HVDC power cable with water-blocking capability

Patent metadata

Field	Value
Publication number	US-11437166-B2
Application number	US-202017595199-A
Country	US
Kind code	B2
Filing date	May 20, 2020
Priority date	May 20, 2019
Publication date	Sep 6, 2022
Grant date	Sep 6, 2022

Abstract

A high voltage DC power cable designed for voltages of 320 kV or higher, including: a multi-wire conductor, an inner semiconducting layer arranged around the multi-wire conductor, the inner semiconducting layer forming a screen layer for the multi-wire conductor, a solid insulation system arranged around the inner semiconducting layer, and a water-blocking compound configured to restrict water migration into the high voltage DC power cable.

First claim

The invention claimed is:

1. A high voltage DC power cable designed for voltages of 320 kV or higher, comprising:
a multi-wire conductor,
an inner semiconducting layer arranged around the multi-wire conductor, the inner semiconducting layer forming a screen layer for the multi-wire conductor,
a solid insulation system arranged around the inner semiconducting layer, and
a water-blocking compound configured to restrict water migration into the high voltage DC power cable,
wherein the water-blocking compound is a liquid with a viscosity greater than 20 Pa·s at a temperature of 20° C.,
wherein the water-blocking compound is electrically conducting, wherein the water-blocking compound includes a carbon-based component which provides the electric conductivity of the water-blocking compound, wherein the carbon-based component is graphite, wherein the water-blocking compound includes polybutadiene, and an antioxidant.

2. The high voltage DC power cable as claimed in claim 1 , wherein the water-blocking compound is provided in interstices between the wires of the multi-wire conductor.

3. The high voltage DC power cable as claimed in claim 2 , wherein the water-blocking compound comprises a hydrocarbon-based component or a silica-based component.

4. The high voltage DC power cable as claimed in claim 2 , wherein the solid insulation system is composed of an electrically insulating material which has an electrical conductivity of at most 1000 fS/m, at most 100 fS/m, or at most 10 fS/m measured at nominal voltage at a temperature of 20° C.

5. The high voltage DC power cable as claimed in claim 2 , comprising an electrically conducting or an electrically non-conducting tape wound around the multi-wire conductor and arranged between the multi-wire conductor and the inner semiconducting layer.

6. The high voltage DC power cable as claimed in claim 2 , wherein the water-blocking compound is provided on an outermost layer of wires of the multi-wire conductor.

7. The high voltage DC power cable as claimed in claim 1 , wherein the water-blocking compound is provided radially outwards of and around the solid insulation system.

8. The high voltage DC power cable as claimed in claim 1 , wherein the water-blocking compound comprises a hydrocarbon-based component or a silica-based component.

9. The high voltage DC power cable as claimed in claim 1 , wherein the solid insulation system is composed of an electrically insulating material which has an electrical conductivity of at most 1000 fS/m, at most 100 fS/m, or at most 10 fS/m measured at nominal voltage at a temperature of 20° C.

10. The high voltage DC power cable as claimed in claim 1 , wherein the solid insulation system is composed of an electrically insulating material which has the inherent property that a non-heat treated 1 mm thick press-moulded plate made from the electrically insulating material has an electrical conductivity of at most 50 fS/m measured after 24 hours at 70° C. and an electric field of 30 kV/mm applied across the thickness dimension of the press-moulded plate.

11. The high voltage DC power cable as claimed in claim 1 , comprising an electrically conducting or an electrically non-conducting tape wound around the multi-wire conductor and arranged between the multi-wire conductor and the inner semiconducting layer.

12. The high voltage DC power cable as claimed in claim 11 , wherein the tape is in direct contact with the multi-wire conductor and/or the water-blocking compound and with the inner semiconducting layer.

13. The high voltage DC power cable as claimed in claim 1 , wherein the multi-wire conductor is formed by a plurality of layers of wires, wherein the water-blocking compound is provided in interstices between each layer of wires.

14. The high voltage DC power cable as claimed in claim 1 , wherein the water-blocking compound is provided on an outermost layer of wires of the multi-wire conductor.

15. The high voltage DC power cable as claimed in claim 1 , wherein the solid insulation system is partially cross-linked so that it only passes a hot set test according to IEC 60811-507 up to 50% of the load specified by IEC 60811-507.

16. The high voltage DC power cable as claimed in claim 15 , wherein the solid insulation system is partially cross-linked so that it only passes a hot set test according to IEC 60811-507 up to 40%, such as up to 30%, such as up to 25%, of the load specified by IEC 60811-507.

17. The high voltage DC power cable as claimed in claim 1 , wherein the solid insulation system comprises a thermoplastic polypropylene-based material.

Assignees

• Nkt Hv Cables Ab

Inventors

• Gustafsson Kristian
• Abbasi Amirhossein
• Johansson Tommy

Classifications

• H01B7/14 Primary

  Submarine cables · CPC title

• H01B9/006

  Constructional features relating to the conductors · CPC title

• H01B7/288 Primary

  using hygroscopic material or material swelling in the presence of liquid · CPC title

• H01B13/322

  the material being a liquid, jelly-like or viscous substance · CPC title

• Y02A30/14

  Extreme weather resilient electric power supply systems, e.g. strengthening power lines or underground power cables · CPC title