JPH0327720A - Control system for switch of distribution line - Google Patents

Abstract

PURPOSE:To prevent electric service interruption from occurring in the sound section on the power-source side of an accident section more than once in addition to that at the time of the accident having occurred, by cutting off a switch prior to the interruption by a circuit breaker of a substation when a grounding current has been detected for a constant time during a time interval K after the switch was operated. CONSTITUTION:A zero phase CT (ZCT) 5 in a switch 4 detects the current of a distribution line 2. An auxiliary CT 7 in a switch controller 6 receives the output of the ZCT 5 and an amplifier 8 amplifies it to a level suitable for inside processing. When a grounding current detected only during a time interval K since the switch 4 was operated is a set point, or more, set beforehand to value being able to cooperate with the action of a protective relay circuit of a substation 1, the switch 4 is cut off before the feeder circuit breaker 3 of the substation 1 is cut off after detecting that that state has continued for a constant time. And, this prevents electric service interruption from occurring in the sound section on the power-source side of an accident section more than once in addition to that at the time of the accident having occurred, and makes it possible to suppress a bad influence on power consumers to a minimum.

Description

[Detailed Description of the Invention] A. Industrial Application Field The present invention is used in a power distribution system to re-open the section switch or partial switch of the distribution line that was opened when a ground fault occurred in the distribution line, and The present invention relates to a method for recognizing points and transmitting power to the accident section and the stage before the accident point.

B. Summary of the Invention The present invention provides that if a ground fault current is continuously detected on the automatic switch side for a certain period of time from the time the switch is turned on to the K time period, the feeder cutoff 2g of the substation is shut off. The switch is opened before the accident occurs, and the power outage in the healthy section on the power supply side of the accident section only occurs once when an accident occurs, making it possible to identify the accident section and the accident point.

C. Conventional electrical power distribution systems are vast facilities that are spread out over a region, and there is a high risk of accidents caused by wind and flood damage, lightning, and other factors. For this reason, measures are being taken to protect the power lines in case an accident occurs.

Figure 4 shows an overview of the power distribution system. 1 is a substation, and 2 is a distribution line. The substation 1 is provided with a feeder circuit breaker (PCB) 3 that stops power transmission when an accident occurs on the distribution line 2. The distribution line 2 is equipped with section switches DM. ~DM, are arranged, and partial switches D, ~D, are arranged in each section. Section switch DM,
-DM. The sections in between are defined as sections 1 to 3, respectively. The section switches DM, ~DM, are automatic switches that automatically open and close during power transmission and when power transmission is stopped. On the other hand, either a manual switch or an automatic switch is used for the partial switches D1 to D3.

Here, it is assumed that a ground fault occurs at a location between the partial switches D and D3 in section 3, as indicated by the x mark in the figure.

Conventional control of the switch at this time will be explained.

FIG. 5 is a time chart showing conventional switch control.

Under normal power transmission conditions before an accident occurs on the distribution line, FCB3 of substation 1 and section switches DM, ~DM. is in the ON state.

When a ground fault occurs, the protection relay circuit reduces the ground fault voltage V at the substation 1. and ground fault current■. is detected.

If this detection continues for Tc time, it is determined that an accident has occurred, and F
Power transmission is turned off by CB3. After this, the protective relay circuit is returned to its initial state.

By turning off FCB3, the section switch DM
,~DM. The partial switches D and -D in each section are in a no-power state, and each section switch DM, ~DM, is automatically opened without voltage (OFF). In addition, if automatic switches are used as partial switches D and -D3, each partial switch D
, -D3 are also turned OFF.

At substation ■, after a predetermined period of time has passed since FCB3 was turned OFF, the FCB is
3 is turned ON again.

On the section switch DM side, time measurement starts from the application of voltage, and is turned ON with the time knob of X time period.

An automatic switch is used as the partial switch D, -D3.
When the voltage is applied, the partial switches D, -D, in the section 1 are immediately turned ON. In addition, if manual switches are used for partial switches D, ~D3 and 1), they are originally ON, so in any case, section switches 1) M, turn ON, and the section switches are immediately switched on. A voltage is applied to the switch DM.

