Laminated Generator Neutral Ring for Up-Tower DFIG Repair
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Doubly-Fed Induction Generators (DFIG) in wind turbines suffer from mechanical and electrical failures due to differential expansion of components under centrifugal forces, leading to fractures and electrical arcing at the neutral ring connections, which are prone to fatigue and hydrogen embrittlement.
Innovation Solution
A novel neutral ring system comprising laminated copper sections and solid copper connectors with cup-shaped fixtures is designed to replace or repair the existing neutral ring connections, distributing stress and reducing strain, using electrolytic tough pitch copper or oxygen-free high conductivity copper to enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid mechanical coupling is used between the outside diameter and inside diameter of rotor components, then structural integrity is maintained, but differential expansion under centrifugal forces causes strain and fatigue leading to fractures
Solution Approach 1:
The patent introduces a flexible neutral ring made of laminated copper sheets that can expand and contract independently under centrifugal forces. This flexible structure accommodates differential expansion between the rotor components while maintaining electrical connectivity, thereby reducing strain and preventing fractures in the rigid connectors.
Solution Approach 2:
The patent changes the physical parameters of the neutral ring by using laminated copper sheets with specific material properties (electrolytic tough pitch copper or oxygen-free high conductivity copper) that provide both flexibility and electrical conductivity. The laminated structure allows controlled deformation under stress while maintaining structural integrity.
2Reliability
If solid copper connectors are used for neutral ring connections, then electrical conductivity is enhanced, but the rigid structure is prone to fatigue and hydrogen embrittlement under cyclic loading
Solution Approach 1:
The patent uses composite construction for the neutral ring by laminating multiple copper sheets together. This composite structure combines the high electrical conductivity of copper with the flexibility and fatigue resistance of the laminated configuration, preventing hydrogen embrittlement while maintaining electrical performance.
Solution Approach 2:
The laminated copper sheet structure acts as a flexible element that can accommodate cyclic deformation without fatigue failure. The thin laminated layers allow controlled flexing under centrifugal forces while maintaining electrical connectivity, extending the lifespan of the connectors.
3Ease of manufacture
If the neutral ring is designed as a single rigid component, then manufacturing is simplified, but in-situ repair and replacement become difficult
Solution Approach 1:
The neutral ring is segmented into multiple laminated copper sheets that can be independently handled and replaced. This segmentation allows the neutral ring to be manufactured using standard processes while enabling easy in-situ repair by replacing individual laminated layers without removing the entire rotor assembly.
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 new neutral ring system significantly extends the life of the connections by reducing strain and preventing fractures, thus improving the mechanical and electrical integrity of the generator, while allowing for in-situ repairs and replacements.
Implementation Method 1
The banding is a semi-rigid material and dilates with centrifugal forces a small but measurable amount. The coils, which are supported by the banding, will dilate with the banding. Other components, such as the wye ring, dilate significantly less than the banding. Components connected between the wye ring and the coils, such as the connectors 18 shown in FIG. 2, are strained by this differential dilation. These strains are typically a combination of elastic and plastic strains
Implementation Method 2
first, second, and third neutral ring connectors. Each of the first, second, and third neutral ring connectors may comprise a solid copper structure having a cup-shaped fixture extending radially outward from the neutral ring. The first, second, and third neutral ring connectors may each comprise a first and second attachment point that is brazed to ends of the first, second, and third ring sections to form a contiguous ring
Data Source
AI summary
Systems for replacement of the neutral ring of a rotating electric machine, such as a doubly-fed induction generator (DFIG) useful in a wind turbine, and methods for up-tower repair of the neutral ring. The system generally includes a neutral ring having first, second, and third ring sections formed or two or more laminated layers of copper, and first, second, and third neutral ring connector formed of solid copper. Each of the first, second, and third neutral ring connectors include a cup-shaped fixture extending radially outward from the neutral ring via a riser and are configured for attachment with coils of the winding.