JP3169976B2 - Distribution line ground fault protection system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distribution line protection system, and more particularly to a distribution line for detecting a distribution line ground fault and separating a section including the ground fault point to eliminate the distribution line fault. Regarding protection system.

[0002]

2. Description of the Related Art Conventionally, in order to distinguish between a healthy section and an accident section when a distribution line accident occurs, a "section switch for automatic detection of a fault section" has been used (for example, published by the Institute of Electrical Engineers of Japan in February 1988). "Electrical Engineering Handbook," p. 1264). According to this, after all the segment switches have been opened due to the occurrence of an accident, each of the segment switches is automatically turned on again sequentially at a preset time interval, and the distribution line outlet of the substation is opened. When an accident is detected by the installed protective relay, the circuit breaker at the distribution line outlet is immediately opened, and the section switch that has been re-entered immediately before that is used to determine in which section the accident has occurred. It is. This system is generally referred to as a timed sequential transmission charging system.

According to the time-sequential transmission power application method, it takes the following time to complete the power application to the end of the distribution line.

[Progressive transport time] × [Number of section switches] As a result, there is a problem that the power failure time becomes longer toward the end.

Further, according to the present system, there is a problem in that when the first fault is detected and when the fault section is detected, the entire distribution line (including a healthy section) loses power twice.

[0006]

The above-mentioned prior art has a problem that a power failure occurs twice in a healthy section and a problem that it takes time to recover.

According to Japanese Patent Laid-Open Publication No. Hei 2-26222, "Distribution Line Protection Relay System", it is possible to reduce the power failure range and the restoration time of the distribution line, but to shorten the operation time of the accident detection relay. By doing so, there is a problem that a power failure occurs even in the case of an instantaneous recovery accident that does not result in a conventional power failure.

An object of the present invention is to provide a distribution line protection system that can eliminate a power failure in a healthy section for detecting and disconnecting a distribution line accident section.

[0009]

According to one aspect of the present invention, there is provided a distribution switch having a plurality of divided switches arranged on a distribution line and a switch for interconnection with another distribution line. In a distribution system provided with a protection device, a protection device having a ground fault detection function and a function of controlling the switching of the switch is provided in one or more of the distributed switchgear and the connection switch for interconnection , and the protection device is provided. Is an accident detection timer that is activated when an accident is detected and sets the opening timing of the switch; and at least a switch protection device that is distributed and arranged .
And a communication means for performing communication between the protection devices of the interconnecting switch, wherein the accident detection timer is shorter than the operation time of the distribution line outlet relay and is housed in the protection device that is away from the power supply side. as those, it is settling so that the operation time is shortened, and, in the protection apparatus of the section switch that is at least distributed, after the accident detection, after the operation time of the accident detection timer, interconnection switching device the closing command for sending via said communication means, and the distribution line ground fault protection system, characterized in that a control means for opening the self-sectionalizing switches is provided.

According to another aspect of the present invention, a plurality of switches are distributed on a distribution line, and switches for interconnection with other distribution lines are provided. Or, when a ground fault occurs in a distribution line ground fault protection system provided with a protective device having a ground fault accident detection function and a function of controlling the switching of the switch in two or more and an interconnecting switch, the detect this by the upstream protective devices, closest protection device to an accident point at the upstream side, for the protection device of the communication system switching device directs the insertion of the tie-switching device,
An operation method of the distribution line ground fault protection system is provided, wherein the switch of the own section is opened after the switch is turned on.

Protective device provided at normally open point ( interconnection switch)
It is preferable to use a switch that can switch the detection direction and that can detect the protection device installation side that has generated the normally open point input command as an accident detection target.

[0012] The protection device also has a reclosing function, and once the switch is opened upon detection of an accident, it is possible to perform the disconnection operation only in the accident section by utilizing the current timed sequential transmission charging system. preferable.

