JPH0437653B2 - - Google Patents

Description

[Detailed Description of the Invention] Purpose of the Invention (Field of Industrial Application) This invention relates to a ground fault detection display device that is attached to a power distribution line and that easily detects a ground fault point when a ground fault occurs. It is.

(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) The present invention has been made to solve the above problems, and provides a ground fault detection display device that can easily detect a ground fault point. This is the purpose. That is, the ground fault detection display device of the present invention includes a current transformer attached to each distribution line of each phase, and a current transformer installed in each distribution line in which a search signal for searching for a ground fault point can be injected. a search signal detection section that detects a search signal flowing through the distribution line through the power distribution line, and a light emitting section that emits light based on the search signal;
An optical sensor detects the amount of light from the light emitting part as an optical signal, and when the optical signal of each phase detected by the optical sensor is above a certain level, the three phases are compared, and the light amount of the three phases is determined to be at the same level or approximate. a light amount level comparison circuit that does not output a display drive current when the two phases are equal, and outputs a display drive current for specifying that one phase when the light amount level of one of the phases is higher than the other two phases; The gist thereof is that, when a display drive current for specifying the one phase is input, the display section specifies and displays the one phase.

(Function) With the above configuration, when a search signal flows to the power distribution line, the search signal detection section detects the search signal flowing to the power distribution line via the current transformer, and the light emitting section emits light based on the search signal. Then, an optical sensor detects the amount of light from the light emitting part as an optical signal, and based on the optical signal, a light amount level comparison circuit compares the three phases when the optical signal of each phase is at a certain level or higher. When they are equal or approximately equal, no display drive current is output; on the other hand, when one phase has a higher light level than the other two phases, a display drive current is output for specifying that one phase.
Then, when a display drive current for specifying the one phase is input, the display section specifies and displays the ground fault phase.

(Embodiment) A preferred embodiment embodying the present invention will be described below with reference to FIGS. 1 to 4.

First, to explain the power distribution line to which the ground fault detection display device H is attached, in FIG. It is a distribution line connected to the
4 is a zero-phase current transformer (hereinafter referred to as ZCT) of the substation installed on the immediate load side of the circuit breaker 2, and 5 is a power transmission line 1.
A grounding transformer (hereinafter referred to as GPT) installed in Then, the power distribution line 3 is disconnected from the power transmission line 1.

The distribution line 3 has a sectional switch attached to the utility pole 7.
When a large number of SSs are arranged, a large number of sections An (n=1, 2, 3...) are divided by the same divisional switch SS, and the circuit breaker 2 of the substation is closed to retransmit power, The circuits are closed sequentially from the power supply side.

The sectional switch SS is a conventionally known sectional switch, and when a ground fault occurs in a certain section, the substation breaker 2 opens, and then when the substation breaker 2 is reclosed, the power is turned off. Power is sequentially turned on from the sectional switch SS on the side to retransmit power to the healthy section, and when the section reaches the ground fault section, the substation circuit breaker 2 is shut off again. Then, when the circuit breaker 2 of the substation is closed again, the section switch SS that separates the ground fault fault section is locked in the open state, so that only the ground fault fault section is isolated.

Reference numeral 8 shown in FIG. 2 is a search signal injection device installed below the utility pole 7, which injects the signal into the three-phase load-side distribution line 3 of the section switch SS located above via the primary cutout PC. It is connected and installed jointly with the section switch SS (see Figure 3). The search signal injection device 8 injects the search signal current into the three phases at once by closing the normally open manual switch 8a. In this embodiment, the drive power source for the search signal injection device 8 uses a power transformer Tr for driving the sectional switch SS provided in the distribution line 3 on the power supply side, but a separate power source such as a battery may be separately provided. You may.

Ground fault detection display devices H provided in each phase in each section of the distribution line 3 and arranged at a predetermined distance from each other.
will be explained according to FIG.

