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Highlights • Smart-grid based based electrical railway network through the use of a Yd transformer with multiple phase connections. • Intelligent control method for RPFC implementing the central Steinmetz-based intelligent (SICS) control system. • Calculating the optimal amounts of active and reactive powers transferring in different phases. • The SICS proposed method performance verification by the FPGA-based real-time laboratory setup results. • Significantly reduction of RPFC converter's power rating and installation costs. Abstract Adoption of smart grids has led to significant opportunities in the optimal operation of systems and energy consumption in utility grid loads. Among the various grid loads, electrical railway networks (ERNs) are known as one of the most important and critical end users due to their high power consumption. Energy management and power quality domination in such a network are already concerns of researchers. The railway power flow controller (RPFC) is a commonly used system to manage the optimal energy consumption and power quality problems of ERNs. This paper presents a comprehensive study of an RPFC power rating and a new compensation strategy with the objective of reducing the installed capacity in several consecutive traction power substations (TPSs). This technique is implemented through the use of a Yd transformer with multiple phase connections and the central Steinmetz-based intelligent control system (SICS). Through coordination with the internal control systems, the optimal mode of the active and reactive powers transferring in different phases is calculated by the central SICs and applied to each TPS. The proposed control strategy substantially diminishes the RPFC converter's power rating and installation costs. A real-time laboratory platform for the smart-grid based proposed method is provided using Opal-RT emulator to confirm the theoretical analysis with the desired precision representing the real power system behavior. [ABSTRACT FROM AUTHOR]

The use of acoustic emissions to evaluate the tribological characteristics of the collector friction system of an electric railway was investigated. Both mechanical wear and wear by arc discharge and melting occur at the sliding interface. When friction and wear experiments were performed with a pin-on-disk-type sliding-friction tester with an electric current flowing between the specimens, an analysis of the frequency of the resulting AE signal showed that each phenomenon produced a distinct AE frequency spectrum. The tribological characteristics of the materials in the presence of an electric current can therefore be evaluated from features of the AE frequency spectrum. [ABSTRACT FROM AUTHOR]

DC electric power systems, including HVDC, HVDC light, dc distribution systems, and dc microgrids, have a significant position in present and, especially, future electric power systems, namely, smart grids. One of the most significant issues of electric power systems, including dc electric power systems, is the calculation of accurate and fair energy costs of the consumers. In this paper, novel, simple, practical, and precise relations between economic and electrical variables in dc electric power systems are extracted. The novel relations prove that there are interesting relations between voltages of nodes, as electrical variables, and prices of nodes, as economic variables, in dc electric power systems. Applying the extracted novel relations in this paper, a new, fair, precise, practical nodal price, i.e., the fair nodal price, is determined to calculate the energy costs of consumers in dc electric power systems, including dc distribution systems and microgrids. Moreover, as an application of the extracted novel relations, a practical method to determine the fair nodal prices of all nodes and, as a result, the real energy cost of each consumer at each node of dc electric power systems is presented. The analyses results demonstrate the mentioned significant characteristics. [ABSTRACT FROM AUTHOR]

Current distribution in the electric traction system is an important factor regarding the electromagnetic influences on the surrounding metallic structures. The current value directly determines the magnetic field and consequently coupling of the systems. A single rail traction system can be equipped with return conductor. The return current flowing through return conductor has an opposite direction of supply current and decreases coupling and interferences. This paper presents the AC current distribution for both designs, with and without return conductor. Also, the soil resistivity is varied. The higher the soil resistivity, the higher is the amount of return current in rails and return conductor. The different construction of return conductor results in different impedance of return path. The relations of return conductor construction and return current value are analysed. Lightning can directly impact different traction system elements such as contact network, tower or return wire. The current distributions in several cases of lightning impacting different traction system elements are presented. [ABSTRACT FROM AUTHOR]

Currently, in electric railways, the old dc supply systems are reaching their limits. In several European railway networks, due to the line-voltage drops between substations, there are several sectors where traffic can no longer increase and where locomotives cannot operate at their nominal ratings. To improve the power capacity, a medium voltage dc (MVdc) three-wire supply system with voltage boosters based on imbricated cell multilevel choppers (ICMC) was proposed. In order to increase efficiency, the authors evaluate the potential of new SiC-mosfets in this topology. An opposition method test bench using two ICMCs was built with 1.7-kV/300-A half-bridge modules. The design of the multilevel converters takes into account the constraints related to high switching frequency operation (up to 50 kHz). Thanks to the opposition method, losses in ICMCs can be determined by electrical and thermal measurements with good accuracy. Finally, solutions with SiC-mosfets and Si-insulated gate bipolar transistors are compared in terms of efficiency. [ABSTRACT FROM AUTHOR]

