V olodymyr Havryliuk

Bio: V olodymyr Havryliuk is an academic researcher from Dnipropetrovsk National University of Railway Transport named after Academician V. Lazaryan. The author has contributed to research in topics: Electromagnetic compatibility & Electromagnetic interference. The author has an hindex of 1, co-authored 1 publications receiving 17 citations.

Modelling of the Return Traction Current Harmonics Distribution in Rails for AC Electric Railway System

Abstract: The problem of determination of the traction current harmonics distribution in rails generated by several trains that operated in AC feeder zone is considered. The investigations were caused by necessity to ensure electromagnetic compatibility of the new types of rolling stock equipped with electronic static converters with track circuits that are used in train movement control systems for detection of their positions. The great diversity of rolling stock, power supply and return current systems, and train detection systems installed in European countries leads to consideration of the electromagnetic compatibility problem taking into account the specific railway systems used in the each country. Investigation of the electromagnetic compatibility between different railway subsystems requires the use of simulation programs that help to reveal most critical conditions for electromagnetic compatibility at an early stage and also makes it possible to estimate electromagnetic interference from rolling stock in rails under the worst-case conditions, realization of which in the operating systems will require a lot of time and cost. This work consider evolved model for distribution of the traction current harmonics in rails from several trains. To illustrate the application of the considered model, the distribution of the traction current harmonics in rails was computed for25 kV AC direct feeding network depending on distance from electrical supply substation, the rail-to-earth conductance, and the number of trains in the feeder zone. The results of modeling of the harmonics distribution are in satisfactory agreement with the experimental data.

Modelling of the Distribution of Return Traction Current Harmonics in Electrically Asymmetric Rails

Abstract: The distribution of return traction current harmonics in electrically asymmetric rails in AC feeder zone is considered. Modelling the traction current harmonics in rails allows to evaluate electromagnetic interference from rolling stock at an early stage and under the worst conditions for its safe operation. The return traction current that flows from rolling stock axles back to electrical supply substation is divided into two currents with different values in two rails due to their electrical asymmetry. The resulting differential traction current and voltage in two rails affect the railway signalling systems and can cause faults in track circuits operation. Rails as a path for return traction current are longitudinally non-uniform due to impedance bonds and track transformers connected to them. Modelling of non-uniform systems is usually carried out by presenting them in the form of series-connected multipoles, which correspond to track transformers and uniform traction lines between them. But such model is awkward and redundant for the problem under consideration due to the need to use excessive specific parameter values for all track circuits in the feeder zone. For the case of small rail asymmetry, the simplified model is proposed in the work. In accordance with it, the distribution of the total current of traction harmonic in two rails between train and traction substation is calculated. Then, using the asymmetry coefficients of the rails, the distributions of the differential current and voltage of harmonics in two rails between train and track transformer or between two track transformers are determined.

Wavelet Based Detection of Signal Disturbances in Cab Signalling System

Abstract: The problem considered in the work is concerned to the methods to reveal and identify the signal disturbances occurred in the railway cab signaling system caused by electromagnetic interference from traction current. The continuous automatic locomotive signalling system (ALSN) is a type of cab signalling systems that provides track status information to the train cab and uses the rails as a continuous communication channel between track and train. To ensure the reliability of the transmission of ALSN commands to the train cab, the basic parameters of the coded current are periodically checked for compliance with certain requirements during planned test trips of a specially equipped railway car-laboratory. The ALSN signal is received by the coils of the car-laboratory and recorded by computer. Then an operator visually analyzes the recorded signal to detect problem segments with interference exceeding the limit level what requires a lot of time and does not provide the necessary accuracy. To automate the detection and identification of the ALSN signal disturbances, the following algorithm has been proposed. At the first stage, the wavelet packet energy Shannon entropy is used to reveal problem segments of ALSN signal. At the second stage, a detailed analysis of the ALSN signal using DWPT is performed to determine the type and parameters of interference at the revealed problem segments. To classify ALSN signal disturbances, an artificial neural network was used. The efficiency of the proposed algorithm was verified by processing of several specially simulated as well as real ALSN signals measured during tests.

Audio Frequency Track Circuits Monitoring Based on Wavelet Transform and Artificial Neural Network Classifier

Abstract: The problem of revealing and identifying of signal disturbances in audio frequency track circuits is considered in the article. Track circuits are a key component of automatic train control system and used to detect whether the rail section is free or occupied. Amplitude-modulated signals used in track circuits have low noise immunity, therefore the power wide-band-frequency interference generated by an electrified railway can cause failure operation of track circuits. To ensure the safety of the track circuits, they are subjected to periodic maintenance with registration of the signal current to the computer and measurements of its parameters. The detection of time intervals during which the interference in the track circuits exceeds certain limit values is performed by simple visual analysis of the recorded signal and is time consuming and expensive. In order to automate the revealing and identification of disturbances in audio frequency track circuits with values exceeding the certain level, a new method for processing of the recorded signal have been proposed. At the first stage, the segments of a signal with interference exceeding a certain permissible level are revealed using the wavelet packet energy Shannon entropy. At the second stage, for the revealed segment with disturbances, a detailed analysis of the signal should be carried out using the digital wavelet packet transform to determine the type and parameters of the disturbances. For automatic identification of the track circuits signal disturbances, an artificial neural network classifier has been used. As a result of investigation the features of the signal disturbances in audio frequency track circuits have been extracted. The processing of the track circuits signals in accordance with the proposed method show high effectiveness in the revealing and identification of the signal disturbances.

Reducing noise influence on an audio frequency track circuit

Abstract: In connection with electromagnetic interference influence on the track circuits, the purpose of the research is finding the means to increase the noise immunity of an audio frequency track circuit. The authors propose a new engineering solution, which enables reducing the effect of noises on the input of the track receiver in the intervals between signal current pulses. The proposed noise-immune audio frequency track circuit is based on inserting a delay line, an adjustable single-pulse generator and a controlled electronic switch into the existing audio frequency track circuit equipment. To analyze its efficiency, the operation of the audio frequency track circuit was simulated under conditions of traction current disturbances, impulse and fluctuation interferences with the known parameters. The results show that proposed device for railway transport allows to increase a signal-to-noise ratio on the track receiver input from 8% to 30%, depending on the interference parameters and the level of the useful signal.

Development and Verification of Dynamic Electromagnetic Model of Asynchronous Motor Operating in Terms of Poor-Quality Electric Power

Abstract: Three-phase asynchronous motor with a short-circuited rotor has been described with the help of a model convenient for the analysis of changes of its power indices in terms of different values of all the indices of supply voltage quality. Mathematical model of electromechanical converter with the power of 11 kW has been verified based upon the results of industrial experiment in the workshop of “Ukrspetsservis” Ltd. While checking the validity of the model, the obtained values of relative mean square error of modeling make it possible to be used for the purpose of computational studies of asynchronous electric motor energy efficiency.