WO2009079920A1 - A compound fiber high-power cable - Google Patents

Abstract

A compound fiber high-power cable is disclosed. The said cable is made of a core and a jacket which surrounds the core. The core has a conductor, an insulating layer and a metal shielding layer. There is at least one channel in the core, and at least an optical cable is configured in the channel, the channel's diameter is bigger than the optical cable's, and the optical cable's length is longer than the channel's, the optical cable is extending in the channel crookedly. At the truncation suface of the cable, the optical cable can be pull out partly, and can move back into the channel entirely or partly.

Description

 Composite optical fiber high voltage power cable

Technical field

 The present invention relates to cables, and more particularly to a high voltage power cable in which a probe fiber is disposed within a cable. Background technique

 To ensure the safe operation of high-voltage underground cable systems, the power sector needs to conduct on-line monitoring. The main contents of online monitoring include load monitoring and fault monitoring.

 Cable load capacity constraints are primarily derived from the allowable operating temperature limits for cable and cable accessory manufacturing materials. For example, for XLPE cables, the temperature of the cable conductor, that is, the temperature of the XLPE adjacent to the conductor, is usually not specified to exceed 85 ° C or 90 ° C. In cable and cable system design, the load capacity is designed primarily in accordance with the conductor temperature limits. The load capacity of cable systems is usually designed in accordance with IEC60287 and IEC853 standards. These standards assume that the load current is constant or varies substantially according to a daily load curve pattern and assumes that ambient environmental conditions are determined. In order to ensure the safety of the design, the assumed conditions are often extreme, resulting in the low actual operating load of the cable system and the possibility of underutilization of assets. In fact, due to the electrical interaction of the cables and the complexity of the heat transfer problems, the above criteria are unlikely to provide a reliable and accurate solution for cables in more complex installation environments, especially multi-circuit. On-line detection of cable temperature provides a way to solve this problem. Conductor temperature is very important and can be used directly as a key indicator of load monitoring.

 The ambient conditions of the actual running cable system are complex, and its state may migrate, with a high degree of uncertainty. Therefore, it is impossible to reliably determine the highest temperature of the cable without detecting the temperature distribution of the entire cable. The highest point of cable temperature is also the de facto load bottleneck. A more complicated reality is that the position of the bottleneck point on the same cable changes, and multiple bottlenecks may occur in the same cable over a period of time.

In the prior art, the online load monitoring of the cable usually adopts the method of distributed temperature sensor (DTS). Using DTS The technology can detect a temperature distribution of several kilometers to several tens of kilometers of fiber, and the sampling point distance can reach 1 to 2 meters. By arranging the temperature measuring fiber along the axial direction of the cable, the axial temperature distribution of the cable can be obtained. It is generally believed that since the conductor of the high voltage cable is at a high voltage potential, it is wrapped by an insulating layer that is not damaged by integrity, and the optical fiber cannot be placed on or in the conductor and drawn out to the outside of the ground potential. Therefore, it is not feasible to directly measure the conductor temperature using DTS technology.

 At present, there are two main methods for measuring the temperature of a conductor - 1. External type: The optical cable containing the temperature measuring fiber is arranged on the surface of the cable;

 2. Built-in type: In the cable manufacturing stage, the temperature measuring fiber or fiber optic cable is added to a layer or a layer outside the cable insulation layer, typically outside the semiconductor insulation shield and in the metal sleeve.

 Although the temperature measured by the above two methods is not the conductor temperature of the cable, it still has important reference value. Taking the temperature-measuring fiber as the outer boundary, a heat transfer partial differential equation model is established for the cable, and the real-time load current and the real-time fiber temperature are continuously input, and the output real-time conductor temperature can be calculated. Korean Patent Publication No. 2003-45864 discloses a system for setting a temperature measuring fiber in a cable for calculating the temperature of an underground power cable conductor.

