JP2581607B2 - Optical fiber laying structure for power cable line fault point detection system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distributed temperature sensor, and more particularly, to a system for detecting an accidental point in a power cable line using a Raman scattering type optical fiber type distributed temperature sensor, and more particularly to a distribution thereof. The present invention relates to a structure in which an optical fiber serving as a temperature detecting unit of a temperature sensor is laid on a power cable line.

2. Description of the Related Art Recently, as a system for detecting an occurrence point of an accident such as a ground fault in a power cable line, for example, as described in Japanese Patent Application Laid-Open No. 1-267428, a Raman scattering type optical fiber type distributed type is disclosed. Systems using temperature sensors have been developed. In other words, the Raman scattering type optical fiber type distribution type temperature sensor can measure the temperature distribution in the length direction of the optical fiber which is the temperature detecting part, and therefore, if the optical fiber is arranged along the power cable, By detecting a position (peak position) at which the temperature rises due to an accident such as a ground fault in the power cable line, it is possible to know the point where the accident has occurred.

The principle of temperature distribution measurement by the above-mentioned Raman scattering type optical fiber type distributed temperature sensor is as follows. That is, when the optical fiber light is incident, slight fluctuation of the refractive index in the optical fiber and light scattering due to absorption by molecules and atoms constituting the optical fiber and re-emission occur. The scattered light includes Rayleigh scattered light having the same wavelength as the incident light and Raman scattered light having a different wavelength from the incident light. The latter Raman scattered light is scattered light generated by thermal vibration of molecules and atoms constituting the optical fiber, and the intensity thereof largely depends on temperature. Therefore, pulsed light of a specific wavelength (usually a laser pulse) is used as the incident light, and the delay in the time until the light returns due to the scattered light and the intensity of the Raman backscattered light are detected. The temperature at each position in the vertical direction can be measured.

In general, when laying a power cable line, power cables (unit cables) of a certain length are sequentially connected, and therefore, a connection portion always exists in the power cable line. On the other hand, regarding the maintenance of power cables, it is rare that the same department or person in charge performs maintenance and management over the entire length of a long-distance power cable line.In general, the power cable line is divided into multiple maintenance sections. Usually, a different department or a maintenance manager is in charge of each maintenance section. In this case, the boundary of the maintenance section (maintenance demarcation point) is generally placed at the connection part of the power cable.

Therefore, in order to actually apply the power cable line fault point detection system using the optical fiber type distributed temperature sensor as described above, a conventional concrete method for laying the detection optical fiber along the power cable line is described. As a method, a method as shown in FIG. 6 has been adopted.

In FIG. 6, the power cable line 1 has connection portions 2A and 2A.
A plurality of unit cables 3A, 3B, 3C and 3D are connected in series via B and 2C.
Is divided into a plurality of maintenance sections 4A to 4D for each unit cable 3A to 3D with the center position of the connection sections 2A to 2C as a section boundary. The unit cables 3A to 3D of the maintenance sections 4A to 4D are provided with independent detection optical fibers 5A, 5B, 5C, and 5D, respectively, along the cables. And each optical fiber
The terminals 5A to 5D are connected to the distributed temperature sensor measuring units 6A to 6D, and the measuring units 6A to 6D are connected to the host computer 9.

In such a system, the temperature rise peak position in the power cable line, that is, the point where an accident such as a ground fault has occurred can be detected independently for each unit cable, in other words, for each maintenance section.

Problems to be Solved by the Invention As described above, in the maintenance management of the power cable line, since the departments and persons in charge of maintenance management are different for each maintenance section, it is necessary to determine in which maintenance section the accident occurred. It is necessary to know, and especially in the vicinity of the boundary of the maintenance section, it is necessary to accurately detect on which side of the maintenance section the accident has occurred. On the other hand, the boundary of the maintenance section is generally the connection part of the unit cable, but this connection part has a much higher frequency of ground faults and other accidents than the normal part of the power cable, so It is strongly desired to improve the accuracy of detecting the location where an accident has occurred.

