Електромагнітна сумісність та безпека на залізничному транспорті
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Науково-практичний журнал "Електромагнітна сумісність та безпека на залізничному транспорті"
Scientific and practical journal "Electromagnetic Compatibility and Safety on Railway Transport"
Scientific and practical journal "Electromagnetic Compatibility and Safety on Railway Transport"
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Browsing Електромагнітна сумісність та безпека на залізничному транспорті 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 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 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 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 An Overview of the Etcs Braking Curves(Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпро, 2017) Havryliuk, Volodymyr I.EN: The purpose of the article is to present an overview of the ETCS braking curves according to the European specifications. Though the ETCS specifications lay down the basic principles for the braking curves and the associated information displayed to the driver, but there is still no harmonized method to compute them. In the absence of any requirement, the algorithms of the ETCS on-board suppliers lead to different braking distances for a given type of rolling stock. For cross border trains, the differences through national rules require the implementation in the ETCS on-board of several national braking curves. The main features of the braking curves have been reviewed in the article, including the following main aspects: basic principle to ensure of the train movement safety, the purpose and main types of ETCS braking curves, the input parameters for braking curve calculation, construction of the emergency brake deceleration curve, and guaranteed emergency brake deceleration. The basic principle to ensure the train movement safety is based on their separation in fixed block distance (for a conventional signalling system) or in moving block-sections (for ERTMS/ETCS level 3). To ensure these principles the ETCS onboard computer must predict the decrease of the train speed in the future, from a mathematical model of the train braking dynamics and of the track characteristics ahead. This prediction of the speed decrease versus distance is called a braking curve. The minimum interval between trains under automatic train protection system is defined by minimum movement authority that comprises odometer tolerance, driver allowance, ATP re-action times, brake application time. Braking curve predict of the train speed decrease versus distance by the ERTMS/ETCS on-board equipment, from a mathematical model of the train braking dynamics and the track characteristics ahead. ETCS supervises both the position and speed of the train to ensure they continuously remain within the allowed speed and distance limits, and if necessary it will command the intervention of the braking system to avoid any risk of the train exceeding those limits. There have been considered in the work the main ETCS braking curves and the supervision limits of the EBD braking curves, the movement authority, the end of authority, the most restrictive speed profile, the supervised location and others.Item A Review of Power Quality Issues in Electrified Rails(Дніпропетровський національний університет залізничного транспорту ім. акад. В. Лазаряна, Дніпро, 2017) Havryliuk, Volodymyr I.EN: Electrified railways are among of the largest consumers of electric energy with longitudinally distributed power supply stations and connected to lines fixed (unmovable) electrical loads (consumers) and moving loads (vehicles), which operate, in general case, in nonlinear pulse modes. Due to the electrical non-linear nature of power stations and loads, current and voltage distortions appear in railway lines that devastating impact on the entire power system and consumers. The development of high-speed railways and the use of new types of rolling stock with power electrical equipment and pulse-width modulation of the traction current lead to problems with electromagnetic compatibility (EMC) and power quality in feeding grids that can adversely influence on train movement safety. The purpose of this article is to give a brief overview of power quality issues in electrified railways and also to consider related PQ standards. The main power quality disturbances are illustrated by using fragments of the traction current and voltage time-dependences measured during tests of the rolling stocks on electromagnetic compatibility with rail circuits. The traction current and voltage were registered in vehicle power equipment circuits, using a current and voltage probes whose signals were converted by analog-to-digital converter and recorded by PC. The different definitions of power quality presented in standards and literature are discussed.The main power quality disturbances were illustrated using specially chosen characteristic fragments of registered traction current, and some their parameters and electrical processes caused them are considered.Item 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.