№ 16 (ЕСБЗТ)

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Browsing № 16 (ЕСБЗТ) by Author "Havryliuk, Volodymyr I."

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    Comparative Analysis of Experimental and Calculation Methods for Determination of the Traction Current Harmonics Distribution in Rails
    (Дніпровський національний університет залізничного транспорту ім. акад. В. Лазаряна, Дніпро, 2018) Havryliuk, Volodymyr I.; Meleshko, V. V.
    EN: The purpose of this work is to perform the comparative analysis of experimental and calculation methods for determination of the distribution of traction current harmonics in rails. To investigate the distribution of traction current in the rails, the special marks ("flags") were set up at a certain distance (100, 300 and 500 m) from the point of measurement along the track. The moments of passing the train past the "flags" were recorded in a computer due to a sound signal from the train, as well as visual observation. The train was moving in the measuring section in a quasistationary mode with an average speed of about 48 km/h. Traction current was measured in circuit of the interthrottle jumper with using an inductive contactless sensor and registered using computer. The distribution of the return traction current harmonics in rails for AC feeding systems were modeled by using the multiconductor transmission line (MTL) model. Some discrepancies in the results of experimental and calculation methods were observed. One of main reason of measurement errors were an inaccuracy in determining distances from the train to the measurement point. Calculation errors were related mainly with using inaccurate electrical parameters of track in model, in particular, the track ballast resistance and the ground resistances. However, in general, the considered model can be used for investigation of the traction current harmonic propagation in rails from train, and their influence on the track circuits receivers for different cases including the variation of the track circuits electrical parameters, as well as the number of rolling stock units in the feeder zone. Such analysis of harmonic in rails is important for revealing the causes of failures in railway signalling system operation under simultaneous affecting on it several factors adverse to safe operation.
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    Using the Wavelet Decomposition Method for Monitoring of Amplitude-Manipulated Signals of Railway Automation
    (Дніпровський національний університет залізничного транспорту ім. акад. В. Лазаряна, Дніпро, 2018) Havryliuk, Volodymyr I.
    EN: In railway signaling systems, some parameters required for monitoring and controlling train movements are transmitted using amplitude shift keying (ASK) signals. ASK signals are more often used in railway automated systems due to their simpler generation by contact transmitters, but such signals have a low level of immunity and interference in them can lead to incorrect op-eration of railway signaling systems. The efficiency of using the signal decomposition method by wavelet transform to reveal distortions for continuous ASK railway signals have been investi-gated in the work. Simulated signals were generated as a pure ASK signals with a carrier frequency of 420 Hz and a modulation frequency of 8 Hz, as well as five variants of the original signal with disturb-ances in the form of signals with distorted signal shape, signals with swells, signals with sags, signals with 50 Hz interferences, and signals with sharp pulses . The signal segments of ten periods were decomposed using a five-level wavelet packet trans-form (WPT). For all investigated signals, the distortions or interferences in them lead, not only to changes in distribution of partial energies at the nodes, but also to the appearance of strong differences in the form of oscillations of the WPT coefficients. The variations in WPT coefficients in low-frequency nodes reflect changes in the waveform due to pulse distortion, sags, swells, etc. The obtained results confirm the efficiency of using the wavelet decomposition method in or-der to detect distortions in the ASK continuous railway signals.