It is preferable that each protection device is provided with a short-circuit detection function, and locks the opening command of the switch when the switching capability of the protection device is exceeded.

[0014]

With the above arrangement, the object of the present invention is achieved by the following operation. First, when a ground fault occurs in the distribution line, the protection device located on the power supply side from the fault point operates. A switch command is output and the switch is opened (the operating protection device is restored).

After that, an accident occurs in the distribution line due to the input of the normally open point, and the protection device for the distribution line starts operating. However, only the normally opened point is opened by the same operation as described above (the accident has been recovered). If this is the case, all sections will continue uninterrupted.)

Here, the range of the power failure is narrowed down to the range of the previously opened switch and the normally open point, and “operating time of the previously opened switch” + “operating time of the normally open switch” < If the coordination time is set so as to satisfy the condition of the operation time of the distribution line outlet relay, the time until the occurrence of a power failure according to the present invention becomes longer than that of the conventional distribution line outlet relay, and the recovery time becomes longer. In the event of a short-to-ground fault (such as contact with a tree), it is expected that a power outage will not occur.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a system configuration of a 6.6 kV distribution line to which an embodiment of a ground fault protection system according to the present invention is applied. As shown in the figure, electric power is supplied from a distribution transformer 1 of a substation to a plurality of distribution lines (in the present embodiment, two and three distribution lines are used for simplicity) via a power supply bus 2 of 6.6 kV. Supplied. Outlet circuit breakers FCB1 and 2 having an interrupting ability are provided at the substation outlet points of the distribution lines 3 and 4, and a protection device for detecting a distribution line accident (also referred to as a distribution line exit relay). By FRY1 and 2,
In the event of an accident, the outlet circuit breakers FCB1 and FCB2 can be opened. In addition, in each of the distribution lines 3 and 4, divided switches (hereinafter sometimes simply referred to as switches) DM1 to 6 are appropriately distributed and arranged, and furthermore, interconnection switches for connecting the distribution lines 3 and 4 are connected. A DM7 (sometimes referred to as a normally open switch or simply a switch) is provided so that power can be interchanged as needed.

In the above-mentioned distribution system, one or more switches (DM2, DM5, DM7 in this embodiment) in the middle of the distribution lines 3 and 4 are provided in order to protect the distribution lines 3 and 4 separately.
Protective devices RY1, RY2, and RY3 for detecting an accident (hereinafter, also referred to as an accident detection relay) are provided. The protection devices RY1, RY2, and RY3 have transformers C for detecting an accident.
T and PT are provided. As the transformers CT and PT,
A current transformer or a zero-phase current transformer, or a voltage transformer or a zero-phase voltage transformer is provided. The state quantity (line current, line voltage or line voltage, zero-phase current, zero-phase voltage, etc.) of the distribution line detected by each transformer is input to the corresponding fault detection relay RY. , An overcurrent relay, a zero-phase overcurrent relay, a ground fault direction relay, an undervoltage relay and the like are incorporated as required. In the protection devices RY1, RY2, RY3, an accident detection timer (cooperation timer) for cooperatively opening and closing the switch can be arbitrarily set in detecting an accident. In this embodiment, the accident detection timer is set to a value that satisfies the following expression in relation to the protection relay FRY provided at the distribution line outlet.

Operation time of FRY> Operation time of RY (accident detection timer) + Opening time of DM + Recovery time of FRY (1) Furthermore, the protection device RY provided on the pillar has a communication function, A communication path TL1 with the interconnection switch DM7;
2 is provided.

Regarding the above-mentioned pole protection device RY,
An example of a more specific configuration will be described with reference to FIG.

