JP2771625B2 - Fault Detection Method for Optical Fiber Composite Overhead Ground Wire and Overhead Transmission Line - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for detecting an accident point of an optical fiber composite overhead ground wire and an overhead power transmission line, and more particularly, to the fact that Raman scattering phenomenon has a functional relationship with temperature. The present invention relates to a technology for detecting a fault point of a transmission line by utilizing the fact that a zero-phase current or the like flows to an overhead ground line when an abnormality occurs in a transmission line, thereby causing a partial rise in temperature.

`` Prior art '' Lightning strikes on towers and overhead ground lines, ground faults,
If an electrical accident such as a reverse flashover occurs based on these, a great deal of labor is required to manually search for the point of the accident.

Conventionally, techniques for searching for an accident point in a transmission line network include, for example, Japanese Patent Application Laid-Open No. Sho 62-206465 [Fault section locating device for overhead power transmission lines] and Japanese Patent Publication No. 63-7626 [Japanese] Detection method], Japanese Patent Publication No. Sho 63-13152 [Transmission line fault remote monitoring device], and the like.

In the technology, based on the occurrence of a ground fault, the fault current flowing through the overhead ground wire is transmitted to the destination using an optical fiber composite overhead ground wire, and a special index is calculated based on the current value and phase to calculate In this connection, the fault section is located, and in the case of a flashover accident in a tower, the current flowing into the tower is detected by a current transformer and the phases are compared. In connection with this, the technology detects the flashlight tower, and the technology in the above section uses an optical fiber to detect the operation signal of the transmission line fault detector installed in each tower when a power line accident occurs due to a lightning strike or the like. By connecting to a follower locator, a fault point is located.When any of these technologies causes a ground fault on a transmission line due to a lightning strike, the point of occurrence is located at a remote location such as a substation. That can be located. .

"Problems to be solved by the invention" However, each of these technologies uses various sensors, such as current transformers, that match each item of abnormal phenomenon.
By installing a large number of each tower or each overhead ground line section between towers, it is possible to transmit detection signals to remote locations such as substations, and to monitor and maintain the transmission line network and detect accidents that occur. However, the method using sensors having various functions complicates data collection and transmission, and increases the cost of the accident point searching system.

The present invention has been made in view of the above circumstances, and in a monitoring setting area, an optical fiber composite overhead ground wire capable of continuously detecting the occurrence of an accident over the entire area and improving the detection accuracy of the accident point. And a method for detecting an accidental point of an overhead transmission line, whereby the system cost can be reduced as compared with the above-mentioned conventional technology.

[Means for Solving the Problems] An optical fiber composite overhead ground wire according to the present invention is an optical fiber composite overhead ground formed by providing an optical fiber cable for signal transmission along a longitudinal direction of a cable conductor at a central portion of the cable conductor. In the ground wire, a Raman scattering optical fiber wire is provided along the longitudinal direction at the center portion or at an inner position of the outermost layer of the stranded wire of the cable conductor.

In addition, the method for detecting an accident point of an overhead transmission line according to the present invention includes:
Light is incident from the end of the Raman scattering optical fiber wire attached to the optical fiber composite ground wire, and the temperature of the cable conductor in the optical fiber composite overhead ground wire is determined by the Raman scattering state generated in the Raman scattering optical fiber wire. The distribution is measured, and the measured temperature distribution data is transmitted to the remote monitoring unit via the optical fiber cable for signal transmission, and the remote monitoring unit analyzes the received signal to determine whether or not a high-temperature portion exists in the cable conductor. It is characterized by detecting and determining.

"Operation" In the optical fiber composite ground wire, when light enters from the end of the Raman scattering optical fiber line, the intensity of the Raman scattering light generated in the Raman scattering optical fiber line is represented by a temperature-dependent function, The temperature distribution in the longitudinal direction of the optical fiber composite overhead ground wire is obtained from the Raman scattered light intensity. The temperature distribution data is converted into an optical signal, and can be transmitted to a remote monitoring unit such as a substation using an optical fiber cable for signal transmission for communication.

Therefore, when a zero-phase current or a ground fault current flows through the optical fiber composite ground wire located in the area where the Raman scattering optical fiber is laid, a heating phenomenon occurs, and the high temperature portion is detected by the Raman scattering optical fiber. In addition, by specifying the position in the longitudinal direction of the Raman scattered optical fiber line, an accident-occurring tower and an accidental overhead ground wire between the towers are identified, and the accident point can be located.

Hereinafter, an embodiment of a method for detecting an accident point of an optical fiber composite overhead ground wire and an overhead transmission line according to the present invention will be described with reference to the drawings.

1 and 2 show two embodiments of an optical fiber composite overhead ground wire according to the present invention.

