Browsing by Author "Havryliuk, Volodymyr I."
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Item The Accuracy of Traction Current Harmonics Parameters Determination by Windowed FFT(Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпро, 2018) Havryliuk, Volodymyr I.EN: In the work the correct choosing of the windowed FFT parameters to achieve the necessary time and frequency resolution of the traction current spectral analysis in accordance with the re- quirements of regulatory documents has been briefly overviewed and investigations of the influence of FFT parameters on the accuracy of the determination of harmonics parameters (such as effective current, frequency, duration) have been carried out.To assess the accuracy of determining the RMS current and frequency of the harmonics, a computer study was performed using a synthesized current with known harmonics parameters, the values of which were chosen in accordance with the permissible values of the parameters determined by regulatory documents and standards.For the spectral analysis of traction current, four types of windows were selected: rectangular, Hann, Hamming and Blackman windows with duration of 0.3 and 1 s. For a sampling frequency of 27500 Hz and a window length of 0.3 s, the frequency resolution is 0.27 Hz for a rectangular window, 0.54 Hz for Hann and Hamming windows and 0.81 Hz for Blackman's window, which is consistent with the requirements of the specifications.The results of spectral analysis of traction current showed that the frequency resolution of harmonics, and accordingly the relative error in determine the frequency and the RMS value of harmonics is lower for high frequencies in spectrum.The type of windows used has a slight effect on the accuracy of determining the frequency of harmonics. The relative error of the effective value of the harmonic current was higher for a rectangular window, and relative error decreased in the row from the rectangular window to the Blackman window. The values of the relative error of the RMS current for several frequencies ofthe harmonics did not meet the requirements necessary for the practical use of the method, and this is due to spectrum leakage and scalloping.For windows with a length of 1 s, the frequency resolution of the traction current was higher. than for windows with a length of 0.3 s, and the relative error of the RMS current and frequen- cies of the harmonics were much lower, but even in this case, the relative error was high for individual frequencies .To ensure the necessary accuracy of the traction current spectral analysis with using win- dowed FFT, proper choosing of the spectral analysis parameters taking into account the traction current parameters is necessary. Taking into account a wide frequency range of traction current, a technique with variable window length and sampling frequency for different parts of the spectrum is perspective for using.Item Analysis and Research of the Causes and Course of Degradation of Lithium Batteries(EDP Sciences-Web of conferences, 2024) Buriak, Serhii Yu.; Gololobova, Oksana O.; Havryliuk, Volodymyr I.; Serdiuk, Tetiana M.; Voznyak, Oleh M.; Manachyn, IvanENG: Energy storage devices based on lithium technology are confidently leading the respective market due to their significant advantages over other technologies in the industry. Despite their relatively recent history of appearance, they managed to undergo many modifications of both physical and chemical components. One of the constant goals of all research in this field is the formation of knowledge about the degradation processes occurring inside a given chemical current source, and ways to influence them. Systematization and identification of the fundamental reasons for the decrease in the performance of lithium batteries still remains a topical issue of today, and therefore is considered in this article. And no matter how studied this issue looks, taking into account the existing many long-term experimental data of a huge number of scientists and a number of different types of companies, but still, optimization of work is impossible without identifying and eliminating as many destructive factors as possible in battery operation. The difficulty of this process lies also in the fact that, taking into account all the high-tech production processes in the world, there are no two identical lithium current sources. On the example of a single battery, the ability to maintain high performance, close to nominal, was demonstrated from a source that, due to its lifetime, should not have had them. The data obtained during the experiment, which confirmed the high performance, show once again that the issue of degradation of lithium current sources can and should be studied further.Item ANFIS Based Detecting of Signal Disturbances in Audio Frequency Track Circuits(IEEE, 2020) Havryliuk, Volodymyr I.EN: The problem considered in the work is concerned to monitoring of signal disturbances occurred in the audio frequency track circuits (AFTC). Track circuits are designed to detect the presence or absence of a train in a particular section of the rail track, and therefore, they are main and safety critical components of an automatic train control systems. Deterioration of the AFTC components appeared during their operation, as well as electromagnetic interference and adverse weather conditions can significantly change the signal current