistor 5 from operating and its current suddenly increasing and its heat duty becoming excessive, the short-circuit switch 6 is closed after the above-mentioned current sudden increase. The closing operation of the short-circuit switch 6 is performed by driving the operation device 50 (FIG. 5) based on the current signal from the current transformer 9 or 10.
After the short-circuit current is removed, the circuit is opened again.

Accordingly, if the operation setting of the short-circuit switch 6 is properly performed, the non-linear resistor 5 and the short-circuit switch 6 operate in a coordinated manner.
The short-circuit current suppressing device 1 functions as a low reactance when a normal current is supplied and a high reactance when a large current is supplied, and can be returned to the low reactance state again when the circuit is closed again.

Returning to the circuit diagram of FIG. 1, the gas insulated switchgear 26 including the short-circuit current suppressing device 1 described above is provided with branch buses 11, 12, 18 to 21 as shown in FIG.
Further, by disposing the disconnectors 13 to 17 and the circuit breakers 22 and 23, only one of the first coil 3 and the second coil 4 as well as the entire short-circuit current suppressing device 1 is separated from the transmission line 81. It has a possible configuration. Therefore, for example, when it is desired to always insert a predetermined amount of reactance, the disconnectors 14, 16, 17 are closed and the disconnector 13,
15 may be opened to insert only the first coil 3 into the circuit. If the short-circuit current suppressing device 1 is not needed, for example, the disconnectors 14 and 15
May be closed and the disconnectors 13, 16, 17 may be opened to disconnect the entire short-circuit current suppressing device 1 from the circuit.
As a result, there is no power loss due to energization of the coils 3 and 4, and the economical efficiency in operation is improved. Further, even when a failure occurs in a part of the short-circuit current suppressing device 1, there is an advantage that the short-circuit current suppressing device 1 can be easily separated from the circuit. Furthermore, as shown in FIGS. 1 and 2, by configuring the whole as a gas insulated switchgear 26, a short-circuit current suppressing device that can be inserted into and disconnected from a power transmission line can be realized at a small size and at low cost. .

Although the number of turns of the coils 3 and 4 is the same in the description of FIG. 3 with respect to the reactor 2, in a range where the magnetic flux interlinking with the coils 3 and 4 becomes substantially zero during a steady current. The number of turns of the two may be slightly different. Further, the reactor 2 may be an air-core type that does not use an iron core. Furthermore,
The insulation system of the reactor 2 may be a gas insulation system instead of oil insulation.

FIG. 7 shows another application example of the reactor 2 in which two iron cores 27A are used, an iron core gap 28 is provided in each leg, and the first coil 3A and the second coil 4A are respectively provided. It is winding. In addition, here
The terminals of both coils 3A, 4A are drawn out to the air by the air bushing 56 via the connection conductor 31.
Applies to substation electrical stations.

With respect to the non-linear resistor 5 described with reference to FIG. 4, an element similar to the zinc oxide type element of an ordinary lightning arrester can be applied to the non-linear resistor 5, but if it has the same non-linear characteristic, Other types of non-linear resistors can be applied. Further, in FIG. 4, the connection to the gas insulated switchgear is made via the branch busbars 7 and 8. However, an air connection may be provided by providing an air bushing at the insulating spacer 38.

In the short-circuit switch 6 described with reference to FIG.
Although it is configured to be connected to the gas insulated switchgear through the branch buses 7 and 8, an aerial bushing may be provided at the insulating spacer 55 to provide an aerial connection method.

Embodiment 2 FIG. FIG. 8 is a circuit configuration diagram showing a short-circuit current suppressing device according to Embodiment 2 of the present invention. Here, the current reducing means of the second coil 4 is only the short-circuit switch 6A, which is connected in parallel with the second coil 4. This short-circuit switch 6A is operated by a current signal from the current transformer 9 or 10, but the closing time is 40 m.
s is required. After the circuit is closed, the circuit is opened after a predetermined time to prepare for a high-speed reclose of the system.

