JPH0437652B2 - - Google Patents

Description

[Detailed Description of the Invention] Purpose of the Invention (Field of Industrial Application) This invention injects a search signal from a search signal injection device into a distribution line to detect a ground fault point occurring in the distribution line. This invention relates to a method of displaying a ground fault from the injection point of a signal injection device to a distribution line to a ground fault point using an appropriate number of display devices, and easily detecting the ground fault point by primary patrol from the search signal injection side.

(Prior art) Conventionally, when a ground fault occurs in a distribution line, the substation circuit breaker is first opened, and then the substation circuit breaker is At the same time, the sectional switches on the power supply side are sequentially turned on to retransmit power to the healthy section, and when the section reaches the ground fault section, the substation circuit breaker is shut off again. When the circuit breaker of the substation is closed again, the section switch that separates the ground fault fault section is locked in the open state, and only the ground fault fault section is isolated, and power is retransmitted only to the healthy section. , searching for ground fault sections. Once a ground fault fault section has been found, the ground fault point is detected by repeatedly measuring the insulation resistance of related power distribution equipment installed on each utility pole in the fault section.

(Problems to be Solved by the Invention) As mentioned above, in the past, after the ground fault fault section was determined, the insulation resistance of the related power distribution equipment installed on utility poles, etc. existing in the ground fault fault section was sequentially determined for each utility pole. Since measurements were being carried out, there was a problem with the work in that it required a lot of time, and there was a drawback that it took a long time to detect the ground fault point.

Structure of the Invention (Means for Solving the Problems) This invention has been made to solve the above-mentioned problems, and the method for detecting a ground fault point in a distribution line according to the present invention is applicable when the distribution line is a sectional switch. When a ground fault occurs between the sectional switches, the substation circuit breaker repeats re-closing, thereby opening the sectional switches at both ends of the section where the ground fault has occurred and detecting the section with the ground fault. A search signal injection device that injects a search signal into each phase on the load side of the substation circuit breaker using a delay opening time from when the substation circuit breaker breaks to when the sectional switch opens. A plurality of display devices are arranged in the section, which always display a normal state display, and when the search signal is detected, display a normal state display to a ground fault display based on the search signal, and the search signal injection device The gist is that a search signal is injected into the power distribution line from the ground fault, and the search signal flowing through the power distribution line and the ground fault point causes the display device to display a ground fault indication.

(Function) With the above configuration, when a ground fault occurs in any section divided by the sectional switch, the substation circuit breaker is shut off. Then, the section switch opens after a delay opening time. A search signal is injected into each phase from the search signal injection device using the delayed opening time from when the substation circuit breaker is cut off to when the section switch is opened. Then, the search signal flows through the power distribution line and the ground fault point. As a result, the display device located between the search signal injection device and the ground fault point changes from the normal display to the ground fault display based on the search signal. As a result, if a primary tour is performed from the injection point side of the search signal, the final point where the ground fault indication is performed becomes the ground fault point.

(Embodiment) A preferred embodiment embodying the present invention will be described below with reference to FIGS. 1 to 8.

1 is the power transmission line, 2 is the substation circuit breaker (hereinafter referred to as CB)
3 is a distribution line connected to the power transmission line 1 via the CB 2, and each phase is represented by 3a, 3b, and 3c as shown in FIG. 4 is a zero-phase current transformer (hereinafter referred to as ZCT) of the substation installed on the immediate load side of the CB 2, 5 is a grounding transformer (hereinafter referred to as GPT) installed on the power transmission line 1,
Both 4 and 5 detect a single-line ground fault occurring in the distribution line 3, and actuate the directional ground fault relay 6 to
The CB2 is stripped and the distribution line 3 is separated from the power transmission line 1.

A large number of section switches SS are arranged on the distribution line 3, and the section switches SS connect many sections An.
(n=1, 2, 3...) are classified.