That is, the ground fault detection display device H includes a current transformer 9 attached to each distribution line of each phase;
A resistor R and a light emitting diode are connected between both terminals of
Series circuit with LED1 and the same light emitting diode LED
1, the light emitting diode
Light emitting diode placed in the opposite direction to LED1
A search signal detection section 10 composed of an LED 2 is provided. The light emitting diode LED1,
A light emitting section is composed of the LED 2.

When the current transformer 9 inputs the search signal current to the search signal detection unit 10, the light emitting diode LED is activated based on the transformed current output from the current transformer 9.
1.LED2 is designed to emit light.

In each phase, an optical sensor 11 is arranged corresponding to the light emitting diodes LED1 and LED2 of the search signal detection unit 10, and the optical sensor 11 is connected to the optical fiber 12.
The light amount of the light emitting diodes LED1 and LED2 is output as an optical signal to the light amount level comparison circuit 13 via the light emitting diodes LED1 and LED2. The same light amount level comparison circuit 13 compares the light emitting diode LED1 detected by the optical sensor 11 of each phase,
When the light signal of the LED 2 is above a certain level, the three phases are compared, and when the light amount levels of the three phases are equal or approximately equal, no display drive current is output. On the other hand, when one phase has a larger light level than the other two phases, a display drive current is output to specify that one phase.

The display section 14 is connected to the light amount level comparison circuit 13, and when a display drive current for specifying the one phase is inputted, the one phase is specifically displayed. The power supply circuit 15 of the ground fault detection display device H is connected to a current transformer CT provided in one phase, and supplies a display drive current to the light amount level comparison circuit 13 and the display unit 14.

Note that AS shown in Figure 3 is a normally closed switch.

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

Now, in FIG. 3, it is assumed that a single line ground fault occurs at point T of phase a in section A3 of distribution line 3. For convenience of explanation, only the a-phase 3a of the distribution line 3 is illustrated in FIG.

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 the circuit breaker 2 via the substation circuit breaker 2, and the substation circuit breaker 2 is opened. Next, the substation circuit breaker 2 recloses the circuit and retransmits power to the healthy section by sequentially turning on the section switch SS on the power supply side, and when it reaches the ground fault section A3, the substation circuit breaker 2 closes again. be done. Then, when the circuit breaker 2 of the substation is closed again, the section switch SS that separates the ground fault fault section is locked in the open state and the ground fault fault section A is closed.
3 will be separated, and power will be retransmitted only to healthy sections.

As mentioned above, the ground fault section A3 is a sectional switch.
Detection is possible when the SS is locked in the open state, so the worker can then check the ground fault area A.
3, the manual switch 8a of the search signal injection device 8 disposed below the section switch SS on the power supply side is operated to close the circuit. By closing the manual switch 8a, the search signal injection device 8 injects the search signal current from the load side of the sectional switch SS to each phase 3a, 3b of the distribution line.
Inject each into 3c.

Then, in the a phase (ground fault phase), a circulating current flows in a closed loop path passing through the search signal injection device 8, the distribution line 3a, the ground fault point T, and the search signal injection device 8. 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 T is formed, but the impedance of this loop is high and the level of the flowing search signal current is low. As a result, the ground fault detection display devices H1 and H3 disposed between the injection point of the search signal injection device 8 and the ground fault point T display the information.

That is, in the ground fault detection display devices H1 and H3, the search signal current flowing in the ground fault phase is transferred to the current transformer 9.
When input, a transformed current is output from the current transformer 9, and a light emitting diode is output based on the transformed current.
LED1 and LED2 emit light. Then, the optical signal output from the optical sensor 11 is input to the light level comparison circuit 13 via the optical fiber 12, and the light level comparison circuit 13 selects the three phases when the optical signals input from each phase are above a certain level. Compare each. At this time, for the above-mentioned reason, the light level of the ground fault phase is higher than that of the other two phases, so a display drive current for specifying that one phase (phase a) is output.

