JPH0787051B2 - Power cable and its temperature distribution measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention measures the temperature distribution in the longitudinal direction of a power cable based on the fact that the intensity of Raman scattered light is a function of temperature to detect thermal behavior and accident points. The present invention relates to a power cable used in a vehicle and its temperature distribution measuring method.

[Conventional technology]

Generally, in order to manage the allowable current of the power cable,
It is conceivable to measure the temperature distribution in the longitudinal direction of the power cable, and as a means for measuring this temperature distribution,
Conventionally, many thermocouples are attached at predetermined intervals along the longitudinal direction of the power cable to measure the temperature.

[Problems to be Solved by the Invention]

However, in such a conventional technique, a large number of thermocouples have to be mounted at a predetermined interval along the longitudinal direction of the power cable, which requires a large number of mounting steps,
There is a problem that the number of measurement points becomes very large and the price as a temperature distribution measuring means becomes enormous. Moreover, since the temperature distribution along the longitudinal direction of the power cable is partially measured, there is a problem that the measurement temperature accuracy is low.

In order to provide the temperature measuring element on the power cable, it is necessary to protect the temperature measuring element from damage when the power cable is attached.

Therefore, the present invention has been made in consideration of the above circumstances,
An object of the present invention is to provide a power cable capable of easily and inexpensively measuring the temperature distribution in the longitudinal direction and highly accurately, and a temperature distribution measuring method thereof.

[Means for Solving the Problems]

The power cable according to the present invention is a power cable in which a cable conductor is insulated with an insulator, a shield layer in which a metal element wire is spirally wound is provided on the outer periphery of the insulator, and a jacket is provided on the outer periphery of the shield layer. It is characterized in that one or more Raman scattering optical fiber core wires are provided between the metal wires of the shielding layer and spirally wound around the outer periphery of the insulator and along the longitudinal direction of the power cable.

The power cable according to the present invention is a power cable in which a cable conductor is insulated with an insulator, and an outer jacket is provided on the outer periphery of the insulator, wherein the outer jacket has a corrugated tube. It is characterized in that one or more Raman scattering optical fiber core wires are provided along the longitudinal direction and spirally wound so as to be positioned in an outer valley portion or an inner valley portion of the corrugated tube.

The method for measuring the temperature distribution of a power cable according to the present invention is such that a cable conductor is insulated with an insulator, a shield layer in which a metal wire is spirally wound is provided on the outer periphery of the insulator, and a jacket is provided on the outer periphery of the shield layer. In the method for measuring the temperature distribution of a power cable provided, one or more Raman scattering optical fibers which are located between the metal wires of the shielding layer, are spirally wound around the outer circumference of the insulator, and are provided along the longitudinal direction of the power cable. Raman scattering is generated in the optical fiber core by injecting pulsed light from the end of the core wire, the Raman scattered light intensity is detected, and the temperature distribution in the longitudinal direction of the power cable is based on the Raman scattered light intensity. Is measured.

Further, the temperature distribution measuring method for a power cable according to the present invention is a method for measuring a temperature distribution of a power cable in which a cable conductor is insulated with an insulator and a jacket is provided on the outer periphery of the insulator, wherein the jacket is a corrugated tube. From one end of one or more Raman scattering optical fiber cores provided along the longitudinal direction of the power cable and spirally wound inside the outer trough or inner trough of the corrugated tube. Raman scattering is generated in the optical fiber core by making pulsed light incident, the Raman scattered light intensity is detected, and the temperature distribution in the longitudinal direction of the power cable is measured based on the Raman scattered light intensity. It is what

[Operation and effect of the invention]

According to the invention of claim 1, one or more Raman scattering optical fiber core wires are located between the metal wires of the spirally wound shield layer, spirally wound around the outer periphery of the insulator, and provided along the longitudinal direction of the power cable. Therefore, the resolution of the temperature distribution measurement in the longitudinal direction is improved as compared with the case where the optical fiber core wire is vertically attached to the power cable (is provided parallel to the power cable). That is, due to the spiral winding of the Raman scattering optical fiber core wire, the winding pitch of the optical fiber core wire with respect to the longitudinal direction of the power cable becomes shorter than that in the case where the optical fiber core wire is longitudinally attached, so that the resolution of the temperature distribution measurement for the power cable becomes high. It is a thing. For example, if the resolution is 1 m vertically and the measurement interval is 1 m, spiral winding Measurement interval. In addition, P is a pitch and D is a winding diameter.