The pole protection device incorporates an operation unit 21 for controlling ON / OFF of the sectional switch DM, and outputs of the zero-phase current transformer ZCT and the zero-phase voltage transformer PD, and outputs a zero-phase overcurrent or an arbitrary ground. A relay unit ry1 for detecting a short-circuit direction, and a relay unit ry2 for receiving an output of the current transformer CT and detecting a short circuit.
And a relay unit ry3 for capturing the output of the voltage transformer Tr and detecting an undervoltage, a communication unit 22 for communicating with the pole protection device RY2 installed at the normally open point, and input / output information of each of the above units. And a logical operation unit 23 for overall management.

Each relay section ry1, ry2, ry3 has
A coordination timer capable of stabilizing the operation time is taken in if necessary. The configuration of each of the relay units ry1, ry2, and ry3 is not a necessary condition, and any configuration may be used as long as at least a ground fault can be detected. Here, only an embodiment of the configuration is shown, and these relay units can be deleted or added as appropriate. Also, the coordinating timer can be in an appropriate mode, such as being fixed and mounted in advance.

Although not shown, the logical operation unit 23 has, for example, a central processing unit, a storage device, an interface, an accident detection timer for performing a cooperative operation, and the like. In the storage device, start control of the timer, open / close control of the switch,
A procedure for coordinating with another protection device, a program for controlling transmission / reception to the communication unit 22, and various parameters are stored. The central processing unit executes various functions according to these programs. As an example of these programs, for example, there is a program that executes a flowchart shown in FIG.

The operation time of the accident detection timer is set differently depending on the position where the protection device is provided. That is, the shorter the accident detection timer of the protection device located farther from the power supply, the shorter the set time.

The protection device installed at the normally open point has the same configuration as the protection device of the switch installed in the distribution line. The accident detection timer of the protection device RY2 at the normally open point is set to a time equal to or shorter than the operation time of the accident detection timer of the protection device (RY3, RY1 in this embodiment) located on the most downstream side of the distribution line.

The operating time of the protective devices RY3, RY1 for the switch and the protective device RY2 at the normally open point is the same as the operating time of the protective devices FRY1, 2 for the distribution line outlets on the upstream side. It is settled so as to satisfy the relationship of equation (1). RY2 installed in the normally open point, when receiving a closing command from the protector RY 3 other section switches (or RY1), the other side of the distribution line and the closing command reception direction (interconnection relative to become distribution lines) 3 (or 4) installed protection devices RY1 (or RY 3), has a function of outputting a signal for locking the fault detection operation.

Each of the protection devices RY has a function of detecting a line current when the switching capability of the switch to which the protection device RY is set is low, and a short-circuit current exceeding a preset switching capability of the switch is provided. A function is provided to stop the cooperative operation of this embodiment immediately upon detection. In addition, each protection device R
Y detects an accident and instructs the normally open point protection device to turn on the switch, then monitors the line voltage or line voltage on the accident detection side of the self-partitioned switch, and within a predetermined time. In the event of a power failure on the accident detection side, a function to wait for at least the opening time of the switch in the power outage section to reclose the circuit, and to set a predetermined time after the reclosement (the time after the switch is applied to the normally open point) If the accident is detected again within the time required for power supply (timed forward time), the switch is opened and the circuit is closed again within a predetermined time. In addition, it is preferable that this function is provided with a function of preventing a reclosing after opening of the switch if an accident is detected before the timed sequential feeding.

The normally open point protection device RY2 is provided with a function of receiving a turn-on command from another protection device only when the voltage at both ends is sound.

The communication unit 22 has a transmission / reception function, and communicates with another communication unit according to a preset format and procedure. The communication paths TL1 and TL2 need only be able to communicate between the pole protection device provided in the middle of the distribution line and the protection device installed at the normally open point, and various types of dedicated lines, optical cables, wireless, etc. are possible. In this embodiment, a dedicated line is used.
Further, in the present embodiment, the communication is directly performed between the protection devices, but is not limited thereto, and may be indirect communication. For example, when a plurality of protection devices are on one distribution line, one protection device may communicate with a normally open protection device via another protection device. Further, a configuration in which all communication is relayed by a management center that manages the distribution system may be adopted. Further, a public telephone line may be used.

