JP2000312436A - Current limiting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current limiting device by which the transient recovery voltage of a breaker does not exceed specifications, in a high-voltage system. SOLUTION: A capacitor 6 is connected at the terminal of a current limiting reactor 4 installed in a substation and a switch station, or a breaker 2 and the current limiting reactor 4 are connected by a cable. Alternatively, the current limiting reactor 4 is mounted between the mutually adjacent substation and switch station through a transmission line 3, or the breaker 2 switching the current limiting reactor 4 is formed in a breaker 2 with a resistor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current limiting device, and more particularly, to a current limiting device provided with a current limiting reactor and installed in a power system.

[0002]

2. Description of the Related Art The power system is steadily expanding, and the short-circuit current at the time of system failure is increasing. The current system has a maximum short circuit current of 63 kA, but in the future, the short circuit current will be 63 kA.
It is also expected to exceed kA. However, 63
It takes enormous amount of time and money to develop a circuit breaker that can handle a kA excess current and replace the operating circuit breaker. Therefore, research has been conducted to limit the short-circuit current with a current limiting device and to interrupt the current with a current circuit breaker.

[0003] As one of current limiting devices, there is one in which a reactor is inserted in series into a system to suppress a short-circuit current. This type of current limiting device is shown in FIG.
And a current limiting reactor 4 connected between the circuit breaker 2 and the power transmission line 3 connected to the power transmission line 3 to suppress a short-circuit current when a ground fault 5 occurs in the system. As shown in FIG. 8, when there is no current limiting device, a large short-circuit current 16 flows, and a large-capacity circuit breaker capable of interrupting the short-circuit current is required. If the short-circuit current exceeds 63 kA, the current breaker will not be able to break. However, with a current limiting device, the short-circuit current
Since the current is suppressed as in 17, it is possible to cut off even with the current circuit breaker, and it is not always necessary to develop a new circuit breaker.

[0004]

However, when a reactor is used to suppress a short-circuit current, a transient recovery voltage generated after the current is cut off by a circuit breaker may become severe. For example, under the condition of the ground fault in FIG. 7, the circuit breaker 2 cuts off the current flowing through the current limiting reactor 4.
At this time, after the current interruption, a high-frequency voltage due to the natural vibration of the current limiting reactor 4 appears at the terminal of the circuit breaker 2 on the current limiting reactor 4 side. On the other hand, a recovery voltage of the system appears at a terminal of the circuit breaker 2 on the substation bus 1 side. The transient recovery voltage of the circuit breaker appearing after the current interruption is expressed as the difference between the voltages at both terminals of the circuit breaker. In FIG. 7, since the frequency of the voltage appearing at the terminal of the current limiting reactor 4 of the circuit breaker 2 is high, FIG. As shown as the recovery voltage 18 when there is a current limiting reactor, the value 8 specified in the circuit breaker standard JEC-2300 may be exceeded.

[0005] In such a case, the increased short-circuit current is suppressed by the current limiting reactor, but the current recovery circuit breaker cannot be applied because the transient recovery voltage exceeds the circuit breaker standard. For low voltage systems, there is a method to apply a higher voltage class breaker, but for 500 kV systems, it is necessary to develop a new circuit breaker or reduce the transient recovery voltage to be within the standard. is there. Accordingly, an object of the present invention is to provide a current limiting device in which a transient recovery voltage of a circuit breaker does not exceed a standard value in a high-voltage system.

[0006]

According to a first aspect of the present invention, there is provided a current limiting device in which a capacitor is connected to a terminal of a current limiting reactor installed in a substation or switchyard. With this capacitor, the natural oscillation frequency of the current limiting reactor can be reduced, and the transient recovery voltage of the circuit breaker can be reduced.

A current limiting device according to a second aspect of the present invention is one in which a circuit breaker and a current limiting reactor are connected by a cable. By utilizing the ground capacitance of the cable, the natural oscillation frequency of the current limiting reactor can be reduced, and the transient recovery voltage of the circuit breaker can be reduced.

A current limiting device according to a third aspect of the present invention is one in which a current limiting reactor is installed between substations and switchyards adjacent to each other via a transmission line. The natural oscillation frequency of the current limiting reactor can be reduced by utilizing the ground capacitance of the transmission line, and the transient recovery voltage of the circuit breaker can be reduced.

According to a fourth aspect of the present invention, the circuit breaker for opening and closing the current limiting reactor is a circuit breaker with a resistor. With this configuration, the magnitude of the natural vibration of the current limiting reactor can be reduced, and the transient recovery voltage of the circuit breaker can be reduced.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A current limiting device according to a first embodiment of the present invention will be described with reference to FIG. That is, the current limiting reactor 4 and the circuit breaker 2 are connected in series between the transmission line 3 connected to the substation bus 1 and the substation bus 1. Then, a capacitor 6 is connected between the current limiting reactor 4 and the circuit breaker 2 between the ground.

