Current selectivity theory-based protection algorithms for railway track transformers: A comprehensive modeling and synthesis approach

Abstract

Railway track transformers are vital for signaling systems, yet traditional electromechanical protection devices like the AVM-2 often lack the required precision and selectivity. This leads to frequent false trippings or equipment failure during overcurrent transients. This paper presents a novel protection algorithm for railway track transformers based on advanced current selectivity theory. We develop a comprehensive mathematical model of the track circuit, incorporating non-linear transformer characteristics and transient fault dynamics. A new synthesis approach is introduced for a microprocessor-based protection device (AVM-MP), utilizing a dynamic thresholding mechanism to enhance fault discrimination. This method allows for a clear distinction between harmless inrush currents and actual short-circuit faults. The algorithm was rigorously validated using MATLAB/Simulink and experimental hardware-in-the-loop testing. Results indicate that the proposed selectivity-based synthesis reduces response time by 30% and significantly improves sensitivity compared to legacy systems. The proposed modeling and synthesis approach provides a robust framework for modernizing railway automation. By implementing this intelligent protection, the reliability and safety of railway power supply networks are substantially increased.