JP2001033509A - Method for locating accident section and accident point of underground distribution line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To instantly locate a point of accident when the accident is generated. SOLUTION: A discharging pulse signal 6 generated at an accident point 3 when an accident of an underground distribution line is generated, and a reflected wave of the discharging pulse signal 6 are detected at a detecting point 2 of the underground distribution line. An accident section which is divided at a branch point 4 is located on the basis of patterns of the detected pulse signals. The accident point is further located on the basis of time difference between the detected pulse signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of locating an accident section and an accident point of an underground distribution line, and more particularly to a method of locating an accident section and an accident point of an underground distribution line which can be instantaneously identified when an accident occurs. It is about.

[0002]

2. Description of the Related Art A conventional method of locating an accident section or point of an underground distribution line involves applying a DC high voltage to the underground distribution line in a power outage state after the occurrence of an accident using a DC high voltage power supply. After firing the accident point, measurement is performed in a bridge circuit. If there is a branch in the underground distribution line, the branch section is measured sequentially while the branch line is separated.

After limiting the accident section in this way, a pulse voltage is applied to the underground distribution line in the section, and the time required for the reflected wave generated at the accident point to reach the incident point due to the pulse voltage is determined by the pulse point. Ask for.

[0004]

The conventional locating method requires a great deal of labor because it requires the work of disconnecting the underground distribution line and the installation work of the equipment (DC high-voltage power supply, bridge circuit, pulse voltage device). At the same time, there is a problem that the working time is prolonged due to the movement of the worker and the repeated measurement.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide an accident section and an accident point locating method for an underground distribution line which can instantaneously identify an accident when an accident occurs.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to an underground distribution line in which a discharge pulse signal generated at an accident point and a reflected wave of the discharge pulse signal are generated when the underground distribution line accident occurs. At the detection points, and based on these detected pulse signal patterns,
Further, an accident point is located based on a time difference between the detection pulse signals.

[0007] As a pattern, the time when the discharge pulse signal reciprocates on the branch line is provided in a time table, and the section divided by the branch point of the branch line in which the time difference between the detected pulse signals matches the time table is defined as an accident section. It may be determined.

The detection pulse signal for locating the fault point includes a reflected wave of the discharge pulse signal reflected or re-reflected at any one of a branch point, an end point of a branch line, a detection point, and a fault point. May be.

A detection level which takes into account the attenuation due to the passage and reflection of the branch point is applied to the detection pulse signal detected thereafter based on the magnitude of the detection pulse signal detected first, and the detection pulse signal satisfying this detection level is applied. A pulse signal may be used for orientation.

[0010]

An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

First, referring to FIGS. 1A and 1B,
A case where an accident occurs at an accident point farther from the branch point when viewed from the detection point will be described. FIG. 1A illustrates an underground distribution line. FIG. 1B shows a pattern of the detection pulse signal.

As shown in FIG. 1A, a detection point 2 is provided at one end of a trunk line 1. In this embodiment, there is a branch between the accident point 3 and the detection point 2, and a branch line 5 having a predetermined length is provided from the branch point 4 to the end.
The description of the side farther from the accident point 3 is omitted, but the case where there is another branch on the side farther than the accident point 3 is also included in the present embodiment.

For the orientation method of the present invention, a pulse detector (not shown) for detecting a discharge pulse signal and its reflected wave is provided at the detection point 2. Further, a location device (not shown) for locating an accident section and an accident point using a detection pulse signal from the pulse detector is provided.

In this underground distribution line, when an accident occurs at an accident point 3 farther from the branch point 4 as viewed from the detection point 2, a discharge pulse signal (current pulse) 6 generated at the accident point 3 passes through the branch point 4. To reach the detection point 2. Thus accident point 3
The discharge pulse signal that reaches the detection point 2 immediately after is referred to as a transmitted wave. Further, the discharge pulse signal generated at the fault point 3 enters the branch line 5 from the branch point 4, is reflected at the end point of the branch line 5, returns to the branch line 5, enters the main line 1, and reaches the detection point 2. In this way, the detection point 2 via the branch line 5
Is referred to as a reflected wave.