Then, the display unit 14 inputs the display drive current for specifying the one phase (a phase), and specifies the one phase (ground fault display) based on the display drive current.
do.

In addition, even with the ground fault detection display device installed on the a phase, the search signal current does not reach a certain level or higher, so the ground fault detection display device H4, etc. installed on the load side from the ground fault point T will not display the normal state. Stay.

In this way, the search signal injection device 8 detects the ground fault point T.
After displaying the ground fault on the ground fault detection display device H up to that point, the vehicle departs toward the load side from the point where the search signal injection device 8 was operated. If the earth fault detection display devices H that are in the ground fault display state are sequentially searched, the display device H3 that is displaying a ground fault is located one place before the display device H4 that is not displaying a ground fault. From this, it can be determined that there is a ground fault point m between the points where the ground fault detection display device H4 is arranged.

In addition, when searching for a ground fault point, at the branch point α, a ground fault detection display device H2 provided on one branch line on the load side, and a ground fault detection display device H3 provided on the branch line on the other load side. All you have to do is compare the numbers and proceed along the branch line on the side where the display device is displaying the cross-contact indication.

In this way, this ground fault detection display device H does not require a display section for each phase and displays on the common display section 14, so it can have a simple configuration. 11. Since the light level comparison circuit 13, the display section 14, etc. need only have a simple configuration, they can be manufactured at low cost, and even when a large number of circuits are arranged in each section, the entire system has the advantage of being inexpensive.

In the above embodiment, the search signal injection device 8 manually injects the search signal current.
Instead, an automatic search signal injection device may be used that automatically injects the search signal current when the sectional switch SS in the ground fault section is locked open when a ground fault occurs.

Further, in the above embodiment, a publicly known sectional switch SS is used, but the sectional switch SS may have a search signal injection device incorporated therein. Further, although the above embodiment uses a permanently installed search signal injection device, a portable search signal injection device may be used instead.

Effects of the Invention As detailed above, the ground fault detection display device of the present invention has a very great advantage of being able to identify ground fault phases with a simple configuration.

Furthermore, since it is equipped with a display section that is activated by the search signal, it has a practical effect that workers can easily identify the ground fault point in no time by simply making a first round from the search signal injection device to the load side. There are advantages.

In this case, the ground fault detection display devices, which 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 do not need to be insulated from the ground. A convenient configuration that does not require consideration can be adopted, and the earth fault detection display device of the present invention can be made even more simple and inexpensive.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a distribution line system diagram, FIG. 2 is a front view of the search signal injection device mounted on a pillar, FIG. 3 is a distribution line diagram for explaining the operation, and FIG. The figure is an electrical circuit diagram of a ground fault detection display device. 1... power transmission line, 2... circuit breaker, 3... power distribution line,
4... Zero-phase current transformer (ZCT), 5... Grounding transformer (GPT), 6... Directional ground fault relay, 7... Utility pole,
8... Search signal injection device, 9... Current transformer, 1
0... Search signal detection unit, 11... Optical sensor, 12
...Optical fiber, 13...Light level comparison circuit, 14...Display section, Tr...Transformer, LED1,
LED2...Light emitting diode, H...Ground fault detection display device, SS...Sectional switch.

Claims (1)

[Scope of Claims] 1. In a distribution line in which a search signal for searching for a ground fault point can be injected, a current transformer is attached to each distribution line of each phase, and a current transformer is connected via the current transformer. A search signal detection section that detects a search signal flowing through the electric wire and includes a light emitting section that emits light based on the search signal; an optical sensor that detects the amount of light from the light emitting section as an optical signal; and each phase detected by the optical sensor. The three phases are compared when the optical signal of a light intensity level comparison circuit that outputs a display drive current for specifying one phase when the light intensity level is greater than that, and a display that specifies and displays that one phase when the display drive current for specifying the one phase is input. A ground fault detection display device comprising: