JPH09200946A - Blind spot fault detecting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect definitively and simply a blind spot fault of a multiple terminal power transmission line system by judging that a blind spot fault having occurred when a circuit breaker connected to a terminal is in open state and a current data detected by the terminal exceeds a preset setting. SOLUTION: For each of terminals A, B... constituting a multiple terminal power transmission line system, a sum of a logical sum 15 of each terminal A, B, C... portion of the logical product 14 of open detections 12 of the breaker CD and overcurrent detections 13 is taken, and a blind spot trouble is judged based on the results of a timer element 16 added to the logical sum 15. And a break command is output for each breaker based on the logical sum 17 of the judged results of blind spot faults and a ratio differential element 11. By doing this, blind spot faults can be detected easily and definitively and thus the reliability of the power transmission can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blind spot failure detection system capable of detecting a blind spot failure occurring in a multi-terminal transmission line system.

[0002]

2. Description of the Related Art Conventionally, for example, a current differential protection method has been widely used as a method applied to a failure detection of a multi-terminal transmission line system due to its high reliability. This current differential protection method is to detect the internal fault of the system by determining the vector sum of terminal currents at each terminal of the transmission line, that is, the differential current. The differential current becomes 0 when the protection section is healthy or when there is an external failure, and has a value equal to the fault current only when there is an internal failure.

FIG. 3 shows a case where a current differential protection system is used.
It is a system diagram showing an example of composition of a terminal power transmission line system. According to the figure, the terminals A of the transmission line L, B, A C, breaker CB _A, CB _B, CB _C (hereinafter. When collectively referred to as "breaker CB"), the current flowing in the transmission line Current transformers CT _A , CT _B and CT _C (hereinafter, collectively referred to as “current transformer CT”) for detecting the current are installed. The current transformer CT includes ratio differential relay devices 1 _A , 1 _B , 1 respectively.
_C (hereinafter, collectively referred to as "ratio differential relay device 1") is connected to the ratio differential relay device 1 and a signal (hereinafter, referred to as a terminal) corresponding to the current value detected by the current transformer CT is connected to the ratio differential relay device 1. Current data) is input. Also, breaker C
B is connected to the ratio differential relay device 1. A break command is given from the ratio differential relay device 1 to the circuit breaker CB when a failure is detected, and the break condition of the auxiliary contact linked to the main contact of the circuit breaker CB is given from the breaker CB to the ratio differential relay device 1. A signal to represent is given.

Each of the ratio differential relay devices 1 is connected to each other by a communication line (not shown) or the like, and the terminal current data is collected in any of the ratio differential relay devices 1 to obtain the sum of the terminal current data. Based on this, internal faults are detected, and faults are quickly removed. However, in the above-mentioned system configuration, there are places or sections where the failure cannot be removed at high speed depending on the positions where the current transformer CT and the circuit breaker CB are installed. For example, now the current transformer CT _c and the breaker CB _c
It is assumed that a failure (ground fault or short circuit) occurs at a point D (see FIG. 3) between and. At this time, the circuit breaker CB _c is
It is not opened by the ratio differential relay device 1 _c , but is opened by another relay device (for example, a differential relay device) that protects the bus bar on the terminal C side. Further, in the protection section protected by the ratio differential relay device 1, the sum of the terminal current data obtained by any one of the ratio differential relay devices 1 which is predetermined as the master station is 0, and therefore the internal failure does not occur. Since it is not determined and it is determined as an external failure, another breaker C
B _A and _{C B B} are not opened, and the failure cannot be removed at high speed.
As described above, depending on the positions where the current transformer CT and the circuit breaker CB are installed, there are places or sections where the failure cannot be removed at high speed, and failures that occur at such locations or sections are called blind spot failures.

For example, as shown in FIG. 4, a current transformer CT
So that it comes inside when viewed from the terminal side of the circuit breaker CB,
A configuration in which the positions of the current transformer CT and the circuit breaker CB are interchanged is also conceivable, but in this case, the problem that maintenance of the current transformer CT is difficult occurs. Therefore,
Conventionally, for example, the following method has been used to remove this blind spot failure at high speed.

When a blind spot failure occurs, the circuit breaker CB of the terminal where the failure occurs is opened by another relay device or the like which protects the bus bar on the terminal C side. The signal of the open / closed state, which is the output of the auxiliary contact that interlocks with the main contact of the circuit breaker CB,
Since it is sent to the connected ratio differential relay device 1,
In the ratio differential relay device 1, it can be seen from the open / close state signal that the circuit breaker CB is open. Therefore, the ratio differential relay device 1 forces the terminal current data sent from the current transformer CT and acquired by the software installed in the ratio differential relay device 1 on condition that the breaker CB is open. Value is set to 0.

Therefore, one of the ratio differential relay devices 1 that sums up the terminal current data determines that it is an internal failure, and each ratio differential relay device 1 outputs a breaking command to each breaker CB. To do. As described above, on the condition that the circuit breaker CB is open, the terminal current data is set to a value of 0 and an apparent differential current is generated to forcibly remove the fault at a high speed. It has been used for a long time.