FIG. 1 (b) shows, on the time axis, transmitted and reflected wave detection pulse signals detected by the pulse detector located at the detection point 2. As shown in the figure, the reflected wave is detected with a delay of the time R required for the discharge pulse signal to reciprocate along the branch line 5 with respect to the transmitted wave. In other words, if there is a branch between the detection point 2 and the accident point 3, the detection pulse signal must include not only a transmitted wave but also a reflected wave delayed by the time R for reciprocating propagation through the branch line 5. I do. In addition, the detection polarity of the reflected wave is indicated by the polarity opposite to the detection polarity of the transmitted wave. Assuming that the discharge pulse signal is reflected at the end point of the branch line 5 with high impedance, a reflected wave of the opposite polarity is generated. Because.

Next, the case where there is no branch near the accident point 3 when viewed from the detection point 2 will be described. FIG. 1 (c)
Shows an underground distribution line. FIG. 1D shows a pattern of the detection pulse signal.

As shown in FIG. 1C, a detection point 2 is provided at one end of the trunk line 1. In this embodiment, there is no branch between the detection point 2 and the accident point 3. Although the description of the side farther from the accident point 3 is omitted, the case where there is a branch on the side farther than the accident point 3 is also included in the present embodiment.

When an accident occurs at the fault point 3 in this underground distribution line, the discharge pulse signal (current pulse) generated at the fault point 3 reaches the detection point. As shown in FIG. 1D, only the transmitted wave exists in the detection pulse signal.

As described above, the pattern of the detected pulse signal differs depending on whether there is a branch between the detection point 2 and the accident point 3. Therefore, the pattern of the detection pulse signal is determined, and whether or not the accidental section is farther than the branch point 4 from the detection point 2 or whether or not the branch point 4
A closer section can be located. That is, an accident section divided at the branch point 4 can be located.

Next, the principle of locating the accident point will be described with reference to FIG.

FIG. 2A shows a branch point 4 viewed from the detection point 2.
FIG. 2B shows an underground distribution line when an accident occurs at a farther accident point 3, and FIG. 2B shows a pattern of a detected pulse signal at that time.

FIG. 2A shows a transmitted wave (discharged directly from the fault point 3 to the detection point 2) and a reflected wave (reflected at the end point of the branch line 5) of the discharge pulse signal 6 described in FIG. In addition, the reflected wave from the end point of the branch line 5 and the reflected wave from the branch point 4 are re-reflected at the accident point 3 in addition to those having reached the detection point 2). That is, the reflected wave is the discharge pulse signal 6 generated at the fault point 3, reflected at the end point of the branch line 5, returns to the fault point 3, and is re-reflected at the fault point 3. The discharge pulse signal 6 generated at 3 is reflected at the branch point 4, returns to the fault point 3, and is re-reflected at the fault point 3.

As shown in FIG. 2B, after the transmitted wave is detected, a reflected wave that can determine that the accident section is a section farther than the branch point 4 from the detection point 2 is detected. Thereafter, reflected waves are sequentially detected.

The time difference between the detected pulse signals will be described.

The time difference A between the reflected wave and the reflected wave appearing in the detection pulse signal is the time required for the discharge pulse signal 6 to reciprocate between the branch point 4 and the accident point 3. Then, the distance F from the branch point 4 to the accident point 3 can be calculated from the following equation.

F = AK / 2 (1) The time difference B between the reflected wave and the reflected wave is represented by the time required for the discharge pulse signal 6 to reciprocate between the branch point 4 and the accident point 3 and the time required for the discharge pulse signal 6 Is the difference from the time required for reciprocating propagation through the branch line 5, and the distance F from the branch point 4 to the accident point 3 can be calculated from the following equation.

F = (R + B) K / 2 (2) The time difference C between the reflected waves is the time required for the discharge pulse signal 6 to propagate back and forth through the branch line 5, and the time difference C = time difference R.