Similarly, the section switches DM, DM3 are also turned ON sequentially with a delay time of X time period. Section switch DM4
remains OFF since no voltage is applied to it.

When the section switch DM, which is immediately before the fault point, becomes ○N, power is supplied to the fault point in section 3, and a ground fault occurs again.

As a result, at the substation 1, the ground fault voltage Vo and the ground fault current ■ are again generated. is detected and the above-described operation is repeated.

Each section switch 1) M, to DM3 side starts counting Y time when the road is turned off again, and monitors whether power transmission is stopped during this timing. Each time period is x>y>'r
The relationship is set as c. Therefore, only the section switch immediately before the fault point (DM3 in this case) detects the stoppage of power transmission during timing.

When the section switch DM3 detects a stop in power transmission during the Y time period, it enters the Y time period locked state. That is, from then on, the state is maintained in the OFF state regardless of the presence or absence of power transmission.

Through the above control procedure, the section where the accident occurred is recognized and
After stopping power transmission to section 3, power can be transmitted to sections 1 and 2, which are healthy sections.

After this, the accident point in section 3 is recognized.

That is, section 3A partial switches D1 to D3 are all manually opened, and section switches DM. After closing the circuit, the partial switches D and -D are sequentially switched on. When partial switch D2 is disconnected, ground fault voltage ■. or ground fault current■.

is detected, so is the accident point a partial opening/closing? r? rDt,0
It can be recognized that it is the part between 3.

D. Problems to be Solved by the Invention However, the above-described switch control method has a problem in that power outages occur many times in healthy sections.

In other words, a ground fault occurred three times: when the accident occurred, when the accident section was recognized, and when the accident point was recognized, and each time the FCB3 turned OFF.
Becomes FF. Therefore, three power outages are inevitable in sections 1 and 2, which are healthy sections, and in the front stage of the partial switch D, which is a healthy section in section 3.

This has the disadvantage of having a negative impact on power consumers and reducing the reliability of power supply.

The present invention has been made in view of these problems, and its purpose is to prevent a power outage from occurring before the location of a ground fault when recognizing the location where a ground fault has occurred. It is in the point of doing.

E. Means for Solving the Problems In order to achieve the above-mentioned object, the present invention has a structure that enables ground current detection on the automatic switch side of the power distribution system, and has a structure in which a normal automatic switch is provided. This K time period is shorter than the Tc time period, which is the standard for recognizing the occurrence of a ground fault at a substation, and has a different purpose from the Y time period, which is in effect when the switch is turned on. Only during this time period, if the detected ground current exceeds a preset value that can coordinate with the operation of the substation's protection relay circuit, it is determined that the ground current has continued for a certain period of time. The system recognizes this and opens the switch before the feeder circuit breaker at the substation shuts off, making it possible to recognize the faulty section by only causing a power outage in the healthy section on the power supply side of the faulty section once when an accident occurs. This provides a switch control method for electric wires.

It can also be used as an automatic switch for X time periods (for example, 10 seconds to 100 seconds).
A section switch that automatically closes after a time period of m (for example, approximately 0.5 seconds) is installed between the section switch and a partial switch that automatically closes after a time period of It is also possible to adopt a configuration that allows not only the recognition of the accident section but also the recognition of the accident point only once at the time of occurrence.

F. When an active ground fault occurs, the protection relay circuit detects the ground fault at the substation, and if this detection continues for the Tc time period, the feeder circuit breaker operates to stop power transmission. This opens all automatic switches placed on the distribution lines.

After this, the feeder circuit breaker operates again at the substation and power transmission resumes. As a result, the section switches are shut down again with a delay of X time periods, and the partial switches are shut down with a delay of m time periods.

Then, when the automatic switch immediately before the accident location is shut down again, a ground fault current is detected in the switch. If it is detected that the ground fault current exceeds the set value for a certain period of time within the K time period, it is determined that the current is immediately before the accident location.

After this, the switch is opened and power transmission to the accident location is stopped. At this time, since Tc>K, the ground fault state is canceled before the detection of the ground fault fault continues for the Tc period at the substation. Therefore, at the substation, the feeder circuit breaker will not operate again and power transmission will not be stopped.

In other words, there is no need for a power outage in the healthy part before the fault location after the ground fault occurs.

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

FIG. 1 shows the structure of a switch and a switch controller used in an embodiment of the present invention.

In the switch 4, the zero-phase CT (ZCT) 5 is connected to the distribution line 2.
Detect the current. In the switch controller 6, the auxiliary CT
7 receives the output of ZCT 5, and amplifier 8 amplifies it to a level suitable for internal processing.

The current reference value setting section 9 receives a current reference value from the outside and stores the input current reference value. The current reference value is ground fault current 1. This value serves as a criterion for determining whether or not the flow is flowing. This current reference value is designed to avoid detecting residual ground fault current that may occur even in normal times when there is no fault in the distribution line 2, and to coordinate with the operating sensitivity of the protective relay circuit in the substation 1. It has been set taking into consideration.

The analog value comparator 10 outputs a ground fault current detection signal when the output of the amplifier 8 exceeds the current reference value.

Further, in the switch 4, a switch operation detection section 1l monitors the opening/closing operation and outputs a closed circuit detection signal.

In the switch controller 6, when this idle road detection signal is input manually, the Y timer 12 and the K timer 13 start operating, and time the Y time and K1 time, respectively. The time limit K is set shorter than the ground current monitoring time limit Tc at the substation 1.

The timer 13 outputs a gate signal to the gate 14 until the timer K expires. The gate 14 is opened only for a time period K when the gate signal is input, that is, after the switch 4 is idled, and outputs the ground fault current detection signal from the analog value comparator 10 to the on-delay timer 15.

The on-delay timer 15 monitors whether the ground fault current detection signal continues for the K2 time period, and outputs an open circuit instruction signal if it continues. Here, the K time period is set slightly shorter than the K1 time period. Therefore, when the detected current value temporarily falls below the current reference value and the ground fault current detection signal from gate l4 is interrupted, on-delay timer 15 repeats the timing operation from the beginning, and the time of K1 timer expires. As the gate 14 becomes quiet, the timing of the K time period is stopped.

When the on-delay timer l5 outputs an opening instruction signal, the switch control circuit l6 operates the switch drive relay 17. As a result, the contact l8 of the switch drive relay 17 is opened, the supply of power to the operating coil 19 of the switch 4 is stopped, and the contact 20 provided on the distribution line 2 is opened.

Next, switch control according to an embodiment of the present invention will be explained.

FIG. 2 is a time chart showing switch control according to one embodiment.

In this embodiment, automatic switches having the configuration shown in FIG. 1 are used as section switches DM, to DM. The closure and partial switches D, to D3 are manually placed so as to be always closed.

The initial state of this time chart is the normal power transmission state before an accident occurs on the distribution line 2, and the FCB 3 of the substation 1
Then, the section switches DM, -DM, are in the N state.

Assume that a ground fault accident occurs in section 3.

When a ground fault occurs, the protection relay circuit reduces the ground fault voltage V at substation L. and ground fault current l. detected.

If this detection continues for Tc time, it is determined that an accident has occurred, and F
Power transmission is turned off by CB3. After this, the protective relay circuit is returned to its initial state.

By turning off FCB3, the section switch DM
,~DM4 becomes a no-power state and automatically opens without voltage (
OFF).

At substation I, after a predetermined period of time has passed since FCB3 was turned OFF, FCB3 is turned ON again by the re-shut circuit function.
It becomes N. This will restart power transmission.