[0008]

However, in the above-mentioned zero data control method, for example, when the circuit breaker CB is turned on at the beginning of the operation of the facility, or when the circuit breaker CB is turned on again after the failure is recovered, the circuit breaker is turned on. There is a case where the system is determined to be defective even though the system is sound, due to the characteristics of the CB.

Specifically, FIG. 5 shows a circuit breaker C.
FIG. 6 is a diagram showing a timing of interruption recognized by software installed in the ratio differential relay device 1 when B is turned on. For example, assume that the circuit breaker CB is manually turned on at the timing shown in FIG. The information that the breaker CB is turned on is sent to the ratio differential relay device 1. At this time, breaker CB
5 or the characteristics of the relay itself, a time delay (for example, 10 msec) occurs in the section indicated by T in FIG. That is, the software recognizes the closing of the circuit breaker CB after a delay of T from the actual closing of the breaker CB.

On the other hand, since a load current flows in the power transmission line L at the same time when the breaker CB is turned on, terminal current data is input to the ratio differential relay device 1 from the current transformer CT. However, since the software installed in the ratio differential relay device 1 recognizes that the circuit breaker CB is open in the section T, the terminal current data is set to 0.

Therefore, in the section indicated by T in FIG. 5, the ratio differential relay device 1 judges that it is an internal failure and operates its own relay by mistake, although the system is sound. Will end up. Therefore, the ratio differential relay device 1 requires more complicated data control so as to avoid the above-mentioned malfunction, and therefore a system capable of more easily removing blind spot failures has been desired.

Further, since the zero data control method is a method of detecting an internal fault and eliminating a blind spot fault, it is not immediately known which of the internal fault and the blind spot fault has occurred. In that case, there is a problem that complicated data analysis must be performed in order to distinguish the failure modes. Therefore, an object of the present invention is to solve the above-mentioned technical problems, and to provide a blind spot failure detection system capable of detecting and eliminating a blind spot failure of a multi-terminal transmission line system more reliably and easily. .

[0013]

A blind spot fault detection system according to claim 1 for achieving the above object, detects a blind spot fault occurring in a multi-terminal (two or more terminals) transmission line system. An open / close detection means for detecting open / close of a circuit breaker installed in any of the terminals in the system,
Current data detecting means for detecting current data at the terminal, open / close state of the breaker detected by the open / close detecting means, and current data detected by the current data detecting means are preset. And a determination means for determining a blind spot failure based on a logical product of the fact that the set point is exceeded.

According to the above construction, when the breaker connected to any of the terminals is in the open state and the current data detected at the terminal exceeds the preset set value. It is determined that a blind spot failure has occurred. If the system is healthy or if there is an internal failure,
When the breaker CB at any terminal is in the open state, the load current flowing through that terminal is zero. Therefore, in that case, the fact that a current exceeding the preset setting value appears indicates that a fault current is flowing between the current transformer CT and the circuit breaker CB, that is, a blind spot failure has occurred. Can be guessed.

The "current data" differs depending on the failure phase to be detected, and the structure of the detecting means also differs accordingly. For example, a zero-phase current is detected when a ground fault occurs, and each phase current is detected when a short-circuit fault occurs.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.
This will be described in detail with reference to the accompanying drawings. FIG. 1 is a system diagram showing an example of the configuration of a three-terminal transmission line system to which the present blind spot failure detection system is applied. As shown in the figure, a breaker CB and a current transformer CT that detects a current flowing through the power transmission line are installed at each of the terminals A, B, and C of the power transmission line L. Current transformer C
A ratio differential relay device 1 and overcurrent relay devices 2 _A , 2 _B and 2 _C (hereinafter collectively referred to as “overcurrent relay device 2”) are connected to T. A signal corresponding to the current value detected by the current transformer CT is input to the ratio differential relay device 1 and the overcurrent relay device 2. Further, the breaker CB is connected to the ratio differential relay device 1. The ratio differential relay device 1 gives a break command to the breaker CB when a failure is detected.
From the above, the ratio differential relay device 1 is provided with a signal indicating the open / closed state of the auxiliary contact interlocking with the main contact of the circuit breaker CB.

The ratio differential relay devices 1 are connected to each other by a communication line (not shown) or the like, and the terminal current data is collected in any of the ratio differential relay devices 1 to obtain the sum of the terminal current data. Based on this, the internal failure is detected. FIG. 2 is a sequence diagram showing blind spot failure determination of the present blind spot failure detection system. According to this sequence diagram, in the present embodiment, the logical product 1 of the open detection 12 of the breaker CB and the overcurrent detection determination 13 for each terminal is obtained.
The blind spot failure is judged based on the result of adding the timer element 16 to the logical sum 15 of each terminal and the logical sum 15 of each terminal. Then, based on the logical sum 17 of the judgment result of the blind spot failure and the ratio differential element 11, a breaking command is output to each breaker CB.

[0018] Specifically, for example, at terminal A, a signal representative of the open or closed state of the auxiliary contacts interlocked with the main contacts of the circuit breaker CB _A is given from the breaker CB _A to the ratio differential relay device 1 _A. If this signal represents the open state of the circuit breaker CB _A corresponds to the open detection 12 of the circuit breaker CB _A of FIG. Further, the terminal current data is supplied from the current transformer CT _A to the overcurrent relay device 2 _A. The overcurrent relay device 2 _A gives a judgment signal to the ratio differential relay device 1 _A when the supplied terminal current data exceeds a preset set value. This determination corresponds to the overcurrent detection determination 13 in FIG.

The ratio differential relay device 1 _A includes a circuit breaker CB.
_{When A} is in the open state and the current flowing through the terminal A exceeds the preset value, the detection signal is output to any one of the ratio differential relay devices 1 which is predetermined as the master station. . In any of the ratio differential relay devices 1, the detection signals are collected for each terminal, and a timer element 16 is added to the output of the logical sum of the collected detection signals,
Output as blind spot failure detection. Then, for example, by displaying this output, the user can quickly start maintenance work by seeing this display.

When either the blind spot fault detection signal or the ratio differential element 11, that is, the internal fault determination signal by the ratio differential relay device 1 is output, each ratio differential relay device 1 A break command is output to each breaker CB. As described above, when the breaker CB connected to the terminal is in the open state and the current flowing through the terminal exceeds the settling value set, it is determined that the blind point failure has occurred at the terminal. To be done.

This is because when the system is healthy or when an internal failure has occurred, and the breaker CB at any terminal is in the open state, the load current flowing through that terminal is zero. Therefore, in this case, the fact that a current exceeding the preset set value appears is that the current transformer C
It is considered that a fault current is flowing between T and the breaker CB, that is, it can be inferred that a blind spot failure has occurred.

The timer element 16 outputs a blind spot failure detection signal when an input above a threshold value continues for a certain time (for example, 10 msec),
This timer element 16 can prevent malfunction of the relay due to noise. It is also possible to remove this timer element 16 from the above sequence, in which case the threshold value in each overcurrent relay device 2 is relatively greater than the load current, for example empirically determined. It is desirable to set it to a value that is two or three times the rated load current, which is another

When detecting a ground fault, the overcurrent relay device 2 is preferably an overcurrent relay device (OCG) for ground fault having a relatively low threshold value, and is connected to the overcurrent relay device 2. The current transformer CT is a zero-phase current transformer (ZC
T) will be connected. The method for realizing the sequence of FIG. 2 may be performed by software installed in the ratio differential relay device 1 as described above, for example, overcurrent detection determination or breaker CB open detection. It may be performed by hardware by outputting information as a contact signal.

As described above, according to this embodiment, the blind spot failure can be eliminated more easily. Further, since the determination of the blind spot failure can be performed independently of the determination of the internal failure that is the ratio differential element 11, for example, when investigating the cause of the failure, is it a blind spot failure or an internal failure? Can be quickly distinguished. Furthermore, since it is possible to detect the presence or absence of a blind spot failure for each terminal, it is possible to easily determine in which terminal the blind spot failure has occurred.

Further, as described in the section "Prior Art", the terminal current data is forcibly set to 0 and apparently an internal failure is caused to detect a blind spot failure. Eliminates the need for sophisticated data control. Further, since it is not necessary to use the zero data control method, complicated software for responding to an erroneous determination as an internal failure due to a time delay is not required even though the system is sound. Therefore, it becomes possible to more easily detect and eliminate the blind spot failure.

Although the present embodiment has been described above, the present invention is not limited to the above embodiment. In the above-described embodiment, the three-terminal system power transmission line has been described, but the present invention can be applied to a two-terminal system power transmission line or an n (n ≧ 4) terminal system power transmission line. In addition, various modifications can be made within the scope of the invention described in the claims.

[0027]

As described above, according to the blind spot failure detection system of the present invention, a blind spot failure can be detected more simply and reliably. Therefore, the reliability of power transmission can be improved.

[Brief description of drawings]

FIG. 1 is a system diagram showing an example of the configuration of a three-terminal transmission line system to which a blind spot failure detection system according to an embodiment of the present invention is applied.

FIG. 2 is a sequence diagram showing blind spot failure determination of the blind spot failure detection system according to the embodiment of the present invention.

FIG. 3 is a diagram showing an example of a configuration of a conventional three-terminal transmission line system in which a current differential protection system is used.

FIG. 4 is a diagram showing a configuration in which the positions of the breaker CB and the current transformer CT are exchanged in the configuration of the three-terminal transmission line system of FIG.

FIG. 5 is a diagram showing a timing of interruption recognized by software installed in the ratio differential relay device 1 when the breaker CB is turned on.

[Explanation of symbols]

1 Ratio differential relay device 2 Overcurrent relay device CB _A , CB _B , CB _C Circuit breaker CT _A , CT _B , CT _C Current transformer L Transmission line

Claims (1)

[Claims] 1. A blind spot fault detection system for detecting a blind spot fault occurring in a multi-terminal transmission line system, comprising open / close detection means for detecting opening / closing of a breaker installed at each terminal, and current data at the terminal. A current data detecting means for detecting the open / close state of the circuit breaker detected by the open / close detecting means, and the current data detected by the current data detecting means exceeds a preset value. And a determination means for determining a blind spot failure based on a logical product of the above.