This paper presents a simulation model of DC traction system which is based on bilateral power supply mode. The model of two substation rectifiers in one track section has been proposed which is according to practical situation. The modeling was conducted with respect to the variations of the starting-up process and short circuit conditions. By comparing and investigating the simulation results of short circuit current and the train starting current, more effective algorithms such as DDL protection has been proposed. The paper presents the principle and analysis of DDL protection scheme, which shows effectiveness of DDL protection for fault detection and discrimination against train starting currents in the DC transit system.

Simulation and algorithm development of protection scheme in DC traction system

An electric arc is an example of a transient event that is quite common in electrified transportation systems as by-product of the current collection mechanism. As a broadband transient, an electric arc excites a wide range of (often oscillatory) responses related to the substation and onboard filters, as well as the line resonances and anti-resonances. Similarly do the charging of onboard filter and other related inrush events. This work considers the electrical characteristics of these transients and of the excited responses in order to define their typical spectral signatures in DC railways and take them into account concerning their impact on Power Quality measurements and the measurements of instruments deployed onboard.

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Experimental characterization of pantograph arcs and transient conducted phenomena in DC railways

The paper deals with the significant results of the research of the current harmonic spectrum in traction drive with permanent magnet synchronous motors (PMSM). The research was done in the experimental workplace with a real traction drive for wheel vehicles. The spectrums were analyzed by the specialized device on the basis of a central measuring station. The knowledge of marked subharmonic components of stator winding currents is the most significant finding of this research. The frequencies of these components are given by frequency multiples of mechanical speeds. The subharmonic components also pass to DC current at the traction inverter input site. This fact is particularly important from the viewpoint of legislative requirements to electromagnetic compatibility (EMC) of drive with railway interlocking devices. Streszczenie. W artykule przedstawiono glowne wyniki badan widma czestotliwościowego prądu obciązenia trakcyjnego ukladu napedowego z silnikami PMSM przeprowadzonych na stanowisku eksperymentalnym wyposazonym w trakcyjny silnik pojazdu szynowego. Najbardziej istotnym wynikiem pomiarow jest znajomośc kluczowych harmonicznych prądu obciązenia, ktorych czestotliwośc jest rowna wielokrotności predkości obrotowej silnika. Niektore harmoniczne przenikają takze do sieci zasilającej prądu stalego, co jest kluczowe z punktu widzenia zagadnien kompatybilności elektromagnetycznej. (Interferencje w trakcyjnym ukladzie napedowym z silnikami PMSM)

Interference in Power system for traction drive with PMSM

The need of transport interoperability in Europe is a relevant issue nowadays. Particular interest is given to the signaling systems. The TEN-T project focuses one of its workpackages on “EMC Axle Counter Validation.” This work developed in the frame of the TEN-T project develops a procedure to assess the frequency spectrum of the magnitude of the magnetic field, due to the traction current, at the track level. Full-wave 3-D numerical models are developed to predict the field values. The measuring system is previously tested and then used for a measurement campaign. Results are reported in terms of tables and frequency spectra.

EMC Analysis of Axle Counters in the Italian Railway Network

Several studies in Sweden have looked into railway electromagnetic interference (EMI) either to discover the source of the interference or to determine if the equipment in the system is performing properly. The movement of rolling stock along an electrified track produces certain EMI events. Transient electromagnetic fields are produced in the signalling system when the train leaves the neutral section of the overhead power line and enters the powered section. These transient EM fields are mainly produced by the engine. The track's infrastructure system has been tested for EMI events, but this phenomenon affects the surrounding environment as well, up to at least 10 meters from the track. The infrastructure is designed so that the return current from locomotives should go through the running rails, but occasionally the ground acts as a conductor, transmitting current to areas that are distant from the rail. The paper reviews the status of Swedish railways with respect to electromagnetic compatibility. This TREND project is a joint project with 7 FP EU.

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Railway EMI impact on train operation and environment

Frequency-dependent effects in railway traction power systems arise from the impedance of substation and locomotive line filters and the traction line. Harmonic noise from traction drives and substations can excite resonances and produce overcurrent or overvoltage conditions at critical points in the network. In this paper, the harmonic feeding impedances of a 3 kV DC traction system seen from the rectifier substation, locomotive drive converter and pantograph terminals are presented. Several substation and locomotive filters are considered with a frequency-dependent traction line. Resonances attributed to the substation filter, locomotive filter and traction line are separate and distinct, the line introducing poles and zeros in the audio frequency (AF) range which vary in frequency and magnitude with locomotive position. >

A frequency domain model for 3 kV DC traction DC-side resonance identification

The use of a constant inductance and resistance model for rail track impedance in traction power system fault transient studies gives rise to inaccuracies due to the actual frequency dependency of the line. In this paper, an accurate frequency-dependent track model for a third-rail metro railway is described in which the track feeding impedance is synthesized from the self and mutual impedances and represented by a discrete-component linear circuit network. The model is used to simulate current rise in a third-rail traction system short-circuit fault. Results are given for short and long track section feeding lengths and show significant differences compared with a constant-parameter track model. >

Accurate track modelling for fault current studies on third-rail metro railways

Electromagnetic field and circuit simulation models are described which enable a railway traction system with substations, traction drives, track signalling equipment, track and traction line to be assessed for low and audio frequency electromagnetic interference. The novel features are the derivation of frequency-dependent track and traction line impedance by the finite-element method of electromagnetic field analysis and the representation of the frequency dependency in circuit simulation by current-dependent voltage sources. Example interference spectra are given for cab signal current with audio frequency track signalling on a 3 kV DC traction system with 12-pulse rectifier substations and an inverter-fed traction drive.<
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Modelling for electromagnetic interference assessment in electric railway traction systems

An accurate, frequency-dependent rail track and traction line feeding impedance model for an overhead catenary electrified railway is described. The model is based on the track self and mutual impedances and admittances which are represented by discrete-component electrical circuit networks. Verification for accuracy is demonstrated by comparing the model track feeding impedance with reference data. The track model is used in a time-domain simulation of a DC traction network with a 12-pulse rectifier substation and a power electronic controlled traction drive to investigate the distribution of traction system current harmonics in the catenary, rails and ground. >

Identification of catenary harmonics in 3 kV DC railway traction systems

http://ieeexplore.ieee.org/iel3/1147/6646/00265078.pdf

P. Pozzobon

Papers

A frequency domain model for 3 kV DC traction DC-side resonance identification

Accurate track modelling for fault current studies on third-rail metro railways

Modelling for electromagnetic interference assessment in electric railway traction systems

Identification of catenary harmonics in 3 kV DC railway traction systems

Modelling and simulation of supply current interference in traction systems arising from multi-level converters in high-power locomotive drives