The control power supply of the protection device uses the secondary output voltage of the voltage transformer Tr. For the power supply, various methods such as a power supply battery and a secondary voltage flow from an existing pole transformer can be adopted. Further, a configuration in which two or more power supplies are prepared and backup can be performed may be adopted.

Now, an example of a method of operating the system according to the present embodiment when an accident occurs in a distribution line in the above-described configuration will be described with reference to FIG.

In FIG. 1, when a ground fault occurs at the point F of the distribution line 4 , the relay section of the pole protection device RY3 is started by the outputs of the fault detecting transformers CT3 and PT3, and the fault detection timer is started. (Step 101). When the operation time of the accident detection timer (coordination timer) elapses, the protection device RY3 is activated, and the communication unit 22 immediately sends a “normally open point switch closing command” to the protection device RY2 provided at the normally open point. It is transmitted (steps 102 and 103). Wait for the normally open point protection device RY2 to be turned on (step 104).
Upon receiving the closing signal, the switching unit DM5 is opened (step 105). As a result, the accident point F is
Side, and the protection relay FRY2 at the distribution line outlet returns (DM5 is at the normally open point).

When an accident occurs at point F, a protection device (protection relay) FRY2 provided at the outlet of the distribution line is also activated, and the protection relay FRY2 operates as described above for the operation time of the accident detection timer. Therefore, the protection device RY3 does not operate in the time until the switch is opened. Therefore, the protection device (protection relay) FRY2
When the protection device RY3 opens the switch, the distribution line 2 returns because there is no apparent fault point.

On the other hand, protection devices RY 2 normally open point receives the closing command, the turning on the switch DM7, sends an on signal to the protection device RY3, the direction (in this embodiment that receives the closing command It is assumed that a ground fault point exists on the DM5 side), and the direction of ground fault direction detection is set to the DM5 side. Also,
Pole protection device R installed on the opposite side of the ground fault detection direction
A command for locking the accident detection function is output to Y1, and the operation time is set so as to cooperate only with the protection relay FRY1 provided at the distribution line outlet.

Thereafter, if the accident continues, the protection relay FRY1 provided at the outlet of the distribution line and the normally open point protection device RY
2 starts. When the protection device RY2 measures the coordination time, the switch DM7 is opened, and only the section including the accident point F is separated. At this time, the protection relay FRY1 at the distribution line outlet is restored, and the distribution line 3 does not cause a power failure.

If the accident has recovered, the normally open point has just moved from the switch DM7 to the switch DM5, and the distribution line is uninterrupted. After the accident recovery, switch D to normal open point.
It is also possible to move from M5 to DM7. In this case, the switch DM7 may be opened after the switch DM5 is turned on.

As described above, the range of the power failure due to the ground fault at the point F is narrowed to only the range of the switches DM5 to DM7.

Here, the protection device RY3, which has opened the switch DM5, monitors the voltage at the accident point F side. It is determined that the switch has been opened, and the switch is closed again after waiting for no-voltage release delay time (about 1 second) of the switch (step 1).
06).

The protection device that has opened the switch DM7 upon detection of an accident waits for a no-voltage release delay time of the switch and recloses the circuit, as described above. Here, as described in the related art, the switch is turned on to the existing segmented switch by the time-sequential feeding function after the elapse of a certain time period. However, if a voltage is applied to both ends before the switch is turned on, the time-sequential forwarding function is locked.

When the fault point is charged again by the time-sequential switching of the switch, the protection device on the side which has been forwarded to the fault point first is activated and opened again. At this time, the protection relay at the distribution line outlet is also activated, but it goes without saying that the operation is not affected by the coordination timer. Further, a protection device that detects an accident due to reclosing should not output a closing command to the protection device installed at the normally open point. Furthermore, a signal when a closing command is received during the re-closing process is not accepted.

