阅读说明：本技术 电力传输电缆 (Power transmission cable ) 是由 M·克拉雅科维克 W·范哈弗 C·德格雷尔 于 2019-09-02 设计创作，主要内容包括：一种电力传输电缆,包括电力导体和多个平行螺旋铠装丝。电力传输电缆沿其长度包括第一区段(I)、第二区段(III)和过渡区段(II)。过渡区段(II)设置在第一区段(I)和第二区段(III)之间。第一区段(I)中的多个平行螺旋铠装丝包括第一铠装丝(121)或由第一铠装丝(121)组成。第一铠装丝(121)是包括金属耐腐蚀涂层的碳钢丝。第二区段(III)中的多个平行螺旋铠装丝的至少部分铠装丝包括奥氏体钢丝(123)。在过渡区段(II)中,第一铠装丝(121)的端部被分别焊接至第二区段(III)的奥氏体钢丝(123)的端部。过渡区段(II)始于第一铠装丝(121)与奥氏体钢丝(123)之间的第一焊接部(137)。过渡区段(II)终止于在第一铠装丝(121)与奥氏体钢丝(123)之间的最后一个焊接部(130)处。过渡区段(II)至少10米长。(A power transmission cable includes a power conductor and a plurality of parallel helical armor wires. The power transmission cable comprises along its length a first section (I), a second section (III) and a transition section (II). The transition section (II) is arranged between the first section (I) and the second section (III). The plurality of parallel helical armouring wires in the first section (I) comprises or consists of first armouring wires (121). The first armouring wire (121) is a carbon steel wire comprising a metallic corrosion resistant coating. At least part of the armouring wires of the plurality of parallel helical armouring wires in the second section (III) comprises austenitic steel wires (123). In the transition section (II), the ends of the first armouring wire (121) are welded to the ends of the austenitic steel wires (123) of the second section (III), respectively. The transition section (II) starts at a first weld (137) between the first armouring wire (121) and the austenitic steel wire (123). The transition section (II) ends at the last weld (130) between the first armouring wire (121) and the austenitic steel wire (123). The transition section (II) is at least 10 meters long.)

1. A power transmission cable comprises

-an electrical power conductor; and

-a plurality of parallel helical armouring wires;

wherein the power transmission cable comprises along its length a first section (I), a second section (III) and a transition section (II);

wherein the transition section (II) is disposed between the first section (I) and the second section;

wherein the plurality of parallel helical armour wires in the first section comprise or consist of first armour wires (121), wherein the first armour wires (121) are carbon steel wires comprising a metallic corrosion resistant coating;

wherein at least part of the armouring wires of said plurality of parallel helical armouring wires in said second section (III) comprise austenitic steel wires (123);

wherein in the transition section (II) the ends of the first armouring wire (121) are welded to the ends of the austenitic steel wires (123) of the second section (III), respectively;

wherein the transition section (II) starts at a first weld (137) between the first armouring wire (121) and the austenitic steel wire (123);

wherein the transition section (II) ends at the last weld between the first armouring wire (121) and the austenitic steel wire (123);

characterized in that the transition section (II) is at least 10 meters long.

2. The power transmission cable according to claim 1, wherein the welds in the transition section (II) between the first armouring wire (121) and the austenitic steel wire (123) are evenly distributed along the length of the transition section (II).

3. The power transmission cable according to any one of the preceding claims, wherein the first armouring wire (121) and the austenitic steel wire (123) have a round cross-section, or have a flat cross-section, or have a Z-shaped cross-section.

4. The power transmission cable according to any one of the preceding claims, wherein the metallic corrosion-resistant coating of the first armouring wire (121) is provided by a hot-dip zinc coating or by a hot-dip zinc alloy coating or by an aluminium alloy coating.

5. The power transmission cable according to any one of the preceding claims, wherein the metallic corrosion-resistant coating at the end of the first armouring wire (121) has been removed before the welding operation; preferably wherein a protective coating has been applied over the wire ends after welding is complete.

6. The power transmission cable according to any one of the preceding claims, wherein some of the armouring wires of the first armouring wires continue from the first section, through the transition section into the second section.

7. The power transmission cable of claim 6, wherein the first armouring wires provide 30 to 70% of the total number of armouring wires in the second section.

8. The power transmission cable according to any one of the preceding claims 1-5, wherein all parallel helical armouring wires in the second section are austenitic steel wires.

9. The power transmission cable according to any one of the preceding claims, wherein the austenitic steel wires (123) of the second section (III) are provided with a metallic corrosion resistant coating.

10. The power transmission cable according to claim 9, wherein the metallic corrosion resistant coating of the austenitic steel wires (123) is provided by a hot-dip zinc coating or by a hot-dip zinc alloy coating or by an aluminium alloy coating.

11. The power transmission cable according to claim 4 or 5 and claim 9 or 10; wherein prior to the welding operation, the metallic corrosion coating is removed by a length at both wire ends in the weld; and wherein after welding is complete a protective coating (340) has been applied at the location where the metal corrosion coating on the wire end has been removed.

12. The power transmission cable of claim 11; wherein the protective coating (340) comprises zinc particles in a binder.

13. The power transmission cable according to any one of the preceding claims, wherein the welding is butt welding or lap welding.

14. The power transmission cable according to any one of the preceding claims, wherein the austenitic steel is an austenitic stainless steel; or wherein the austenitic steel is a hadfield high manganese steel; or wherein the austenitic steel is a TWIP steel.

15. The power transmission cable according to any one of the preceding claims, wherein the cable is a three-phase power transmission cable.

Technical Field

The present invention relates to high voltage power transmission cables, and more particularly, to Alternating Current (AC) high voltage power transmission cables. A particular use of the power transmission cable of the invention is for offshore submarine cables.

Background

A typical submarine cable for AC power transmission comprises one or more conductors. The cable comprises a circumferential armouring of helically wound metal wires or tapes. The armor may be covered by a polymer jacket or by one or more layers of yarn. A thin polymer jacket may also be applied to each individual armouring wire.

The armor has the effect of improving the mechanical properties and performance of the cable and provides the ability to resist external damage. Typically, the armour is made of one or two layers of wire, round or flat, made of steel with a medium to low carbon content. Steel is commonly used because of its low cost, ready availability and good mechanical properties. Galvanized steel is preferably used (especially but not exclusively) when the armouring wires are exposed to an environment without any polymer jacket or yarn layer to ensure better corrosion resistance.

In AC power cables, the magnetic field generated by the current flowing in the conductor(s) causes losses of ferromagnetic material, such as medium and low carbon steel used as armouring wires. Where "ferromagnetic material" refers to a material having a high magnetic permeability, i.e., a material capable of concentrating magnetic flux by a factor greater than 10. The magnetic domains of ferromagnetic material rotate with the magnetic field in the ac cable. This rotation of the magnetic domains in the material causes friction and heat. The heat generated by this friction is called hysteresis loss. This induced heat, coupled with the heat generated by the conductors due to current transfer, can compromise the overall current carrying capacity of the cable, especially when the cable is deployed in an environment with low or zero heat dissipation capacity.

In use, the submarine cable is typically installed underwater, usually buried beneath the bottom ground, but some of it may be laid in a different environment; i.e. situations such as the shore end of a subsea link, a mid-island crossing, a continuous land section, a canal edge, etc. Key aspects of these environments are typically poorer thermal properties and/or higher temperatures than the main routes offshore.

US2012/0024565a1 discloses a power transmission cable comprising at least one first section provided with a cable armouring made of a first metallic material and at least one second section provided with a cable armouring made of a second metallic material. The ferromagnetic properties of the second metallic material are substantially lower than the ferromagnetic properties of the first metallic material.

EP0173402a1 discloses armored submarine power cables designed for laying in water at different depths. In shallow water the cable has a heavy and strong armouring (steel wires). In very deep waters the weight of steel armouring is prohibitive and therefore in these areas the armouring is made of synthetic light material. The transition between the two types of armouring is made physically concentrated but flexible enough to prevent the cable core from bending sharply when passing through the cable laying machine. The armor joint is displaceable from the cable core joint and is effective to transfer substantially all longitudinal strain in the cable.

Disclosure of Invention

The invention is a power transmission cable comprising a power conductor and a plurality of parallel helical armouring wires. Preferably, the power conductor is a continuous power conductor. The power transmission cable includes a first section, a second section, and a transition section along its length. The transition section is disposed between the first section and the second section. The plurality of parallel helical armouring wires in the first section comprises or consists of first armouring wires. The first armouring wire is a carbon steel wire comprising a metallic corrosion resistant coating. At least a portion of the armor wires of the plurality of parallel helical armor wires in the second section comprise austenitic steel wires. In the transition section, the ends of the first armouring wire are welded to the ends of the austenitic steel wires of the second section, respectively. The transition section begins at a first weld between the first armouring wire and the austenitic steel wire. The transition section ends at the last weld between the first armouring wire and the austenitic steel wire. The transition section is at least 10 meters long; and preferably at least 25 meters long, more preferably at least 40 meters long.

Due to the use of different types of spiral armouring wires the heat generation in the first section and in the second section of the power transmission cable will be completely different. The first section comprises a first armouring wire which is a carbon steel wire comprising a metallic corrosion resistant coating and is therefore ferromagnetic. Due to the ferromagnetic armouring wires in the first section a considerable amount of heat is generated in the first section. The second section comprises a substantially non-magnetic austenitic steel wire. In these austenitic steel wires, little or limited heat is generated by the magnetic field generated by the current flowing in the conductor. Advantageously, by providing a transition section at least 10 metres long (and preferably at least 25 metres long, more preferably at least 40 metres long), a gradual change in the heat generated in the helical armour wires caused by the magnetic field is provided along the length of the cable, rather than an abrupt change.

Preferably, the carbon steel has a ferritic or ferritic/pearlitic microstructure.

Preferably, the carbon steel is a low alloy steel; wherein low alloy steel refers to a steel alloy having an alloying element content of less than 5% by weight.

Preferably, the carbon steel is a low carbon steel.

Preferably, the continuous power conductor comprises stranded copper wire.

Preferably, the continuous power conductors (e.g. stranded copper wires) comprise an insulating layer to insulate the continuous power conductors from each other. The insulating layer may be made of, for example, cross-linked polyethylene (XLPE).

Preferably, the power transmission cable comprises a bedding (e.g. made of polyvinyl chloride (PVC)) between the continuous power conductor and the parallel helical armouring wires. The bedding layer provides a protective boundary between the inner and outer layers of the cable.

Preferably, the electrical power transmission cable comprises an outer sheath surrounding the parallel helical armour wires. A jacket (which may be made of black PVC, for example) holds the cables together and provides additional protection against external stresses.

Preferably, the welds in the transition section between the first armouring wire and the austenitic steel wire are evenly distributed along the length of the transition section.

Preferably, the first armouring wire and the austenitic steel wire have a round cross-section, or have a flat cross-section, or have a Z-shaped cross-section.

In one embodiment of the invention, the diameter of the first armouring wire is different from the diameter of the austenitic steel wire. In a more preferred embodiment, the diameter of the austenitic steel wire is larger than the diameter of the carbon steel wire. More preferably, the amount of power conductor in the second section (expressed as surface area of the power conductor in the cable cross-section) is larger than the amount of power conductor in the first section. This may be required when the first section is disposed in a warmer environment such that the specific conductivity of the copper conductor is lower. Thus, it may be useful to provide a higher conductivity in the first section; and the diameter of the armouring wire is also larger due to the larger total conductor cross-sectional area in the first section.

Preferably, the metallic corrosion-resistant coating of the first armouring wire is provided by a hot-dip zinc coating, a hot-dip zinc alloy coating, an aluminium coating or an aluminium alloy coating. The aluminium coating or aluminium alloy coating may be applied on the first armouring wires, for example by a cladding or extrusion process.

Preferably, the metal corrosion-resistant coating at the end of the first armouring wire has been removed prior to the welding operation. More preferably, the protective coating has been applied to the wire ends after welding is complete. More preferably, the protective coating comprises zinc particles in a binder. The protective coating may be, for example, a zinc-based enamel coating.

Preferably, part of the armouring wires in the first armouring wire continues from the first section, passing through the transition section into the second section. More preferably, the first armouring wire provides 30% to 70% of the total number of armouring wires in the second section.

In embodiments in which part of the armouring wires of the first armouring wires continue from the first section, through the transition section into the second section, preferably the first armouring wires (being carbon steel wires comprising a metallic corrosion resistant coating) and austenitic steel wires are arranged in the second section according to a regular pattern around the circumference of the power transition cable.

Preferably, all of the parallel helical armour wires in the second section are austenitic steel wires.

Preferably, the austenitic steel wire of the second section is provided with a metallic corrosion resistant coating. More preferably, the metallic corrosion-resistant coating of the austenitic steel wire is provided by a hot-dip zinc coating, a hot-dip zinc alloy coating, an aluminium coating or an aluminium alloy coating. The aluminum coating or aluminum alloy coating may be applied to the austenitic steel wire, for example, by a cladding or extrusion process.

When the austenitic steel wire of the second section is provided with a metallic corrosion coating, preferably the metallic corrosion coating is removed for a length at both wire ends in the weld prior to the welding operation. More preferably, after welding is complete, a protective coating has been applied to the welded wire ends to cover the locations where the metal corrosion coating was removed. More preferably, the protective coating comprises zinc particles in a binder. Examples of protective coatings that may be applied include zinc-based enamels.

Preferably, the welding is butt welding or lap welding. When lap welding is used, it is preferred to use a filler material in the welding; more preferably, the filler material is an austenitic stainless steel grade comprising more alloying elements by weight than the austenitic steel in the austenitic steel wire.

Preferably, the austenitic steel is an austenitic stainless steel; or the austenitic steel is hadfield high manganese steel; or the austenitic steel is TWIP steel. Hadfield high manganese steel is a steel alloy with a carbon content between 0.8 and 1.25% by weight and a manganese content between 11 and 15% by weight. TWIP steel (or twinning induced plasticity steel) is a steel alloy with a Mn content of more than 20 wt.%, a carbon content of less than 1 wt.%, a Si content of less than 3 wt.% and an aluminium content of preferably less than 3 wt.%.

The preferred power transmission cable is a three-phase power transmission cable.

Drawings

Fig. 1 shows an example of a power transmission cable according to the present invention.

Fig. 2 shows a detail of the power transmission cable of fig. 1.

Fig. 3 shows a detail of a butt weld between a first armouring wire and an austenitic steel wire that can be used in the present invention.

Fig. 4 shows a detail of a lap weld between a first armouring wire and an austenitic steel wire that can be used in the present invention.

Detailed Description

Fig. 1 shows an example of a three-phase power transmission cable 10. The continuous power conductor 12 may be made of stranded copper wire. The insulation 14 in the cable ensures that the conductors do not contact each other or other metal parts. The insulation 14 on the conductor, for example made of cross-linked polyethylene (XLPE), has good water resistance and excellent insulation properties. A bedding layer 16, such as made of polyvinyl chloride (PVC), is used to provide a protective boundary between the inner and outer layers of the cable. A plurality of parallel helical armouring wires 18 made of steel wire provides mechanical protection, in particular protection against external impacts. In addition, the armouring wires 18 can release the tension during installation and thus prevent the copper conductors from elongating. A sheath 19, such as made of black PVC, may be provided to hold all the components of the cable together and provide additional protection against external stresses.

Fig. 2 shows a detail of the exemplary inventive power transmission cable of fig. 1, with the jacket removed. The power transmission cable comprises along its length a first section I, a second section III and a transition section II. The transition section is disposed between the first section and the second section. The plurality of parallel helical armouring wires 121 in the first section consists of first armouring wires which are carbon steel wires comprising a hot dip zinc coating in order to provide corrosion resistance to the carbon steel wires.

In the second section, parallel helical armouring wires are provided alternately by austenitic stainless steel wires 123 (for example made of AISI 202 austenitic stainless steel and having a diameter of 6mm) and by carbon steel wires 124 (for example made of carbon steel according to EN10257-2 standard and having a diameter of 6 mm). The carbon steel wire is the first armor wire that continues from the first section, through the transition section, and into the second section. Thus, 50% of the armouring wires in the second section are provided by austenitic stainless steel wires and the other 50% are provided by carbon steel wires. The austenitic stainless steel wire of the second section is provided with a hot dip zinc coating to impart corrosion resistance to the austenitic stainless steel wire. In the transition section, the ends of the first armouring wires 121 are butt-welded (butt-welded 130) to the ends of the austenitic stainless steel wires 123 of the second section, respectively. The transition section II starts at a first butt weld (137) between the first armouring wire and the austenitic stainless steel wire; and terminates at a last butt weld (130) between the first armouring wire and the austenitic stainless steel wire. In this example, the butt welds between the carbon and austenitic steel wires are evenly distributed along the length of the transition section. The transition zone II is for example 14 meters long.

Fig. 3 shows a detail of the butt weld between the first armouring wires and the austenitic steel wires in the cable of fig. 2. In the transition section, the ends of the carbon steel wire 321 are butt-welded to the ends of the austenitic steel wire 323. Prior to the welding operation, the hot dip galvanizing coating 331, 333 is removed by a certain length at both wire ends in the butt weld 330. After the butt weld is complete, a protective coating 340 has been applied at the locations where the metal corrosion coating on the wire ends has been removed. The protective coating may be, for example, an enamel containing zinc particles.

Fig. 4 shows a lap weld that may be used as an alternative to butt welding in the present invention. In the transition section, the end of carbon steel wire 421 is lap welded to the end of austenitic steel wire 423 using filler material 444. A length of metallic corrosion coating (e.g., hot dip zinc coating 331, 333) is removed from both wire ends prior to welding. After the welding operation, a protective coating 440 has been applied at the locations where the metal corrosion coating has been removed on both wire ends. The protective coating may be, for example, an enamel containing zinc particles.