By the way, the Raman scattering type optical fiber type distributed temperature sensor can detect the temperature rise peak position fairly accurately due to its characteristics. Therefore, the power cable line accident detection system using the temperature sensor has considerable accuracy. Can be used to detect the location of a ground fault, etc., but it is still insufficient to accurately detect which section the accident location belongs to near the boundary of each maintenance section as described above. In addition, it is still insufficient from the viewpoint of accurately detecting the position where an accident occurs at a connection part where the frequency of occurrence of the accident is high.

The present invention has been made in view of the above circumstances,
It is an object of the present invention to accurately detect a point where an accident such as a ground fault has occurred near a boundary position of a maintenance section in a power cable line or at a connection between unit cables.

Means for Solving the Problems The optical fiber laying structure for detection of the invention according to claim 1 is to arrange an optical fiber, which is a temperature detecting portion of a Raman scattering type optical fiber type distributed temperature sensor, along an electrode cable line,
In a power cable line fault point detection system that detects a temperature rise position in a power cable line to detect an accident point, the power cable line is divided into a plurality of sections, and optical fibers independent of each other in each section. In the vicinity of each section boundary, both the part of the optical fiber along one adjacent section and the part of the optical fiber along the other section overlap and are laid along the electrode cable. It is characterized by being along.

Further, in the optical fiber laying structure for detection according to the invention of claim 2, the optical fiber which is the temperature detecting portion of the Raman scattering type optical fiber type distributed temperature sensor is arranged along the power cable line in the same manner as described above. In a power cable line fault point detection system that detects a temperature rise position and detects an accident occurrence point, the power cable line has a configuration in which a plurality of unit cables are connected in series, and each unit cable is independent of each other. In the connection part of each unit cable, both a part of the optical fiber along one adjacent unit cable and a part of the optical fiber along the other unit cable are connected. It is characterized by being overlapped along.

In the optical fiber laying structure according to the first aspect of the present invention, in the area near the section boundary in the power cable line (hereinafter referred to as the section boundary area), the cable is routed along the cable in one of the two adjacent sections. A part of the optical fiber for detection and a part of the optical fiber for detection along the cable in the other section overlap with each other.
Therefore, when the temperature rises due to an accident such as a ground fault accident in the section boundary area, the temperature increase peak position, that is, the accident occurrence position is detected by two different optical fibers. If the accident occurrence position is detected by two different optical fibers in this way, the detection accuracy is significantly higher than that in the case of detecting by using only one optical fiber. For example, even if the temperature rise peak position obtained by one optical fiber is not always clearly defined, it can be clarified by superimposing information from two optical fibers, or can be obtained from the optical fiber. Even when the temperature peak position information deviates from the true position, an error can be reduced by averaging the position information obtained by the two optical fibers. Therefore, it is possible to accurately detect the accident occurrence position in the section boundary area and determine to which section the accident occurrence position belongs.

In the optical fiber laying structure according to the second aspect of the present invention, in each connection portion of the power cable line in which a plurality of unit cables are connected in series via the connection portion, the connection is made along one adjacent unit cable. A part of the optical fiber for detection and a part of the optical fiber for detection along the unit cable on the other side are overlapped.
Therefore, when the temperature rises due to an accident such as a ground fault at the connection part, the peak position of the temperature rise, that is, the accident occurrence position is detected by two different optical fibers. The location where the accident occurred can be detected with high accuracy within the department.

In an actual power cable line, the connection portion of the unit cable is often the boundary of the maintenance section, as described above. Therefore, in this case, the accident in the section boundary area in the invention of claim 1 occurs. The fact that the occurrence position is detected by the two optical fibers is the same as the fact that the accident occurrence position in the connecting portion is detected by the two optical fibers in the invention of claim 2. That is, in this case, it is possible to accurately detect an accident occurrence position such as a ground fault accident in the section boundary region and the connection portion at the same time.

