JPH0834664B2 - Switch control system for distribution lines - Google Patents

Description

[Detailed Description of the Invention] A. Field of Industrial Application The present invention relates to a ground fault by performing reclosing of a section switch or a partial switch of a distribution line which is opened when a ground fault of the distribution line occurs in a distribution system. The present invention relates to a method of recognizing an accident section and an accident point where an accident occurs and transmitting power to the preceding stage of the accident section and the accident point.

B. Summary of the Invention The present invention is, on the automatic switch side, when the ground fault current is detected for a certain period of time continuously from the time when the switch is turned on to the K ₁ time period, the feeder is shut off at the substation. The switch is opened before the power is cut off, and the power failure in the healthy section on the power supply side of the accident section can be recognized only once when the accident occurs, making it possible to recognize the accident section and the accident point.

C. Conventional technology The distribution system is an enormous facility that spreads across the area, and there is a high risk of accidents due to wind and water damage, lightning, and other factors. Therefore, protective measures are taken in the event of a distribution line accident.

Figure 4 shows the outline of the distribution system. 1 is a substation, 2 is a distribution line. The substation 1 is provided with a feeder circuit breaker (FCB) 3 that stops power transmission when an accident occurs on the distribution line 2. On the distribution line 2, section switches DM _{1 to} DM ₄ are arranged for each predetermined section, and a partial switch D ₁ is arranged on each section.
~ D ₃ is located. The sections between the section switches DM _{1 to} DM ₄ are referred to as sections 1 to 3, respectively. The section switches DM _{1 to} DM ₄
An automatic switch that automatically opens and closes when power is transmitted or stopped is used. On the other hand, for the partial switches D _{1 to} D ₃ , either a manual switch or an automatic switch is used.

Here, it is assumed that a ground fault accident has occurred at a location between the partial switches D ₂ and D ₃ in the section 3 as indicated by the mark X in the figure. The conventional control of the switch at this time will be described.

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

In the normal power transmission state before an accident occurs in the distribution line, and FCB3 substation 1, section switch DM ₁ to dm ₄ is in the ON state.

When a ground fault occurs, the ground fault voltage V ₀ and the ground fault current I ₀ are detected by the protection relay circuit in the substation 1. If this detection continues for T _c time, it is determined that an accident has occurred and power transmission is turned off by FCB3. After that, the protection relay circuit is returned to the initial state.

By turning off FCB3, the section switches DM _{1 to} DM ₄
And the partial switches D _{1 to} D ₃ in each section are in a non-powered state, and the section switches DM _{1 to} DM ₄ are automatically turned off (OFF). In the case where the automatic switch is used as a partial switch D ₁ to D _3, each partial switches D ₁ to D ₃ is also turned OFF as well.

At substation 1, FCB3 is turned on again by the function of the reclosing circuit (not shown) after a predetermined time has passed since FCB3 was turned off.
Turns on.

On the section switch DM ₁ side, timing is started from the application of voltage, and is turned on when the X time expires.

If automatic switch is used as a partial switch D ₁ to D _3, when a voltage is applied, the partial switch D ₁ to D ₃ becomes ON immediately in the section 1. Partial switch D ₁ ~
Originally ON when a manual switch is used as D _3.
Therefore, in each case, the section switch DM ₁ is turned on, so that the voltage is immediately applied to the section switch DM ₂ .

Similarly, the section switches DM ₂ and DM ₃ are sequentially turned on with a delay time of X time. The section switch DM ₄ remains off because no voltage is applied.

When the section switch DM ₃ just before the accident point is turned on, power is supplied to the accident point in section 3 and a ground fault occurs again.

As a result, in the substation 1, the ground fault voltage V ₀ and the ground fault current I ₀ are detected again, and the above operation is repeated.

In each section switches DM ₁ to dm ₃ side starts counting the Y timed when reclosing, monitors whether the transmission is stopped during this time measurement. Each time period is set to have a relationship of X>Y> T _c . Therefore, only the section switch (DM _{3 in} this case) immediately before the accident point detects the stop of power transmission during timing.

When the section switch DM ₃ detects the stop of power transmission during the Y time period, it enters the Y time period locked state. That is, after that, the state is kept OFF regardless of the presence or absence of power transmission.

By the above control procedure, it is possible to recognize the section in which the accident has occurred, stop the power transmission to the section 3, and then perform the power transmission to the sections 1 and 2 which are healthy sections.