With respect to the switch that has been reopened, the protection device waits for the non-voltage release delay time of the switch again, closes again, and ends the processing. The reclosing process is the same as the operation procedure of the reclosing device installed in the current substation, and the details are omitted. It is clear that only the section is separated, but the number of sections is small, so that the separation time is short.

FIG. 3 shows the above operation in chronological order.
In FIG. 3, the number of sections is increased to clarify the operation. FIG. 4 shows a case according to the prior art.

Comparison between the two shows that, until an accident occurs, the distribution line from the lead voltage of the substation A and the distribution line from the substation B are disconnected at the normally open point NOP. ing. In this state, if an accident occurs at the point F, the conventional distribution line protection system opens the circuit breaker by the protection device at the substation outlet as shown in FIG.
The power supply area loses power. Thereafter, the time-sequential forwarding process is performed, and when the fault point F is charged again, the circuit breaker is opened again by the protection device at the substation outlet, and the power is cut off in the same manner as described above. Timed sequential processing is performed up to this point. Then, the switch at the normally open point is turned on, and power is supplied to the range from the substation B side to the switch just before the accident point.
In this conventional method, along with the power outages of 2 times occurs in the whole area of distribution lines, it is taking time to recover from a power failure in a healthy range. On the other hand, in the method of the present embodiment shown in FIG. 3, when an accident occurs, the protection device on the upstream side closest to the accident point operates, the normally open switch is turned on, and the accident is detected. The switch of the protection device is opened. Thereafter, the accident point is separated by the above-described procedure. Therefore, if the accident is recovered before the protection device at the normally open point detects the accident and the timer operates, the power failure is prevented as shown in FIG. On the other hand, if the accident does not recover, the accident point separation process is performed between the protection device that detected the accident and the normally open point protection device. Even in the area, the accident point separation processing can be performed for a short time.

In this embodiment, the pole protection device RY2 installed at the normally open point locks the relay function of the pole protection device on the non-accident point side, but is released when the reclosing procedure is completed. .

Although the embodiment of the present invention has been described above, the present invention is not limited to this. For example,
The following may be performed.

In the above-described embodiment, when the normally open point is closed after the detection of an accident, the switch is opened after confirming the closing. However, in order to allow a margin for coordination time, after the closing command is transmitted, the switch is closed. The switch may be opened after waiting for the response time. That is, after the switch is opened, the reclosing function is performed when the power failure occurs on the fault point side, so that the fault point can be separated even if the normally open point is not turned on.

After the normally open point switch is turned on, the relay function of the pole protection device on the non-accident point side is locked. Even without locking, it is possible to cooperate with the relay unit in a timed manner. The object of the invention can be achieved. However, since ground faults are often recoverable, the previous example was explained in consideration of the fact that it is better to extend the opening time of the switch and that it is advantageous to set the coordination time. did.

In the above embodiment, one pole protection device is provided for each distribution line. However, it is more preferable to provide a plurality of protection devices as long as the relay operation time can be coordinated. Needless to say, the protection division becomes possible and the effect is large. In addition, the emphasis is only on coordination with the protection relay at the outlet of the distribution line, and there is no problem even if the coordination between the pole protection devices is insufficient. However, in this case,
It is necessary for the pole protection device to have a timed forward function. The function may use an existing device, or may be newly added.

In consideration of shifting from a single-line ground fault to a two-line ground fault, the opening operation of the switch is locked by an overcurrent detection relay according to the breaking ability of the switch. In this case, the circuit breaker FCB is opened by the protection relay operation at the distribution line outlet, which is the same as the current one.

[0051]

According to the present invention, it is possible to protect the distribution line in each section where the pole protection device is provided, and there is a great effect that the power supply side of the accident section becomes uninterrupted, and there is a resilient ground fault. In response to an accident, the time from the occurrence of the accident to the occurrence of the power outage section can be made longer than before, so that there is also an effect that unnecessary power outages are reduced.