By using the equation (1) or the equation (2), the distance F from the branch point 4 to the accident point 3 can be calculated by measuring the time difference A or the time difference B.

Incidentally, the reflected wave is divided into the branch point 4 and the accident point 3
, And does not reflect at the end point of the branch line 5, so that the detection polarity is the same as the detection polarity of the transmitted wave and opposite to the detection polarity of the reflected wave. It is.

FIG. 2C shows an underground distribution line when an accident occurs at an accident point 3 closer to a branch point 4 when viewed from the detection point 2, and FIG. Shows the pattern of the detected pulse signal at that time.

FIG. 2C shows, in addition to the transmitted wave of the discharge pulse signal 6 described above with reference to FIG. 1 (directly reaching the detection point from the accident point), the reflection reflected or re-reflected from each point. Waves are shown. The reflected wave is a discharge pulse signal 6 generated at the fault point 3 is reflected at the detection point 2 and returns to the fault point 3 and is re-reflected at the fault point 3. The reflected wave is generated at the fault point 3. The discharge pulse signal 6 is reflected at the branch point 4 and transmitted through the accident point 3. The reflected wave is such that the discharge pulse signal 6 generated at the accident point 3 enters the branch line 5 from the branch point 4, and
The light is reflected at the end point of the branch line 5, returns to the main line 1, and passes through the accident point 3.

As shown in FIG. 2D, after a transmitted wave is detected, a reflected wave is detected. The time difference D between the transmitted wave and the reflected wave is equal to the time required for the discharge pulse signal 6 to propagate back and forth between the branch point 4 and the detection point 2, and the distance Fk from the detection point 2 to the accident point 3 is calculated from the following equation. Can be calculated.

Fk = DK / 2 (3) Further, when the fault point resistance is large or when the fault condition disappears immediately and the insulation is restored, the magnitude of the reflected wave becomes small. In this case, a reflected wave and a reflected wave by the discharge pulse signal propagated from the accident point 3 to the opposite side to the detection point 2 are detected. The time difference E between the transmitted wave and the reflected wave is equal to the time required for the discharge pulse signal 6 to propagate back and forth between the branch point 4 and the fault point 3, and the distance F from the branch point 4 to the fault point 3 is calculated from the following equation. Can be calculated.

F = EK / 2 (4) Next, a case where an accident occurs on a branch line will be described with reference to FIGS. 3 (a) and 3 (b).

FIG. 3A shows an underground distribution line. FIG. 3B shows a pattern of the detection pulse signal.

As shown in FIG. 3A, there is an accident point 3 on a branch line 8 from a branch point 7, and the branch point and the detection point 2
And there is another branch (branch point 4, branch line 5). When an accident occurs on the branch line 8, the discharge pulse signal 6 generated at the accident point 3 enters the main line 1 from the branch line 8, and the transmitted wave transmitted through the branch point 4 reaches the detection point 2. Also,
This discharge pulse signal 6 enters the branch line 5 from the main line 1,
After returning to the trunk line 1 after reciprocating along the branch line 5, the reflected wave reaches the detection point. Further, the discharge pulse signal 6 is reflected at the branch point 7 and returns to the accident point 3, so that the reflected wave re-reflected at the accident point 3 reaches the detection point.

As shown in FIG. 3B, after the transmitted wave is detected, the reflected wave is detected, and then the reflected wave is detected. The time difference G between the transmitted wave and the reflected wave appearing in the detection pulse signal is determined by the fact that the discharge pulse signal 6
It is the time required for reciprocating propagation between the point and the accident point 3, and the distance Fb from the branch point 7 to the accident point 3 can be calculated from the following equation.

Fb = GK / 2 (5) Note that the correlation between the detection time of the reflected wave and the detection time of the reflected wave depends on the length of the sound branch line 5 and the distance between the branch point 7 and the accident point 3. Depends on distance.

