HVDC Cable Joint Insulation Alleviating Electric Field Distortion
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Solution Overview
Problem
The existing direct-current power cable systems face challenges with excessive space charge accumulation in the sleeve member of ultra-high voltage direct-current power cables, leading to electric field distortion and potential insulation breakdown.
Innovation Solution
A direct-current power cable system is designed with an electric field alleviation layer between the second electrode and the outer semiconductive layer, ensuring they are in a non-contact state while being in contact with the outer semiconductive layer. This configuration expands the microcurrent path, allowing charges to be easily discharged without accumulation, thus preventing electric field distortion and insulation breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the second electrode and outer semiconductive layer are in direct contact in the sleeve member, then the structure is simpler and easier to manufacture, but space charges accumulate excessively at the contact region causing electric field distortion and insulation breakdown
Solution Approach 1:
The patent introduces an electric field alleviation layer as an intermediary between the second electrode and the outer semiconductive layer. This intermediate layer prevents direct contact while managing space charge accumulation, thereby maintaining insulation performance without significantly complicating the manufacturing process.
2Reliability
If the electric field alleviation layer is positioned to contact both the second electrode and outer semiconductive layer, then space charge accumulation is reduced, but the device complexity increases
Solution Approach 1:
The electric field alleviation layer is strategically positioned only at specific regions where space charge accumulation is most problematic (at the edge end region of the first electrode and where the second electrode contacts the electric field alleviation layer), rather than throughout the entire sleeve member. This localized approach improves electric field distribution while minimizing added complexity.
3Reliability
If the sleeve member structure is optimized to prevent space charge accumulation, then insulation breakdown is prevented, but the manufacturing process becomes more complex and costly
Solution Approach 1:
The electric field alleviation layer is constructed from composite materials that provide both electrical field management properties and mechanical compatibility with adjacent layers. This allows the layer to perform multiple functions (space charge management, electrical insulation, mechanical support) simultaneously, improving insulation durability while keeping manufacturing complexity manageable.
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 proposed system effectively alleviates electric field concentration and prevents space charge accumulation within the sleeve member, thereby enhancing the dielectric strength and reducing the risk of insulation breakdown in the cable joint box.
Implementation Method 1
the electric field alleviation layer 330' operates as an insulating layer with sufficiently high resistance; however, when space charges accumulate and an excessive electric field form, the resistance of the electric field alleviation layer 330' nonlinearly decreases, allowing charges to dissipate along the electric field alleviation layer 330'
Data Source
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AI summary
The present invention relates to a direct-current power cable system. More specifically, the present invention relates to a direct-current power cable system capable of preventing or minimizing electric field distortion due to a local electric field concentration and insulation breakdown of a cable joint box by alleviating the electric field of a portion where space charges are excessively accumulated inside a sleeve member of an intermediate connection structure of an ultra-high voltage direct-current power cable.