WO2024155179A1

WO2024155179A1 - Offshore wind power submarine cable with enhanced water-blocking characteristics

Info

Publication number: WO2024155179A1
Application number: PCT/KR2024/095032
Authority: WO
Inventors: 이재복; 양이슬; 정현정
Original assignee: 엘에스전선 주식회사
Priority date: 2023-01-18
Filing date: 2024-01-18
Publication date: 2024-07-25

Abstract

The present invention relates to an offshore wind power submarine cable with enhanced water-blocking characteristics. Specifically, the present invention relates to an offshore wind power submarine cable, which effectively suppresses the formation of water trees in an insulation layer by suppressing the penetration of moisture into a power unit of the cable, thereby improving insulation strength and preventing damage to a metal shielding layer provided in the power unit, and consequently securing a long-term service life.

Description

Submarine cable for offshore wind power with improved water resistance characteristics

The present invention relates to a submarine cable for offshore wind power with improved water resistance characteristics. Specifically, by suppressing the infiltration of moisture into the power unit of the cable and effectively suppressing the formation of water trees within the insulating layer, the dielectric strength is improved and damage to the metal shielding layer provided in the power unit is prevented, resulting in a long service life. This concerns submarine cables for offshore wind power that can be secured.

Submarine cables have been installed for a long time to transmit power in island areas and connect communication between continents, and recently, offshore wind power, which installs wind power generators in the sea, has many advantages over onshore wind power in terms of wind direction conditions, site security, and noise issues, so offshore wind farms As construction continues to increase, interest in submarine cables for offshore wind power is increasing.

In an offshore wind farm, submarine cables for offshore wind power are connected between wind turbines installed at sea or from an offshore substation to power facilities on land.

Since submarine cables for offshore wind power are laid in the submarine environment, water blocking performance that prevents moisture from infiltrating and diffusing into the cable must be guaranteed, and the submarine cables for offshore wind power that are laid in the section fixed to the ground from the power facilities on land are fixed to the ground on the sea floor. The cable is called a so-called static cable, and static cables are generally designed to have a metal shielding layer with a soft sheath extruded on the end face of the power cable to suppress moisture infiltration toward the side of the cable.

Submarine cables for offshore wind power that are not fixed to the ground on the sea floor but connect between offshore wind turbines or from an offshore substation to a static cable fixed to the ground on the sea floor are called dynamic cables. Dynamic cables are capable of responding to external forces such as ocean currents or waves. It is difficult to apply the soft sheath, which has low bending fatigue durability, as a metal shielding layer for the reason that durability against bending caused by bending must be guaranteed.

Therefore, in order to suppress the penetration and diffusion of moisture into the dynamic cable, a wire shield made of metal wire and metal tape was used as a metal shielding layer instead of the soft sheath, but it was difficult to suppress moisture from penetrating into the insulating layer. , damage to the metal shielding layer made of metal wire and metal tape could occur due to bending caused by external forces such as ocean currents or waves.

Therefore, by suppressing the penetration of moisture into the power unit of the cable and effectively suppressing the formation of water trees in the insulating layer, the dielectric strength is improved and damage to the metal shielding layer provided in the power unit is prevented, resulting in long-term lifespan. There is an urgent need for submarine cables for offshore wind power.

The present invention suppresses the penetration of moisture into the core of the cable, effectively delays the formation of water trees in the insulating layer, and prevents damage to the metal shielding layer provided in the power unit, resulting in long-term lifespan for offshore wind power. The purpose is to provide submarine cables.

In order to solve the above problems, the present invention,

A submarine cable for offshore wind power, comprising: a conductor, an internal semiconducting layer surrounding the conductor, an insulating layer surrounding the internal semiconducting layer, an external semiconducting layer surrounding the insulating layer, a metal shielding layer provided outside the external semiconducting layer, and the metal shielding. Provided is a submarine cable for offshore wind power, which includes one or more power units including a polymer sheath layer surrounding the layer, and a coating layer of a hydrophobic material is provided on the surface of the polymer sheath layer.