This sectional switch SS is a conventionally known sectional switch, and as shown in Figure 8, when a ground fault occurs in a certain section (time T1), substation CB2 selectively cuts off the faulty line (T2). (time), when the fault line becomes de-energized, each section switch SS opens after a delay opening time Z (at time T6). Then,
When voltage is applied by re-closing CB2 (at time T3), the first section switch SS adjacent to CB2 closes after X hours (at time T7), and then the section switches SS on the load side are sequentially closed. When a voltage is applied, each similarly closes after X hours.

In this way, power is sequentially input from the power supply side section developer SS and retransmitted to the healthy section, and when the ground fault section is reached, substation CB2 is shut off again (at T4).
be done. Then, when CB2 of the substation is closed again (at T5), the section switch SS that separates the ground fault section is locked in the open state, and only the ground fault section is isolated. There is.

Reference numeral 7 denotes a search signal injection device connected to the distribution line 3 of each phase at the nearest load side of the ZCT 4, and is grounded (see FIG. 1). This search signal injection device 7 is activated when substation CB2 is cut off (T2
time), when a trip signal from CB2 is input and CB2 shuts off based on the trip signal (at time T2)
When the first section switch SS opens from (T6
The search signal is injected into all three phases at once using the delay release time Z up to (time).

The injection of the search signal is set to end before the first section switch SS is opened (time from T8 to T9 shown in FIG. 8). The driving power source of this exploration signal injection device 7 is CB2
It consists of a transformer Tr connected to the power supply side.

H shown in FIG. 3 is a plurality of display devices provided for each phase in each section An of the distribution line 3, and are arranged at a predetermined distance from each other.

This display device H will be explained.

8 is a current transformer attached to the distribution line 3; 9 is a ground fault detection sensor connected to the current transformer 8; when a search signal current of a certain level or higher flows through the distribution line 3, The transform signal output from the current transformer 8 is detected and a ground fault detection signal is output.

Reference numeral 10 indicates the entire display section connected to the ground fault detection sensor 9. In this display section 10, a plurality of magnetic reversal display devices are arranged adjacent to each other as shown in FIGS. 6 and 7.

This magnetic reversal display device will be described in detail with reference to FIGS. 4 and 5. A disk 11 whose image edges are magnetized to N and S poles is rotatably supported around a rotation shaft 12, and A round bar-shaped stator 13 is formed to have a magnetic pole portion 13a corresponding to the south pole of the disk 11 and a magnetic pole portion 13b corresponding to the north pole of the disk 11. In addition, the stator 13
is preferably made of a material with low holding power. The magnetic pole portions 13a and 13b are placed between the two magnetic pole portions 13a and 13b when the disk 11 is placed in the state shown in FIG.
A coil 14 is wound so as to be magnetized with the same polarity with respect to the magnetic poles at both ends.

Front surface 11a and back surface 11b of the disk 11
are displayed with signs of different colors (in this embodiment, the front side 11a is black and the back side 11b is red),
It is visible from below the display device H.

When the display unit 10 receives a ground fault detection signal from the ground fault detection sensor 9, a drive current flows through the coil 14, and as shown in FIG.
a is magnetized as an S pole, and the magnetic pole portion 13b is magnetized as an N pole, and the disk 11 has its N pole as the magnetic pole portion 13a (S pole).
The S pole is reversely rotated so as to face the magnetic pole part 13b (N pole), and a mark attached to the back surface 11b of the disk 11 is displayed on the outside. Further, the stator 13 of the display unit 10 is provided with a coil (not shown) wound in the opposite direction to the coil 14, and this coil (not shown)
When the return drive current flows, the magnetic pole portions 13a and 13b in the ground fault display state return to the normal display polarity, and as a result, the disk 11 reverses and returns to normal display (see FIGS. 4 and 6).

Reference numeral 15 shown in FIG. 3 is a timer connected to the display unit 10, which starts the recovery drive current after a predetermined period of time (for example, 3 to 4 hours) after the display unit 10 displays a ground fault. Said coil (not shown)
is applied to return the display section 10 from the ground fault display to the normal display.

Note that 16 is a driving power source for the display section 10, the ground fault detection sensor 9, and the timer 15 connected to the current transformer 8.

Furthermore, this display device H has a function that also serves as a short circuit display. That is, 17 is a short circuit detection sensor connected to the current transformer 8, and when a short circuit current of a certain level or more flows through the distribution line 3, the display section is activated based on a transformation signal output from the current transformer 8. A short circuit detection signal is output to the terminal 10, and based on the short circuit detection signal, the display section 10 displays a short circuit as in the case of the ground fault detection. Note that the display unit 10 is activated by applying a recovery drive current from the timer 15 after a predetermined period of time (3 to 4 hours) after entering the short circuit display state.
As in the case of the ground fault display, the display section 10 is adapted to return from the short circuit display to the normal display.

Note that AS shown in Figure 2 is a normally closed switch.

Next, the operation of the system configured as described above will be explained.

Now, as shown in Fig. 2, it is assumed that a single line ground fault occurs at point m of phase a in section A3 of distribution line 3 (at time T1). For convenience of explanation, only the a-phase 3a of the power distribution line 3 is shown in FIG. 2.

Then, ZCT4 of the substation transfers the zero-sequence current to GPT
5 outputs the zero-phase voltage as a ground fault signal, and relay 6
A trip signal is sent to CB2 via
CB2 is opened (at T2).

Then, the search signal injection device 7 inputs the trip signal from CB2 and performs the trip based on the trip signal.
The search signal current is applied to each phase of the distribution line 3a, 3b, 3 using the delayed opening time Z from when CB2 is cut off (at T2) to when the section switch SS is opened (at T6).
(from T8 as shown in Figure 8)
time until T9 o'clock).

Then, a circulating current flows in a closed loop path passing through the search signal injection device 7, the distribution line 3a, the ground fault point m, and the search signal injection device 7, and as a result, the injection point of the search signal injection device 7 and the ground fault point T display devices disposed between the
3 is displayed.

That is, when a search signal current of a certain level or more flows through the distribution line 3a, the display devices H1, etc. in the A1 section and A2 section and the display devices H2 and H3 in the A3 section
The current transformer 8 outputs a transform signal based on the search signal current, and the ground fault detection sensor 9 outputs a ground fault detection signal in response to the transform signal. Then,
The display unit 10 inputs the ground fault detection signal, and a drive current flows through the coil 14 based on the ground fault detection signal.

Then, from the state shown in FIG. 4, the magnetic pole part 13a is magnetized to the S pole and the magnetic pole part 13b is magnetized to the N pole, as shown in FIG.
(S pole), and rotates in reverse so that the S pole faces the magnetic pole portion 13b (N pole). By this,
A color mark attached to the back surface 11b of the disk 13 is displayed externally to indicate a ground fault (see FIG. 7).

On the other hand, regarding the b and c phases, a closed loop including the ground capacitance of the distribution line 3 instead of the ground fault point 10 is formed, but the impedance of this loop is high, the flowing search signal current level is low, and the other two phases 3b,
The display device H placed at 3c remains in normal display mode.

Furthermore, even if the display device is attached to the a-phase, the search signal current does not reach a certain level or higher, so the display device H4 and the like provided on the load side of the ground fault point m remain in normal display.

In this way, the search signal injection device 7 detects the ground fault point m.
Although a ground fault is displayed on the display device up to this point, the injection of the search signal current ends before the section switch SS is opened (at time T9).

After the search signal injection device 7 injects the search signal current as described above (that is, after Z time has passed since the substation CB2 was cut off), the section switch SS
operates to open the circuit (at T6). Then, when voltage is applied by re-closing CB2 (at time T3), the first section switch SS adjacent to substation CB2 closes after X hours (at time T7), and then the sections on the load side are switched in sequence. When a voltage is applied to SS, the circuit similarly closes after X hours.

In this way, power is sequentially turned on from the section switch SS on the power supply side to retransmit power to the healthy section, and when it reaches the ground fault section, substation CB2 is shut off again (at T4). Then, when the circuit breaker 2 of the substation is closed again (at time T5), the ground fault section A3
The sectional switch SS that separates the area is locked in the open state, and only the ground fault area A3 is isolated, and power is retransmitted only to the healthy area.