parameters, which can lead to dangerous situations for train movement. To ensure safety of railway signalling system, it is necessary to use an automatic diagnostic system that allows timely detection of appearance of significant disturbances in AFTC signal. The use for this purpose the classifiers with sharp boundaries for input diagnostic parameters and strict rules for signal classification does not allows to reveal incipient defects that arise in the ALSN system. The work investigates the effectiveness of using adaptive neuro-fuzzy inference system (ANFIS) and wavelet packet energy Shannon entropy (WPESE) for timely detecting of signal disturbances in audio frequency track circuits. The obtained results confirmed the efficiency of AFTC signal processing using ANFIS and WPESE for detecting of railway sections with unstable or faulty track circuits operation.Item Application of Fourier Transform and Wavelet Decomposition for Decoding the Continuous Automatic Locomotive Signaling Code(Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпро, 2017) Hololobova, Oksana O.; Havryliuk, Volodymyr I.EN: Purpose. The existing system of automatic locomotive signaling (ALS) was developed at the end of the last century. This system uses the principle of a numerical code which is implemented on the basis of relay engineering, and therefore, it is exposed to various types of interferences. Over the years, the system has been upgraded several times, but the causes of faults and failures in its operation are still the subject of research. It is known that the frequency and the phase modulation of signal has a higher interference immunity as compared to the amplitude modulation. Therefore, the purpose of the article is to study the possibility of using the frequency methods such as Fourier series expansion and wavelet decomposition to extract the informational component of the received code from ALS signals under the action of various types of interferences. Methodology. One can extract the information unavailable in time representation of the signal using the signal studies in the frequency domain. The wavelet decomposition has been used for this purpose. This makes it possible to represent the local characteristics of the signal and to provide time-frequency decomposition in two spaces at the same time. Due to the high accuracy of the signal representation it is possible to analyze the time localization of spectral components and eliminate interference components even in the case of coincidence of interference frequency with the signal carrier frequency. Findings. To compare informativity of the methods of Fourier expansion and wavelet decomposition it was studied the reference and noisy signal of green fire code using the software package MATLAB. Detailed analysis of the obtained spectral characteristics showed that the wavelet decomposition provides a more correct decoding of the signal. Originality. Replacing the electromagnetic relays in the ALS system by microprocessor hardware involves the use of some mathematical tool for decoding, in order to obtain more information about the code. More often than not, as a mathematical tool, the classical Fourier decomposition is used. But because of a number of drawbacks in this method, it was suggested to use the wavelet decomposition, which has a number of advantages and accounts the disadvantages of the Fourier transform. Practical value. The presented method of code signal research can be the basis for developing dynamic model of the ALS receiver and decoder using digital processing module, which will enable to increase the reliability and accuracy of extraction of the code information component.Item Artificial Neural Network Based Detection of Neutral Relay Defects(Dnipro National University of Railway Transport named after Academician V. Lazaryan, 2019) Havryliuk, Volodymyr I.EN: Abstract. The problem considered in the work is concerned to the automatic detecting and identifying defects in a neutral relay. The special design of electromechanical neutral relays is responsible for the strong asymmetry of its output signal for all possible safety-critical influences, and therefore neutral relays have negligible values of dangerous failures rate. To ensure the safe operation of relay-based train control systems, electromechanical relays should be periodically subjected to routine maintenance, during which their main operating parameters are measured, and the relays are set up in accordance with technical regulations. These measurements are mainly done manually, so they take a lot of time (up to four hours per relay), are expensive, and the results are subjective. In recent years, fault diagnosis methods based on artificial neural networks (ANN) have received considerable attention. The ANN-based classification of relay defects using the time dependence of the transient current in the relay coil during its switching is very promising for practical utilization, but for efficient use of ANN a lot of data is required to train the artificial neural network. To reduce the ANN training time, a pre-processing of the time dependence of relay transient current was proposed using wavelet transform and wavelet energy entropy, which makes it possible to reveal the features of the main defects of the relay armature, contact springs, and magnetic system. The effectiveness of the proposed approach for automatic detecting and identifying of the neutral relays defects was confirmed during testing of the relays with various artificially created defects.Item Audio Frequency Track Circuits Monitoring Based on Wavelet Transform and Artificial Neural Network Classifier(Institute of Electrical and Electronics Engineers, IEEE, 2019) Havryliuk, Volodymyr I.EN: 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 the of the recorded signal have been proposed. At the first stage of the proposed method, 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.Item The Comparative Analysis of Calculating Methods for Ac Impedance of R65 Type Rails and Track 1520 Mm Gauge in the Audio Frequency Range(Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпро, 2017) Havryliuk, Volodymyr I.EN: Knowledge of the exact AC rail impedance in a wide frequency range is necessary for designing and modeling audiofrequency track circuits, determining of the traction return current distribution in rails of high-speed railways, testing new types of vehicles on electromagnetic compatibility with track circuits, etc. The aim of the work is to perform a comparative analysis of the methods for calculating of the AC impedance of the R65 type rails of a track 1520 mm gauge in the audiofrequency range. Results of AC rail impedance measurements and theoretical description of frequency dependence of impedance for wires above lossy ground are briefly reviewed. Mathematical formulation of Carson's method and the complex image method proposed by Deri with co-workers for impedance of transmission lines were represented. The impedance of running rails of R65 type and track of 1520 mm gauge have been calculated by using Carson's method and the complex image method. Due to the insufficient amount of literature data concerning AC impedance measurements for rails of type R65 of 1520 mm gauge, the results of calculations for these rails were compared with the measured values for both rails of type R65, 1520 mm gauge, as well as for rails of type UIC 60 with 1435 mm gauge. Calculated frequency dependencies of the AC impedance of R65 type rails are in good qualitative agreement with literature data for rails UIC60 in frequency range Hz... The results for rails of R65 type and 1520 mm gauge calculated according to Carson's method and complex image method differ from reference data presented in literature, and these differences increase with increasing of frequency. Such behavior may be due to error of calculation methods caused by small height of rails above lossy ground and high electrical conductivity between rails and a ground.Item 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.Item Detecting of Signal Distortions in Cab Signalling System Using ANFIS and WPESE(IEEE, 2020) Havryliuk, Volodymyr I.EN: The problem considered in the work is concerned to detecting of signal distortions occurred in the railway ALSN cab signaling system. The ALSN system is designed to transmit track status information into the train cab and uses rails as a continuous communication channel between track and train. The amplitude and duration of the pulses in the ALSN code combinations are changed over time due to deterioration of the track transmitters and other devices in the signal transmission channel, as well as due to electromagnetic influence of the traction current, rails magnetization, and other sources of electromagnetic interference. Due to distortions of ALSN signals, their decoding becomes unstable, which leads to intermittent failures in the form of temporary incorrect indication at the cab traffic light or to complete failure of the ALSN system. Diagnostic of the ALSN system and the revealing of signals with distortions is carried out by analyzing the signal current, recorded using the railway car-laboratory. However, the use for this purpose of the classifiers with sharp boundaries for input diagnostic parameters and strict rules for signal selection does not allow us to reveal incipient defects that arise in the ALSN system. The work investigates the effectiveness of using adaptive neuro-fuzzy inference system (ANFIS) and wavelet packet energy Shannon entropy (WPESE) for timely detecting of signal distortions in the ALSN system. The obtained results confirmed the efficiency of ALSN signal processing using ANFIS and WPESE for detecting of railway sections with unstable or faulty ALSN system.Item Experimental Determination of Basic Data for Probabilistic Research of Electrical Tonal Track Circuit(Дніпропетровський національний університет залізничного транспорту ім. акад. В. Лазаряна, Дніпро, 2017) Romantsev, Ivan O.; Havryliuk, Volodymyr I.EN: Purpose. Determination of mathematical model with the probabilistic parameters of tonal-frequency railway circuit, leadthrough of the concomitant measurings and their analysis, forming of maximum sizes of the probabilistic states of object. Methodology. At research of the probabilistic states of railway circuit the terms of measurings of probabilistic descriptions, parameters of transformations of frequency-temporal descriptions of signals are certain, the statistical results of the conducted measurings are analyzed, the table of the probabilistic diagnostic is formed, and the probabilistic scopes of diagnostic of the states of tonal-frequency railway circuit are got. Findings. Determination of scopes of premature exit from working condition state of tonal-frequency railway circuit. Originality. Principle of determination of statistical information is presented for the system of the probabilistic diagnosticating of tonal-frequency railway circuit, laws of distributing of parameters and finding of premature exit state and maximum scopes of electric parameters. Practical value. Findings enable to form the system of the probabilistic diagnosticating of tonal-frequency railway circuit.Item Fault Diagnosis for Electromagnetic Relay Using Discrete Wavelet Transform and Wavelet Packet Entropy(Wydawnictwo Wyższej Szkoły Technicznej w Katowicach, 2017) Havryliuk, Volodymyr I.EN: In order to fault features extraction for neutral electromagnetic relays of railway automatics, the time dependences of the relays transient currents during relays switching have been measured. The results of measurements, performed for the relay in operable condition and for relays with artificially created defects, were analyzed in the time and frequency domains. The discrete wavelet transform (DWT), discrete wavelet packet transform (DWPT) and wavelet packet energy Shannon entropy (WPESE) were used for relay fault feature extraction. Increased values of the WPESE of the transient current for electromagnetic relay with armature defects as compared with the value for the relay in operable condition, provides an integrated assessment of the relay fault existence. Analysis of relay transient currents by using DWT and WPT allows to identify the defects of the relay contacts and armature. Defects of the relay electromagnetic system can be revealed by measuring the time constants of the transient current when the relay is energized but the anchor does not move yet, because it is in one of the two end positions.Item Improving the Positioning Accuracy of Train on the Approach Section to the Railway Crossing(Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпропетровськ, 2016) Havryliuk, Volodymyr I.; Voznyak, Oleg M.; Meleshko, V. V.EN: Purpose. In the paper it is necessary to analyze possibility of improving the positioning accuracy of train on the approach section to crossing for traffic safety control at railway crossings. Methodology. Researches were performed using developed mathematical model, describing dependence of the input impedance of the coded and audio frequency track circuits on a train coordinate at various values of ballast isolation resistances and for all usable frequencies. Findings. The paper presents the developed mathematical model, describing dependence of the input impedance of the coded and audio-frequency track circuits on the train coordinate at various values of ballast isolation resistances and for all frequencies used in track circuits. The relative error determination of train coordinate by input impedance caused by variation of the ballast isolation resistance for the coded track circuits was investigated. The values of relative error determination of train coordinate can achieve up to 40-50 % and these facts do not allow using this method directly for coded track circuits. For short audio frequency track circuits on frequencies of continuous cab signaling (25, 50 Hz) the relative error does not exceed acceptable values, this allow using the examined method for determination of train location on the approach section to railway crossing. Originality. The developed mathematical model allowed determination of the error dependence of train coordinate by using input impedance of the track circuit for coded and audio-frequency track circuits at various frequencies of the signal current and at different ballast isolation resistances. Practical value. The authors propose the method for train location determination on approach section to the crossing, equipped with audio-frequency track circuits, which is a combination of discrete and continuous monitoring of the train location.Item An Integrated Approach to Lithium-Ion Battery Cell Management through Accurate Voltage Measurement and Cell Balancing(IEEE, 2023) Nibaruta, Regis; Venugopal, Prasanth; Rietveld, Gert; Havryliuk, Volodymyr I.; Soeiro, Thiago BatistaENG: Battery packs have become a critical component in various applications from portable electronics to electric vehicles. Accurate voltage measurement is essential for effective battery management, ensuring safety and reliability, which is especially important in high-power battery packs that consist of multiple cells connected in series or parallel configurations, such as Electric Vehicles (EVs). This paper explores the voltage measurement topologies, pack configuration principles, and implementation of cell balancing in a lithium-ion battery pack. We review the various types of faults that can occur in lithium-ion batteries, different voltage sensor placement strategies, and their impact on the accuracy and robustness of voltage measurement. Our results show that proper cell balancing can improve battery performance, reduce the risk of safety incidents, and extend the battery lifespan.Item Level Crossing Activation Time Prediction in Dependence on the Train Real Speed(Polskie Stowarzyszenie Telematyki Transportu, PL, 2018) Havryliuk, Volodymyr I.EN: Th e analysis of accidents at level crossings showed that a signifi cant number of them have been occurred at the automatic crossings with signalling lights and automatic half barrier crossings. One of the main causes of accidents is that road users do not obey the warning signals