In the optical fiber composite overhead ground wire 1A shown in FIG. 1, an aluminum tube 3 is inserted into a central portion of a cable conductor 2 formed by twisting a plurality of aluminum-coated steel wires, and a groove is formed in the aluminum tube 3. In addition to the structure in which the aluminum wire 4 is housed and the signal carrying optical fiber cable (optical fiber wire) 6 is inserted into the plurality (three) of the groove portions 5 of the grooved aluminum wire 4, one of the grooves 5 is provided. Finally, a Raman scattered optical fiber line 7 as a temperature sensor is housed in a juxtaposed state. That is,
The Raman scattering optical fiber line 7 is provided in parallel with the length of the cable conductor 2 along the length direction of the cable conductor 2 while being housed in the aluminum tube 3.

In addition, the optical fiber composite overhead ground wire 1B of the example of FIG.
2A and a stranded inner layer 2B. An aluminum tube 3 is inserted into a center portion of the stranded inner layer 2B, and a grooved aluminum wire 4 and a signal carrying optical fiber cable (optical fiber A wire 6 is provided, and a Raman scattering optical fiber wire 7 is brought into contact with and attached to a shoulder portion of an aluminum-coated steel wire on the outer periphery of the stranded inner layer 2B.

As shown in FIG. 3, the Raman scattering optical fiber wire 7 is formed by coating an optical fiber wire 7a with a ceramic layer 7b such as alumina (Ar ₂ O ₃ ).
The configuration is such that a metal layer 7c of copper, aluminum, stainless steel or the like is provided.

Therefore, by attaching the Raman scattering optical fiber line 7 inside the cable conductor 2 or the outermost layer 2A of the stranded wire in a housed state, it becomes easy to incorporate the Raman scattering optical fiber line 7 into the cable conductor 2 during manufacturing. When pulse light is incident from the end of the Raman scattered optical fiber line 7, Raman scattering occurs in the Raman scattered optical fiber line 7, and continuous intensity in the length direction of the cable conductor 2 is obtained from the intensity of the Raman scattered light. A temperature distribution will be determined.

On the other hand, FIG. 4 shows a schematic configuration (model diagram) for implementing the fault point detection method for an overhead transmission line. The fault point detection range of the overhead transmission line network is the entire area between the transmission-side substation and the reception-side substation. In this case, the range (length) where the temperature distribution can be measured by the Raman scattering optical fiber line 7 The overhead transmission line network is divided into a plurality of ranges in consideration of the limitations of the overhead transmission line 9 and the plurality of spans of the overhead transmission line 9 in the overhead line state in the transmission line structure (pylon) 8 in one of the divided monitoring ranges. (FIG. 4 shows an example represented by A, B, and C). In addition, a Raman scattering optical fiber line 7 is installed in one monitoring area, the optical terminal unit 10 and the optical Installation of the fiber joint box 11 and the like are performed.

The optical terminal device 10 includes a temperature distribution measuring device (see FIG. 5) 12 using the Raman scattering optical fiber line 7 and an electric / electrical device that converts information information measured by the temperature distribution measuring device 12 from an electric signal to an optical signal. And an optical signal converter, which is connected to the optical fiber cable 6 for signal transmission in the optical fiber joint box 11 and transmits the measurement information data signal of each divided monitoring range to, for example, the remote monitoring unit 13 which is a power transmission side substation. Is what you do.

In the remote monitoring unit 13, the measurement information data received by the receiver 14 having the optical / electrical signal converter is analyzed and determined by the data processing device 15, and is monitored as needed by displaying it on the display device 16, and the like. When a change occurs in the temperature distribution of the cable conductor 2 within the divided monitoring range, an alarm is output and a record display of an accident point is performed.

Next, the temperature distribution measuring device 12 will be described with reference to FIG. 5. A light source 18 is provided at one port of the optical branching device 17 connected to the Raman scattering optical fiber line 7, and a detection system is provided at the other port. Light source 18, a light source driving device 19,
A pulse delay circuit 20 and a pulse generator 21 are connected, and a signal output from the pulse generator 21 is directly input to a data processing circuit 22, while a pulse signal delayed by a predetermined time in the pulse delay circuit 20 is The data is input to the light source driving device 19. The light source driving device 19 drives the light source 18 in accordance with the input pulse signal, and the light source 18 emits pulsed light having a frequency ωo. The pulsed light passes through the optical splitter 17 and the optical fiber joint box 11 to be Raman The light enters the end of the scattered optical fiber line 7. Inside the Raman scattering optical fiber line 7, in addition to the Rayleigh scattered light of the frequency ωo, Raman scattered light composed of two components of the frequency ωo−ωf (Stokes light) and ωo + ωf (anti-Stokes light) is generated.

Then, a part of the Rayleigh scattering and the Raman scattered light generated in the Raman scattering optical fiber line 7 returns to the optical fiber line 7, is emitted from the terminal portion thereof, and is branched by the optical branching device 17.
Further, the light is split into Stokes light and anti-Stokes light by another optical splitter 23, the intensities of these lights are detected by the photodetectors 24 and 25, respectively, and the output signal is sent to the data processing circuit 22. The data processing circuit 22 calculates the temperature of the Raman scattered optical fiber line 7 and calculates the distance based on the time difference between the pulse signal from the pulse generator 21 and the detection signal of the Raman scattered light from the photodetectors 24 and 25. Then, by performing continuous scanning on the display 26, a continuous temperature distribution in the longitudinal direction of the cable conductor 2 is detected through the temperature distribution of the Raman scattering optical fiber line 7. When the Raman scattering optical fiber line 7 is used, for example, the measurement temperature range is −20 to + 150 ° C., the measurement temperature accuracy is ± 1 ° C., and the measurement distance is 2 km.
(Resolution: 1m).

As described above, if the optical fiber composite overhead ground wires 1A and 1B in which the Raman scattered optical fiber wire 7 is provided along with the cable conductor 2, when an abnormal phenomenon such as lightning strike occurs on a part of the overhead transmission line 9, The occurrence point can be detected as described below.

<Detection of Temperature Distribution in Normal State> In a case where the area A to C shown in FIG. 4 is a monitoring area, if the monitoring area is in a normal state in which no abnormality occurs, the cable conductor 2 in that area Is close to the atmospheric temperature, the temperature distribution at this time is monitored as needed and adopted as a reference value. In the following description of abnormal phenomenon detection, for convenience, it is assumed that the temperature distribution in a normal state is uniform (a state in which there is no temperature difference in a flat state).

<Detection of Lightning Strike to Overhead Ground Wire> When a lightning strike occurs at a point in the area B in FIG. 4, the temperature of the cable conductor 2 at the point becomes extremely high locally due to arc heat, and Raman scattering occurs. By generating Raman scattered light based on the fact that the optical fiber line 7 is heated in the vicinity of the point to be in a high temperature state, it is detected that there is an abnormal portion (lightning point) in the temperature distribution.

Also, the so-called ground fault current flowing from the point to the ground is
A route from the tower 8 to the earth via the cable conductors 2 in the areas A and C via the route to the ground through the components of the transmission line structure (pylon) 8 on both sides of the point, and further to the adjacent area And the like via the cable conductor 2 of FIG. Therefore, when the cable conductor 2 in the section B is compared with the cable conductors 2 in the sections A and C, the cable conductor 2 in the section B has a relatively large Joule heating value due to the flow of a large ground fault current, and thus has a high temperature. And an abnormality in the temperature distribution is detected.

<Detection of ground fault point from transmission line to overhead ground line> In the area B in Fig. 4, a flashover accident in which a ground fault current flows from the point of the overhead transmission line 9 to the point of the optical fiber composite overhead ground lines 1A and 1B. Occurs, the vicinity of a point in the cable conductor 2 is heated by flash arc heat and the temperature locally rises,
When a large zero-sequence current flows, the Joule heat value becomes relatively large, and the temperature of the cable conductor 2 becomes higher than that of the A section or the C section, and the abnormality of the temperature distribution is detected. It becomes clear that the accident point exists in the area B.

<Detection of Lightning Lightning Point on Tower> When a lightning strike occurs on the tower 8 at the point in FIG. 4, a ground fault current from the point passes through the components of the lightning tower 8 to the ground, Area A and B on both sides of
The adjacent tower 8 through the cable conductor 2 of the area,
The route branches to the route to the ground through the next cable conductor 2 and the next steel tower 8. Therefore, the temperature of the cable conductors 2 in the sections A and B on both sides of the lightning strike becomes relatively high, and it is detected that an abnormal phenomenon has occurred between the sections A and B.

<Detection of reverse flashover due to lightning tower impact> If a lightning strike occurs at a point in Fig. 4 and a flashover phenomenon occurs between the points under the influence, the ground based on the lightning strike The short-circuit current and the ground fault current based on the grounding of the overhead transmission line 9 are superimposed, and current flows through the components of the tower 8, the cable conductors 2 in the B and C sections, and the cable conductors in the B and C sections. 2 is relatively high, and it is detected that an abnormal phenomenon has occurred between the area B and the area C.

As described above, when a lightning strike or a ground fault accident occurs somewhere in the transmission line network, the Raman scattering optical fiber wire 7 attached to the cable conductor 2 causes a change in the temperature distribution at which the occurrence point of the abnormal phenomenon becomes a high temperature state. The temperature distribution information signal is transmitted to the remote monitoring unit 13 by the optical fiber cable 6 for signal transmission and detected by
Alternatively, the faulty point of the cable conductor 2 between each diameter can be detected with high accuracy.

