JP2002122628A - Specifying method for fault point - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and efficiently specify a fault point such as a ground fault point or a short circuit point in a fault section in a short time without measuring all electric poles in the fault section even when a short circuit between lines occurs in a pole transformer. SOLUTION: In this method, ground impedances and inter-phase impedances in respective phases of distribution lines 10, 12 are measured by use of a high-frequency power source, a voltage measurement sensor and a current measurement sensor. When the ground impedance in one phase is extremely smaller than the ground impedances in the other phases, it is decided that on accident is a ground fault accident. When one inter-phase-ground impedance is extremely smaller than the other inter-phase-ground impedances, it is decided that the accident is a short circuit accident. Currents are measured in two points sandwiching a connection point of the high-frequency power source, and it is decided that the short circuit accident occurs in a direction showing a larger current value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fault point locating method for locating a fault point in a power distribution system after a trip accident (a ground fault accident or a short circuit accident) occurs in a power distribution system.

[0002]

2. Description of the Related Art When a trip accident occurs in a power distribution system, it is necessary to locate a fault point in a fault section isolated by a sectional switch. As a fault point locating method for locating such a fault point, Japanese Unexamined Patent Application Publication No. 9-10576
No. 5 and JP-A-11-326437. Japanese Unexamined Patent Publication No. Hei 9-105765 discloses a method in which an AC signal having a specific frequency is applied to the ground terminal of each telephone pole, and a ground line voltage is measured to locate a fault point. Japanese Unexamined Patent Application Publication No. 11-326437 discloses a method in which a direct current is applied to an electric wire in a power outage section, and two currents sandwiching the direct current application point are detected to determine a ground fault point direction. It is.

[0003]

Problems to be Solved by the Invention Japanese Patent Application Laid-Open No. 9-10576
The method described in Japanese Patent Publication No. 5 has a problem that it is necessary to measure all the electric poles in the failure section, which is time-consuming and troublesome, and is inefficient. On the other hand, JP-A-11-3
In the system disclosed in Japanese Patent No. 263737, it is not possible to determine when the pole transformer is in a line-to-line short-circuit state. Therefore, unless all the primary cutouts of the pole transformer are opened, a failure point There is a problem that can not be located.

[0004] The present invention has been made in view of the above points, and is simple and can be performed in a short time even if the pole transformer is short-circuited between lines without measuring all poles in the fault section. It is an object of the present invention to provide a fault point locating method capable of efficiently locating a fault point such as a ground fault point and a short-circuit point in a fault section.

[0005]

According to a first aspect of the present invention, there is provided a fault locating method, comprising measuring a phase impedance and a ground impedance of a distribution line using a high-frequency power supply, a voltage measuring sensor, and a current measuring sensor. This is to determine the fault type of the short-circuit accident and the short-circuit accident. In this method, first,
The inter-phase impedance and the ground impedance of each phase of the distribution line are measured using a high-frequency power supply, a voltage measurement sensor, and a current measurement sensor. If the ground impedance is extremely small compared to the other phases, it can be determined that the ground fault has occurred. If the inter-phase impedance is extremely smaller than the other inter-phase impedances, it can be determined that a short circuit has occurred.

[0006] A fault point locating method according to a second aspect is characterized in that:
A high-frequency power supply is connected to a distribution line, and current measurement sensors are installed on both sides of the distribution line so as to sandwich the connection point, and it is determined that a ground fault has occurred in a direction in which the current value measured by the current sensor is larger. Is what you do. In this method, when the current is measured at two points across the connection point of the high-frequency power supply, the magnitude of the current flowing due to the difference in the ground impedance is different as described above, so that a short circuit accident has occurred in the direction of the larger current value. Can be determined.

[0007] According to a third aspect of the present invention, there is provided a failure point locating method.
3. The method according to claim 1, wherein the measurement using the high-frequency power supply is performed via a primary cutout of a utility pole on which a pole transformer is installed. 4. According to the fault point locating method of claim 1 or 2, when applying high-frequency power to a distribution line, power can be easily supplied to the distribution line by using a primary cutout of a pole transformer.