 In detail, the external temperature measuring fiber can be used to fix the cable to the surface of the cable by manually tying or bonding the cable in the cable tunnel and the direct buried cable in front of the backfill. However, for the cable laid by the pipe, the cable is usually pulled into the pipe after the cable is piped. At this time, the cable is unlikely to be in close contact with the cable surface as in the above case, some of the cables may be in contact with the cable surface, and some may not be in contact with the cable and suspended in the medium in the tube. This will introduce the model into uncertain factors, resulting in larger calculation errors.

Chinese Patent Publication No. CN1624812A, Japanese Patent Publication Nos. 1990-144810, 1994-148001, 1994-181013, 1994-181014 and 1994-181015 disclose high-voltage power cables of various composite optical fibers, which are all arranged in cable insulation. Between the layer and the sheath, it is built-in. In the built-in method, the cable is very consistently located in a layer outside the cable insulation, which solves the above-mentioned external problem, but must deal with the problem of the connection of the fiber at the cable connector, which complicates the cable connector installation process. Usually use a jumper The optical cable, two welding points, are respectively welded to the optical fiber taps of the two cables. That is to say, in order to monitor the temperature distribution of a cable, the number of fusion points on the temperature measuring fiber is at least twice the number of cable joints. For longer cables, the number of fiber splices may be too large. The fiber fusion splice has a certain loss and unreliability, which has a negative impact on DTS temperature measurement. Another significant disadvantage of the built-in type is that it is subject to tension during the manufacturing, coiling, transport, installation, and operation phases of the cable due to the location of the fiber. The mechanical strength of the fiber is very low and cannot be repaired once it is damaged. Therefore, high requirements are placed on the design, manufacture and construction of optical fiber protection.

 In addition to damage from external forces, manufacturing defects in cables and their accessories, defects in mounting quality, and aging of insulation can cause cable failure. These faults usually have a process in which the insulation is degraded and a partial discharge occurs before the cable is finally destroyed. The detection of partial discharge is an important means of fault monitoring. Optical fiber sensing technology can be used for the detection of partial discharges, such as ultrasonic waves and other abnormal mechanical vibrations generated by partial discharge of cables. This requires the placement of the probe cable along the length of the cable, as well as the problems associated with the placement of the cable described above. Moreover, since the propagation of the ultrasonic waves is directional and rapidly decays, partial discharges of the same intensity occur on the same cross section, and the detection fibers disposed on the eccentric side may give different detection amounts due to different angles of the partial discharge positions. , may not even detect it.

Statistics show that the cable joints and cable terminals have a failure rate far greater than the failure rate of the cable body in the years before the cable system was put into operation. Types of failure include both overheating due to poor connections of the cable conductors or the poor connection of the terminals, as well as insulation faults caused by defects or defective points introduced in the cable intermediate joints and cable terminations during the design, manufacturing and installation phases. In the above cable arrangement, the detecting fiber is located outside the cable insulation of the ground potential, and the geometrical dimension of the insulating portion is greater than the insulation of the cable body. In more cases, the optical fiber even has to be arranged with a larger geometric size. The cable metal shield or cable connector is waterproof outside the sleeve. At this time, the temperature at which the position of the detecting fiber is located is relatively weak and lagging as compared with the case of the cable body. The mathematical model for calculating the conductor temperature established for the cable body cannot be applied here, and the temperature abnormality of the cable is not easily detected. Similarly, the partial discharge signal generated by the internal insulation fault is also attenuated by the thicker insulation and other protection, and is not easily detected by the probe fiber. Summary of the invention

 SUMMARY OF THE INVENTION It is an object of the present invention to overcome the above-discussed deficiencies of the prior art and to provide a high voltage power cable including a probe fiber. The high-voltage power cable of the composite optical fiber of the present invention directly detects the cable conductor temperature, provides a critical state variable for load monitoring, and is in an optimal position for detecting ultrasonic waves generated by partial discharge, and the detection fiber is located at a minimum deformation when the cable is bent. In the area, the optical fiber is protected by the structure of each layer of the cable, which reduces the possibility of damage by external force, and also enables the fiber connection between the intermediate connector and the terminal of the cable.

 The technical solution provided by the present invention is as follows:

 A composite optical fiber high-voltage power cable consisting of a core and an outer sheath surrounding the core, the core being composed of a conductor, an insulating layer and a metal shielding layer arranged in order from the inside to the outside, characterized in that the conductor At least one channel is disposed in each channel, and at least one optical cable is disposed in each channel, and each cable is wrapped with at least one optical fiber, and the channel and the optical cable extend along the axial direction of the cable, and are distributed over the entire length of the cable, and the channel is The diameter is greater than the diameter of the cable, the length of the cable is greater than the length of the channel, and the cable is flexibly disposed within the channel.

 The high-voltage power cable provided by the present invention may be a plastic insulated cable or an oil-filled cable, and may be a single core or a multi-core. Typically, there is also a conductor shield and an insulating shield made of a semiconductor material.

 The cross section of the passage is larger than the cross section of the optical cable, and the passage space is large enough to allow the accommodated optical cable to move within a certain range, the inner diameter of the passage is between 3 and 30, and the outer diameter of the optical cable is from 1 mm to 5 mm. The channel then allows radial and axial movement of the cable, and the length of the cable is verbose relative to the length of the channel to allow the cable to be naturally curved or spiral or serpentine.

The passage may be a hollow formed by the conductor of the cable, or it may preferably be provided by a hollow conduit embedded in the conductor. The conduit is preferably located at the axis of the cable conductor Straight round tube. For cables with large cross-section fan-shaped wire conductors, the conduit can be a straight polygonal tube located at the axis of the conductor.

 The conduit can provide more than one passage. A preferred solution is to separate a plurality of centrally symmetrical fan-shaped cross-section channels within the conduit.

 In order to accommodate a plurality of optical cables, another preferred embodiment of the present invention is symmetrically arranged in the center of the conductor by a plurality of independent circular conduit centers, one or more optical cables being disposed within each conduit. ,

 The conduit can be made of copper 'aluminum. The conduit of the conductor material such as copper or aluminum selected can also be part of the cable conductor. The conduit can also be made of stainless steel or other metal materials with good mechanical properties and non-magnetic properties. to make. The catheter can also be made of a non-metallic material.

 The conduit may also preferably be of a two-layer construction, the jacket being a metal providing mechanical strength and the inner layer being a plastic providing thermal cushioning. When the outer sheath of the cable is metal, the plastic layer can also self-lubricate the cable and the cable.

 The conduit may also be coated with a lubricant. The lubricant is graphite powder, zeolite powder or mineral oil. Lubrication of the inner wall of the conduit is necessary in some cases. Because the cable needs to be pulled out when the intermediate connector is installed, and it is pushed into the pipe after being pulled out, the cable and the inner wall of the pipe will be rubbed.

 In the present invention, a preferred optical cable is composed of an optical fiber and a metal sheath enclosing the optical fiber. More preferably, the metal sheath has a plastic sheath outside the metal sheath for thermal buffering and self-lubricating action. The seamless stainless steel sheath can be made with an outer diameter of 1. 5mm to 2. 0匪, which contains several fibers. The fiber optic metal sheath may also be tightly wound from a thin metal wire into a metal hose. These cables provide the tensile strength and resistance to over-bending required to pull the conductor and push the conductor during installation of the cable attachment. Even in a suitable spiral or serpentine shape, there is a certain retractive force, and the pulled-out portion can be fully or partially retracted into its passage in the cable conductor.

In the present invention, the optical fiber refers to a bare optical fiber mainly composed of quartz or a bare optical fiber having a coating layer, which is not capable of being pulled and easily broken; the optical fiber cable includes optical fibers and tensile and/or radial pressure buffering. Protection structure. Typically, the cable has a plastic or metal sheath or sheath. High voltage refers to AC or DC voltages of 35kV and above, including high voltage, ultra high voltage and extra high voltage.

