JPH05130731A - Grounding switch - Google Patents

Abstract

PURPOSE:To prevent a fault current induced by other phase and line from continuously flowing and effectively protect power transmission line by detecting any fault current cutoff in a breaker in order to automatically close the grounding switch on the transmission line side of the breakers on both ends of a transmission line after the breaker is cut off, and then, automatically opening it through a timer. CONSTITUTION:When a ground fault occurs at the A point of a circuit 1, the breakers 3A1 and 3A2 on both ends of the transmission line of the circuit 1 are cut off. This cutoff is detected by limit switches 3L1 and 3L2. The closing coil 4C of a grounding switch is excited by the contact 10a of an auxiliary relay 10 to close a grounding switch 4A1. Then, the leader coil 4T of the grounding switch is excited by the a contact 4a of the grounding switch and the timer contact 11a through a timer 11 to automatically open the grounding switch 4A1. Thus, after the grounding switches 4A1 and 4A2 are opened, the breakers 3A1 and 3A2 are again closed by an automatic re-closing instruction 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grounding switch for grounding a transmission line, and more particularly to a high speed grounding switch for eliminating a fault current in the transmission line.

[0002]

2. Description of the Related Art In recent power transmission systems, long distances and high voltage are increasingly promoted due to difficulty in locating power sources, and they are in the range of 500 KV to 1000 KV. In such a power transmission system, the distance from other lines that are installed in parallel or transmission lines of the same phase in other phases is larger than the voltage as it becomes the ultra-high voltage class mentioned above due to structural restrictions such as towers. Can not be removes.

Normally, up to about 500 KV, when a ground fault occurs due to a lightning strike, the circuit breakers installed at the substations at both ends of the transmission line of each line are shut off to eliminate the ground fault current. You can

However, in the ultra-high voltage class of 1000 KV, as described above, the distance from another line or a transmission line of another phase of the same line cannot be increased in proportion to the voltage, and the transmission line of another healthy line is not. If the circuit breakers at the substations at both ends of the accident point are simply shut off due to the induced current from the other, the induced currents from other healthy transmission lines will continue as if the accident current remained. Flow, and the arc continues, so that the circuit breaker will operate again when the circuit breaker is turned on again.

[0005]

As one of the methods for solving such a problem, conventionally, a protection system as shown in FIG. 3 has been used. It should be noted that FIG. 3 is a schematic diagram of a single phase of a conventional parallel two-line transmission system protection system. That is, in general, the substations at both ends of the transmission lines of the lines 1 and 2 are respectively provided with circuit breakers 3A ₁ and 3A ₂ and, although not shown, a circuit breaker is connected to each circuit breaker in series. It consists of a grounding switch and other auxiliary equipment connected in parallel.

In the conventional power transmission system configured as described above, when the voltage of the power transmission system is 500 KV or less, a ground fault current flows to the point A of the power transmission line of the line 1 of the two lines due to a lightning strike. , By breaking the circuit breakers 3A ₁ and 3A ₂ of each substation at both ends of the transmission line, the ground fault current at point A of the transmission line is eliminated, and then the circuit breakers 3A ₁ and 3A ₂ are turned on again. Thus, the power transmission line of the line 1 can be transmitted and is restored.

However, the voltage of the transmission system is 1000
Above the KV level, the ground fault current continues to flow at the accident point due to the induced current from the power transmission line of the other line 2, so that when the circuit breaker is reclosed, the circuit breaks again. There is a drawback that power transmission via the power transmission line of the line 1 becomes impossible.

The present invention has been proposed in order to solve the above-mentioned drawbacks of the prior art, and an object thereof is to enable the opening / closing operation of the earthing switch to be performed in conjunction with the accident breaking operation of the circuit breaker. The purpose is to provide a grounded switch that is based on the above.

[0009]

According to the present invention, in a grounding switch provided on the power transmission line side of a circuit breaker connected to both ends of each power transmission line of a circuit, the circuit breaker interrupts a fault current. It is characterized in that it is provided with a detecting means, and is configured to automatically close after the circuit breaker is cut off, and then automatically open after a predetermined time through a timer.

