Dual On-Load Tap Changer Switching for Wider Transformer Control Range
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Solution Overview
Problem
Existing switching arrangements for electrical systems with multiple control windings face limitations in extending control range and increasing the number of stages without requiring higher voltage and current capacities, and existing transformer designs do not efficiently utilize control windings for voltage regulation and phase shifting.
Innovation Solution
A switching arrangement with two on-load tap-changers and two control windings, where the tap-changers are connected in series and include preselectors or reversing switches, allowing parts of the control windings to be connected or bridged, thereby expanding the control range and increasing the number of stages without increasing voltage and current requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two on-load tap-changers are connected in parallel to extend control range, then the control range and number of stages are increased, but the voltage and current capacities required increase
Solution Approach 1:
The control winding is divided into two separate control windings (first control winding and second control winding), each with its own on-load tap-changer. This segmentation allows independent control of each winding, enabling extended control range through series connection without requiring higher voltage and current capacities from individual tap-changers.
Solution Approach 2:
The patent transitions from parallel connection to series connection of the on-load tap-changers. This dimensional change in the connection topology allows the control range to be extended while maintaining the same voltage and current capacity requirements, as the series connection distributes the voltage across both tap-changers.
2Adaptability or versatility
If existing transformer designs are used with control windings, then the structure is simple, but the control range is limited and the utilization of control windings for voltage regulation and phase shifting is inefficient
Solution Approach 1:
The patent combines two on-load tap-changers with their respective control windings into a unified switching arrangement. This merging allows the control windings to be connected in series, enabling extended control range and improved utilization for voltage regulation and phase shifting, while maintaining a relatively simple overall structure.
Solution Approach 2:
The patent introduces dynamic switching capability through the on-load tap-changers, which can continuously adjust the number of turns in the control windings. This dynamic adjustment enables flexible voltage regulation and phase shifting, significantly improving the adaptability and control range compared to fixed transformer designs.
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 switching arrangement enhances the control range and stage count, enabling flexible voltage regulation and phase shifting, while maintaining efficient operation within existing voltage and current constraints.
Implementation Method 1
a first on-load tap-changer (16) with a first diverter terminal (161) and at least three first switching terminals (162), of which at least two are or can be connected to associated first taps (12) of the first control winding (11)
Implementation Method 2
at least one of the on-load tap-changers (16, 17) comprises a preselector (18) with two preselector terminals (181, 182) and a base terminal (183)
Implementation Method 3
the preselector terminals (181, 182) can be connected to the ends of a coarse winding (19, 20) inductively coupled to this control winding (11, 13)
Data Source
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AI summary
A switching arrangement (15) for an electric system (10) that includes a first and a second tapped winding (11, 13) comprises: - a first on-load tap changer (16) that includes a first discharge terminal (161) and three first switching terminals (162), at least two of which can be connected to associated first taps (12) of the first tapped winding (11); - a second on-load tap changer (17) that includes a first discharge terminal (171) and three second switching terminals (172), at least two of which can be connected to associated second taps (14) of the second tapped winding (13); - the second discharge terminal (171) is connected to the first discharge terminal (161) or to a first switching terminal (162") that is not associated with a first tap (12).