The operation of the current limiting device of the first embodiment having such a configuration will be described with reference to FIGS. That is, when a ground fault 5 occurs at the current limiting reactor 4 end as shown in FIG.
The recovery voltage of the substation side system appears at the substation bus 1 side terminal, and the voltage due to the natural oscillation of the current limiting reactor 4 appears at the terminal on the current limiting reactor 4 side. Current limiting reactor 4
Has a high frequency, but since the capacitor 6 is connected to the terminal of the current limiting reactor 4, the frequency can be lowered as shown as the transient recovery voltage 10 when the capacitor 6 is present in FIG. JEC standard 2 transient recovery voltage
It is possible to keep the voltage within the transient recovery voltage 8 defined by −2300.

As described above, in the first embodiment of the present invention, the configuration in which the capacitor is connected between the current limiting reactor terminal installed in the substation and the ground,
The natural oscillation frequency of the current limiting reactor after the current interruption can be reduced, the transient recovery voltage of the circuit breaker can be suppressed within the standard value, and the existing circuit breaker can be used.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIG. In the present embodiment, the current limiting reactor 4 and the circuit breaker 2 are connected by a cable 11. By using the capacitance of the cable 11 to ground, the natural oscillation frequency of the current limiting reactor 4 can be reduced without connecting a capacitor to the terminal of the current limiting reactor 4, and the transient recovery voltage can be reduced.

(Third Embodiment) A third embodiment of the present invention will be described with reference to FIG. In the present embodiment, a current limiting reactor 4 is installed between a substation bus 1 and an adjacent substation bus 12 via a transmission line 3. Transmission line 3
Is smaller than cables, etc., but the distance between substations is generally several km to several tens of km. The natural oscillation frequency of the flow reactor 4 can be reduced, and the transient recovery voltage can be reduced.

In the underground power transmission system, which is currently increasing in urban areas and the like, underground substations are interconnected by cables. Even when the transmission line 3 is a cable, the same effect of reducing the transient recovery voltage can be obtained.

(Fourth Embodiment) A fourth embodiment of the present invention will be described with reference to FIG. In the present embodiment, a circuit breaker that opens and closes the current limiting reactor 4 is a circuit breaker 20 with a resistor. The circuit breaker with resistor 20 includes a main circuit breaker 13 and a resistor breaker 15 having a resistor 14. Main cutoff
When the current is interrupted by the resistor 13, the resistor 14 and the resistance interrupting unit 15 are connected in series with the current limiting reactor 4, so that the transient recovery voltage can be reduced. When the resistance cutoff unit 15 cuts off the current, the AC voltage applied to the current limiting reactor 4 is reduced by the resistor 14, and the transient recovery voltage is reduced.

[0017]

The current limiting device of the present invention suppresses short-circuit current,
The transient recovery voltage of the circuit breaker can be reduced, and the existing circuit breaker can be used.

[Brief description of the drawings]

FIG. 1 is a connection diagram of a current limiting device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a ground fault in the first embodiment of the present invention.

FIG. 3 is an explanatory view of a transient recovery voltage reduction according to the first embodiment of the present invention.

FIG. 4 is a connection diagram of a current limiting device according to a second embodiment of the present invention.

FIG. 5 is a connection diagram of a current limiting device according to a third embodiment of the present invention.

FIG. 6 is a connection diagram of a current limiting device according to a fourth embodiment of the present invention.

FIG. 7 is a diagram showing connection of a conventional current limiting device.

FIG. 8 is a diagram illustrating suppression of short-circuit current by a current limiting reactor.

FIG. 9 is a view for explaining the influence of a current limiting reactor on a transient recovery voltage.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substation bus, 2 ... Circuit breaker, 3 ... Transmission line, 4 ... Current limiting reactor, 5 ... Ground fault, 6 ... Capacitor, 7 ... Interruption current,
8: Transient recovery voltage of standard, 9: Transient recovery voltage without capacitor 6, 10: Transient recovery voltage with capacitor 6, 11: Cable, 12: Bus of adjacent substation, 13: Main cutoff, 14 … Resistor, 15… Resistance cutoff part, 16… Short-circuit current without current limiting reactor, 17… Short-circuit current with current limiting reactor, 18… Transient recovery voltage with current limiting reactor, 19… Limit Transient recovery voltage when there is no flow reactor, 20 ... breaker with resistor, 21 ... ground.

Claims (4)

[Claims] 1. A current limiting reactor connected between a transmission line and a circuit breaker for electrically connecting or disconnecting the transmission line to a bus of a substation or a switchyard, and a current limiting reactor and the circuit breaker A current limiting device comprising: a capacitor connected between the connection point of (1) and the ground. 2. A current-limiting reactor connected between a transmission line and a circuit breaker for electrically connecting or disconnecting the transmission line to a substation or switchyard bus; A current limiting device comprising: a cable connected between the two. 3. A current limiting device comprising a current limiting reactor connected in the middle of a transmission line interconnecting a substation and a switching station via a circuit breaker. 4. A current limiting reactor and a circuit breaker with a resistor connected in series between a power transmission line and a substation or switchyard electrically connected to or disconnected from the power transmission line, and The current limiter is characterized in that the circuit breaker comprises a series circuit of a resistor and a resistance breaking section and a parallel circuit of a main breaking section.