Here, the hydrophobic material provides a submarine cable for offshore wind power, characterized in that it has a melting point that is 10°C or more lower than the melting point of the material forming the polymer sheath layer.

Furthermore, a submarine cable for offshore wind power is provided, wherein the hydrophobic material contains beeswax.

In addition, the hydrophobic material provides a submarine cable for offshore wind power, characterized in that it at least partially fills a plurality of micropores formed on the surface of the polymer sheath layer.

Meanwhile, the power unit has an internal water-water tape layer provided between the external semiconducting layer and the metal shielding layer to surround the external semiconducting layer, and an external tape layer provided between the metal shielding layer and the polymer sheath layer to surround the metal shielding layer. Provided is a submarine cable for offshore wind power, characterized in that it includes at least one of the water-order tape layers.

Here, the inner water taping layer or the outer water taping layer is characterized in that it includes at least one selected from the group consisting of a powder containing a super absorbent polymer (SAP), a tape, a coating layer, and a film. We provide submarine cables for wind power.

Meanwhile, a cable insert including a plurality of power units and provided in an area between the plurality of power units; A binding tape layer for finishing a plurality of power units and cable inserts in a circular shape; A bedding layer provided outside the binding taping layer and including polypropylene yarn; An armor layer provided outside the bedding layer; and an outermost layer provided outside the armor layer and containing a polymer resin material.

The submarine cable for offshore wind power according to the present invention suppresses moisture penetration into the core through a hydrophobic coating on the core surface, suppresses the formation of water trees inside the insulating layer, improves the insulation strength, and improves the insulation strength of the metal shielding layer provided in the power unit. It has an excellent effect by preventing damage and ultimately securing a long lifespan.

Figure 1 is a cross-sectional view schematically showing the cross-sectional structure of one embodiment of a submarine cable for offshore wind power according to the present invention.

FIG. 2 is a longitudinal cross-sectional view of one power unit in the submarine cable for offshore wind power shown in FIG. 1.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosure will be thorough and complete, and so that the spirit of the invention can be sufficiently conveyed to those skilled in the art. Like reference numerals refer to like elements throughout the specification.

Figure 1 is a cross-sectional view schematically showing the cross-sectional structure of one embodiment of a submarine cable for offshore wind power according to the present invention, and Figure 2 is a longitudinal cross-sectional view of one power unit in the submarine cable for offshore wind power shown in Figure 1. am.

The submarine cable 1000 for offshore wind power according to the present invention may be a three-phase AC power cable in which three

power units

300a, 300b, and 300c are arranged in a triangle shape, as shown in FIG. 1.

In the case of a three-phase AC power cable equipped with three power units (300a, 300b, 300c), the three power units (300a, 300b, 300c) are placed in the area between adjacent power units to form a circular shape and are made of plastic. A cable interposer 400 may be provided, including

intersperses

400a, 400b, and 400c made of material. At least one of the

interpositions

400a, 400b, and 400c may be provided with an optical unit accommodating portion (a) in which the optical unit 100 can be accommodated and mounted.

Here, the optical unit 100 may include at least one optical fiber 110 and a tube 120 that accommodates the optical fiber 110. Each optical unit 100 includes a predetermined number of optical fibers 110 mounted with filler in a tube 120, and the tube may be made of a rigid material such as stainless steel. The optical unit 100 may further include a sheath 130 surrounding the tube 120.

The cable insert 400 is mainly made of plastic material, preferably foam plastic material. When forming a submarine cable for offshore wind power by combining the power units (300a, 300b, 300c), the optical unit 100, and the intervening elements (400a, 400b, 400c), they are combined into a circle with a predetermined pitch. You can.

Additionally, a binding tape layer 500 may be provided to finish the

power units

300a, 300b, and 300c and the intervening

elements

400a, 400b, and 400c in a circular shape. A bedding layer 600 may be provided outside the binding taping layer 500. The bedding layer 600 may serve to provide a mounting surface on which the armor layer 700 provided outside the bedding layer 600 is mounted.

Here, the bedding layer 600 may be provided including polypropylene (PP) yarn. An armor layer 700 may be provided outside the bedding layer 600. The armor layer 700 may be comprised of a lower layer 700a and an upper layer 700b, in which a plurality of armor wires 710 are disposed. The armor layer 700 can perform the function of protecting submarine cables for offshore wind power in rough underwater environments. Outside the armor layer 700, an outermost layer 800 containing a polymer resin material may be provided.

As shown in Figures 1 and 2, the power unit 300 sequentially includes a conductor 310, an inner semiconducting layer 320, an insulating layer 330, an outer semiconducting layer 340, and an inner order tape layer ( 350), a metal shielding layer 360, an external water blocking tape layer 370, a polymer sheath layer 380, and a coating layer 390.

The conductor 310 serves as a passage through which current flows to transmit power, and is made of a material that has excellent conductivity to minimize power loss and has appropriate strength and flexibility for cable manufacturing and use, such as copper or aluminum. It can be achieved.

The conductor 310 may be a circular compressed conductor in which a plurality of circular wires are stranded and compressed into a circle, and is provided with a rectangular wire layer consisting of a circular center wire and a square wire stranded to surround the circular center wire, and is generally circular. It may be a rectangular conductor with a cross-section of, and the rectangular conductor has a relatively high space factor compared to a circular compressed conductor, so it has the advantage of being able to reduce the outer diameter of the cable.

However, the surface of the conductor 310 is not smooth, so the electric field may be non-uniform, and corona discharge is likely to occur locally. Additionally, if a gap is created between the surface of the conductor 310 and the insulating layer 330, which will be described later, an electric field may be concentrated in the gap, thereby deteriorating the insulation performance.

Accordingly, an internal semiconducting layer 320 may be provided outside the conductor 310. The internal semiconducting layer 320 is made of ethylene vinyl acetate (EVA), ethylene methyl acrylate (EMA), ethylene methyl methacrylate (EMMA), ethylene ethyl acrylate (EEA), ethylene ethyl methacrylate (EEMA), ethylene Carbon black, carbon nanotubes, Conductive particles such as carbon nanoplates and graphite may be added to provide semiconductivity.

The internal semiconducting layer 320 functions to stabilize insulation performance by preventing sudden changes in electric field between the conductor 310 and the insulating layer 330, which will be described later. In addition, by suppressing non-uniform charge distribution on the conductor surface, the electric field can be made uniform and the formation of voids between the conductor 310 and the insulating layer 330 can be prevented, thereby suppressing corona discharge, insulation breakdown, etc.

Additionally, the internal semiconducting layer may include 0.1 to 5 parts by weight of a crosslinking agent based on 100 parts by weight of the base resin. Since crosslinking by-products generated during crosslinking of the inner semiconducting layer may penetrate into the insulating layer 330 and act as crystal nuclei, it is necessary to control the crosslinking agent content of the inner semiconducting layer.

The insulating layer 330 is provided outside the internal semiconducting layer 320 to electrically insulate it from the outside to prevent current from leaking to the outside along the conductor 310. In general, the insulating layer 330 must have a high breakdown voltage and maintain its insulating performance stably for a long period of time. Furthermore, it must have low dielectric loss and have heat resistance properties such as heat resistance.

Therefore, the insulating layer 330 may be made of polyolefin resin such as polyethylene and polypropylene, and polyethylene resin is preferred. Here, the polyethylene resin may be composed of XLPE, a crosslinking resin, including a crosslinking agent, and the crosslinking agent may be dicumyl peroxide, benzoyl peroxide, lauryl peroxide, t-butyl cumyl peroxide, and di(t-butyl peroxy). It may include peroxide crosslinking agents such as isopropyl) benzene, 2,5-dimethyl-2,5-di(t-butyl peroxy)hexane, and di-t-butyl peroxide. Furthermore, the insulating layer may further include antioxidants, extrudability improvers, tree inhibitors, crosslinking aids, etc. as other additives.

An external semiconducting layer 340 may be provided outside the insulating layer 330. The outer semiconducting layer 340, like the inner semiconducting layer 320, is formed of a semiconducting material by adding conductive particles, such as carbon black, carbon nanotubes, carbon nanoplates, and graphite, to an insulating material, Insulating performance is stabilized by suppressing non-uniform charge distribution between the insulating layer 330 and the wire shield layer 360, which will be described later. In addition, the external semiconducting layer 340 smoothes the surface of the insulating layer 330 in the cable to alleviate electric field concentration to prevent corona discharge, and also performs the function of physically protecting the insulating layer 330. You can.