[0008] According to a fourth aspect of the present invention, there is provided a failure point locating method.
3. The high-frequency power supply according to claim 1, wherein the high-frequency power supply does not output a sine wave continuously, but outputs a pulse-like output. This is a technique in which when a failure is caused by insulation deterioration, insulation breakdown occurs, and a pulse-like output is performed by a high-frequency power supply in order to measure a ground impedance or an interphase impedance at that moment.

[0009] A fault point locating method according to a fifth aspect of the present invention comprises:
In claim 1, the high-frequency power supply, the voltage measurement sensor, and the current measurement sensor are configured as an integrated impedance meter. This is because when the cause of the failure is a metal contact or the like, the failure point can be sufficiently located even with a small capacity of the high-frequency power supply, so that the high-frequency power supply, the voltage measurement sensor, and the current measurement sensor are integrally configured. A relatively small capacity impedance meter can be used.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In FIGS. 1 and 2 below, for simplification of the explanatory diagram, illustration of one-phase distribution line among three phases is omitted. FIG. 1 is a diagram showing an embodiment of a fault point locating method of the present invention in the case of a ground fault. In the figure, distribution lines 10 and 12 are installed on utility poles 20 to 30, respectively. The poles 20, 25, and 30 have pole transformers 4
1 to 43 are provided respectively. Pole-mounted transformers 41-
43 is each primary cutout PC1 to P
It is connected to distribution lines 10 and 12 via C6. FIG.
In, the distribution line 10 is grounded near the utility pole 29. This ground fault point 50 is located by this failure point location method.

When a ground fault point 50 as shown in FIG. 1 exists, a high-frequency power source, a voltage sensor, and a current sensor are used.
The ground impedance of each phase of the distribution lines 10 and 12 is measured. When the ground impedance of each phase of the distribution lines 10 and 12 is measured, the ground impedance of the distribution line 10 that is the ground fault phase is smaller than the ground impedance of the distribution line 12 that is the other phase. Can be easily determined. The high frequency power supply is connected to each of the primary cutouts PC1 to PC6 of the pole transformers 41 to 43.

At this time, the direction in which the ground fault point 50 exists can be determined by measuring the current at two points sandwiching the connection point of the high-frequency power supply with a current sensor. This is because the current value in the direction in which the ground fault point 50 is present is larger, so it can be determined that the ground fault point 50 exists in the direction of the larger current value between the two points.

Further, the distribution lines 10 and 12 have 1 [mH
/ Km], the closer the power supply connection point is to the ground fault point 50, the smaller the ground impedance becomes. By measuring the ground impedance in the ground fault phase while changing the power supply connection point, the failure point is determined. Orientation can be easily performed.

Next, a case of a short-circuit fault will be described.
FIG. 2 is a diagram showing one embodiment of the fault point locating method of the present invention in the case of a short-circuit fault. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. FIG. 2 differs from FIG. 1 in that a short-circuit accident (short-circuit point 51) occurs near the utility pole 29. When such a short-circuit point 51 exists, the inter-phase impedance of each phase of the distribution lines 10 and 12 is measured using a high-frequency power supply, a voltage sensor, and a current sensor. Distribution lines 10, 1
When the inter-phase impedance of each phase is measured, the short-circuit point 5
Since the inter-phase impedance where 1 exists is smaller than the inter-phase impedance, the short-circuit phase can be easily determined. High frequency power supply is pole transformer 41-
43 are connected to the primary cutouts PC1 to PC6. Since the distribution lines 10 and 12 have an inductance component of about 1 [mH / km], the closer the power supply connection point is to the short-circuit point 51, the lower the inter-phase impedance becomes. By measuring the impedance, the fault point can be easily located.