 Technical effects of the present invention:

 First, the probe fiber can directly detect the cable conductor temperature and provide critical state variables for load monitoring. Secondly, since the detecting fiber is located at the axis of the insulating member, it is in an optimum position for detecting the ultrasonic wave generated by the partial discharge. 'Finally, this position is also the area where the deformation is minimal when the cable is bent. The fiber is protected by the structure of the cable at the same time, and there is almost no possibility of damage by external force. In the cross section of the cable of the present invention, the cable can be partially pulled out and returned to the passage in whole or in part. With the cable of the present invention, it is possible to secure the fiber optic cable connection between the intermediate indirect head of the cable and the cable termination. DRAWINGS

 BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic cross-sectional view showing a high voltage power cable of a composite optical fiber according to a first embodiment of the present invention.

 Fig. 2 is a schematic cross-sectional view showing a second embodiment of a high voltage power cable of a composite optical fiber of the present invention.

 Figure 3 is a schematic cross-sectional view showing a third embodiment of a high voltage power cable of a composite optical fiber of the present invention.

 Figure 4 is a schematic cross-sectional view showing a fourth embodiment of a high voltage power cable of a composite optical fiber of the present invention.

 Figure 5 is a schematic illustration of an embodiment of a high voltage power cable cable placement of a composite optical fiber of the present invention.

among them,

 1 a conduit 2 - conductor 3 - conductor shield 4 an insulating layer

 5—Insulation shield 6—Metal shield 7—Outer sheath 8—Optical cable

 9-three conduit 10-optical cable 11-three-channel conduit 12-optical cable

13—four-channel duct 14—a cable 15—catheter detailed description

 The high-voltage power cable of the composite optical fiber of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of the present invention is not limited thereby.

 The high-voltage power cable of the composite optical fiber of the present invention is composed of a core and an outer sheath surrounding the core, wherein the core is composed of a conductor, an insulating layer and a metal shielding layer arranged in order from the inside to the outside, and the conductor is provided therein. At least one channel, each channel is provided with at least one optical cable, the diameter of the channel is larger than the diameter of the cable, the length of the cable is greater than the length of the channel, and the cable is curvedly distributed in the channel Inside. A semiconductor shielding layer is disposed between the conductor and the insulating layer and between the insulating layer and the metal shielding layer.

 The primary structure of a composite optical fiber high voltage power cable includes at least one core having a conductor and an insulating layer and a metal shield surrounding the conductor; the core has an outer sheath that is insulated. Under operating conditions, the conductor is at a high voltage potential and delivers power. The cable includes at least one passageway located inside the conductor; at least one fiber optic cable received by the passageway; the cable having at least one optical fiber therein. The above-mentioned channels, cables and fibers extend longitudinally along the cable and are distributed over the entire length of the cable. Relative to the cross-section of the cable, the cross-section of the channel is large, so that the cable can be moved not only in it, but also in a curved state, and the cable has a certain length with respect to the length of the channel. The cable can also be made directly into a spiral or a serpentine shape. In the cross section of the cable conductor, the cable can be pulled out of the channel by a portion, and the drawn cable can be retracted into the channel in whole or in part.

 In a preferred embodiment, the passage space is large enough to allow the accommodated cable to move freely, the inner diameter of the passage is between 3 mm and 30, and the outer diameter of the cable is from 1 to 5 flat.

 The passage may be a hollow formed by the coiling of the conductor of the cable or, preferably, provided by a conduit. In the present invention, the conduit is preferably a straight tube located at the axis of the cable conductor. The round tube has an appropriate wall thickness to obtain sufficient mechanical strength to ensure that it does not undergo significant deformation when the conductor wires are tied. For cables with large cross-section fan-shaped wire conductors, the conduit can be a straight polygonal tube located at the axis of the conductor.

The conduit can provide more than one passage, the main purpose of which is to accommodate multiple cables. One A preferred solution is to divide a plurality of centrally symmetrical fan-shaped cross-section channels within a circular tube. In order to accommodate a plurality of optical cables, another preferred embodiment of the invention is that a plurality of independent circular conduit centers are symmetrically arranged at the center of the conductor. In practical applications, the conduit with the fiber optic cable can be prefabricated and then tied to the conductor.

 The material of the conduit is preferably copper or aluminum, and the conduit of the conductor material such as copper or aluminum selected may also be part of the cable conductor to carry the task of delivering power. The conduit can also be made of stainless steel or other metallic materials with good mechanical properties and non-magnetic properties. The conduit can also be made of a non-metallic material, and the non-metallic material used has an operating temperature limit not less than the operating temperature limit of the cable conductor. Non-metallic materials generally have a relatively high thermal resistance. Although the fiber temperature detection is delayed, a thermal buffer layer can be formed to protect the internal fiber optic cable and the optical fiber from being damaged when the cable has a large instantaneous current. Therefore, more preferably, the catheter has a two-layer structure, the outer casing is made of metal, provides mechanical strength, and the inner layer is plastic, providing thermal cushioning. If the outer sheath of the cable is metal, the plastic layer can also provide self-lubricating properties for the cable.

 The conduit is coated with a lubricant. The lubricant is graphite powder, zeolite powder or mineral oil. Lubrication of the inner wall of the conduit is necessary in some cases. Because the cable needs to be pulled out when the intermediate connector is installed, and it is pushed into the pipe after being pulled out, the cable and the inner wall of the pipe will be rubbed. In addition, mechanical vibration of the cable may also cause friction between the cable and the inner wall of the conduit during the service life of the cable for up to 30 years. Lubricants such as graphite, talc, and mineral oil can be added to the pipe when it is manufactured.

In the present invention, a preferred optical cable is composed of an optical fiber and a metal sheath enclosing the optical fiber. More preferably, the metal sheath has a plastic sheath outside the metal sheath for thermal buffering and self-lubricating. The seamless stainless steel sheath can be made to have an outer diameter of 1.5 to 2. 0 awake, which contains a number of fibers. The fiber optic metal sheath may also be tightly wound from a thin metal wire into a metal hose. These cables provide the tensile strength and resistance to over-bending required to pull the conductor and push the conductor during installation of the cable accessory. Even in a suitable spiral or serpentine shape, there is a certain retractive force, and the pulled-out portion can be fully or partially retracted into its passage. Example 1

 BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic cross-sectional view showing a high voltage power cable of a composite optical fiber according to a first embodiment of the present invention. As shown in the figure, the high-voltage power cable of the composite fiber includes a conduit 1, a conductor 2, a conductor shielding layer 3, an insulating layer 4, an insulating shielding layer 5, a metal shielding layer 6, an outer sheath 7, and an optical cable 8, in this embodiment. The outer sheath 7 is in the form of a sheath, and may have other forms. The insulating sheath may be disposed in the outer sheath or in the inner and outer portions of the outer sheath, and the center of the catheter 1 is a passage for accommodating the optical cable 8.

 Conductor 2, located at the center of the cable, transmits power. The conduit 1 is a straight tube made of copper and tightly packed on the axis of the conductor 2, and has excellent thermal conductivity, so that the probe cable 8 in the conduit 1 can directly detect the degree of the conductor 2. The cross-sectional space of the passage in the duct 1 is larger than the cross-section of the cable 8. The conductor has a cross-sectional area of 1000 mm 2 in this embodiment. The inner diameter of the catheter 1 is 10 mm and the wall thickness is 2 mm. The catheter 1 has a double-layer structure, the outer casing is a copper tube, provides mechanical strength, and the inner layer is plastic, providing thermal cushioning. The fiber optic cable 8 consists of an optical fiber and a stainless steel fiber optic conduit with an outer diameter of 2.5 mm. The straightening length of the optical cable 8 has a margin of 5% with respect to the length of the cable, and the cable of 10 cm length can be pulled out in the section of the cable, and can be completely retracted into the channel, so that the electrical connection of the cable at the intermediate joint of the cable can be realized. And optical connection.

 Example 2

2 is a schematic transverse cross-sectional view showing a second embodiment of a high voltage power cable of a composite optical fiber of the present invention. As can be seen from the figure, in this embodiment, except that the outer layer is the same as the structure of the first embodiment, that is, the outer sheath 7, the metal shield layer 6, the insulating shield layer 5, the insulating layer 4, and the conductor shield layer are sequentially arranged from the outside to the inside. 3 and conductor 2, three conduits 9 are placed in the conductor 2, and a cable 10 is placed in each conduit. In this embodiment, the conductor 2 has a cross section of 2000 mm 2 . In the cable cross section, the three conduits are placed in a centrally symmetrical manner. The conduit 9 is a hollow tube made of copper, each having an inner diameter of 6 mm and a wall thickness of 1 mm. The inner wall of the conduit 9 is coated with graphite powder as a lubricant. Of course, in this embodiment, the number and specific arrangement of the conduits may be increased or decreased according to different needs. This can meet the requirements of placing multiple cables in the cable to meet different requirements.

 Example 3

 Figure 3 is a schematic cross-sectional view showing a third embodiment of a high voltage power cable of a composite optical fiber of the present invention. This embodiment differs from the above embodiment in that the conduit 11 is a profile having three channels therein, one optical cable placed in each channel.

 Example 4

 Figure 4 is a schematic cross-sectional view showing a fourth embodiment of a high-k power cable of a composite optical fiber of the present invention. This embodiment differs from the above embodiment in that the conduit 13 is a profile having four passages therein, one optical cable being placed in each passage.

 Figure 5 is a schematic illustration of an embodiment of a high voltage power cable cable placement of a composite optical fiber of the present invention. The fiber optic cable 14 is placed in the conduit 15 in a naturally curved manner.

 If there is a special requirement, the cable having a certain rigidity can be processed into a serpentine or spiral shape in a natural state within a radius allowed by the optical cable 14, so that the optical cable itself has a certain elasticity, and when the optical cable is pulled out of the conductor, Its own flexibility can provide self-retracting ability.

 The material of the conductor may be made of copper or an alloy containing copper as a main component, aluminum or an alloy mainly composed of aluminum, or stainless steel, or may be made of a high temperature resistant non-metal material or a material composed of the above materials. Multi-layer structure to meet specific needs.

Claims

Rights request  A high-voltage power cable of a composite optical fiber, comprising: a core and an outer sheath surrounding the core, wherein the core is composed of a conductor, an insulating layer and a metal shielding layer disposed in order from the inside to the outside, wherein At least one channel is disposed in the conductor, and each channel is provided with at least one optical cable extending along the axial direction of the cable and distributed over the entire length of the cable, the diameter of the channel being larger than the diameter of the cable. The length of the cable is greater than the length of the channel, and the cable is curvedly distributed within the channel.  2. The composite optical fiber high voltage power cable according to claim 1, wherein a semiconductor shielding layer is disposed between the conductor and the insulating layer and between the insulating layer and the metal shielding layer.  3. The composite optical fiber high voltage power cable according to claim 1, wherein the optical cable is composed of an optical fiber and a metal sheath enclosing the optical fiber.  4. The composite optical fiber high voltage power cable according to claim 1, wherein the optical cable is spirally or serpentinely distributed in the channel.  5. The composite optical fiber high voltage power cable of claim 1 wherein said passageway is enclosed by a conduit extending longitudinally with the passageway and distributed over the entire length of the cable.  The high-voltage power cable of a composite optical fiber according to claim 5, wherein the duct is made of aluminum, or copper, or an alloy mainly composed of aluminum or copper, or a stainless steel material.  7. The composite optical fiber high voltage power cable according to claim 5, wherein the conduit has a two-layer structure, the outer layer is a metal material, and the inner layer is a plastic.  8. A composite optical fiber high voltage power cable according to claim 5, wherein said conduit is coated with a lubricant.  9. The composite optical fiber high voltage power cable according to claim 8, wherein the lubricant is graphite powder, or zeolite powder, or mineral oil.  10. The composite optical fiber high voltage power cable according to claim 1, wherein the inner diameter of the passage is 3 mm to 30, and the outer diameter of the optical cable is 1 to 5 。.