A superconducting power cable has merits of a high power transmission capacity, transmission losses reduction, a compactness, etc., therefore, we have been studying the feasibility of applying superconducting power cables to DC electric railway feeding systems. However, a superconducting power cable is required to be cooled down and kept at a very low temperature, so it is important to reveal its thermal and cooling characteristics. In this study, electric circuit analysis models of the system and thermal analysis models of superconducting cables were constructed and the system behaviors were simulated. We analyzed the heat generation by a short circuit accident and transient temperature distribution of the cable to estimate the value of temperature rise and the time required from the accident. From these results, we discussed a feasibility of superconducting cables for DC electric railway feeding systems. The results showed that the short circuit accident had little impact on the thermal condition of a superconducting cable in the installed system. [ABSTRACT FROM AUTHOR]

The line-side converter, which can represent an ac–dc–ac drive electric vehicle when analyzing the low-frequency oscillation in electric railways, is modeled in dq frame with the proposed single-phase dq-decomposition method. With this model, an underdamped mechanism of the vehicle-grid interaction is confirmed. Besides, a low-frequency stability prediction approach is presented, based on the dominant-pole analysis and verified by the simulation and the testing result. The proposed modeling method and prediction approach benefit in three aspects: It is more convenient to rebuild the model with a change of either the line-side converter controller or the system condition, much quicker to predict the low-frequency instability and more explicit to guide the modification of the controller software to damp the low-frequency oscillations. [ABSTRACT FROM AUTHOR]

Balance transformers can usually eliminate the zero sequence current and suppress the negative sequence current. This paper develops a novel approach for balance transformers, which is different from the traditional one with two-phase or three-phase symmetrical windings. First, the basic principle and the connected scheme of the transformer are clarified. Second, this paper derives the relationship between the primary and the second windings from a mathematical model for the new approach. Third, the balance condition (i.e. the neutral current in the primary side is zero) and the decoupling condition of the two-phase system are also obtained. Finally, the correctness and feasibility of the new approach are verified by the experimental results of a 1-kVA model transformer. Compared to the traditional balance transformers, the new approach has better performance and can be applied to the two-phase or single power supply, such as the traction power supply in electric railway. [ABSTRACT FROM AUTHOR]

The problem of optimally sizing hybrid energy storage systems (HESS) installed in electric railway systems, considering the effect of regenerative braking is studied in this paper. HESSs combine traditional batteries and newly developed ultracapacitors, taking advantage of the high energy capacity of batteries and of the flexibility and ability to capture high power density of ultracapacitors. A novel mixed integer linear programming formulation that includes the counting of battery cycles is presented. Some particularities of battery operation are included in the model, like the dependence of its performance on the number of cycles and the depth of discharge (DOD). Results are reported first for a illustrative case study, allowing us to perform sensitivity studies for several parameters; results are also reported and for a larger case, closely resembling the problem faced by railway energy systems planners and operators. [ABSTRACT FROM PUBLISHER]

Facing the challenges brought by the negative sequence current (NSC) pollution in power supply system of electric railway, a new topology named half-bridge winding compensation-based railway power conditioner (HBWCRPC) without auxiliary step-down transformer is proposed to suppress the NSC injected into the public networks. It has the advantages of high integration, low losses, and more functions. The compensation principle is discussed, and its physical interpretation is presented. Besides, the mechanism of the voltage perturbation and its various representations in steady state are analyzed. Considering the complexity of voltage perturbation, an optimal control method is adopted to improve the robustness of the control system, and a linear quadratic regulator with integral action, which is applicable for this system, is designed. Finally, simulation and experiment results validate the HBWCRPC system and its control method. [ABSTRACT FROM AUTHOR]

To produce DC current by using a multiphase revers-ible chopper, smoothing reactors are needed. When smoothing reactors are employed, the chopper device be-comes large and heavy, especially if electromagnetic inter-ference is avoided. The reduction in the ripple current by electromagnetic coupling contributes to making the chopper device smaller and lighter. We deduced the relationships among the ripple current amplitude, duty factor, and electromagnetic coupling coefficient. To determine the loss and gain, we introduced the ratio of the amplitude of the ripple current in each phase and in the total combined current of the multiphase chopper system to that of the ripple current in a one-phase chopper, Aph, Asum, respectively. This value indicates the reduction not only in the ripple current amplitude but also in the selfinductance. The minimum value of the above-mentioned ratio obtained analytically is accurately determined. We derived the minimum values and obtained the range within which reduction of the ripple current amplitude for both each phase and total combined is achieved. Finally, we applied an optimal electromagnetic coupling coefficient to the design of on-board reactors of electric railway vehicles. [ABSTRACT FROM AUTHOR]