at crossings due to excessive waiting time because real speeds of diff erent trains can vary greatly, while approach distance to crossings is determined for the fastest trains with maximum permissible speed. Th e purpose of this work is the mathematical justifi cation of the method for the level crossing activation time prediction in dependence on the real speed of an approaching train, based on measurements of input track circuits’ impedance at approach section. Th e investigations have been carried out by mathematical modeling of track circuits’ operation modes during train movement. Th e relative error of the method has been determined.Item Mathematical Modelling of the Communication Channel between the Rail Circuit and the Inputs Devices of Automatic Locomotive Signalization(Dnipro National University of Railway Transport named after Academician V. Lazaryan, 2019) Hololobova, Oksana O.; Buriak, Serhii Yu.; Havryliuk, Volodymyr I.; Skovron, Ihor Ya.; Nazarov, Oleksii A.ENG: Abstract. In modern practice of operating under traffic safety conditions, the traffic light signal must be transmitted to the locomotive that moves to it, and duplicate in the driver's cab. However, this communication channel is not protected from external interference. In order to prevent the occurrence of code failure, it is necessary to create conditions under which the automatic locomotive signalling system will distinguish between signals with useful information, from signals with false information. The best way to solve this problem at the first stage is to model the devices. Using the simulation tools of graphical environment of simulation modelling Simulink from Matlab software environment, the software model of the communication channel between the railroad and the input devices of automatic locomotive signalling system was constructed. The created mathematical model with the actual parameters allows us to obtain diagnostic signs of a proper condition, on the basis of which the research is aimed at the identification, recognition and definition of various types of malfunctions, failure, damages and defects in the work of the constituent elements of the system and the signal transmission channel of the automatic locomotive signalling system.Item The Method for Detecting Defects in Movable Armature of the Signalling Relay(Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпро, 2017) Havryliuk, Volodymyr I.EN: Despite significant progress in the development of microelectronic rail automatic systems observed in recent decades, relay-contact devices are still widely used in railway signalling systems, that are fundamental to the safe operation of railways and must perform predictably and reliably. Thus, signalling relays used for safety-critical or safety-related applications in railway signalling systems should be properly maintained and tested to ensure their performing safely and reliably throughout their expected service life. With the purpose of developing a method for detecting defects in movable armature of the signalling relay, the time dependences of transient currents during relays switching have been investigated for relay in various technical conditions: in operable condition, as well as with arti-ficially created defects (bends) of contact springs. The measured data have been analyzed in the time and frequency domain using the wavelet transform modifications (CWT, DWT, DWPT). The analysis of the transient currents was carried out using segmentation of the current characteristics of the relay. The relay transient current at first and third segments which corresponded to unmovable anchor state, increase with time during relay switchon approximately as the exponential function. The time constants of the relay current were calculated by approximating the measured currenttime dependences at the first segment of the current curve by exponential function. The presence of defects in the movable armature of the relay had practically no effect on the values of calculated time constants. However, these values strongly depended on the technical condition of the relay magnetic circuit and the relay coil, as well as on the voltage applied to the coil terminals. This behavior of the relay time constant on the first segment of the relay current characteristic makes it possible to use this parameter to monitor the technical state of the electromagnetic relay system. Defects of the armature and contact springs led to the appearance of additional features at the second segment of the relay transient current, which corresponded to the movement of the armature. The magnitude of these features on the current curve depended on the value of bending of the relay's contact spring. The width and appearance time of the features at the second segment of the current-switching curve correspond to the non-simultaneous switching of the relay contacts. To determine the amplitude (energy) of these features (peaks) on transient current curve, their duration and the times of appearance, the wavelet transform was used. The results of investigations confirmed the possibility of determining the defects of the relay movable armature by using wavelet analysis of the second segment of the relay transient current characteristic.Item Modeling of the Traction Current Harmonics Distribution in Rails(Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпро, 2017) Havryliuk, Volodymyr I.EN: Electrified railways are one of the most powerful wide frequency range sources of disturbances that interference on signaling and radio communication systems. This is especially true for new types of vehicles equipped with electronic static converters with pulse width modulation (PWM), from which high-frequency interferences in rails can have frequencies up to several tens of kHz. To ensure the electromagnetic compatibility (EMC) of new types of rolling stock with signaling and radio communication systems, they are subjected to an acceptance procedure that includes on EMC tests in accordance with European and national regulatory standards and norms. But under some unfavorable operation conditions for the trains that were successfully tested and are in operation with old vehicles on the same lines (sometimes with old feeding system), the disturbing current generated by vehicles may reach values greater than the allowed values. As such unfavorable operational conditions may be considered increasing number of trains, low distance between track circuit receiver and vehicles or supply substation, low rail-to-earth conductivity and conductivity of earth. To proof the electromagnetic compatibility (EMC) between rolling stock and signalling systems it is need accurate modeling of the test cases with taking into account particular operation conditions. The aim of the work is to establish mathematical and computer model for distribution of traction current harmonics in direct feeding traction network with multiple vehicles in feeder zone. This model is an evolution and simplification of models represented earlier. The work has been performed in order to proof the electromagnetic compatibility of new trains equipped with electronic static converters with existing traction lines and has been used during tests of new types of train. The model has been simplified as follows. The lines with equal or close to each other potentials are represented as a single line with equivalent electrical parameters. The disturbing vehicles are modeled as sinusoidal current sources with several set of frequencies that are represented by currents vector. Only return current harmonics with frequencies that lie in frequency range of track circuit receiver were considered. Depended of simulation aim the values of harmonics are taken as values measured during train tests or as the maximum interference values according to norms. The distribution of the traction return current harmonics was computed for AC direct feeding traction network 1x25 kV with two-side ESS and with 1 to 5 vehicles in feeder zone. The maxi-mum interference from trains is in the areas nearest to trains and also to the point of connection of return feeder to rails (at ESS terminals). The traction harmonic current in rails are increased with increasing of train number in feeder zone and with decreasing of the rail-to-earth conductivity. The interference at 25 Hz in the rails area near the ESS for one locomotive in feeder zone don’t exceed a limit value of 1 A even in unfavorable operation conditions for of the rail-to-earth conductivity equal 0.02 Sm/km. If number of trains are increased (from 1 to 5) the interference at 25 Hz also increased and it values at rail-to-earth conductivity equal 0.02 Sm/km reach to 1.073 A for two locomotives and to 1.233 A for five locomotives, that exceed the limit value of the interference in rails at 25 Hz.Item Modelling of the Distribution of Return Traction Current Harmonics in Electrically Asymmetric Rails(IEEE, 2020) Havryliuk, Volodymyr I.EN: 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.Item Modelling of the Return Traction Current Harmonics Distribution in Rails for AC Electric Railway System(Institute of Electrical and Electronics Engineers, IEEE, 2018) Havryliuk, Volodymyr I.EN: 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.Item Monitoring of Distortions and Interferences in Ask-modulated Currents of Railway Signaling Systems(MATEC Web of Conferences, 2024) Havryliuk, Volodymyr I.; Radzikhovskyi, Kostiantyn; Voznyak, Oleh M.ENG: The problem considered in the work concerns the automation of the monitoring of ACK signals, which are widely used in railway signaling systems, namely in track circuits, due to the simplicity of their generation. Due to the low interference immunity of ACK signals under the influence of traction current and other electromagnetic sources at the railways, malfunctions can occur in the operation of train control systems. To prevent possible failures in the operation of track circuits, measurements of the signal parameters on generators and receivers of track circuits are periodically carried out. Such measurements are mainly made manually, therefore they are expensive and do not provide the necessary accuracy of the results. The problem of automating the control of signals in track circuits is related to the correct choice of characteristic features of signal distortions in order to identify excessive distortions that can lead to failures in the operation of track circuits. The article discusses methods for analyzing the signal current in the time and frequency domains to detect signal distortions. It is shown that in addition to the current measurements of the rms voltage of signals in track circuits, it is necessary to monitoring the voltage levels in the pulses and pauses of the signals, as well as the spectral composition of the signals.