HVDC Bushing Tapered End Insulation Stress Control
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Solution Overview
Problem
Existing bushings in high voltage direct current (HVDC) applications face challenges in withstanding high electrical stress from both DC and AC components, requiring complex and costly insulation structures to manage creep and tangential stresses effectively.
Innovation Solution
A bushing design featuring a tapering end portion with distinct axial inclinations and conductive layers in a stair-like formation, allowing for controlled creep stress and dielectric withstand strength, reducing the complexity and cost of insulation structures by providing two degrees of freedom in design parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional bushing design with uniform insulation structure is used, then the insulation provides basic electrical isolation, but the creep stress and tangential stress are not effectively controlled, requiring larger and more complex insulation structures
Solution Approach 1:
The bushing employs a tapered end portion with varying radial distance that creates different stress distribution characteristics in different axial regions. The transition from uniform to tapered geometry provides localized stress control where needed most, reducing maximum creep and tangential stresses without requiring uniform increase in insulation dimensions throughout the entire bushing structure.
Solution Approach 2:
The invention changes the geometric parameter of the insulation structure by introducing a tapered end portion with a specific angle (5-15 degrees). This parameter change optimizes the voltage distribution and stress distribution along the bushing surface, allowing for reduced insulation complexity while maintaining or improving electrical withstand strength.
2Reliability
If the insulation structure is enlarged to withstand high electrical stress, then the dielectric withstand strength increases, but the amount of material, complexity and cost of the turret insulation structure increases
Solution Approach 1:
Instead of uniformly increasing insulation dimensions, the tapered end portion concentrates the stress-mitigating geometry where it is most effective - at the high-stress region near the conductor exit. This localized geometric modification provides enhanced dielectric performance without proportionally increasing the total amount of insulation material required.
Solution Approach 2:
The tapered end portion introduces a curved geometric transition that smooths the electric field distribution and reduces stress concentration. This curvature effect allows for more efficient use of insulation material by creating a more favorable stress distribution pattern rather than relying solely on increased material quantity.
3Ease of manufacture
If the bushing design uses a simple cylindrical shape, then the manufacturing is easier, but the creep stress control and voltage distribution are not optimized
Solution Approach 1:
The invention modifies only one key geometric parameter - introducing a taper angle to the end portion - while maintaining the overall cylindrical bushing structure. This single parameter change provides significant creep stress control and voltage distribution optimization without fundamentally complicating the manufacturing process or requiring multiple complex components.
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 bushing design enhances dielectric withstand strength, simplifies insulation structures, and optimizes voltage distribution, effectively managing electrical stresses in HVDC systems while reducing the complexity and cost of insulation.
Implementation Method 1
the radial distance Δr(x) between the edges of the conductive layers and the surface of the condenser core varies in the axial direction X in the tapering end portion of the bushing
Implementation Method 2
the condenser core has a tapering end portion arranged to be in contact with a fluid dielectric having higher dielectric withstand strength than air
Data Source
AI summary
It is presented a bushing (1) comprising a condenser core (3) arranged to house an electrical conductor (15) along a central axis (X) of the condenser core (3), wherein the condenser core (3) has a tapering end portion (3-2a) arranged to be in contact with a fluid dielectric having higher dielectric withstand strength than air, the tapering end portion (3-2a) presenting a surface having a first portion (4-1) with a first inclination (I-1) in the axial direction and a second portion (4-2) with a second inclination (I-2) in the axial direction, which second inclination (I-2) differs from the first inclination (I-1), wherein the first portion (4-1) and the second portion (4-2) define planes that intersect the central axis (X). A system comprising such a bushing is also presented herein.