[0010]

According to the grounding switch of the present invention, when a ground fault occurs in a line, first, the circuit breakers at both ends of the power transmission line are cut off. The accidental interruption of the circuit breaker is detected by the detection means provided in the grounding switch, and the closing coil of the grounding switch is excited by the auxiliary relay to close the grounding switch. Next, the trip coil of the grounding switch is excited via the timer of the grounding switch, and the grounding switch is automatically opened. The circuit breaker is closed again immediately after the grounding switch is opened.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to FIGS. The same members as those of the conventional type shown in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted.

In this embodiment, as shown in FIG.
Grounding switches 4A ₁ , 4A ₂ , 4B are provided on the transmission line sides of the circuit breakers 3A ₁ , 3A ₂ , 3B ₁ and 3B ₂ of the substations at both ends of the transmission lines of the lines 1 and 2 arranged in parallel. ₁ and 4
B ₂ is installed.

Further, the earthing switches 4A _{1 to} 4B ₂ are provided with a control circuit as shown in FIG. 1. After the circuit breaker is broken, the earthing switch is opened and closed at a high speed to prevent a fault current. It is configured to forcibly commutate and eliminate the ground fault current at the accident point. That is, in FIG. 1, the auxiliary relay 10 includes an output contact 5 of a protection relay and a circuit breaker 3A that detect an accident in a power transmission line and give a breaking command to the circuit breaker.
_The limit switch 3L ₁ for detecting the completion of the opening of circuit ₁ and the limit switch 3L ₂ for detecting the completion of the opening of circuit breaker 3A ₂ are configured to operate.

The contact 10a connected in parallel with the output contact 5 of the protection relay is the a contact of the auxiliary relay 10 and holds the auxiliary relay 10 by itself because the output contact 5 operates for a short time. Also, for resetting the auxiliary relay 10,
The b contact 4b of the ground switch 4A ₁ is connected.

When the interlock device 14 is satisfied by the a contact 10a of the auxiliary relay 10, the earthing switch 4A ₁ is opened and closed.
C is excited and the ground switch 4A ₁ is turned on. Then, by the a contact 4a of the grounding switch, the predetermined timer 1
1, the timer contact 11a excites the trip coil 4T of the grounding switch, and the grounding switch 4A ₁ is automatically opened.

Further, the selection switch 12a is a switch for selecting the operation mode of the ground switch, and is constituted by a contact 12a of the automatic side selection switch and a contact 12b of the manual side selection switch. Here, if the manual side is selected, the ground switch 4A ₁ has a circuit configuration that can be manually opened / closed by the operation switches 13a and 13b. As a result, the grounding switch 4A ₁ can be used for high-speed switching operation in the event of a power line accident and for grounding when the power line or the circuit breaker 3A ₁ is maintained for a long time, such as maintenance work.

The interlock device 14 has two
It is configured to operate under two conditions. That is, one is the related circuit breaker 3A ₁ , 3A for high speed automatic operation.
_The other condition is the non-voltage condition for maintenance or the like when the item ₂ is opened, and although not shown, it is usually the time when the disconnector related to the earthing switch is opened.

Further, since the grounding switch of the present invention operates at high speed automatically in the event of a power transmission accident, the circuit breakers 3A ₁ and 3A ₂ are reclosed immediately after the grounding switch is opened. Therefore, the earthing switches 4A ₁ and 4A ₂ are closed when the circuit breaker 3A is closed.
If A ₁ and 3 A ₂ are turned on again, the power transmission system will be in a forced grounding state, which may cause a very dangerous and large power failure.

In order to prevent this, circuit breakers 3A ₁ and 3A
The input circuit of ₂ is configured as follows. Normally, the circuit breakers 3A ₁ and 3A ₂ are automatically reclosed by sending an automatic reclosing command 6 from the protection relay side. Therefore, this re-input command 6
To a series, to connect the b-contact 4b ₂ of the grounding switches 4A ₂ of the b-contact 4b and the mating end of the earthing switch 4A _1, to energize the circuit breaker 3A _1, 3A ₂ of closing coil 3C in these conditions I have to. Accordingly, upon re-introduction of breaker 3A _1, 3A _2, it can be prevented to remain the grounding switch 4A _1, 4A ₂ in closed.

In the figure, reference numeral 15 is a circuit breaker switch. Further, P and N are the positive pole side P of the power supply of the control circuit.
And the negative pole side N is shown.

The grounding switch of the present embodiment having such a structure operates as described below. That is, line 1 in FIG.
When a ground fault occurs at point A, the circuit breakers 3A ₁ and 3A ₂ at both ends of the transmission line of the circuit ₁ are cut off. If the interruption of the circuit breaker is detected by the limit switches 3L ₁ and 3L ₂ , and if the interlock device 14 is satisfied by the a contact 10a of the auxiliary relay 10, the closing coil 4C of the earthing switch is excited. The grounding switch 4A ₁ is turned on.

Next, the a-contact 4a of the grounding switch excites the trip coil 4T of the grounding switch by the timer contact 11a via the predetermined timer 11, and the grounding switch 4A ₁ is automatically opened. It Then, the circuit breakers 3A ₁ and 3A ₂ are reclosed immediately after the ground switch is opened.

[0023] Incidentally, so as not to be grounding switch 4A _1, 4A ₂ is breaker 3A _1, 3A ₂ in closed continuous turned on again, as described above, re-closing command 6 in series with the circuit breaker in, so as to connect the b-contact 4b ₂ of the grounding switches 4A ₂ of the b-contact 4b and the mating end of the earthing switch 4A _1, to energize the circuit breaker 3A _1, 3A ₂ of closing coil 3C in these conditions There is.

As described above, according to this embodiment, since the earthing switch is turned on / off in conjunction with the interruption of the circuit breaker, the fault current continues due to the induction of another phase / circuit. Can be prevented and the transmission line can be effectively protected. Further, the grounding switch of the present embodiment can be used also for grounding during maintenance of a power transmission line or the like, and is therefore economically superior.

[0025]

As described above, according to the present invention, the grounding switch provided on the power transmission line side of the circuit breaker is provided with means for detecting that the circuit breaker has interrupted the fault current, and The earthing switch is automatically closed after the circuit breaker is cut off, and then opened automatically after a predetermined time via a timer. It is possible to provide a grounding switch that can be operated in conjunction with the operation.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a control circuit of an embodiment of a grounding switch of the present invention.

FIG. 2 is a single-phase circuit diagram showing the protection principle of the transmission system of the line using the earthing switch of the present invention.

FIG. 3 is a single-phase circuit diagram showing a general parallel two-line power transmission system.

[Explanation of symbols]

1,2 ... line _{3A 1, 3A 2, 3B 1} , 3B 2 ... breaker 3C ... breaker closing coil 3L _1, 3L ₂ ... breaker limit switch _{4A 1, 4A 2, 4B 1} , 4B 2 ... ground switch 4C ... grounding switches of closing coil 4T ... earthing switch tripping coil 4a ... earthing switch of a contact 4b, 4b ₂ ... output contacts 6 ... automatic cycle the contact b 5 ... protection relay of the earthing switch Command 10 ... Auxiliary relay 10a ... A contact of auxiliary relay 11 ... Timer 11a ... Timer contact 12a, 12b ... Selection switch contact 13a, 13b ... Operation switch 14 ... Interlock device 15 ... Circuit breaker open switch

Claims (1)

[Claims] 1. A grounding switch provided on the power transmission line side of a circuit breaker connected to both ends of each power transmission line of the circuit, comprising means for detecting that the circuit breaker interrupts a fault current, and After closing the circuit breaker, it automatically closes,
A grounding switch characterized by being configured to automatically open after a predetermined time via a timer.