Further, if a plurality of Raman scattering optical fiber core wires are provided, the temperature of each optical fiber core wire can be measured at positions apart from each other in the circumferential direction of the power cable, so that the temperature distribution measurement of the power cable in the circumferential direction can be performed.

Further, since the Raman scattering optical fiber core wire is spirally wound, when the power cable is subjected to bending stress, the Raman scattering optical fiber of the present invention is compared to when the Raman scattering optical fiber is erected on the power cable. Bending stress on the core wire is small and bending strain is small. Since the optical fiber core wire causes a loss in the guided light due to bending strain, the Raman scattering optical fiber core wire of the present invention has a small loss of the guided light because the bending strain is small as described above. Also,
Since the bending stress is reduced, damage to the optical fiber can be prevented.

In addition, since the Raman scattering optical fiber core wire is positioned between the metal wires of the shield layer and spirally wound around the outer periphery of the insulator, in the conventional power cable manufacturing process, the metal wire is used when the shield layer is formed. It can be provided on the power cable by winding at the same time. Therefore, the temperature distribution of the power cable can be measured without changing the manufacturing process of the conventional power cable.

Further, since the Raman scattering optical fiber core wire is located between the metal wires of the shielding layer and covered by the outer cover, it is not subjected to external compressive strain. Therefore, the Raman scattering optical fiber core wire is surely protected from damage.

Further, the Raman scattering optical fiber core wire is usually covered with a metal sheath, and even if it is located between the metal wires, the electric field generated from the cable conductor is not concentrated on the Raman scattering optical fiber core wire. Therefore, the temperature distribution of the cable can be detected without disturbing the electric field distribution of the conventional power cable.

Further, according to the invention of claim 2, one or more Raman scattering optical fiber core wires are provided by being spirally wound in the outer valley portion or the inner valley portion of the corrugated tube, and thus provided. The stress applied to the power cable after laying or laying is not applied to the Raman scattering optical fiber core, and the fiber core is reliably protected from damage. If the Raman scattering optical fiber core is located in the outer valley of the corrugated tube, the stress applied to the power cable is supported by the crest of the corrugated tube, and if it is located in the inner valley of the corrugated tube. It is supported by the tube itself, and in any case no stress is applied to the Raman scattering optical fiber core.

Further, since the Raman scattering optical fiber core wire is positioned in the outer valley portion or the inner valley portion of the corrugated tube, the Raman scattering optical fiber core wire can be easily positioned when winding the fiber core wire.

In addition, since the Raman scattering optical fiber core wire in the longitudinal direction of the power cable is provided, it is possible to measure the temperature distribution in the longitudinal direction with high accuracy, and it is possible to detect the fault point of the cable and monitor the thermal behavior. It will be possible. In particular, by providing the optical fiber core wire in a part of the shielding layer, the hot spot portion of the insulator can be detected, and the portion where the insulation performance is impaired can be predicted. As a result, the current carrying capacity can always be maintained efficiently. Further, since the Raman scattering optical fiber core wire is provided on the outer jacket, the outside air temperature of the power cable can be measured together.

Further, according to the invention of claim 3 or 4, said claim 1
In addition, when pulsed light is incident on the end portion of the optical fiber core wire of No. 2, Raman scattering occurs in the optical fiber core wire, and the intensity of this Raman scattered light is represented by a function that depends on temperature. The temperature distribution in the longitudinal direction of the power cable can be obtained from the strength. Therefore, by providing one Raman scattering optical fiber core wire, it is possible to monitor the thermal behavior of the power cable and detect an accident point. Further, since the Raman scattering optical fiber core wire is used, the measurement work becomes easier and the measurement can be performed at a lower cost as compared with the method of measuring the temperature distribution by a thermocouple.

〔Example〕

 Hereinafter, the present invention will be described based on illustrated embodiments.

FIG. 1 shows a power cable according to a first embodiment of the present invention. As shown in the figure, a power cable 1 includes a cable conductor 2 in which a plurality of copper strands are twisted together to form each divided conductor, an inner semiconductive layer 3, a polyethylene insulating layer (insulator) 4, and an outer semiconductive layer 5 Are usually provided sequentially, and the inner semiconductive layer 3, the polyethylene insulating layer 4, and the outer semiconductive layer 5 are usually formed by a coextrusion method.
And the insulating layer 4 and the outer semiconductive layer 5 are integrated. Then, a cushion layer 6 formed by winding a semiconductive cushion tape is provided on the outer periphery of the outer semiconductive layer 5, and a shielding layer 8 is provided on the cushion layer 6 by spirally winding a large number of copper strands. A cable sheath 9 made of plastic, metal or the like is coated thereon.

Further, the shielding layer 8 is located between the metal wire tubes, is spirally wound around the outer periphery of the cushion layer 6 (outer periphery of the insulating layer 4), and is electrically insulating along the longitudinal direction of the power cable. Four Raman scattering optical fiber core wires 7 are provided in the circumferential direction. As shown in FIG. 2, the optical fiber core wire 7 is obtained by coating an optical fiber wire 7a with a lubricating powder such as talc powder or a ceramic layer 7b such as alumina (Al ₂ O ₃ ) and the outer periphery of the ceramic layer 7b. Is provided with a metal layer 7c of copper, aluminum, stainless steel or the like. Although four Raman scattering optical fiber core wires 7 are provided on the outer periphery of the insulating layer 4 in the present embodiment, the present invention is not limited to this, and at least one or more may be provided. Therefore, by providing the Raman scattering optical fiber core wire 7 in a part of the shielding layer 8,
When pulsed light is incident from the end of the optical fiber core wire 7, Raman scattering occurs in the optical fiber core wire 7, and the temperature distribution in the longitudinal direction of the insulating layer 4 can be obtained from the intensity of this Raman scattered light. .

As described above, according to this embodiment, the temperature distribution in the longitudinal direction of the insulating layer 4 can be measured without impairing the insulating performance. In addition, the Raman scattering optical fiber core wire 7 is positioned between the metal wires of the spirally wound shield layer 8 and the insulator 4
Since it is spirally wound around the outer circumference of and is provided along the longitudinal direction of the power cable 1, the optical fiber core wire 7 is provided in the longitudinal direction as compared with the case where the optical fiber core wire 7 is provided upright on the power cable 1 (provided in parallel to the power cable 1). The resolution of temperature distribution measurement is improved. That is, the spiral winding of the Raman scattering optical fiber core wire 7 makes the pitch in the length direction of the power cable 1 shorter than that in the case where the power cable 1 is erected.
The resolution of the temperature distribution measurement with respect to is higher.

Further, if a plurality of Raman scattering optical fiber core wires 7 are provided, as shown in FIG. 1, it is possible to measure the temperature at positions separated in the circumferential direction of the power cable 1 with each optical fiber core wire 7. The temperature distribution in the circumferential direction of the power cable 1 can be measured.

In addition, since the Raman scattering optical fiber core wire 7 is spirally wound, when the power cable 1 receives bending stress, the Raman scattering optical fiber core wire 7 is compared to when the Raman scattering optical fiber core wire 7 is erected on the power cable 1. The bending stress on the scattered optical fiber core wire 7 is small, and the bending strain is small. Since the optical fiber core wire 7 causes a loss in the guided light due to bending strain, the Raman scattering optical fiber core wire 7 of the embodiment has less bending loss because the bending strain is further reduced.

Further, since the Raman scattering optical fiber core wire 7 is positioned between the metal wires of the shield layer 8 and spirally wound around the outer periphery of the insulating layer 4, the shield layer 8 is used in the conventional power cable manufacturing process.
It can be provided on the power cable by winding it at the same time as forming the metal wire. Therefore, the temperature distribution measurement of the power cable 1 can be detected without changing the conventional manufacturing process of the power cable 1.

Further, since the Raman scattering optical fiber core wire 7 is located between the metal wires of the shielding layer 8 and covered with the cable sheath (outer sheath) 9, it is not subjected to external compressive strain.

Further, the Raman scattering optical fiber core wire 7 is covered with the metal layer 7c, and even if the fiber core wire 7 is located between the metal wires, the electric field generated from the cable conductor 2 is not concentrated on the Raman scattering optical fiber core wire 7. . Therefore, the temperature distribution of the power cable 1 can be detected without disturbing the electric field distribution of the conventional power cable. In particular, in the case where the metal wires of the shielding layer 8 and the Raman scattering optical fiber core wire 7 of the embodiment are arranged at equal intervals, the electric field distribution is not disturbed or small.

