Self-cooling coaxial high voltage cable with natural convection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-voltage direct current transmission cables face challenges with significant electrical and magnetic field emissions, overheating, and limited distance due to their construction, which is disruptive and harmful, especially at high voltages above 120 kV.
Innovation Solution
A self-cooling coaxial high-voltage cable design featuring a metallic inner and outer conductor with an insulating spacer, where the spacer covers minimal surface area to allow for natural convection of a liquid or solid insulating medium, such as palm oil, between the conductors, effectively dissipating heat and minimizing field emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional high-voltage cables are used with solid insulation and close conductor spacing, then electrical insulation is improved, but heat dissipation deteriorates causing overheating
Solution Approach 1:
The patent replaces solid insulation with a liquid insulating medium that enables convective heat transfer. The liquid circulates between the conductors, absorbing heat through convection currents while maintaining electrical insulation, thus resolving the contradiction between insulation reliability and heat dissipation.
Solution Approach 2:
The patent changes the physical state of the insulating medium from solid to liquid, fundamentally altering the heat transfer mechanism from conduction to convection. This parameter change enables efficient heat removal while maintaining insulation, directly addressing the overheating problem.
2Object-affected harmful factors
If conductors are combined closely to reduce field emissions, then electrical and magnetic field emissions are reduced, but stray fields increase causing harmful emissions
Solution Approach 1:
The liquid insulating medium acts as an intermediary between the conductors, allowing them to be positioned closer together while the liquid circulation system manages the resulting electromagnetic interactions and heat generation, preventing harmful stray field accumulation.
3Ease of manufacture
If overhead lines are used for cost-effective long-distance transmission, then transmission cost is reduced, but visual impact and safety hazards increase
Solution Approach 1:
The invention extracts the harmful effects (visual impact, safety hazards, field emissions) from the transmission system by moving it underground and using the self-cooling technology to eliminate overheating concerns, enabling cost-effective long-distance transmission without the drawbacks of overhead lines.
4Stability of the object's composition
If spacer surface coverage is increased to improve mechanical support, then structural stability is improved, but heat transfer surface area is reduced
Solution Approach 1:
The patent applies local quality by making the spacer's thermal conductivity much higher than its mechanical support function requires. The spacer is designed with high thermal conductivity material to compensate for its small surface coverage, ensuring efficient heat transfer from the conductor to the liquid medium despite minimal contact area.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design significantly reduces electrical and magnetic field emissions, enables efficient heat transfer and power transmission from 10 MW to 5 GW, and provides self-clogging and environmental safety features, making it suitable for underground or submarine use.
Implementation Method 1
the insulating agent being either liquid or itself liquefied by the operating temperature occurring during operation of the high-voltage cable, in order to bring about natural convection of the insulating medium between the inner conductor and the outer conductor
Implementation Method 2
heat is transferred from the metallic inner conductor to the metallic outer conductor and from the metallic outer conductor to the environment
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The cable (1) has a spacer (4) whose inner support part (4a) covers 15% of a surface of a metallic inner conductor (2) in a running direction while an outer support part (4d) covers 50% of an inner surface of a metallic outer conductor (3). The conductors limit an intermediate space (5a) filled with an insulation unit. The insulation unit is either refined palm oil or liquefied by operating temperature produced during operation of the cable to enable a natural convection of the insulation unit between the conductors at the operating temperature in the space. The spacer is made of plastic. : An independent claim is also included for a method for natural cooling of a self-cooling coaxial high voltage cable. USE : Self-cooling coaxial high voltage cable e.g. submarine cables or underground cable, for transferring large amount of electrical power i.e. high voltage direct current, over large distances about 1000-3000 km. ADVANTAGE : The insulation unit is either refined palm oil or liquefied by the operating temperature produced during operation of the cable in order to enable the natural convection of the insulation unit between the inner- and outer conductors at the operating temperature in the space, thus reducing electrical and/or magnetic field emissions while enabling even cooling of the cable. The utilization of insulation unit prevents the cable from environmental damage. DESCRIPTION OF DRAWINGS : The drawing shows a sectional perspective view of a self-cooling coaxial high voltage cable. 1 : Self-cooling coaxial high voltage cable 2 : Metallic inner conductor 3 : Metallic outer conductor 4 : Spacer 4a : Inner support part of spacer 4d : Outer support part of spacer 5a : Intermediate space.