As a result, the section switch DM. A voltage is applied to. Here, each section switch DM. -DM. A time limit X for power-on delay is set for the purpose of recognizing the fault section in the substation 1. This X time period has a width of, for example, about 10-100 seconds, and usually each section opens/closes i5DM, ~DM,
The X time periods are set to the same time period.

On the section opening/closing "&N D M r side, time measurement starts from the application of voltage, and turns ON when the X time period is up.

Furthermore, when ONL is reached, the above-mentioned time measurement of K,,K, is started, and the ground fault current ■. monitoring. Since section 1 is a healthy section, the ground terminal current is I. is detected, the on-delay timer 15 does not operate. Therefore, after the time limit K has elapsed, the gate 14 is closed, and the section switch DM1 remains in the ON state.

When the section switch DM is turned ON, a voltage is immediately applied to the section switch 1) M. In the section switch DM, the ONL and ground fault current are similarly monitored with a delay time of X time period. Since section 2 is also a healthy section, the ground fault current I. is not detected, and the section switch DM
, will also maintain the ON state.

By turning on the section switch DM, the section switch D
M, also turns on with a delay time of X time, and the earth terminal current I
. monitoring. Since the section switch DM3 is the section switch immediately before the fault section 3, when the section switch DM3 is turned on, if the cause of the accident has not been resolved, the ground fault current I will start again. Opening/closing section where ``A''j'r D M 3 is O
N.L. During this period, the ground fault current (O) continues to flow, so the on-delay timer 15 or K measures the time limit in the section switch DM to perform time associating. This causes the contact 20 of the switch 4 to open, and thereafter maintains the OFF state. This causes ground fault current I. disappears.

On the other hand, the ground fault current I that occurred when the section switch DM3 was turned ON.
. is also detected at substation l. However, ground fault current■
. , the earth fault current detection time limit TC at the substation L does not expire (T c>
K I > K 2), substation 1 continues power transmission. Furthermore, at substation I, a ground fault current I occurred after power transmission was resumed.

The accident zone can be recognized by measuring the time it takes to detect the accident.

That is, in this case, the ground fault current I after 3·X hours.

, it is possible to recognize that section 3 is an accident section.

In this manner, in this embodiment, after an accident occurs, the accident section can be recognized and power transmission to the accident section can be stopped without interrupting power transmission in the healthy section 1.2-.

Next, another embodiment of the present invention will be described.

FIG. 3 is a time chart showing switch control according to another embodiment.

In this embodiment, the automatic opening/closing devices shown in FIG. 1 are arranged as section switches DM, -DM and paralyzed partial switches D1 to D3. Then, the same time limit X for delaying input is set for the section opening/closing 2B DM 1 to DM4,
Also, for each partial opening 1: iD, -'-D, a closing delay time m is set instead of the X time period in order to wait for the elapse of the K time period in the previous stage switch. This m time period is, for example, about 0. It is set to about 5 seconds.

Here, it is assumed that a ground fault occurs at a location between partial switches D2 and D3 in section 3.

When a ground fault occurs, the ground fault voltage V at the substation 1.

and ground fault current 1. continues for Tc time, power transmission is turned off by FCB3, and section switch DM. ~DM. The partial switches D1 to D3 in each section are automatically opened without voltage (OF
F). After this, the substation 1 turns on the FCB 3 again, and voltage is applied to the distribution line 2.

In sections 1 and 2, which are healthy sections, even if each switch is turned on, the ground final current is I. Since this does not occur, ONL is performed sequentially from section opening/closing IDM to section opening/closing ADM3 with a predetermined delay time.

In section 3, the section up to partial switch D is a healthy section, so section switch DM3 is turned on for X time period.
Thereafter, the partial switch D1 is turned ON after m time periods and each maintains the ON state.

Furthermore, partial switch D. After ○N, partial switch D, is also turned ON with a time limit of m, but since partial switch D is the switch immediately before the fault point, when partial switch D2 turns ON, a ground fault occurs again. Current I. occurs.

On the partial switch D side, the section switch "A" in the above example is
It operates in the same way as HDM3, and the ground fault current I. or K
, By confirming that the time period has continued, it is recognized that the failure point is at the latter stage of partial switch D2, and partial switch D
, and maintains the OFF state. As a result of this, the earth terminal current ■o disappears.

On the other hand, ground fault current ■. is detected again at substation I, but the ground fault current I is detected before the ground fault current detection time limit TC is timed. disappears, so substation 1 continues transmitting power. Earth fault current I after restarting power transmission. The fault section can be detected by measuring the time it takes to detect the fault, and the fault point can be recognized by receiving information from the partial switch indicating that it is open due to the detection of ground fault current. becomes possible.

H. Effects of the Invention As explained above, according to the present invention, when the circuit is shut down again after a ground fault occurs, the automatic switch side detects the ground fault current, and the substation recognizes the occurrence of the ground fault. Tc is the standard for
By opening the switch before the time limit expires, the fault section can be recognized without the feeder circuit breaker of the substation being cut off.

Therefore, a power outage in a healthy section on the power supply side from the accident section only needs to occur once when an accident occurs, and the negative impact on power consumers can be minimized, which has the advantage of improving power supply reliability.

Furthermore, by applying the present invention to the control of partial switches arranged in each section, there is an advantage that it becomes possible to recognize not only the accident section but also the accident point.

[Brief explanation of drawings]

Fig. 2 is a functional configuration diagram of a switch and a switch controller according to an embodiment of the present invention, Fig. 2 is a time chart showing switch control according to an embodiment of the present invention, and Fig. 3 is a functional configuration diagram of a switch and a switch controller according to an embodiment of the present invention. A time chart showing switch control according to another embodiment, FIG. 4 is a configuration diagram showing an outline of a power distribution system, and FIG. 5 is a time chart showing conventional switch control. 1... Substation, 2... Distribution line, 3... FCB, 4
...Switch, 5...ZCT, 6...Switching controller, 9...Current reference value setting section, 10...Analog value comparator, l3...K1 timer, 14... ··Gate,
15... On-delay timer, 16... Switch control circuit. Procedural amendment written by two other persons. E, Yosei September 11, 1999 1. Indication of the case 1999 Patent Application No. 160098 2. Name of invention Switch control system for power distribution line 3. Relationship with the case of the person making the amendment Applicant Okinawa Electric Power Co., Ltd. Meidensha Co., Ltd. 4. Agent Address: 1-29 Akashi-cho, Chuo-ku, Tokyo 104 Kisaikai Pill 5. Figure 3 of the drawing to be corrected.

Claims (2)

[Claims] (1) On the automatic switch side of the power distribution system, the structure is such that it is possible to detect ground fault current, and it has a time limit that has a different purpose from the Y time limit that normal automatic switches have, and is suitable for substations. This K time period is shorter than the Tc time period, which is the standard for recognizing the occurrence of a ground fault at the substation, and only during this time period from the time the switch is turned on, the detected ground fault current will be detected in advance at the substation. If the voltage exceeds the set value that can be coordinated with the operation of the protection relay circuit in the substation, it recognizes that it has continued for a certain period of time and activates the switch before the feeder circuit breaker in the substation shuts off. A distribution line switch control method characterized in that the fault section can be recognized by opening the fault section and only causing a power outage in the healthy section on the power supply side of the fault section once when an accident occurs. (2) In the power distribution system, a section switch that automatically closes after a relatively long X time period and a partial switch that automatically closes after a relatively short m time period are installed between these section switches, and these automatic switches Both have a structure that enables ground fault current detection, and have a K time period that has a different purpose from the Y time period that normal automatic switches have, and are standards for recognizing the occurrence of a ground fault accident at a substation. This K time period is shorter than the Tc time period, and only during this K time period from when the switch is turned on, the detected ground fault current is set in advance to a value that can coordinate with the operation of the substation's protection relay circuit. If the voltage exceeds the set value set in A distribution line switch control system that is characterized by a power outage in a section only once when an accident occurs, and the fault section and fault point can be recognized.