Embodiment FIG. 1 shows an embodiment of the invention described in claim 1 and claim 2.
1 schematically shows the overall configuration of an embodiment that also serves as the embodiment of the invention described in FIG.

In FIG. 1, a power cable line 1 has a configuration in which a plurality of unit cables 3A to 3D are connected in series via connecting portions 2A, 2B, and 2C as in the conventional technology shown in FIG.
In addition, the power cable line 1 is divided into a plurality of maintenance sections 4A to 4D with the center of the connection sections 2A to 2C as section boundaries 7A to 7C. Therefore, the connection parts 2A to 2C are section boundary areas 8A to 8C, respectively. Optical fibers 5A to 5D are laid along the unit cables in the unit cables 3A to 3D of the maintenance sections 4A to 4D, respectively. These optical fibers 5A to 5D are connected to distributed temperature sensor measuring units 6A to 6D, respectively, and these distributed temperature sensor measuring units
6A to 6D are connected to the host computer 9. Here, each of the optical fibers 5A to 5D has a part thereof, that is, the leading end or the first part along the power cable line 1 is arranged along the connecting parts 2A to 2C, that is, the section boundary areas 8A to 8C. Therefore, two optical fibers are provided along each of the connection parts 2A to 2C, that is, each of the section boundary areas 8A to 8C. Specifically, as shown in FIG. 2A, at the connection portion 2A (ie, the section boundary area 8A) or the connection section 2C (ie, the section boundary area 8C), both of the optical fibers 5A and 5B or the optical fiber As shown in FIG. 2 (B), in both of 5C and 5D, the portion of the power cable line 1 at the beginning of the alignment is overlapped, and at the connection portion 2B (ie, section boundary area 8B), The distal ends of both optical fibers 5B and 5C are overlapped along.

The specific configuration of the distributed temperature sensor measuring units 6A to 6D to which the optical fibers 5A to 5D are connected may be the same as a general configuration, but is usually configured as shown in FIG. That is, the measurement units 6A to 6D are for applying laser pulse light as incident light to the optical fiber, separating the Raman backscattered light returning from the optical fiber, receiving the light, and amplifying and averaging it. As shown in FIG. 3, a laser light source 10 for oscillating laser pulse light as incident light, a driving circuit 11 for driving the laser light source 10, and reflections returning from the optical fibers 5A to 5D. A separation duplexer 12 for separating the Raman scattered light from the scattered light, a cut duplexer 13 for cutting a light component other than the Raman light in the Raman scattered light, and the cut duplexer 13 Light-receiving element 14 for converting Raman scattered light output from the optical signal into an electric signal, an amplifier 15 for amplifying the electric signal from the light-receiving element 14, and an averaging circuit for improving the S / N ratio of the electric signal 1
And 6. The output signals of the measuring units 6A to 6D (output signals of the averaging circuit 16) are supplied to the host computer 9, and a signal for control from the host computer 9 is supplied to the measuring unit 6. The host computer 9 calculates the temperature distribution in the length direction of each of the optical fibers 5A to 5D by performing arithmetic processing on the electric signals from the measuring units 6A to 6D. Accident occurrence point is required. At this time, as described above, in the connecting portions 2A to 2C (section boundary regions 8A to 8C), each part of the two optical fibers is overlapped along, so that two light The information obtained from the signal from the fiber is subjected to arithmetic processing in the host computer 9 so that the temperature rise peak position, that is, the accident occurrence position such as a ground fault accident can be obtained with high accuracy.

The specific mode of arranging the optical fibers 5A to 5D along the unit cables 3A to 3D and the connecting portions 2A to 2C is arbitrary,
For example, as shown in FIGS. 2 (A) and 2 (B), it is supported along a straight line along its length by a suitable supporting means (not shown), or as shown in FIG. It may be spirally wound. Also here the connection
In 2A to 2C, a part of each of the two optical fibers is overlapped and along, not limited to the case where the double optical fibers are overlapped or arranged side by side on the same side of the connection parts 2A to 2C, For example, as shown in FIG.
And the case of arranging them on the opposite side.