In the example of FIG. 4, the Raman scattered optical fiber line 7 is provided along with the areas A to C as one monitoring area, and the temperature distribution in this monitoring area is measured, and the optical terminal unit 10 and the optical fiber for signal transmission are measured. Although it is assumed that the signal is transmitted to a remote place by the cable 6, the number of the towers 8 monitored by the Raman scattered optical fiber line 7 and the optical terminal unit 10 can be of any number.

[Effect of the Invention] According to the method for detecting an accident point of an optical fiber composite overhead ground wire and an overhead transmission line according to the present invention: Since the scattered optical fiber line is also provided, by detecting the Raman scattering state when light is incident on the Raman scattered optical fiber line, it becomes possible to detect the temperature distribution of the entire overhead ground wire. In addition, by arranging the Raman scattering optical fiber line in a position surrounded by the cable conductor, it is protected from the outside and reduces the cooling of the Raman scattering optical fiber line when the cable conductor generates heat, thereby detecting the temperature distribution. It is to make it easier.

(2) The temperature distribution is measured using a Raman scattering optical fiber line, and the temperature distribution measurement data is transmitted to a remote monitoring unit via a signal carrier path using an optical fiber cable for signal transmission of an optical fiber composite overhead ground line, and is remotely controlled. By analyzing the received signal in the monitoring unit, it is possible to centrally manage the detection and determination of the occurrence position of the abnormal phenomenon of the overhead ground line in a remote place, and to reduce the temperature distribution of the overhead ground line by one Raman scattered light. By measuring with a fiber line, the monitoring range can be expanded with fewer devices compared to the conventional technology, and the labor can be reduced and the time until abnormality determination can be reduced.

(3) The detection of the point of occurrence of an abnormality is performed in units of a span of a steel tower or an overhead ground wire or in smaller units based on the accuracy of detecting the temperature distribution of a Raman scattered optical fiber line. The point of occurrence can be accurately located in a remote place.

(4) Since it is not necessary to use various devices such as various sensors having different functions as in the related art, it is possible to reduce the cost of the system configuration.

[Brief description of the drawings]

1 and 2 are cross-sectional views showing two embodiments of an optical fiber composite overhead ground wire according to the present invention. FIG. 3 is an enlarged view of the Raman scattering optical fiber line in FIGS. 1 and 2. FIG. 4 is a model diagram showing an embodiment of the method for detecting an accidental point of an overhead transmission line according to the present invention, and FIG. 5 is a block diagram showing an example of a temperature distribution measuring device for a cable conductor. 1A / 1B: Optical fiber composite ground wire, 2: Cable conductor, 2A: Outermost layer of twisted wire, 2B: Inner layer of twisted wire, 3 ... Aluminum tube, 4 ... Aluminum wire with groove, 5 ... Groove, 6 ... Optical fiber cable (optical fiber line) for signal transmission, 7 ... Raman scattering optical fiber line, 7a ... Optical fiber wire, 7b ... Ceramic layer, 7c ... Metal layer, 8 ... Wire structure (pylon), 9 overhead transmission line, 10 optical terminal equipment, 11 optical fiber joint box, 12 temperature distribution measuring device, 13 remote monitoring unit, 14 reception Unit, 15 Data processing device, 16 Display device, 17 Optical splitter, 18
…… Light source, 19 …… Light source driving device, 20 …… Pulse delay circuit, 21 …… Pulse generator, 22 …… Data processing circuit, 23
…… Optical splitter, 24 ・ 25 …… Receiver, 26 …… Display.

Claims (2)

(57) [Claims] An optical fiber composite overhead ground wire (1A) (1B) having a signal carrying optical fiber cable (6) provided along the longitudinal direction of the cable conductor (2) at the center of the cable conductor (2). ), A Raman scattering optical fiber line (7) is provided along the longitudinal direction at the center portion or at an inner position of the outermost layer (2A) of the stranded wire of the cable conductor (2). Optical fiber composite overhead ground wire. 2. Light is incident from the end of a Raman scattering optical fiber line (7) attached to an optical fiber composite overhead ground wire (1A, 1B) and is generated in the Raman scattering optical fiber line (7). Optical fiber composite overhead ground wire (1A)
The temperature distribution of the cable conductor (2) in (1B) is measured, and the measured temperature distribution data is transmitted to the remote monitoring unit (13) by the signal carrying optical fiber cable (6),
A fault detection method for an overhead transmission line, comprising: detecting whether a high-temperature portion exists in a cable conductor (2) by analyzing a received signal in a remote monitoring unit (13).