On-Load Tap Changer Switching via Capacitor Energy Storage
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Solution Overview
Problem
On-load tap changers face safety issues due to mechanical energy storage failures, leading to potential destruction of step transformers, especially during energy supply failures during switching processes.
Innovation Solution
A method that divides the switching process into phases to identify and monitor critical and non-critical states, using a voltage monitoring device and capacitors to ensure safe switching by maintaining energy supply during critical phases, preventing contact welding or failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If mechanical energy storage devices (springs) are used to enable sudden switching, then switching capability is improved, but reliability deteriorates due to spring breakage and mechanical failures
Solution Approach 1:
The patent replaces mechanical energy storage devices (springs) with an electric drive system powered by a capacitor bank. The capacitor bank stores electrical energy and supplies it during switching operations, eliminating mechanical components that are prone to failure. This substitution maintains the necessary switching capability while significantly improving reliability by removing mechanical failure points.
Solution Approach 2:
The patent changes the energy storage parameter from mechanical (spring tension) to electrical (capacitor charge). The capacitor bank can be charged during normal operation and discharged during switching, providing the necessary power without the mechanical degradation issues of springs. This parameter change allows for monitoring and replacement without complete system shutdown.
2Reliability
If electric drive is used to operate on-load tap changer, then reliability is improved by eliminating mechanical energy storage failures, but safety deteriorates during energy supply failures at critical switching positions
Solution Approach 1:
The patent implements preliminary action by charging the capacitor bank before switching operations begin. The capacitor is charged during normal voltage conditions and then supplies energy during critical switching phases if voltage drops occur. This preliminary energy storage ensures that switching can complete safely even if the main power supply fails during operation.
Solution Approach 2:
The capacitor bank acts as an energy buffer or cushion that compensates for voltage drops during critical switching positions. When the electric drive encounters insufficient voltage that could cause contact welding, the capacitor releases stored energy to maintain adequate voltage levels, cushioning against the harmful effect of incomplete switching.
3Object-affected harmful factors
If voltage monitoring and phase division are implemented, then safety is improved during switching, but device complexity increases
Solution Approach 1:
The patent segments the switching process into distinct phases (opening phase, closing phase, intermediate positions) and applies voltage monitoring specifically during critical phases. Rather than continuous complex monitoring, the system divides the switching trajectory into manageable segments, checking voltage at key points. This segmentation reduces complexity while maintaining safety by focusing monitoring resources on critical moments.
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
Ensures that switching contacts never assume critical states, preventing damage to the on-load tap changer or the entire transformer, thus enhancing safety and reliability of the switching process.
Implementation Method 1
compensate for voltage drops using the energy present in the capacitors of the control
Implementation Method 2
processes the value of the supply voltage detected at the beginning of an intended switching process by means of a voltage monitoring device
Data Source
Figure 1
Figure 2a~2d
Figure 2e~2h
AI summary
The invention relates to a method for performing a switching process in an on-load tap changer between winding taps of a tapped transformer. The switching process for an on-load tap changer is subdivided into a plurality of phases according to the reactor switching principle. In these phases, the switching contacts in use are monitored during the actuation and are completely opened or closed by capacitors in the controller in the event of failure of the energy supply. Thereby critical switching states are prevented.