On-Load Tap Changer Self-Powering for Uninterrupted Switching
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Solution Overview
Problem
Existing on-load tap-changers require an additional external power supply for the power electronic switching means, which complicates the switching process and increases system complexity.
Innovation Solution
An on-load tap-changer design that incorporates an auxiliary contact mechanically coupled to a selector arm, allowing power to be derived from the step voltage during switching, eliminating the need for an external power supply by using semiconductor switching elements and an energy storage device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external power supply is provided for the power electronic switching means, then the semiconductor switching elements can be operated, but the system complexity increases and the switching process is complicated
Solution Approach 1:
The patent combines the power supply function with the existing fixed contacts and selector arms of the on-load tap-changer. The auxiliary contact is mechanically coupled to the selector arm, and both the auxiliary contact and fixed contacts are connected to winding taps, thereby deriving power from the transformer's own windings without requiring an external power supply. This merging eliminates the need for separate power supply circuits while ensuring reliable operation of the semiconductor switching elements.
Solution Approach 2:
The on-load tap-changer uses its own operational components (fixed contacts, selector arms, and winding taps) to generate the necessary power for the control unit and semiconductor switching elements. The auxiliary contact derives power during the switching process from the voltage difference between the selector arm and fixed contacts, allowing the system to be self-powered without external intervention.
2Productivity
If power is derived from step voltage during switching, then uninterrupted switching is enabled without external power, but the power availability is limited to switching moments
Solution Approach 1:
The auxiliary contact is mechanically coupled to the selector arm such that it is positioned to make contact with the appropriate fixed contact just before or during the switching operation. This preliminary positioning ensures that power is available exactly when needed for the semiconductor switching elements, enabling uninterrupted switching without requiring continuous power supply.
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
Enables uninterrupted switching between transformer taps without an external power supply, simplifying the system and ensuring continuous power to the control unit and semiconductor switching elements.
Implementation Method 1
the auxiliary contact and the first selector arm are never located on the same fixed contact or on the connecting contact at the same time
Implementation Method 2
a voltage equal to a step voltage is present between the first selector arm and the auxiliary contact, which supplies power to the control unit
Implementation Method 3
The semiconductor switching elements are preferably designed as IGBT switching elements and/or as thyristors and/or as JFET switching elements and/or as MOSFET switching elements and/or as integrated gate commutated thyristors (IGCTs)
Data Source
Figure 1
Figure 2a~2b
Figure 2c~2d
AI summary
The invention relates to an on-load tap changer (10) for uninterrupted switching between winding taps (NJ, NJ+1,..., NN) of a tap-changing transformer (1), comprising: - a first fixed contact (12), which can be connected to a first winding tap NJ of the tap-changing transformer (1); - a second fixed contact (13), which can be connected to a second winding tap NJ+1 of the tap-changing transformer (1); - a first selector arm (31), which can contact each of the fixed contacts (12, 13); - a second selector arm (32), which can contact each of the fixed contacts (12, 13); - a load transfer switch (20) for carrying out a switch from a first fixed contact (12) to a second fixed contact (13) of the on-load tap changer (10). The on-load tap changer (10) also comprises a connection contact (11), which is provided in addition to the fixed contacts (12, 13), and an auxiliary contact (33), which can selectively contact either the connection contact (11) or one of the fixed contacts (12, 13).