As mentioned above, the ground fault section A3 is a sectional breaker
Detection can be made by locking the SS open, and the worker then departs from the source side to the load side in that ground fault section. Then, by sequentially searching for display devices H that are displaying a ground fault, display device H4 that is not displaying a ground fault
It can be determined that there is a ground fault point m between the point where the display device H3 is placed and the point where the display device H4 is placed one place before the ground fault is displayed.

In addition, in searching for the ground fault point, at the branch point α, the display device H5 provided on one load-side branch line and the display device H3 provided on the other load-side branch line are compared, and the display device All you have to do is proceed along the branch line on the side where H is indicating a ground fault.

It should be noted that the display device H that has displayed the ground fault display as described above starts the recovery drive current at time 15 after a predetermined period of time (for example, 3 to 4 hours) after the display unit 10 displays the ground fault display. Said coil (not shown)
As a result, the display section 10 returns from the ground fault display to the normal display.

Note that when CB2 is cut off again (at time T4), the search signal injection device 7 again uses the delayed opening time Z of the section switch SS to inject the search signal current, but the ground fault has already been indicated. The display device H continues to display the ground fault as it is, and the display device H that is displaying the normal state displays the normal state for the same reason as described above.

Next, the case of a short circuit accident will be explained.

When a short circuit current of a certain level or higher flows through the distribution line 3, the current transformer 8 outputs a transformation signal based on the short circuit current, and the short circuit detection sensor 17 responds to the transformation signal to display the short circuit detection on the display unit 10. Output a signal. Then, based on the short circuit detection signal, the display section 10 displays a short circuit as in the case of the ground fault detection. Then, after a predetermined period of time (3 to 4 hours) from the time when the display unit 10 enters the short-circuit display state, the reset drive current from the timer 15 is applied, and the display unit 10 displays a short-circuit display in the same way as in the case of the ground fault display. Returns from normal display to normal display.

In this embodiment, since a magnetic reversal display device is used in the display unit 10, the display device H can have a simple configuration and can be manufactured at low cost, and even if a large number of display devices are arranged in each section. The entire system has the advantage of being inexpensive.

Furthermore, in this embodiment, even if substation CB2 recloses and retransmission is successful, the search signal injection device 7 injects the search signal current even after CB2 is initially cut off, so retransmission, which was previously impossible, is possible. There is an advantage that the ground fault point can be easily discovered when the fault is successful.

Next, a second embodiment will be explained with reference to FIG.

This embodiment differs from the previous embodiment only in the configuration of the display device H. That is, the display device H is a current transformer 8 attached to each phase distribution line.
and a series circuit of a resistor R connected between both terminals of the current transformer 8 and a light emitting diode LED1, and a series circuit connected in parallel to the light emitting diode LED1,
A search signal detecting section 18 is provided, which includes a light emitting diode LED2 arranged in the opposite direction to the light emitting diode LED1.

When the current transformer 8 inputs the search signal current, the search signal detection unit 18 detects the light emitting diode LED based on the transformed current output from the power transformer 8.
1.LED2 is designed to emit light.

In each phase, an optical sensor 19 is arranged corresponding to the light emitting diodes LED1 and LED2 of the search signal detection section 18, and the optical sensor 19 is connected to the optical fiber 20.
The light amount of the light emitting diode is output as an optical signal to the light amount level comparison circuit 21 via the light emitting diode. The same light amount level comparison circuit 21 compares the three phases when the optical signals of the light emitting diodes LED1 and LED2 detected by the optical sensor 19 of each phase are above a certain level, and drives when the three phases are equal or approximately equal. It is designed not to output current. On the other hand, when one phase has a higher light intensity level than the other two phases, a drive current is output to characterize that one phase.

The display section 22 is connected to the light amount level comparison circuit 21, and when a drive current for specifying the one phase is inputted, the one phase is specifically displayed. The power supply circuit 23 of the display device H is connected to a current transformer CT provided in one phase, and supplies a driving current to the light amount level comparison circuit 21 and the display section 22.

Therefore, in this embodiment, when the current transformer 8 inputs the search signal current flowing in the ground fault phase, a transformed current is output from the current transformer 8, and the light emitting diodes LED1 and LED2 emit light based on the transformed current.
Then, the optical signal output from the optical sensor 19 is input to the light level comparison circuit 21 via the optical fiber 20, and the light level comparison circuit 21 selects the three phases when the optical signals input from each phase are above a certain level. They are compared, and when the optical signal level of one phase is higher than the other two phases, a drive current for specifying that one phase is output.

Then, the display unit 22 inputs the drive current for specifying the one phase, and specifies and displays the one phase based on the drive current.

In this embodiment, the display device H is not provided for each phase, and the display is displayed on the common display section 21, so that the display device H can have a simple configuration.

Note that the present invention is not limited to the embodiments described above; for example, in the first embodiment, the search signal injection device 7 was configured to inject the search signal even when CB2 was cut off again; The search signal injection device 7 may be driven to inject only when the signal is cut off.

Further, in the first embodiment, the display device H has a timer 1.
5, the display device H can be configured so that when retransmission is successful, the display is restored by a commercial frequency current that flows after retransmission. In this case, a ground fault display will be made only in the case of a permanent fault among ground faults.

Effects of the Invention As detailed above, this invention injects the search signal current from the search signal injection device in the ground fault fault section, so a large number of expensive ZCT and V0 capacitors are newly installed in order to detect the ground fault point. There is no need to do so, and there is an advantage that ground fault point detection can be carried out at extremely low cost. It also has the great advantage of being able to identify ground fault phases.

In addition, since it is only necessary to install search signal injection devices as many as there are substation CBs, the number can be greatly reduced, and since search signals can be automatically injected, ground fault indication can be performed reliably. .

Furthermore, since the power source of the substation can be used as the drive power source of the search signal injection device, the power of the injection current can be increased, resulting in a truly convenient configuration.

In addition, because it is equipped with a display device that is activated by the search signal current, workers can easily identify the point of a ground fault in a short period of time by simply going around from the power supply side to the load side in the area where the fault has occurred. There are significant practical advantages.

In this case, display devices that need to be installed in large numbers at various locations on power distribution lines do not require a function to send information about their display status to relay points such as substations, and therefore insulation from the ground is not considered. Therefore, the detection method of the present invention becomes significantly simpler and cheaper.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a distribution line system diagram provided with a search signal injection device, FIG. 2 is a distribution line diagram for explaining the operation, and FIG. 3 is an electric circuit diagram of a display device. , FIG. 4 is a perspective view of a magnetic reversal display device,
FIG. 5 is an explanatory diagram showing the operation of the magnetic reversal display device, and FIG. 6 is a bottom view of the display section in the normal display state.
FIG. 7 is a bottom view of the display unit in a ground fault display (short circuit display) state, FIG. 8 is a time chart, and FIG. 9 is an electric circuit diagram of the display device of the second embodiment. 1... Transmission line, 2... Circuit breaker (CB), 3... Distribution line, 4... Zero phase current transformer (ZCT), 5... Grounding transformer (GPT), 6... Directional ground fault Relay, 7...
Search signal injection device, 8...Current transformer, 9...Ground fault detection sensor, 10...Display section, 17...Drive power source, H...Display device, SS...Sectional switch.

Claims (1)

[Scope of Claims] 1. A distribution line is divided by sectional switches, and when a ground fault occurs between the sectional switches, reclosing is repeated at a substation circuit breaker, thereby closing both ends of the section where the ground fault occurs. In a distribution system in which a ground fault fault section is detected by opening a sectional switch, each phase on the load side of the substation breaker has a delayed opening from the time the substation breaker breaks until the sectional switch opens. A search signal injection device that injects a search signal using time is coupled, and a normal display is always displayed in the section, and when the search signal is detected, the normal display is changed to a ground fault display based on the search signal. A search signal is injected into the distribution line from the search signal injection device, and the search signal flowing through the distribution line and the ground fault point causes the display device to display a ground fault. A method for detecting a ground fault point in a power distribution line, characterized in that: