Overhead Line Mixed Wire Layers Reduce Corona Discharge
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Solution Overview
Problem
High-voltage overhead lines experience corona discharges leading to energy losses and noise, which conventional methods attempt to mitigate by increasing cable diameter, but this results in increased weight and installation challenges, particularly with hollow cables that require complex production and installation.
Innovation Solution
An overhead conductor with a metallic core wire and multiple wire layers, where the outer layer is metallic and inner layers are mixed, comprising metallic and non-metallic wires acting as placeholders without tensile function, allowing for increased diameter without weight increase, enabling easy manufacturing and installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the cable diameter is increased to reduce corona discharges, then corona effects are reduced, but the rope weight increases significantly
Solution Approach 1:
The cable structure is segmented into multiple wire layers around a core wire, with inner layers being mixed (metallic and non-metallic) and outer layers being metallic. This segmentation allows the cable to achieve a larger effective diameter for corona reduction while the non-metallic wires in inner layers reduce the overall weight compared to a solid metallic cable of the same outer diameter.
Solution Approach 2:
Different wire layers have different material compositions optimized for their specific functions: inner layers use mixed metallic and non-metallic wires where non-metallic wires provide placeholder function with lower density, while outer layers use metallic wires for electrical conductivity and mechanical strength. This local differentiation resolves the contradiction by placing lightweight materials where weight matters less and conductive materials where electrical function is critical.
2Object-affected harmful factors
If hollow cables are used to increase diameter without weight increase, then corona effect is reduced and weight is maintained, but production and installation complexity increases
Solution Approach 1:
Instead of using a single hollow tube structure, the invention segments the cable into multiple layers of individual wires, with non-metallic wires distributed in inner layers. This segmentation transforms the complex hollow tube production into simpler wire stranding processes that can use standard equipment and procedures.
Solution Approach 2:
The invention extracts the placeholder function from the complex hollow tube structure and distributes it across multiple non-metallic wires in inner layers. These non-metallic wires are taken out as simple placeholder elements without tensile function, eliminating the need for complex tube manufacturing while achieving the same diameter-increasing effect for corona reduction.
3Weight of moving object
If non-metallic wires are used as placeholders in inner layers, then cable diameter increases with reduced weight, but manufacturing stability may be affected
Solution Approach 1:
The invention merges metallic and non-metallic wires into mixed wire layers, combining the advantages of both material types. The non-metallic wires provide weight reduction and diameter increase, while the metallic wires maintain structural integrity and electrical conductivity. This merging ensures manufacturing stability by using conventional wire stranding techniques that can handle mixed materials.
Solution Approach 2:
Non-metallic wires are placed specifically in inner layers where they serve as placeholders without bearing tensile loads, while metallic wires are positioned in outer layers where mechanical strength and conductivity are critical. This local quality assignment maintains manufacturing stability by ensuring that load-bearing functions are always performed by metallic wires regardless of the presence of non-metallic placeholders.
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 solution effectively reduces corona discharges while maintaining stability and ease of installation, as the placeholders do not affect the cable's functionality post-installation, allowing for degradable materials and standard installation tools.
Implementation Method 1
the non-metallic wires are stranded as placeholders without a management function and without taking over tensile forces
Implementation Method 2
corona discharges, which occur with high electrical voltages and lead to energy losses and disturbing noise. It is known that this effect can be reduced by increasing the cable diameter, because increasing the diameter leads to a reduction in the edge field strength and thus to a reduction in the corona effects described
Data Source
AI summary
It is a cable for high-voltage overhead lines with at least one metallic core wire (1) and several wire layers (2, 4) arranged around the core wire (1), wherein at least the outer wire layer (2) as a metallic wire layer (2) consists exclusively of metallic wires (3) and wherein several of the inner wire layers (4) arranged between the core wire (1) and the outer wire layer (2) as mixed wire layers (4) each consist of metallic wires (5) on the one hand and non-metallic wires (6) on the other.