JPH0222606B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a current suppressing device that suppresses short circuits, ground fault currents, and the like.

Recently, ultra-high-voltage, large-capacity power systems have been envisioned, which will require circuit breakers with large breaking capacities to cope with the increase in short-circuit capacity.

However, with the types of circuit breakers currently in practical use, it is not easy to expect a dramatic increase in their breaking capacity, and it takes a considerable amount of time to develop new circuit breakers. There is a demand for the development of current suppressing means to reduce the breaking current.

The present invention has been made in view of the above-mentioned circumstances, and includes winding a primary winding through which line current flows around the legs of the iron core, and winding a secondary winding around the legs around which the primary windings are wound. By connecting an impedance circuit to this secondary winding in parallel, and controlling the coupling relationship between the primary winding and the impedance circuit to the power system by opening and closing operations of a circuit breaker connected in parallel to the secondary winding. It is an object of the present invention to provide a current suppressing device that can accurately suppress short circuits, ground fault currents, transformer excitation inrush currents, etc.

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

FIG. 1 shows an embodiment of the present invention, in which a pair of divided primary windings 21A and 21B are connected to a leg 11 of an iron core 10 having five legs 11 to 25.
A pair of split primary windings 22A, 22B are wound around the legs 13, and a pair of split primary windings 23A, 23B are wound around the legs 13, respectively, and one end of each leg 11 to 13 is connected in common to the power system. It is connected to the load side line, and circuit breakers 31, 32, and 33 are connected between the other ends, and one end thereof is connected to the power supply side line of the power system. In this case, each divided primary winding 21A, 21B, 22A,
It is assumed that 22B, 23A, and 23B have the same number of turns so that the line current is equally divided, and are connected so that the magnetic flux due to the divided current is canceled out for each leg 11 to 13. In addition, circuit breakers 31 to 33
To suppress fault currents (short circuits, ground fault currents), the circuit is closed during normal operation, and the circuit is opened when an accident is detected.

The legs 11, 12, 13 of the iron core 10 are wound with secondary windings 24, 25, 26, respectively.
A series circuit of a resistor 41A, a reactor 41B, and a capacitor 41C, that is, an impedance circuit, is connected between both ends of the secondary winding 24 of the leg 12.
A series circuit of a resistor 42A, a reactor 42B, and a capacitor 42C is connected between both ends of the leg 13, and a series circuit of a resistor 43A, a reactor 43B, and a capacitor 43C is connected between both ends of the secondary winding 26 of the leg 13. The impedance circuit is an adjustment load and is used to suppress short circuits and ground fault currents, adjust phase, and adjust the time constant of the system.

Next, we will discuss the effect. When the purpose is to suppress fault current, the circuit breakers 31 to 33 are kept in a closed state. In this state, the legs 11 of the iron core 10
~13 split primary windings (21A, 21
B), (22A, 22B), and (23A, 23B), and the magnetic flux due to this shunt current is canceled out. Therefore, the coupling between the impedance circuit and the primary winding becomes substantially irrelevant, and the impedance circuit does not affect the impedance of the system.

By the way, if a short circuit or ground fault occurs in the grid,
When this is detected, all of the circuit breakers 31 to 33 or the fault phase circuit breaker is opened. This circuit breaker 31
- 33, one winding 21B, 22B, 23B of the pair of divided primary windings is disconnected, and current flows only through the other divided winding 21A, 22A, 23A.
As a result, a magnetic flux flow is generated in the legs 11 to 13, and a voltage is induced in the secondary windings 24, 25, and 26. As a result, the impedance of the impedance circuit is present in the system, the fault current is suppressed, and its phase and time constant are adjusted.
Adjusting the time constant is effective for quickly suppressing ground faults and short circuit currents. In order to suppress short circuit and ground fault current quickly, it may be better to reduce the reactance of the system and suppress it with resistance, so to reduce the reactance of the system, use a series capacitor. This is because the current value is suppressed by the resistance.