A specific example of the fault locating method according to this embodiment will be described below. Pole transformer 4 as high frequency power supply
Frequency range in which 1 to 43 are inductive (for example, 1 [kHz]
z]). Using this high-frequency power source, a fault point is located as follows.

First, at the primary cutouts PC1 and PC2 of the pole transformer 41 installed on the utility pole 20 located near the center of the fault section, the ground impedance Za1 and the inter-phase impedance Zp1 are measured, and a ground fault is detected. A failure type and a failure phase are determined. In the case of FIG. 1, it is determined that a ground fault has occurred in the distribution line 10, and in the case of FIG. 2, it has been determined that a short-circuit failure has occurred between the distribution lines 10 and 12. Primary cutout PC3, P of upper transformer 42
It moves to the nearest utility pole 25 where C4 exists. As shown in FIG. 1, when the failure type determination result is a ground fault of the distribution line 10, the primary cutout PC 3
The ground impedance Za2 of the ground fault phase (distribution line 10) is measured. If the ground impedance Za2 is smaller than the above-described ground impedance Za1, a failure point (ground fault point 5
0) exists in the direction in which the utility pole 25 is viewed from the utility pole 20, and does not exist before the utility pole 20 in the direction in which the utility pole 20 is viewed from the utility pole 25. Conversely, ground impedance Za
2 is larger than the above-mentioned ground impedance Za1, the fault point is the electric pole 2 in the direction in which the electric pole 25 is viewed from the electric pole 20.
It is found that it does not exist after 5 and exists in the direction in which the utility pole 20 is viewed from the utility pole 25.

When the result of the above-described fault type determination is a short-circuit fault, a similar short-circuit point is narrowed down by using the measured value of the inter-phase impedance instead of the ground impedance. That is, primary cutout PC3, PC
In 4, the inter-phase impedance Zp2 between the distribution line 10 and the distribution line 12, which is a short-circuit phase, is measured. If the inter-phase impedance Zp2 is smaller than the inter-phase impedance Zp1, the failure point (short-circuit point 51) is from the utility pole 20 to the utility pole 25.
It is found that the power pole 20 exists in the direction in which the power pole 20 is viewed from the power pole 25 and does not exist before the power pole 20 in the direction in which the power pole 20 is viewed from the power pole 25. vice versa,
If the inter-phase impedance Zp2 is larger than the inter-phase impedance Zp1, the fault point is from the utility pole 20 to the utility pole 25.
It can be seen that it does not exist after the electric pole 25 in the direction in which the electric pole 20 is viewed, but exists in the direction in which the electric pole 20 is viewed from the electric pole 25. In addition,
A current sensor (CT) may be mounted on both sides of the distribution line so as to sandwich the application point of the high-frequency power supply, and it may be determined that a ground fault point exists in the direction of a large current value. In the case of FIG. 1, the current value in the direction in which the utility pole 30 is viewed from the utility pole 25 is large, and it is found that a fault point exists after the utility pole 25 in the direction in which the utility pole 30 is viewed from the utility pole 25.

Next, the electric pole in the direction in which the fault point is determined to exist is moved to the electric pole 30 in which the primary cutouts PC5 and PC6 of the pole transformer 43 are present, and the same measurement is performed. Perform point refinement.
As shown in FIG. 1, when the failure type is determined to be a ground fault, the primary cutout PC5 measures the ground impedance Za3 of the ground fault phase (distribution line 10). If the ground impedance Za3 is smaller than the above-described ground impedance Za2, a failure point (ground fault point 50)
Exists in the direction in which the telephone pole 30 is viewed from the telephone pole 25, and the telephone pole 3
It is determined that it does not exist before the electric pole 25 in the direction in which the electric pole 25 is viewed from 0.