Further, in the embodiment of FIGS. 1 and 2 (A) and (B) described above, the section boundaries 7A to 7C are shown as being located at the center of the connection parts 2A to 2C, but the section boundaries 7A to 7C are In some cases, the section boundary areas 8A to 8C may be set to the same area as the connection sections 2A to 2C as in the above-described example. Depending on the area including both sides of the section boundaries 7A to 7C of the ends of the connection parts 2A to 2C, that is, the area including both the connection part and the end of the unit cable subsequent thereto may be defined as the section area. good.

In addition, the section boundaries 7A to 7C may be set at positions independent of the connection sections 2A to 2C, and in such a case, the section boundary areas 8A to 8C are also located at positions away from the connection sections 2A to 2C. Therefore, the embodiment of the invention of claim 1 and the embodiment of the invention of claim 2 are different.

According to the optical fiber laying structure in the power cable line fault point detection system of the first aspect of the present invention, a part of the optical fiber for detection of another system overlaps with the area near the section boundary in the power cable line. In that area, the temperature rise peak position, that is, the position where an accident such as a ground fault has occurred is detected by two separate optical fibers,
Therefore, the position can be detected with high accuracy, and it can be easily determined in which of the adjacent sections the accident occurrence position has occurred.

Further, according to the optical fiber laying structure for detection in the power cable line fault point detection system according to the second aspect of the present invention, the optical fiber of another system is overlapped along the connecting portion of each unit cable in the power cable line. ,
At that connection, the temperature rise peak position, that is, the position where an accident such as a ground fault has occurred, is detected by two separate optical fibers. Can be detected.

[Brief description of the drawings]

FIG. 1 is a schematic illustration showing an entire configuration of an example of a detection optical fiber laying structure in a power cable line accident occurrence point detection system according to the present invention, and FIGS. 2 (A) and 2 (B) each show an example in FIG. FIG. 3 is a block diagram showing an example of a measuring unit used in the power cable line accident occurrence detection system of the present invention; FIG. 4 and FIG. FIG. 6 is a front view showing another example of the main part of the optical fiber installation structure, and FIG. 6 is a schematic illustration showing an example of a detection optical fiber installation structure in a conventional power cable accident point detection system. 1 ... power cable line, 2A, 2B, 2C ... ... connection part, 3A, 3B,
3C, 3D: Unit cable, 4A, 4B, 4C, 4D: Maintenance section, 5
A, 5B, 5C …… Optical fiber, 7A, 7B, 7C …… Section boundary, 8A, 8
B, 8C, 8D ... Section boundary area.

Claims (2)

(57) [Claims] 1. An electric power cable for locating an optical fiber, which is a temperature detecting portion of a Raman scattering type optical fiber distributed temperature sensor, along a power cable line, detecting a temperature rise position in the power cable line, and detecting an accident occurrence point. In the line fault point detection system, the power cable line is divided into a plurality of sections, and in each section, optical fibers independent from each other are laid along the power cable, and are adjacent to each other near the section boundary. In the power cable line fault point detection system, both the part of the optical fiber along one section and the part of the optical fiber along the other section are overlapped along. Optical fiber laying structure for detection. 2. An electric power cable for locating an optical fiber which is a temperature detecting portion of a Raman scattering type optical fiber type distributed temperature sensor along an electric power cable line, detecting a temperature rise position in the electric power cable line and detecting an accident occurrence point. In the line fault point detection system, the power cable line has a configuration in which a plurality of unit cables are connected in series, and an optical fiber independent of each unit cable is run along each unit cable. Is a power cable, wherein both a part of the optical fiber along the one adjacent unit cable and a part of the optical fiber along the other unit cable are overlapped and run. Optical fiber laying structure for detection in track fault point detection system.