Traction Transformer Phase Switching to Suppress Magnetizing Inrush
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Solution Overview
Problem
The existing power electronic passing neutral section apparatus for traction transformers experiences low safety and reliability due to magnetizing inrush currents caused by sudden voltage phase changes during power supply transitions, which can damage the transformer.
Innovation Solution
A method and device for suppressing magnetizing inrush current by determining a no-power time interval based on phase angles and magnetic flux thresholds to control power electronic switches, ensuring the magnetic flux remains within a safe range during power transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If ground over-phase suppression is implemented to reduce inrush current, then the harmful inrush current is suppressed, but the device complexity increases due to additional control circuits
Solution Approach 1:
The patent introduces a current transformer as an intermediary device to detect the inrush current and a control circuit as a mediator to process the detection signal and generate suppression control signals. These intermediary components enable the suppression function while maintaining system modularity and manageable complexity through standardized interfaces and separate functional modules.
Solution Approach 2:
The patent replaces traditional mechanical or hardware-based suppression methods with electronic control mechanisms. By using electronic detection circuits and control signals to suppress the inrush current, the system achieves more precise control with reduced mechanical complexity and improved response characteristics compared to mechanical suppression approaches.
2Device complexity
If traditional protection devices are used, then the structure is simple, but they cannot effectively distinguish between inrush current and fault current leading to misoperation
Solution Approach 1:
The patent employs dynamic characteristics of the inrush current, specifically its non-periodic and decaying nature, to differentiate it from fault current. The control circuit dynamically analyzes the detection signal characteristics and adjusts the suppression control accordingly, enabling reliable distinction between inrush and fault conditions without requiring overly complex protection device structures.
Solution Approach 2:
The patent changes the parameter analysis approach by monitoring the frequency characteristics and decay patterns of the current signal. By analyzing these parameter variations over time, the system can reliably distinguish between inrush current (which decays and changes frequency) and fault current (which maintains steady characteristics), improving protection accuracy without significantly increasing structural complexity.
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 effectively suppresses magnetizing inrush currents, enhancing safety and reliability of the power electronic passing neutral section apparatus while minimizing speed loss during train passage through neutral sections.
Implementation Method 1
a detection signal corresponding to the inrush current is obtained through a current transformer
Implementation Method 2
a differentiated detection signal corresponding to the differentiated inrush current is obtained through a high-pass filter
Implementation Method 3
a differentiated and amplified detection signal corresponding to the differentiated and amplified inrush current is obtained through an amplifier
Data Source
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AI summary
A method and a device for ground passing neutral section suppression of magnetizing inrush current of a traction transformer, includes: determining a no-power time interval of a traction transformer (S301) according to an acquired first phase angle of a voltage of a second feeding section that is lagging behind a phase angle of a voltage of a first feeding section, an acquired second phase angle of a voltage of primary current of the traction transformer that is lagging behind the phase angle of the voltage of the first feeding section when a locomotive is powered by the first feeding section, and an acquired off moment of a first power electronic switch corresponding to the first feeding section (S300); and determining an on moment of a second power electronic switch corresponding to the second feeding section according to the off moment of the first power electronic switch and the no-power time interval, such that the magnetic flux of the traction transformer is located within a preset magnetic flux range (S302).