In addition, since the line current is shunted and the shunted current is interrupted, the breaking capacity of circuit breakers 31 to 33 only needs to be half the capacity of the fault current, and if the breaking times are coordinated, a general circuit breaker can be used. I can endure it.

2 to 4 respectively show other embodiments of the present invention, and FIG. 2 shows a case where circuit breakers 31 to 33 are connected between both ends of secondary windings 24 to 26.
In this case, the primary windings are not divided into separate windings, but single primary windings 21, 22, 23 are wound around the legs 11, 12, 13.

FIG. 3 shows a case in which only reactors 41B, 42B, and 43B are required as impedances to be input into the system, and gaps 16, 17, and 18 are provided in leg portions 11, 12, and 13 of iron core 10. Note that, as in the embodiment shown in FIG.
When provided on the next side, the secondary windings 24 to 26 are omitted and gaps 16, 17, 18 are provided to the legs 11 to 13.
All you need to do is set up

FIG. 4 shows a case where a circuit breaker is provided on the secondary side similarly to the embodiment shown in FIG. It is set at 32. Note that even when the circuit breakers 31 to 33 are provided on the primary side as in the embodiment shown in FIG. 1, the secondary windings 24 to 26 can be Y-connected or Δ-connected.

In each of the above-mentioned embodiments, when the purpose is to suppress fault current, the circuit breakers 31 to 33 are closed during normal operation and opened when a fault is detected.

Although the above description is about suppressing fault current, each of the embodiments can be applied to suppressing magnetizing inrush current of a transformer. In that case, the configuration is the same, but the circuit breaker is controlled to be open (impedance on state) when the transformer is powered on, and closed after a certain period of time has passed after the transformer is powered on. Also, the iron core 10 is 5
It is not limited to legs, and may be four legs or three legs. However, the use of a three-legged core is limited to cases where the purpose is to suppress short-circuit current.

This is due to the following reason.

That is, the three-legged iron core has magnetic fluxes of each leg φ〓 _u , φ〓 _v ,
It is used when the vector sum of φ〓 _w is zero (φ〓 _u + φ〓 _v + φ〓 _w = 0), and in cases such as ground faults, this relationship does not hold (φ〓 _u + φ〓 _v + φ 〓 _w ≠ 0), it is necessary to create a magnetic path through which the magnetic flux does not become zero. For this purpose, a four-leg iron core can be used by adding one leg, but it is common to use a five-legged core because it is easier to manufacture.

As described above, according to the present invention, the primary winding through which the line current of the power system passes is wound around the leg of the iron core, and the secondary winding is wound around the leg around which the primary winding is wound. An impedance circuit is connected in parallel to this secondary winding, and the coupling relationship between the primary winding and the impedance circuit to the power system is controlled by the opening/closing operation of a circuit breaker connected in parallel to the secondary winding. So,
The generation and disappearance of impedance used for current suppression and phase and time constant adjustment can be easily controlled, and short circuits, ground fault currents, and transformer excitation inrush currents are accurately suppressed. Therefore, it can contribute to solving the problem of breaking capacity of circuit breakers in power systems with large power transmission capacity.

[Brief explanation of drawings]

FIG. 1 is a configuration explanatory diagram showing one embodiment of a current suppressing device according to the present invention, and FIGS. 2 to 4 are configuration explanatory diagrams showing other embodiments of the present invention. 10...Iron core, 11-15...Legs, 16-1
8...Gap, 21-23...Primary winding, 21
A, 21B, 22A, 22B, 23A and 24B
...Divided primary winding, 24-26...Secondary winding, 3
1 to 33...breaker, 41A to 43A...resistance,
41B~43B...Reactor, 41C~43C
...Capacitor.

Claims (1)

[Claims] 1 An iron core having three or more legs, a primary winding wound around a predetermined leg of this iron core to conduct the line current of the power system, and a primary winding wound around the leg around which the primary winding is wound. A wound secondary winding, an impedance circuit connected in parallel to the secondary winding, and a coupling relationship between the primary winding and the impedance circuit connected in parallel to the secondary winding to a power system. A current suppressing device comprising: a circuit breaker controlled by opening/closing operations.