Next, a method for measuring the temperature distribution in the longitudinal direction of the insulating layer 4 using the temperature distribution measuring device 10 as shown in FIG. 3 will be described. In the figure, the power cable 1 including the Raman scattering optical fiber core wire 7 is arranged in a power transmission system in which the temperature distribution is to be measured. Temperature distribution measuring device 10
Has an optical branching device 15, a light source 14 is provided at one port of the optical branching device 15, and a detection system is provided at the other port. The light source 14 includes a light source driving device 13 and a pulse delay circuit 1
2, pulse generator 11 is connected, pulse generator 11
The signal output from the light source driving device 13 is directly input to the data processing circuit 19, while the pulse signal delayed by the pulse delay circuit 2 for a predetermined time is input to the light source driving device 13. Light source drive
The light source 14 drives the light source 14 in accordance with the input pulse signal, and the light source 14 emits pulsed light of frequency ω ₀ . The pulsed light from the light source 14 passes through the optical branching device 15 and enters the end portion of the Raman scattering optical fiber core wire 7 in the power cable 1. Other Rayleigh scattered light of the frequency omega ₀ is in the optical fiber 7, the Raman scattering of two components of the frequency ω ₀ -ω _{f (Stokes} light) and ω _{0 +} ω _{f (anti-Stokes} light) occurs.

Part of the Rayleigh scattered light and Raman scattered light generated in the Raman scattering optical fiber core wire 7 returns through the optical fiber core wire 7,
The light is emitted from the terminal portion and branched by the optical branching device 15, further branched by the optical branching device 16 into Stokes light and anti-Stokes light, and the intensities of these lights are respectively detected by the light receivers 17 and 18,
This output signal is sent to the data processing circuit 19. In the data processing circuit 19, the temperature of the optical fiber core wire 7 is obtained, and the distance is determined based on the time difference between the pulse signal from the pulse generator 11 and the Raman scattered light detection signals from the light receivers 17 and 18. Then, by continuously scanning the display 20, the temperature distribution in the longitudinal direction of the insulating layer 4 can be obtained through the temperature distribution of the Raman scattering optical fiber core wire 7. Here, the measurement temperature range of the Raman scattering optical fiber core wire 7 in this embodiment is −20 to + 150 ° C., the measurement temperature accuracy is ± 1 ° C., and the measurement distance is 2 km (resolution: 1 m).

As described above, according to this embodiment, since the two-wavelength measurement method is adopted, there is no influence of disturbance. Also,
Since the temperature distribution in the longitudinal direction of the insulating layer 4 of the power cable 1 can be measured with one Raman scattering optical fiber core wire,
It is possible to provide an inexpensive power cable for measuring temperature distribution, which is easy to perform the measurement work.

FIG. 4 shows a power cable according to a second embodiment of the present invention. The same parts as those of the first embodiment will be designated by the same reference numerals and will be described. In this embodiment, the power cable 1 shown in FIG. A power cable 1A is configured by sequentially providing a cushion layer 31, a corrugated pipe 32 made of aluminum or stainless steel, and an anticorrosion layer 33 on the outer periphery of the power cable 1A to form an anticorrosion layer 33.
A Raman scattering optical fiber core wire 7 having electrical insulation is spirally wound along the longitudinal direction. in this case,
As shown in FIG. 4 (b), the optical fiber core wire 7 is provided with a corrosion protection layer 33
It is provided inside by a spiral winding so as to be located inside the valley outside the corrugated pipe 32 and in contact with the valley.
Therefore, the optical fiber core wire 7 is protected without being damaged when the power cable 1A is installed. Then, when pulsed light is incident from the end of the optical fiber core wire 7, Raman scattering occurs in the optical fiber core wire 7, and the temperature distribution in the longitudinal direction of the power cable 1A can be obtained from the intensity of the Raman scattered light. become. Of course, similarly to the first embodiment, the resolution of temperature distribution measurement for the power cable 1 is higher than that in the case where the Raman scattering optical fiber core wire 7 is stood upright. Further, since the Raman scattering optical fiber core wires 7 are separated from each other in the circumferential direction, the temperature distribution can be measured in the circumferential direction.

Next, the method for measuring the temperature distribution in the longitudinal direction of the power cable 1A of this embodiment is performed using the temperature distribution measuring device 10 of FIG. 3 as in the first embodiment. That is, similarly to the first embodiment, the power cable 1A is arranged in a power transmission system whose temperature distribution is to be measured, and the Raman scattering optical fiber core wire 7 is provided along the longitudinal direction of the anticorrosion layer 33 of the jacket 30. The pulsed light is incident from the end of the optical fiber to generate Raman scattering in the optical fiber core wire 7, the Raman scattered light intensity is detected, and the temperature distribution is measured in the longitudinal direction of the power cable 1A based on the Raman scattered light intensity. can do.