The system according to the present invention has the advantage that the existing equipment can be used as it is, the equipment investment is small, and the effect is large.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a power distribution system diagram and an arrangement configuration of devices for explaining an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an example of a pole protection device that can be used in an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a time-series power supply situation at the time of an accident by the distribution line ground fault protection system of the present invention.

FIG. 4 is an explanatory diagram showing a power supply situation at the time of an accident according to a conventional technique in a time-series manner.

FIG. 5 is a flowchart illustrating an operation of the protection device that has performed the accident detection according to the embodiment.

[Explanation of symbols]

1. Distribution transformer, 2 distribution bus, 3, 4 distribution line,
21 operation unit, 22 communication unit, 23 logical operation unit, PD
… Zero-phase voltage detection voltage divider, ZCT… Zero-phase current transformer, C
T: current transformer, DM: sectional switch, RY: protection device (fault detection relay).

Claims (6)

(57) [Claims] 1. A distribution system in which a plurality of segmented switches are dispersedly arranged on a distribution line and one or more of the segmented switches arranged in a distributed manner are provided in a distribution system provided with switches for interconnection with other distribution lines. An interconnecting switch is provided with a protective device having a ground fault detecting function and a function of controlling the opening and closing of the switch. The protective device is activated when an accident is detected, and an accident detecting timer for setting an opening timing of the switch. And at least a switch protection device that is distributed and arranged , and communication means for performing communication between the interconnection switch protection devices. The accident detection timer includes a distribution line outlet relay. The operation time is shorter than that of the power supply side, and is set so that the operation time becomes shorter as it is housed in the protection device. After the operation time of the accident detection timer, a closing command for the interconnection switching device and transmitted via the communication means, and distribution line ground fault, characterized in that a control means for opening the self section switch Protection system. 2. The protection device for an interconnecting switch according to claim 1, wherein an operation time of the accident detection timer is set shorter than an operation time of an accident detection timer provided in another protection device. when receiving a closing command which is transmitted from the protection device, after turning the tie-switching device, the ground fault detection
The orientation of the ground fault direction detection output function, and sends the closing command
Distribution line ground fault protection system, wherein the this <br/> the protective device is set in the direction of the distribution line which is disposed a. 3. An accident detection timer for a segmented switch and an accident detection timer for an interconnecting switch according to claim 1, wherein the operating time of the segmented switch to be opened first + the operating time of the interconnecting switch. Operation time ”<Distribution line ground fault protection system in which each operation time is set so that the distribution line outlet relay operation time is satisfied. 4. A well as distributed a plurality of switches in the distribution lines, provided interconnection switching device with another distribution line, in one or more and the interconnection switching device of the distributed arranged switch In a distribution line ground fault protection system equipped with a protection device having a ground fault detection function and a function to control the opening and closing of a switch, when a ground fault occurs, it is detected by a protection device on the upstream side of the fault point. and closest protection device to an accident point at the upstream side, for the protection device of the communication system switching device directs the insertion of the tie-switching device, characterized by opening the switch of its own segment Operation method of distribution line ground fault protection system. 5. The distribution line provided in the distribution line outlet according to claim 4, wherein the protection device closest to the fault point on the upstream side measures the time from when the fault is detected until the switch of its own section is opened. Settle to a time shorter than the operation time of the outlet relay,
Operation method of distribution line ground fault protection system. 6. A protection device according to claim 5, wherein when the protection device provided at the normally open point receives an input command transmitted from another protection device, the protection device transmitting the input command is arranged.
Outputs a signal to lock the operation of the protection device to the protection device installed on the distribution line opposite to the direction of the existing distribution line (distribution line to be interconnected), and sets a pre-set distribution line outlet relay. The protection equipment that sent the closing command
A method for operating a distribution line ground fault protection system, characterized by detecting an accident in the direction of the distribution line where the installation is located .