Embodiment 3 FIG. 9 is a circuit diagram showing a short-circuit current suppressing device according to Embodiment 3 of the present invention. Here, a gap 57 is used for the current reduction means of the second coil 4, and this gap 57 is connected in parallel with the second coil 4. FIG. 10 is a sectional view showing the internal structure of the gap 57. In the figure, 58 is a contact 59
Vacuum switches provided with a and 59b, 60a and 60b are shields, and 61 is a supporting insulator. The vacuum switch 58 and the like are connected to the grounding vessel 63 together with the SF ₆ gas 62.
Housed within. Both poles of the vacuum switch 58 are connected to the branch bus 7 and the branch bus 8 via the conductor 64 and the insulating spacer 65.

Next, the operation will be described. In the case of a steady current, the magnetic fluxes of both coils 3 and 4 cancel each other out, and the apparent reactance of reactor 2 is only the leakage reactance of coils 3 and 4, which is an extremely small value, as in the case of the first embodiment. . Therefore, in this state, even if the reactor 2 is inserted into the transmission line, its reactance is extremely small, so that the stability of the power system is not affected.

Next, when a large current that greatly exceeds a steady current such as a short-circuit current flows, the voltage between the terminals of the coils 3 and 4 increases, and when the voltage of the second coil 4 reaches the discharge voltage of the gap 57. The gap 57 discharges and short-circuits the second coil 4 at high speed. As a result, the apparent reactance of the reactor 2 becomes a sufficiently large value close to the reactance of the first coil 3, and suppresses the short-circuit current of the circuit. That is, it functions as a short-circuit current suppressing device.

Since the vacuum switch 58 is employed in the discharge portion of the gap 57, when the short-circuit current is removed and the level returns to a level lower than the steady current after the gap 57 is discharged, the vacuum switch 58 easily cuts off the steady current. And reactor 2
Returns to the original state of low reactance characteristics, and can respond to high-speed reclosing.

Embodiment 4 FIG. FIG. 11 is a circuit diagram showing a short-circuit current suppressing device according to Embodiment 4 of the present invention. Here, a normal gas gap type is used as the gap 57A. Since the gas gap does not have the current interrupting performance unlike the vacuum switch 58, FIG.
As shown in FIG. 1, the circuit breaker 6 is connected in series with the gap 57A.
6 are connected. And, the circuit breaker 66 has a gap 57.
After the discharge of A, it is detected from the current signal from the current transformer 9 or 10 that the current of the circuit has become equal to or less than the predetermined value, and the subsequent flow of the gap 57A is cut off. Thereby, the reactor 2
Returns to the original low reactance characteristics. The circuit breaker 66
After a predetermined time elapses after the shutoff operation, the circuit is closed and returns to the original state.

The current transformers 9 and 9 shown in the above circuit diagrams
10 has been described as means for determining the operation timing of the short-circuit switch 6 and the like, but by detecting the differential output of both current transformers at the time of steady current, the ground generated in either of the coils 3 and 4 is detected. It can also be used as a means for detecting an accident or the like.

In each of the above embodiments, a single-phase circuit has been described, but it goes without saying that the present invention can be applied to a three-phase circuit or the like as it is.

[0040]

As described above, the AC current suppressing device according to the first aspect is inserted into the AC current passage.
First and second coils connected in series with each other and wound in such a direction that magnetic fluxes generated by the passage of the alternating current cancel each other, and flows through the second coil when the alternating current exceeds a predetermined value. A current reducing means for reducing the current is provided, so that when the steady current is applied, the reactance is low and the system stability is secured, and when the large current is applied, the reactance is high and the applied current can be effectively suppressed. .

Further, the first and second coils of the AC current suppressing device according to the second aspect of the present invention are arranged such that when the number of turns is substantially equal to each other and the AC current is equal to or less than a predetermined value, the magnetic flux linked to both coils is substantially zero. As a result, the reactance when the steady current is supplied becomes extremely small, and there is almost no influence on the AC system.

Further, the current reducing means of the alternating current suppressing device according to the third aspect is connected in parallel with the second coil, and is a non-linear resistance whose current sharply increases when the voltage exceeds a predetermined value. With a simple configuration, the current suppressing effect is reliably obtained from the initial stage when the current in the conducting path starts to increase, and the high-speed reclosing method can be applied.

Further, the AC current suppressing device according to claim 4 is connected in parallel with the non-linear resistance, and is closed when the current of the non-linear resistance sharply increases, and is closed when the current of the current path becomes equal to or less than a predetermined value. Since the switch is provided, the heat duty of the non-linear resistance is reduced and the reliability is improved.