FIG. 5 shows a modified example of the second embodiment of the present invention. In this modified example, a Raman scattering optical fiber core having an electrically insulating property is provided along the longitudinal direction of the cushion layer 31 in the jacket 30. The wire 7 is spirally wound to form the power cable 1B. According to this modification, since the optical fiber core wire 7 is positioned in the inner valley portion of the corrugated tube 32 and provided by spiral winding, the optical fiber core wire 7 is provided in comparison with the power cable 1A shown in FIG. It becomes more difficult to damage and durability is improved. The rest of the configuration, action, and temperature distribution measuring method are the same as in the first embodiment, so description thereof will be omitted.

In the second embodiment, four Raman scattering optical fiber core wires 7 are provided in the circumferential direction, but if at least one Raman scattering optical fiber core wire 7 is provided, the temperature distribution can be measured.

As described above, according to the second embodiment, the Raman scattering optical fiber core wire 7 is insulated even when a large number of power cables are stacked and installed regardless of the configuration in which the Raman scattering optical fiber core wire 7 is provided on the jacket 30. By having the property, it becomes possible to measure the temperature distribution accurately without inducing obstacles.

[Brief description of drawings]

1 is a schematic sectional view showing a power cable according to a first embodiment of the present invention, FIG. 2 is a schematic sectional view showing a Raman scattering optical fiber core wire of FIG. 1, and FIG. 3 is used in the present invention. A block diagram showing a temperature distribution measuring device, FIGS. 4 (a) and 4 (b) are a schematic sectional view showing a power cable according to a second embodiment of the present invention, a partial longitudinal sectional view, and FIGS. 5 (a) and 5 (b). 4] A schematic sectional view and a partial vertical sectional view showing a modified example of FIG. 1,1A, 1B ... Power cable, 2 ... Cable conductor, 4 ...
... polyethylene insulation layer (insulator), 7 ... Raman scattering optical fiber core wire, 8 ... shielding layer, 10 ... temperature distribution measuring device, 30 ... jacket, 31 ... cushion layer, 32 ... corrugated layer , 33 …… Anticorrosion layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Isao Kaji 1-5-1 Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. (72) Inventor Hajime Takehana 1-1-5 Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. (72) Inventor Isao Miura 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. (56) Reference JP-A-1-267428 (JP, A)

Claims (4)

[Claims] 1. A power cable in which a cable conductor is insulated by an insulator, a shield layer in which a metal element wire is spirally wound is provided on the outer periphery of the insulator, and a jacket is provided on the outer periphery of the shield layer. A power cable, characterized in that it is located between the metal wires of a layer, spirally wound around the outer periphery of the insulator, and provided with one or more Raman scattering optical fiber cores along the longitudinal direction of the power cable. 2. A power cable in which a cable conductor is insulated with an insulator and an outer jacket is provided on the outer periphery of the insulator, wherein the outer jacket has a corrugated tube and extends along the longitudinal direction of the power cable. A power cable, wherein one or more Raman scattering optical fiber core wires are provided by being spirally wound in an outer valley portion or an inner valley portion of the corrugated tube. 3. A temperature distribution measurement of a power cable, wherein a cable conductor is insulated with an insulator, a shield layer in which a metal element wire is spirally wound is provided on the outer periphery of the insulator, and a jacket is provided on the outer periphery of the shield layer. In the method, pulsed light is emitted from the end portions of one or more Raman scattering optical fiber core wires which are positioned between the metal wires of the shielding layer, spirally wound around the outer circumference of the insulator, and provided along the longitudinal direction of the power cable. Raman scattering is generated in the optical fiber core upon incidence, and the Raman scattered light intensity is detected,
A temperature distribution measuring method for a power cable, comprising measuring a temperature distribution in a longitudinal direction of the power cable based on the Raman scattered light intensity. 4. A temperature distribution measuring method for a power cable, wherein a cable conductor is insulated with an insulator, and a jacket is provided on the outer periphery of the insulator, wherein the jacket has a corrugated tube and the length of the power cable is long. Along the direction of the corrugated pipe, one or more Raman-scattering optical fibers provided inside the outer or inner valley of the corrugated tube and spirally wound, and pulsed light is incident from the end of the optical fiber. Raman scattering is generated in the core wire, the intensity of the Raman scattered light is detected, and the temperature distribution in the longitudinal direction of the power cable is measured based on the Raman scattered light intensity. .