A metal shielding layer 360 may be provided outside the external semiconducting layer 340. The metal shielding layer 360 is grounded at the end of the cable and serves as a passage through which fault current flows in the event of an accident such as a ground fault or short circuit, protects the cable from external shock, and has the function of shielding the electric field from being discharged outside the cable. It can be done.

As shown in FIG. 2, the metal shielding layer 360 includes a plurality of metal wires 361 and metal tapes 362, and the metal wires 361 and metal tapes 362 are made of copper, copper aluminum, etc. It may be composed of materials.

The metal wire 361 may be provided with a size of 0.2 millimeter (mm) to 2.0 millimeter (mm), and the plurality of metal wires 361 may be spaced apart and wound horizontally in a spiral shape.

The metal tape 362 is provided in a helically wound manner on the outside of the plurality of metal wires 361, so that each metal wire 361 can be energized and the fault current can quickly flow to the ground.

In addition, the power unit 300 may further include at least one water

absorption taping layer

350, 370 for moisture absorption. For example, the power unit 300 is provided between the outer semiconducting layer 340 and the metal shielding layer 305 and includes an inner water blocking tape layer 350 and a metal shielding layer 360 that surround the outer semiconducting layer 340. It may include at least one of the outer order tape layers 370 provided between the polymer sheath layers 380 and surrounding the metal shielding layer 360.

In the embodiment shown in FIGS. 1 and 2, the order taping layer is shown as having an inner order taping layer 350 and an outer order taping layer 370 on the inside and outside of the metal shielding layer 360, respectively. However, it is not limited to this, and only the inner water taping layer 350 or only the outer water taping layer 370 may be provided. Preferably, since moisture mainly penetrates from the outside, only the outer water taping layer 370 is used. It may be provided.

The order tape constituting the order taping layers 350 and 370 is made of super absorbent polymer (SAP), which has a high rate of absorbing moisture penetrating into the cable and has an excellent ability to maintain the absorption state in a swollen state. It is composed of powder, tape, coating layer, or film and serves to prevent moisture from penetrating in the longitudinal direction of the cable. The order taping layers 350 and 370 may also have semiconductivity to prevent sudden changes in electric field. The order taping layers 350 and 370 may be comprised of 0.2 millimeters (mm) to 1.4 millimeters (mm).

A polymer sheath layer 380 may be provided on the outside of the metal shielding layer 360 or the outside of the outer order taping layer 370. The polymer sheath layer 380 improves corrosion resistance, water resistance, etc., and protects the power unit 300 from various environmental factors and fault currents such as moisture penetration, mechanical trauma, and corrosion that may affect the power transmission performance of the cable. It can play a role in protecting.

The polymer sheath layer 380 may be made of a resin such as polyethylene. However, the polymer sheath layer 380 made of polyethylene (PE) has inherent hygroscopicity and water permeability, and the cause of such hygroscopicity and water permeability is the surface of the polymer sheath layer 380 formed by extruding polyethylene (PE) at high temperature. This is because a large number of micropores are formed in the cable, and when moisture penetrates into the cable, the moisture fills the micropores and causes moisture to penetrate into the power unit 300 for a long period of time.

On the other hand, when lateral pressure due to cable bending generated by external forces such as ocean currents or waves is applied to the power unit 300, the metal wire 361 or metal tape 362 of the metal shielding layer 360 may be damaged. there is. For example, the metal wire 361 may be disconnected or deformed, resulting in damage such as kinks that do not resolve the twisted state, and the metal tape may be damaged, such as tearing, by the metal wire 361. there is.

Therefore, the present inventors performed a coating of a hydrophobic material that at least partially fills the micropores on the surface of the polymer sheath layer 380 simultaneously with or after extrusion of the polymer sheath layer 380 to form a coating layer 390. By forming it, it is possible to further improve the water barrier characteristics of the submarine cable for offshore wind power, effectively suppressing the formation of water trees by moisture penetrating into the insulating layer 330 of the power unit 300, and the coating layer 390 made of a hydrophobic material. ), the friction between the power unit 300 and the outer structure of the power unit 300 is lowered, thereby reducing the lateral pressure applied to the power unit 300 due to cable bending caused by external forces such as ocean currents or waves, thereby reducing the metal By preventing damage to the shielding layer 360, the lifespan of the cable can be extended.

Here, the hydrophobic material is suitable for application of a material having a melting point lower than the melting point of the material forming the polymer sheath layer 380, and ideally, the hydrophobic material is lower than about 10° C. to prevent the polymer sheath layer 380 from melting. , preferably a material with a low melting point of 30℃ or higher, for example, beeswax (melting point: 66-68℃) or a fluorine-based or siloxane-based polymer, and may further contain other components such as additives. The coating layer 390 may be formed by extrusion or spraying of a hydrophobic material.

The above-described embodiments illustrate a three-phase AC power cable equipped with three power units, but are not limited thereto. For example, it may be a direct current power cable equipped with one power unit. In the case of a direct current power cable, the power unit may be provided with a coating layer of a hydrophobic material on the surface of the polymer sheath layer, similar to the above-described embodiments. In the case of a direct current power cable equipped with one power unit, the above-described bedding layer, armor layer, and outermost layer may be provided outside the power unit.

Even in the case of a DC power cable equipped with one power unit, the coating layer provided on the surface of the polymer sheath layer prevents moisture from penetrating into the power unit of the cable, effectively suppressing the formation of water trees within the insulating layer, thereby increasing the dielectric strength. This is improved and damage to the metal shielding layer provided in the power unit is prevented, resulting in a long-term lifespan.

Although this specification has been described with reference to preferred embodiments of the present invention, those skilled in the art can make various modifications and changes to the present invention without departing from the spirit and scope of the present invention as set forth in the claims described below. It will be possible to implement it. Therefore, if the modified implementation basically includes the elements of the claims of the present invention, it should be considered to be included in the technical scope of the present invention.

Claims

As a submarine cable for offshore wind power,

A conductor, an internal semiconducting layer surrounding the conductor, an insulating layer surrounding the internal semiconducting layer, an external semiconducting layer surrounding the insulating layer, a metal shielding layer provided outside the external semiconducting layer, and a polymer sheath layer surrounding the metal shielding layer. Comprising one or more power units comprising,

A submarine cable for offshore wind power, wherein a coating layer of a hydrophobic material is provided on the surface of the polymer sheath layer.
According to paragraph 1,

A submarine cable for offshore wind power, wherein the hydrophobic material has a melting point that is at least 10°C lower than the melting point of the material forming the polymer sheath layer.
According to paragraph 2,

A submarine cable for offshore wind power, characterized in that the hydrophobic material contains beeswax.
According to paragraph 1,

A submarine cable for offshore wind power, wherein the hydrophobic material at least partially fills a plurality of micropores formed on the surface of the polymer sheath layer.
According to paragraph 1,

The power unit includes an inner water blocking tape layer provided between the outer semiconducting layer and the metal shielding layer and surrounding the outer semiconducting layer, and an outer water blocking tape provided between the metal shielding layer and the polymer sheath layer and surrounding the metal shielding layer. A submarine cable for offshore wind power, characterized in that it includes at least one of the layers.
According to clause 5,

The inner water taping layer or the outer water water taping layer is for offshore wind power, characterized in that it includes at least one selected from the group consisting of powder, tape, coating layer, and film containing a super absorbent polymer (SAP). Undersea cable.
According to paragraph 1,

Comprising a plurality of the power units,

A cable insert provided in the area between the plurality of power units;

A binding tape layer for finishing a plurality of power units and cable inserts in a circular shape;

A bedding layer provided outside the binding taping layer and including polypropylene yarn;

An armor layer provided outside the bedding layer; and

A submarine cable for offshore wind power, which is provided outside the armor layer and further includes an outermost layer containing a polymer resin material.