This paper presents an easy and a robust sensor fault detection and isolation (FDI) and fault tolerant control (FTC) of a single phase PWM rectifier for electrical railway traction application. Catenary current sensor and dc link voltage sensor failures are considered. The FDI method is based on observers and residual generation. The different FDI algorithm steps allow a good detection and isolation of the sensor fault and identify the faulty sensor. The reconfiguration strategy consists of two steps with open loop control and closed loop control working. Simulation results are presented to illustrate the good performance of the FTC procedure. Experimental results are also presented to show the effectiveness of the proposed FDI and FTC algorithms and good performances of the rectifier after the reconfiguration. [ABSTRACT FROM AUTHOR]

In this paper, we propose a protection scheme using a superconducting fault current limiter (SFCL) for the electric railway with traction power supply system with the automatic power changeover switch (ACS) system. The Korean electric railway uses a Scott transformer with many traction power substations. Each traction power substation has a neutral section. The ACS system is being installed at the neutral section and studied. In this system, shorting between the M- and T-phases prevents phase-to-phase faults, which was not considered for the conventional AC railway, due to the ACS. The proposed protection scheme using the SFCL mitigates this problem. In addition, we analysed the effect of the proposed protection scheme using the time-domain transient simulation software PSCAD/EMTDC. [ABSTRACT FROM PUBLISHER]

In this work is presenting the study of the electric current's parameters and characteristics, obtained by means of an electric power's quality analyzer. The measurements were made into an AC railway electric traction substation of 27 kV, during more hours, being registered momentary and average values. The data acquired with the electric power's quality analyzer were registered into a computing system, for their further analysis. In order to achieve the adaption between the analyzer's input measures and the traction line's values, the measurements were made in the secondaries of the voltage and current transformers existent in the traction substation. [ABSTRACT FROM AUTHOR]

A multi-purpose balanced (MPB) transformer is proposed in this paper for electric railway applications. The MPB transformer is developed from impedance-matching (IM) transformers widely used in China's railway systems. The proposed MPB transformer has three main functions: 1) it provides a symmetrical two-phase voltage of 27.5 kV for railway overhead lines to power electric trains; 2) it supplies a three-phase balanced voltage of 10.5 kV for railway substations; and 3) it can accommodate a three-phase harmonic filter with improved power factor and reduced manufacturing cost. In this paper, the operating principles of the MPB transformer are elaborated, the design of the harmonic filters is discussed, and the results of computer simulations are provided. A 16-MVA MPB transformer was designed and commissioned, and real-time field measurements are provided. [ABSTRACT FROM AUTHOR]

The problem of determination of the accurate distribution of the return current in AT (autotransformer) electric traction systems (supplied at 2 × 25 kV) for High Speed Railways is considered. The path of the traction return current flowing from the rolling stock axles back to the supply (i.e., substation) is composed of the traction rails and additional earth potential conductors. The overhead supply conductors in contact with the train pantograph are connected to a symmetrical circuit (the feeder) with the purpose of current balancing. This arrangement and its influence on current to earth are considered: the return current divides among rails (as signalling disturbing current) and earth, depending on the value of the electric parameters of the system and the earth and on the circuit arrangement and on the relative position of system devices. The amplitude (as a percentage of the total return current) of the disturbing current may be high enough to cause interference to signalling. This work investigates the behavior of the return current in AT electric railway systems, on the basis of a reference system for the variation of the most important electrical parameters. [ABSTRACT FROM AUTHOR]

Many single-phase 25kV electrified railway systems carry a large number of conventional thyristor-based locomotives, which draw current rich in harmonic content. A possible solution to mitigate this harmonic complication is to connect a power quality conditioner based on voltage detection at the end of the traction feeder. However, the performance of the installed power quality conditioner depends strongly on the accuracy and stability of the harmonic extraction algorithm used to generate the command harmonic current reference to be tracked by the inverter inner current control loop. A high performance, computationally efficient harmonic extraction algorithm is presented, implemented using delta-operator-based digital resonant filters for traction applications. Unlike most other extraction algorithms, the implementation of the algorithm presented does not require complex mathematical transformations, and therefore has a significantly faster computation speed and is suitable for single-phase traction applications. Also, through delta-operator-based implementation, the proposed algorithm exhibits improved accuracy and robustness over a wider range of operating conditions. The accuracy and robustness of the proposed algorithm have been verified by both simulation and experiment. [ABSTRACT FROM AUTHOR]

