Thyristor Switching for Railway Phase Separation
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Solution Overview
Problem
Current automatic split phase crossing technologies for electrified railways face issues with power interruptions and transient electrical processes, leading to potential component damage and performance degradation, especially in high-speed trains.
Innovation Solution
An automatic split phase crossing system utilizing normally-closed thyristor switches, load switches, current and voltage transformers, and high-voltage resistors, which are controlled by a central unit to manage power supply arms and neutral sections, ensuring instantaneous switching during zero-crossing points to maintain uninterrupted power supply and suppress transient processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If ground-switch automatic split phase crossing is used, then power interruption time is reduced to 200ms-400ms, but switching transient processes cause over-voltage or over-current that may damage components
Solution Approach 1:
The system performs preliminary detection of train position using sensors and control units before the actual switching operation. The control unit receives position information and prepares the switching sequence in advance, ensuring that switching occurs at the optimal moment when train current draw is minimal, thereby reducing transient over-voltage and over-current effects while maintaining fast switching time
Solution Approach 2:
The system employs a feedback mechanism where the control unit continuously monitors train position, switching state, and electrical parameters. Based on this feedback, the control unit dynamically adjusts the switching timing and sequence, optimizing the switching moment to avoid transient electrical disturbances while maintaining the fast switching performance needed to minimize power interruption time
2Device complexity
If switching action is performed without restriction on switching time point, then device complexity is reduced, but transient processes easily cause over-voltage or over-current during operations
Solution Approach 1:
The system uses the train's own operational characteristics (current draw patterns, position information) to automatically determine the optimal switching moment. The control unit processes position signals from sensors and autonomously decides when to execute switching, eliminating the need for complex external control mechanisms while ensuring switching occurs at safe moments that minimize transient electrical disturbances
3Extent of automation
If on-board automatic split phase crossing is used, then driver manual operation is eliminated, but train has long power interruption time and large speed loss
Solution Approach 1:
The system replaces traditional mechanical ground switches with electronic thyristor-based switching devices controlled by a microprocessor unit. This electronic switching system operates much faster than mechanical switches, reducing power interruption time from seconds to milliseconds, while the automated control eliminates driver response delays and ensures optimal switching timing to minimize speed loss
4Reliability
If ground-switch automatic split phase crossing is used, then power supply dead zones are eliminated, but switching time of 200ms-400ms still affects high-speed train performance
Solution Approach 1:
The system dynamically adjusts switching parameters based on real-time train position and electrical load conditions. The control unit modifies switching timing and duration according to the specific operational context, enabling the system to achieve both reliability (no power dead zones) and high productivity (minimal impact on high-speed train performance) by optimizing switching for each specific situation
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 system provides uninterrupted power supply to trains, reduces interference with the power grid, and prevents over-voltage and over-current issues, enhancing performance and safety by minimizing switching time and transient effects.
Implementation Method 1
the thyristor switch is turned off at a zero-crossing point of the current to complete the instantaneous switching from the first power supply arm to the second power supply arm
Data Source
Figure 1~2
AI summary
The present invention discloses an automatic split phase crossing system and method for electrified railway section posts. The system comprises: a pantograph identifier for sensing a traveling position and direction of a train; a voltage transformer for detecting a voltage of a first power supply arm; a first resistor and a first thyristor switch, which are connected to two ends of a first sectionalizer in parallel, respectively; a second resistor and a second thyristor switch, which are connected to two ends of a second sectionalizer in parallel, respectively; and a control unit for executing the following operations: in the event that the train travels from the first power supply arm to the first sectionalizer, controlling the first thyristor switch to be turned on during voltage zero-crossing of the first power supply arm; in the event that the train travels from the first power supply arm into the neutral section via the first sectionalizer, controlling the first thyristor switch to be turned off and simultaneously controlling the second thyristor switch to be turned on by means of current zero-crossing of the first thyristor switch for the time being; and in the event that the train travels from the neutral section into the second power supply arm via the second sectionalizer, controlling the second thyristor switch to be turned off.