After that, the accident point in section 3 is recognized. That is, all the partial switches D _{1 to} D ₃ of the section ₃ are manually opened, the section switch DM ₃ is closed, and then the partial switch D
Cycle from _{1 to} D ₃ in sequence. When closing the partial switch D _2, since the ground voltage V ₀ and the ground fault current I ₀ are detected, it can recognize that the fault point is portion between partial switch D _2, D _3.

D. Problem to be Solved by the Invention However, the above-described switch control method has a problem that power failure occurs many times in a sound section.

In other words, a ground fault occurs three times when an accident occurs, when an accident section is recognized, and when an accident point is recognized, and FCB3 is turned off each time.
Becomes Therefore, in the sections 1 and 2 which are sound sections and the front stage of the partial switch D ₂ which is a sound section in section 3, three blackouts are forced.

Therefore, it has a drawback that it adversely affects electric power consumers and lowers the reliability of electric power supply.

The present invention has been made in view of such a problem, and an object thereof is to prevent a power failure from occurring in the preceding stage of the ground fault accident occurrence point when recognizing the ground fault accident occurrence point. There is a point to do.

E. Means for Solving the Problem In order to achieve the above-mentioned object, the present invention has a structure capable of detecting a ground fault current on the automatic switch side in a power distribution system, and has a normal automatic switch. It has a time period of K ₁ which has a different purpose from the time period of starting timing at the time of reclosing, and the K ₁ time period is shorter than the T _c time period which is the standard for recognizing the occurrence of a ground fault accident at a substation, When the detected ground fault current is equal to or greater than the preset value that can be coordinated with the operation of the protection relay circuit of the substation only during this K ₁ time period from when the switch is turned on. And that is K ₂
Recognizing that the time has continued, open the switch before the feeder circuit breaker at the substation shuts off, and recognize the accident section only once when a power failure in the healthy section on the power supply side of the accident section occurs. It is intended to provide a switch control method for distribution lines that enables the above.

Also, as an automatic switch, X time limit (for example, 10 seconds to 100
Seconds) and a section switch that automatically turns on after a time limit of m (for example, about 0.5 seconds) is installed between the section switches to prevent a power failure in the healthy section on the power supply side of the accident section when an accident occurs. Only once, it is possible to recognize not only the accident section but also the accident point.

F. Action When a ground fault occurs, the protective relay circuit detects the ground fault at the substation, and if this detection continues for the time _Tc , the feeder breaker operates and power transmission is stopped. This opens all the automatic switches placed on the distribution line.

After that, the feeder circuit breaker operates again at the substation to restart power transmission. As a result, the section switch is sequentially reclosed with a delay of X time and the partial switch with a delay of m time.

And when the automatic switch just before the accident location is closed again,
A ground fault current is detected in the switch. When it is detected that the ground fault current exceeds the set value continuously for the K ₂ time period within the K ₁ time period, it is determined that this is immediately before the accident location.

After that, the switch is opened and power transmission to the location of the accident is stopped. At this time, since T _c > K ₁ , the ground fault state is released before the detection of the ground fault at the substation continues for the time period T _c . Therefore, in the substation, the feeder circuit breaker does not operate again, and power transmission does not stop.

That is, in the sound part before the accident site, after the occurrence of the ground fault, there is no need for power failure.

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

FIG. 1 shows the configuration 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 detects the current of the distribution line 2. In the switch controller 6, the output of ZCT5 is received by the auxiliary CT7 and amplified by the amplifier 8 to a level suitable for internal processing.

The current reference value setting unit 9 receives a current reference value from the outside and stores the input current reference value. The current reference value is a value that serves as a criterion for determining whether or not the ground fault current I ₀ is flowing. This current reference value should not detect residual ground fault current that may occur even in normal time when there is no accident in the distribution line 2 and should be coordinated with the operating sensitivity of the protection relay circuit of the substation 1. Is set in 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, the switch operation detector 11 monitors the open / close operation and outputs a closed circuit detection signal. Switch controller 6
At, by inputting this closed circuit detection signal,
Y time timer 12 and K ₁ time timer 13 start operating,
Time Y and K ₁ respectively. The K ₁ time period is set shorter than the ground fault current monitoring time period T _{c at} substation 1.

The K ₁ time limit timer 13 outputs a gate signal to the gate 14 until the K ₁ time limit elapses. The gate 14 is opened only when the gate signal is input, that is, after the switch 4 is closed and only during the K ₁ time period, 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 or not the ground fault current detection signal continues for the K ₂ time period, and outputs an open circuit instruction signal when the signal continues. Here, the K ₂ time period is set slightly shorter than the K ₁ time period. Therefore, when the detected current value temporarily falls below the current reference value and the ground fault current detection signal from the gate 14 is interrupted, the on-delay timer 15 repeats the time counting operation from the beginning, and the time for the K ₁ time period increases. By the gate
Closing 14 cancels the K ₂ timekeeping.