When the result of the above-described fault type determination is a short-circuit fault, a similar short-circuit point is narrowed down using the measured value of the inter-phase impedance instead of the ground impedance. That is, primary cutout PC5, PC
At 6, the inter-phase impedance Zp3 between the distribution line 10 and the distribution line 12, which is a short-circuit phase, is measured. If the inter-phase impedance Zp3 is smaller than the above-described inter-phase impedance Zp2, the failure point (short-circuit point 51) is from the utility pole 25 to the utility pole 30.
It is found that the power pole 25 exists in the direction in which the power pole 25 is viewed from the power pole 30 and does not exist before the power pole 25 in the direction in which the power pole 25 is viewed from the power pole 30. In addition,
A current sensor (CT) may be mounted on both sides of the distribution line so as to sandwich the application point of the high-frequency power supply, and it may be determined that a ground fault point exists in the direction of a large current value. In the case of FIG. 1, the current value in the direction of viewing the utility pole 25 from the utility pole 30 is large, and a failure point is located before the utility pole 30 in the direction of viewing the utility pole 25 from the utility pole 30, that is, in the section between the utility pole 25 and the utility pole 30. It is determined that it exists. When the determination by the current sensor is not performed, the same processing as described above is performed on the next telephone pole, thereby determining that a fault point exists in the section between the telephone pole 25 and the telephone pole 30.

In the case where the cause of the failure is a metal contact or the like, even if the capacity of the high-frequency power supply is small, it is possible to locate the failure point by the above procedure. Therefore, as the integrated high-frequency power supply, voltage sensor, and current sensor, a commercially available LCR meter having a measurement frequency on the order of [kHz] can be used. On the other hand, when the failure is caused by insulation deterioration, the insulation state is maintained as it is unless the required voltage is applied, and the impedance at the failure point may remain high. In such a case, insulation breakdown may be generated using a high-frequency power supply capable of outputting a required high voltage. The necessary data is the ground impedance or inter-phase impedance at the moment of the dielectric breakdown, so that the high-frequency power supply can be used without any problem with either a sine wave output or a pulse output, but the pulse output is more preferable for causing the dielectric breakdown.

As described above, in this embodiment, it is possible to finally narrow down the locations of the fault points in units of the installation interval of the primary cutout. Because there is no need for measurement in the section where it is determined that there is no failure point,
Early detection and restoration of a fault point after a trip accident has occurred. Also, even if the failure point has been restored to insulation,
Failure point location is possible based on the measured data at the moment of insulation breakdown.

[0022]

According to the fault locating method of the present invention, even if all poles in a fault section are not measured, even if a pole transformer is short-circuited between lines, it can be efficiently performed in a short time. There is an effect that fault points such as a ground fault point and a short-circuit point in a fault section can be located.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a fault point locating method of the present invention in the case of a ground fault.

FIG. 2 is a diagram showing an embodiment of a fault point locating method according to the present invention in the case of a short-circuit fault;

[Explanation of symbols]

 10, 12 Distribution line 20 to 30 Utility pole 41 to 43 Pole transformer 50 Ground fault point 51 Short circuit point PC1 to PC6 Primary cutout Za1 to Za3 Impedance to ground Zp1 to Zp3 Interphase impedance

Claims (5)

[Claims] A fault characterized in that a high-frequency power supply, a voltage measuring sensor and a current measuring sensor are used to measure a phase impedance and a ground impedance of a distribution line to determine a fault type of a ground fault and a short circuit. Point location method. 2. A high-frequency power supply is connected to a distribution line, current measuring sensors are installed on both sides of the distribution line so as to sandwich the connection point, and a ground fault point is set in a direction in which a current value measured by the current sensor is large. A failure point locating method characterized by determining that there is a failure. 3. The fault locating method according to claim 1, wherein the measurement using the high-frequency power supply is performed through a primary cutout of a utility pole on which a pole transformer is installed. 4. A fault point locating method according to claim 1, wherein the high-frequency power supply does not output a sine wave continuously but outputs a pulse. 5. The fault point locating method according to claim 1, wherein the high-frequency power supply, the voltage measurement sensor and the current measurement sensor are constituted by an impedance meter integrally formed.