In this article the chapter is shortened that corresponds to the evaluation of the environmental contamination, of the project "Electrification of sub-urban railroads. The case Havana-City of the Havana that is part of a Program National Scientific-technician. Inside their main conclusions is that for this project the circulation of vehicles is the action but impactante, which reaches the category of severe about the factor quality of the air for any modality of transport employee. To obtain a bigger level of details in this respect they were considered the emissions of gases according to the methodology of the IPCC (International Panel for Climatic Change) being the transportation with electric carmotors the but advisable environmentally. [ABSTRACT FROM AUTHOR]

The problem of the determination of the real distribution of the return current in electric railway traction systems is considered. One or more conductors (depending on the specific supply system) are purposely set up to carry the traction return current flowing from the rolling stock axles back to the supply (i.e., substation); yet, part of the return current flows through signailing conductors (disturbing current) and through the earth, depending on the value of the electric parameters of the system, on the circuit arrangement, and on the relative position of the supply, the rolling stock, and signalling devices. The amplitude (as a percentage of the total return current) of the disturbing current.may be high enough to cause interference to signalling. This work investigates the behavior of the return current in ac and dc electric railway systems, on the basis of a reference system for the variation of the most important electrical parameters. The definition of the transfer function between the return current and the signaling circuit variables is an important element for the compatibility analysis between train detection systems, rolling stock and infrastructure, to promote the cross-acceptance of rolling stock in Europe and abroad. [ABSTRACT FROM AUTHOR]

Transients caused by field-to-wire coupling due to lightning strikes in the vicinity of multiconductor transmission lines (TL) have been widely studied. In those studies, the lines represent single overhead lines, power lines, and the like with lumped loads/devices at line terminations. In electrified railway power systems, series or shunt devices, such as transformers, converters, switchgear, and signal equipments, are distributed along the TL system. In this paper, the indirect lightning effects on a typical railway catenary-track multiconductor TL system with lumped components, namely, booster and auto transformers (BT and AT systems), and track circuits, are studied. It is found that the induced voltage wave shapes and amplitudes at any point along the line are dominated by BT or AT system type, and that the voltages appearing across AT windings are higher than for the corresponding BT windings. However, the induced voltages across the track circuits are less dependent on system type and most affected by the introduction of components. [ABSTRACT FROM PUBLISHER]

A railway derailment is usually an unpredictable event where the damage could range from a simple train delay to a big loss of goods, assets (rolling stock and permanent way) and, in extreme cases, even human lives. Therefore, Brazil’s railways are always implementing actions that minimize the risk of a derailment. One of the main actions is to establish tight maintenance criteria for rolling stock and for track geometry. However, these criteria usually do not consider the vehicle dynamics and the geometry of the permanent way together. Thus, this paper develops a mathematical model of a high capacity railcar together with the flexible support of the track to determine a method of assessing bounce, roll and pitch motions from instrumented wagons, so this method can be used in routine inspections. The mathematical model was satisfactorily validated by comparing the natural frequencies obtained from the model and from a real vehicle tested in the field. In addition, the model results were compared against field measurements from an instrumented wagon and a track geometric vehicle. A strategic method for operational safety analysis was suggested and used, which was able to determine the wavelength of permanent way anomalies that should be given priority for maintenance actions as well as considered when adopting speed restrictions. [ABSTRACT FROM PUBLISHER]

SUMMARY To produce DC current by using a multiphase reversible chopper, smoothing reactors are needed. When smoothing reactors are employed, the chopper device becomes large and heavy, especially if electromagnetic interference is avoided. The reduction in the ripple current by electromagnetic coupling contributes to making the chopper device smaller and lighter. We deduced the relationships among the ripple current amplitude, duty factor, and electromagnetic coupling coefficient. To determine the loss and gain, we introduced the ratio of the amplitude of the ripple current in each phase and in the total combined current of the multiphase chopper system to that of the ripple current in a one-phase chopper, A ph, A sum, respectively. This value indicates the reduction not only in the ripple current amplitude but also in the self-inductance. The minimum value of the above-mentioned ratio obtained analytically is accurately determined. We derived the minimum values and obtained the range within which reduction of the ripple current amplitude for both each phase and total combined is achieved. Finally, we applied an optimal electromagnetic coupling coefficient to the design of on-board reactors of electric railway vehicles. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(2): 68-82, 2014; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22480 [ABSTRACT FROM AUTHOR]