As described above, if the pattern of the detection pulse signal and the propagation time of the discharge pulse signal are known, it is possible to locate the fault section divided at the branch point, and to determine the time difference between the detection pulse signals. It is possible to locate the accident point based on this.

Next, a time table for locating an accident section will be described with reference to FIG.

FIG. 4 (a) shows an underground distribution line. FIG. 4B shows a time table of the detected pulse signal.

As shown in FIG. 4A, a detection point 2 is provided at one end of the trunk line 1. The trunk line 1 has a plurality of branch points 9, 10, 11, and 12, and branch lines 13, 14, 15, and 1 having different lengths from the respective branch points.
6 is branched. If the detection point 2 to install a pulse detector, advance discharge pulse signal to previously obtain the time t ₁₃ ~t ₁₆ required to round-trip propagation of the branch lines 13 to 16,
A time table is created based on the time difference between the detection time of the transmitted wave, which is the detection pulse signal detected first, and the detection time of the reflected wave detected after the reciprocating propagation on each of the branch lines 13 to 16.

As shown in FIG. 4B, the detection time at which each reflected wave is detected after the detection time t ₀ of the transmitted wave is:
Determined according to the length of each branch line, t ₁₆ , t ₁₃ ,
made in the order of t _15, t _14.

According to this time table, the detection times t ₁₆ , t ₁₃ , t ₁₅ , and t ₁₆ of the detection pulse signal detected with the opposite polarity after the detection time t ₀ of the transmitted wave which is the detection pulse signal detected first. It determines whether or not to match the t _14. When there is a coincident detection time, a section farther than the branch point corresponding to the detection time, as viewed from the detection point 2, is determined to be an accident section. If there is no matching detection time,
A section on the detection point side from the branch point 9 closest to the detection point 2 is determined as an accident section.

In order to make the above determination, it is necessary to determine whether the detected pulse signal is valid.
In an underground distribution line, there are reflected waves that are multiple-reflected at each point, and these reflected waves gradually become smaller. However, if the detection sensitivity is increased, these reflected waves are also detected. Therefore, if the detection sensitivity is excessively increased, an erroneous determination may be caused. Therefore, it is preferable to discriminate the detection pulse signal used for orientation based on the magnitude of the detection pulse signal.

A method for discriminating the detection pulse signal will be described with reference to FIG.

As shown in FIG. 5, the magnitude of the transmitted wave which is the first detected pulse signal is defined as a reference S,
A detection level T having a predetermined magnitude is applied to a detection pulse signal detected thereafter, and a detection pulse signal exceeding the detection level T is used for orientation. Thereby, the reflected wave is excluded, and the reflected wave is adopted.

Next, a method for setting the detection level will be described with reference to FIGS.

FIGS. 6 to 10 show the same underground distribution line. The underground distribution line is divided from branch points 17, 18, and 19 on the trunk line 1 by branch lines 20, 21, and 20, respectively. 22 is branched, and a detection point 2 (not shown) is provided on the left side of the figure. In these figures, different paths of the discharge pulse signal 6 from the same fault point 3 are additionally shown. The sign of each path of the discharge pulse signal 6 does not always match the sign used in the description so far.

Assuming that the path until the discharge pulse signal 6 generated at the fault point 3 reaches the detection point 2 is a reciprocating reflection at each reflection point (branch point, branch line end point, detection point, fault point, etc.). , Exists infinitely. For this reason, there are infinitely many reflected waves, but in consideration of the attenuation pulse in each branch point and the appearance time of a detection pulse signal that is useful for orientation, only the reflected waves with a small number of reflections need to be obtained.

Here, it is assumed that the underground distribution lines are of the same cable type, and the fault point 3 and the branch lines 20, 21, 22
Assuming that the reflection at the end point is total reflection, the following detection level is set.