When the on-delay timer 15 outputs the opening instruction signal, the switch control circuit 16 operates the switch drive relay 17. This opens the contact 18 of the switch drive relay 17,
The supply of power to the operation 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 described.

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

In this embodiment, the automatic switches having the configuration shown in FIG. 1 are section switches DM _{1 to} DM ₄ , and the partial switches D _{1 to} D ₃ are manually arranged as normally closed circuits.

The initial state of this time chart is the normal power transmission state before the accident on the distribution line 2, and FCB3 of the substation 1
And the section switches DM _{1 to} DM ₄ are in the ON state.

 It is assumed here that a ground fault has occurred in section 3.

When a ground fault occurs, the ground fault voltage V ₀ and the ground fault current I ₀ are detected by the protection relay circuit in the substation 1. If this detection continues for T _c time, it is determined that an accident has occurred and power transmission is turned off by FCB3. After that, the protection relay circuit is returned to the initial state.

By turning off FCB3, the section switches DM _{1 to} DM ₄
Will be in a non-powered state, and will automatically be turned off (OFF).

At substation 1, FCB3 is turned on again by the function of the reclosing circuit after a predetermined time has passed since FCB3 was turned off.
This restarts power transmission.

As a result, a voltage is applied to the section switch DM ₁ . Here, each section switch DM _{1 to} DM ₄ is set with a closing delay time period X for the purpose of recognizing an accident section in the substation 1. The X time period has a width of, for example, about 10 to 100 seconds, and normally, the X time periods of the section switches DM _{1 to} DM ₄ are set to the same time period.

On the section switch DM ₁ side, timing is started from the application of voltage, and is turned on when the X time expires. Further, when the power is turned on, the above K ₁ and K ₂ are started to measure the ground fault current I ₀ . Since section 1 is a healthy section, ground fault current
I ₀ is not detected and the on-delay timer 15 does not operate. Therefore, when the K ₁ time period elapses, gate 14 closes and the section switch
DM ₁ will remain ON.

By interval switch DM ₁ is turned ON, the voltage is applied to the section switch DM ₂ immediately. Similarly, the section switch DM ₂ is also turned on with a delay time of X period to monitor the ground fault current. Since section 2 is also a healthy section, ground fault current
I ₀ is not detected, and the section switch DM ₂ also maintains the ON state.

When the section switch DM ₂ turns ON, the section switch DM
₃ also turns ON with a delay time of X time period and monitors the ground fault current I ₀ . Since the section switch DM ₃ is the section switch immediately before the accident section 3, the ground fault current I ₀ is generated again when the cause of the accident is not released when the section switch DM ₃ is turned on.

While interval switch DM ₃ is turned ON, since the ground fault current I ₀ continues to flow, in a section switch DM _3, on- Ray timer 1
5 clocks the K ₂ time limit and improves time. As a result, the contact 20 of the switch 4 is opened, and thereafter the OFF state is maintained.
As a result, the ground fault current I ₀ disappears.

On the other hand, the ground fault current I ₀ generated when the section switch DM ₃ is turned on is also detected in the substation 1. However, the ground fault current I ₀ is K ₂
Since it disappears in the time limit, the ground fault current detection time period T _c in the substation 1 does not time up (T _c > K ₁ > K ₂ ), and the substation 1 continues power transmission. Further, in the substation 1, the fault section can be recognized by measuring the time from the restart of power transmission to the detection of the ground fault current I ₀ . That is, in this case, since the ground fault current I ₀ is detected after 3 · X hours, it can be recognized that the section 3 is the accident section.

As described above, in the present embodiment, after the occurrence of the accident, it is possible to recognize the accident section and stop the power transmission to the accident section without interrupting the power transmission to the sections 1 and 2 which are the healthy sections.

 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 switches shown in FIG. ₁ are arranged as section switches DM _{1 to} DM ₄ and partial switches D _{1 to} D ₃ . Then, the interval switches DM _{1 to} DM ₄ are all set with the closing delay time X at the same time period, and the partial switches D ₁ to D _{4 are connected} .
In D ₃ , the closing delay time period m is set instead of the X time period in order to wait for the K ₁ time period in the switch in the preceding stage. This m time limit is set to about 0.5 seconds, for example.

Here, at the location between the partial switches D ₂ and D ₃ in section 3,
Assume that a ground fault has occurred.

When a ground fault occurs, the ground fault voltage V _{0 at} substation 1
And the ground fault current I ₀ are continued for T _c time, the power transmission is turned off by FCB3, and the section switches DM _{1 to} DM ₄ and the partial switches D _{1 of} each section are connected.
To D ₃ is automatically non-voltage open (OFF). After that, the substation 1 turns on the FCB3 again, and the voltage is applied to the distribution line 2.

In sections 1 and 2 that are sound sections, the ground fault current I ₀ does not occur even if each switch is turned on, so the section switches DM ₁ to DM ₃ are turned on sequentially with a predetermined delay time. .

In section 3, since the part up to partial switch D ₂ is a sound part, section switch DM ₃ is turned on in the X time period, and thereafter, partial switch D ₁ is turned on in the m time period and is turned on respectively. maintain.

Further portions switches D ₁ is also part switch D ₂ with m timed after ON ON Suruga, since the partial switch D ₂ is a switch immediately before the fault point, when the partial switch D ₂ is turned ON Then, the ground fault current I ₀ is generated again.

On the partial switch D ₂ side, the section switch DM in the above example
By performing the same operation as ₃ and confirming that the ground fault current I ₀ has continued for the K ₂ time period, it is recognized that the latter stage of the partial switch D ₂ is the fault point and the partial switch D ₂ is turned off. And O
Maintain the FF state. As a result, the ground fault current I ₀ disappears.

On the other hand, the ground fault current I ₀ is detected again in the substation 1, but the ground fault current I ₀ disappears before the ground fault current detection time period T _c expires, so the substation 1 continues power transmission. . By measuring the time from when power transmission is restarted until the ground fault current I ₀ is detected, the fault zone can be detected and information indicating that it is in an open state due to the detection of the ground fault current is displayed. It is possible to recognize the accident point by receiving from the.

H. Effects of the Invention As described above, according to the present invention, at the time of reclosing after the occurrence of the ground fault accident, the ground fault current is detected on the automatic switch side to prevent the occurrence of the ground fault accident at the substation. T _c , which is the reference for recognition
By opening the switch before the time limit elapses, the accident section can be recognized without the feeder circuit breaker of the substation breaking.

Therefore, there is an advantage that power failure in a healthy section on the power supply side of the accident section can be performed only once when an accident occurs, the adverse effect on electric power consumers can be minimized, and power supply reliability is improved.

Further, by applying the present invention to the control of the partial switch arranged in each section, there is an advantage that not only the accident section but also the accident point can be recognized.

[Brief description of drawings]

FIG. 1 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 view of the present invention. FIG. 4 is 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 ... Z
CT, 6 ... Switch controller, 9 ... Current reference value setting unit, 10 ... Analog value comparator, 13 ... K ₁ time timer, 14 ... Gate, 15 ...
On-delay timer, 16… Switch control circuit.

Claims (2)

[Claims] 1. An automatic switchgear side in a power distribution system,
It has a structure that enables detection of a ground fault current, and has a time limit of K ₁ that has a different purpose from the time limit that starts timing at the time of reclosing when an ordinary automatic switch has a ground fault. This K ₁ time period should be shorter than the T ₀ time period, which is the standard for recognizing the occurrence, and the detected ground fault current should protect the substation in advance only during this K ₁ time period from when the switch is closed. If the value exceeds the set value that can be coordinated with the operation of the relay circuit, recognize that it has continued for the K ₂ time period and switch on the switch before the feeder circuit breaker at the substation shuts off. This is a switch control method for distribution lines, which is opened and the faulty section can be recognized only once when there is a power failure in the healthy section on the power supply side of the faulty section when an accident occurs. 2. A distribution system is provided with a section switch that automatically turns on after a relatively long X time period and a partial switch that automatically turns on after a relatively short m time period between these section switches to automatically open and close these. All of the switches have a structure capable of detecting a ground fault current, and have a time period of K ₁ which has a purpose different from the time period for starting timing when the circuit is closed again that an ordinary automatic switch has. The K ₁ time period is shorter than the T ₀ time period, which is the standard for recognizing the occurrence of a ground fault accident, and the detected ground fault current is preliminarily measured only during this K ₁ time period from when the switch is turned on. If it is equal to or higher than the set value set to a value that can cooperate with the operation of the protection relay circuit of the substation, it is K ₂
Recognizing that the time has continued, open the switch before the feeder circuit breaker at the substation shuts off, and recognize the accident section only once when a power failure in the healthy section on the power supply side of the accident section occurs. A switch control method for distribution lines, which enables