According to a fifth aspect of the present invention, there is provided an AC current suppressing device, wherein the current reducing means is a means for detecting a current in an energizing path, and is connected in parallel with the second coil when the detected current exceeds a predetermined value. Since the switch is provided with a closing switch, the operation of the above-described switch realizes a high / low switching of the reactance as a device, a reliable current suppressing effect is obtained, and a high-speed reclosing method can be applied.

Further, the current reducing means of the AC current suppressing device according to claim 6 is a gap connected in parallel with the second coil and discharging when the voltage exceeds a predetermined value.
With a simple configuration, a reliable current suppressing effect can be obtained, and a high-speed reclosing method can be applied.

Further, the AC current suppressing device according to claim 7 is provided with a switch connected in series with the gap, and which is opened after the discharge of the gap and closed when the current of the energized path becomes a predetermined value or less. Therefore, it is possible to apply a gap having no follow-up blocking capability.

Further, the alternating current suppressing device according to claim 8 is provided with means for disconnecting at least one of the first and second coils from the current path, so that the current suppressing function is not required, or the high reactance is used. Can be performed simply, smoothly, and economically.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a gas-insulated switchgear provided with a short-circuit current suppressing device according to Embodiment 1 of the present invention.

FIG. 2 is a side view showing the outer shape of the gas insulated switchgear of FIG.

FIG. 3 is a sectional view showing an internal structure of a reactor 2.

FIG. 4 is a sectional view showing an internal structure of the nonlinear resistor 5;

FIG. 5 is a sectional view showing the internal structure of the short-circuit switch 6.

FIG. 6 is a circuit configuration diagram extracting and showing a part of the short-circuit current suppressing device 1 of FIG. 1;

FIG. 7 is a cross-sectional view showing an internal structure of reactor 2A different from FIG.

FIG. 8 is a circuit configuration diagram showing a short-circuit current suppressing device according to a second embodiment of the present invention.

FIG. 9 is a circuit diagram showing a short-circuit current suppressing device according to Embodiment 3 of the present invention.

FIG. 10 is a sectional view showing an internal structure of a gap 57.

FIG. 11 is a circuit diagram showing a short-circuit current suppressing device according to Embodiment 4 of the present invention.

FIG. 12 is a circuit configuration diagram showing a conventional short-circuit current suppressing device.

FIG. 13 is a conventional circuit configuration diagram different from FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Short-circuit current suppression device, 2 reactor, 3rd coil, 4th coil, 5 Non-linear resistance, 6, 6A
Short-circuit switch, 9,10 current transformer, 26 gas-insulated switchgear, 27,27A core, 57,57A gap, 6
6 Circuit breaker, 81 transmission line.

Claims (8)

[Claims] A first coil and a second coil, which are inserted into an AC current path, are connected in series with each other, and are wound in directions in which magnetic fluxes generated by the AC current flow cancel each other; AC current suppression means comprising current reduction means for reducing the current flowing through the second coil when the current exceeds a predetermined value. 2. The first and second coils are configured such that when the number of turns is substantially equal to each other and the alternating current is equal to or less than a predetermined value, the magnetic flux linked to both coils is substantially zero. The alternating current suppressing device according to claim 1. 3. The device according to claim 1, wherein the current reducing means is a non-linear resistance connected in parallel with the second coil, the current increasing rapidly when the voltage exceeds a predetermined value. AC current suppression device. 4. A switch which is connected in parallel with the non-linear resistance, and is closed after the current of the non-linear resistance sharply increases, and is opened when the current in the current path becomes equal to or less than a predetermined value. Item 3. The alternating current suppressing device according to Item 3. 5. The current reducing means includes means for detecting a current in an energizing path, and a switch connected in parallel with the second coil and closing when the detected current exceeds a predetermined value. The alternating current suppressing device according to claim 1 or 2, wherein 6. The AC current suppressing device according to claim 1, wherein the current reducing means is a gap connected in parallel with the second coil and discharging when a voltage exceeds a predetermined value. . 7. A switch connected in series with the gap, wherein the switch is opened after the gap is discharged and closed when the current in the current path becomes a predetermined value or less.
The alternating current suppressing device according to any one of the preceding claims. 8. The alternating current suppressing device according to claim 1, further comprising means for disconnecting at least one of the first and second coils from the current path.