When passing through one branch point, the discharge pulse signal 6 decreases in magnitude to 2/3. Therefore, the transmitted wave shown in FIG. 6 has three branch points on the way, and its magnitude is (2/3) × the discharge pulse signal generated at the accident point.
(2/3) × (2/3) = 8/27 times. By standardizing the magnitude of the detection pulse signal of the transmitted wave and setting it to 1, it is possible to calibrate the attenuation due to the branch point existing from the accident point 3 to the detection point 2.

As shown in FIG. 7, one branch line 17
The reflected wave that reaches the detection point 2 after being reflected at the end point of the above passes through one more branch point than the transmitted wave, so that the detection pulse signal of the reflected wave is detected with a size of 2/3 of that of the transmitted wave. . Therefore, the detection pulse signal used for the accident section determination is set to a detection level that has a margin in consideration of other attenuation for 2/3 of the magnitude of the transmitted wave and exceeds this detection level. You only need to adopt it.

As shown in FIGS. 8 (a) to 8 (c), the reflected wave reflected at any of the branch points 17, 18, and 19, reflected at the accident point 3 and reaching the detection point 2 is: Since the number of passages at the branch point is different, the attenuation amount is also different. Since the reflection ratio at the branch point is 1/3, in the case of the reflected wave reflected at the first branch point 19 from the accident point, the detection pulse signal is detected with a magnitude of 1/3 of that of the transmitted wave. In the case of the reflected wave reflected at the second branch point 18 from the accident point, the detected pulse signal is (1/1 /
3) × (2/3) × (2/3) = 4/27. In the case of the reflected wave reflected at the third branch point 17 from the accident point, the detected pulse signal is that of the transmitted wave (1
/ 3) x (2/3) x (2/3) x (2/3) x (2 /
3) It is detected with a size of = 16/243.

Since the detected pulse signal actually required for the fault point locating is a reflected wave reflected at the first branch point 19 from the fault point 3, the reflected wave reflected at another branch point distant from the fault point 3 is detected. No need to detect. Therefore, the detection pulse signal of the reflected wave reflected at the branch point is 1 / the magnitude of the transmitted wave.
It is sufficient to set a detection level with a margin for 3 in consideration of other attenuations, and to employ only a detection level exceeding this detection level.

As shown in FIG. 9, one branch line 22
The reflected wave that is reflected at the end point of and reaches the detection point 2 after being reflected at the accident point 3 passes through two more branch points than the transmitted wave, so that the detection pulse signal of the reflected wave is (2 / 3) × (2/3) = 4/9.

In addition to the above, there are a plurality of reflected waves which are reflected back and forth between the branch points. However, since the reflection ratio at the branch point overlaps one-third due to the attenuation on the assumption of reflection, the detection is performed. The magnitude of the pulse signal decreases.

As described above, based on 1/3 of the magnitude of the transmitted wave which is the first detected pulse signal, the detection level is set in consideration of the attenuation during propagation, and exceeds this detection level. By employing only the detection pulse signal, only the detection pulse signal necessary for orientation can be obtained.

Actually, the reflection ratio and propagation attenuation at the branch point are obtained by sending an accident simulation pulse signal to an underground distribution line in advance, and the detection level is calibrated based on these measurements. Thereby, accuracy can be improved.

In the above, the reflection at the accident point is assumed to be total reflection, and the state where the resistance at the accident point is small has been described. This is because the underground distribution line is generally several kilometers long, and the detection of the detection pulse signal is completed in a short time of several tens of μs from the occurrence of the accident. . However, the accident condition may disappear and the resistance at the accident point may increase. The case where the reflection at the accident point becomes extremely small due to the increase in the accident point resistance will be described.

In this case, as mentioned in the description of FIG. 2C, the reflected wave by the discharge pulse signal propagated from the accident point 3 to the opposite side to the detection point 2 is detected and used for the orientation. As shown in FIG. 10, the discharge pulse signal 6 generated at the fault point 3 is reflected at the end of the main line 1, the end of the branch line or the branch point on the right side of the figure, and reaches the detection point 2. Main line 1
Since the reflected wave reflected at the end of is totally reflected, it can be detected with the same size as the transmitted wave. When the light is reflected at the branch point, the size is 1/3.
/ 3 can be detected. Therefore, the setting of the detection level is the same as when the accident point resistance is small.

In the above description, the discharge pulse signal 6 is a current pulse. However, the method of the present invention can be implemented by using a voltage pulse. However, in the case of the voltage pulse, the polarity of the reflected wave is opposite to that of the current pulse. For example, in the reflection at the end point, the reflected wave of the current pulse has the opposite polarity to the transmitted wave, while the reflected wave of the voltage pulse has the same polarity as the transmitted wave.

Although the detection point 2 is provided at one end of the trunk line 1, the present invention is not limited to this. In order to improve the orientation accuracy, the detection point 2 is provided at both ends of the trunk line 1 or at other points. The final orientation may be performed by integrating the orientation results of (2).

[0064]

The present invention exhibits the following excellent effects.

(1) Since the location of the accident point can be instantaneously performed immediately after the accident, the recovery time can be shortened.

(2) It is not necessary to perform a special operation for orientation when an accident occurs, and it is not necessary to install special equipment.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an underground power distribution line and a pattern diagram of a corresponding detection pulse signal according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an underground distribution line and a corresponding detection pulse signal pattern diagram illustrating an embodiment of the present invention.

FIG. 3 is a configuration diagram of an underground distribution line and a corresponding detection pulse signal pattern diagram illustrating an embodiment of the present invention.

FIG. 4 is a diagram illustrating a configuration of an underground distribution line and a corresponding time table according to the embodiment of the present invention.

FIG. 5 is a pattern diagram of a detection pulse signal according to the embodiment of the present invention.

FIG. 6 is a configuration diagram of an underground distribution line showing an embodiment of the present invention.

FIG. 7 is a configuration diagram of an underground distribution line showing an embodiment of the present invention.

FIG. 8 is a configuration diagram of an underground distribution line showing an embodiment of the present invention.

FIG. 9 is a configuration diagram of an underground distribution line showing an embodiment of the present invention.

FIG. 10 is a configuration diagram of an underground distribution line showing an embodiment of the present invention.

[Explanation of symbols]

 1 main line 2 detection point 3 accident point 4 branch point 5 branch line 6 discharge pulse signal

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichi Sato 5-1-1, Hidakacho, Hitachi City, Ibaraki Prefecture Power Systems Research Laboratory, Hitachi Cable, Ltd. (72) Inventor Kazuo Kotani 5 Hidakacho, Hitachi City, Ibaraki Prefecture No. 1-1, Hitachi Cable Co., Ltd. Power System Laboratory F-term (reference) 2G033 AA01 AB01 AB02 AC05 AD07 AE02 AE04 AF02

Claims (4)

[Claims] 1. An underground distribution line detects a discharge pulse signal generated at an accident point and a reflected wave of the discharge pulse signal at a detection point of the underground distribution line when an accident occurs. An accident section and an accident point locating method for an underground distribution line, comprising: locating an accident section divided by a branch point; and locating an accident point based on a time difference between the detected pulse signals. 2. A time table having a time in which a discharge pulse signal reciprocates on a branch line as the pattern, and an interval in which a time difference between the detected pulse signals is divided by a branch point of the branch line corresponding to the time table is set as an accident. The fault section and fault point locating method for an underground distribution line according to claim 1, wherein the fault is determined as a section. 3. The detection pulse signal for locating the fault point includes a point where the discharge pulse signal is a branch point, an end point of a branch line,
3. The fault section and fault point locating method for an underground distribution line according to claim 1 or 2, further comprising a reflected wave reflected or re-reflected at any one of the detection point and the fault point. 4. A detection level based on the magnitude of a detection pulse signal detected first, and a detection level that allows for attenuation due to passage and reflection of a branch point is applied to detection pulse signals detected thereafter. The fault section and fault point locating method for an underground distribution line according to any one of claims 1 to 3, wherein the detected pulse signal that satisfies the condition is used for locating.