Stereo-triangular Wound-core Transformer for High Voltage
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Solution Overview
Problem
Laminated core power transformers with voltage classes above 110 kV suffer from air gaps causing magnetic resistance, unbalanced three-phase currents, noise, and inefficiencies due to misaligned magnetic circuits and suboptimal lamination.
Innovation Solution
A stereo-triangular wound-core power transformer with iron yokes and core pillars arranged in a regular triangle shape, featuring high-voltage and low-voltage windings, and a regulating winding, along with insulating components and oil ducts, to minimize magnetic resistance and noise while ensuring balanced phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If laminated core is used in power transformers with voltage class of 110 kV or above, then the transformer can be manufactured with conventional processes, but air gaps formed by seams cause greater magnetic resistance and larger no-load loss and no-load current
Solution Approach 1:
The core is divided into three separate single frames that are pieced together to form the stereo-triangular structure. Each single frame is wound continuously by several trapezium strips, eliminating the need for slitting and reducing air gaps at seams while maintaining manufacturability through modular assembly.
Solution Approach 2:
Three identical single frames are pieced together and arranged in a regular triangle shape to form the complete core. This merging of multiple frames into a unified stereo-triangular structure reduces overall magnetic resistance and no-load losses compared to conventional laminated cores with numerous seams.
2Ease of manufacture
If laminated core is used in power transformers with voltage class of 110 kV or above, then the transformer can be assembled with standard components, but the direction of local magnetic circuits is not in conformity with the high magnetic direction of the silicon steel sheets
Solution Approach 1:
The silicon steel strips are wound in specific directions to ensure that the high magnetic direction of the sheets conforms to the local magnetic circuit direction at each position in the core. This localized optimization of material orientation maximizes magnetic efficiency and reduces losses.
3Ease of manufacture
If laminated core is used in power transformers with voltage class of 110 kV or above, then the core can be constructed with stacked sheets, but the sheets are not close enough which reduces the lamination factor and increases noise
Solution Approach 1:
The core transitions from a two-dimensional stacked sheet structure to a three-dimensional stereo-triangular wound structure. The continuous winding of trapezium strips creates a compact, tightly-bound core that eliminates gaps between sheets, reducing noise while maintaining manufacturability.
4Ease of manufacture
If laminated core is used in power transformers with voltage class of 110 kV or above, then the transformer can be built with conventional core structures, but the three phase currents are not balanced due to unbalanced three-phase magnetic circuits
Solution Approach 1:
The core employs a symmetric stereo-triangular structure with three identical single frames arranged in a regular triangle. This geometric symmetry ensures that all three phases have equal magnetic paths and impedance, resulting in balanced three-phase currents and improved reliability.
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 reduces magnetic resistance, no-load losses, and noise, while maintaining balanced three-phase currents and optimizing material usage, resulting in a more efficient and reliable transformer design.
Implementation Method 1
there are many air gaps formed by the seams in the magnetic circuits, causing greater magnetic resistance
Implementation Method 2
the direction of the local magnetic circuits is not in conformity with the high magnetic direction of the silicon steel sheets
Implementation Method 3
the magnetic conduction direction of the silicon steel strips is in line with the magnetic circuit direction of the core
Implementation Method 4
The windings comprise high-voltage windings and low-voltage windings, or a regulating winding; the high-voltage windings and low-voltage windings are wound on the core pillars
Data Source
AI summary
A stereo-triangular wound-core power transformer with a voltage class more than or equal to 110 kV is disclosed, which includes a stereo-triangle wound-core and windings, wherein the core includes iron yokes and core pillars which are arranged in a stereo-triangle shape, with every two adjacent core pillars connected through an iron yoke. The power transformer further includes angle rings, end rings, insulating end rings, insulating end plates and a frame-type clamp, wherein the angle rings, insulating end rings, end rings and insulating end rings are arranged at both ends of the core pillars in sequence, respectively, and the ends of the core pillars are arranged on the insulating end plates. The frame-type clamp covers the iron yokes, and the supporting boards of the frame-type clamp are connected with the insulating end plates through pressing screws.