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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]

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]

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]

Abstract: For novel design and efficient operation of next-generation DC electric railway systems, especially for their substantial energy saving, we have studied the feasibility of applying superconducting power cables to them. In this paper it is assumed that a superconducting power cable is applied to connect substations supplying electric power to trains. An analysis model line was described by an electric circuit, which was analyzed with MATLAB-Simulink. From the calculated voltages and currents of the circuit, the regenerative brake and the energy losses were estimated. In addition, assuming the heat loads of superconducting power cables and the cryogenic efficiency, the energy saving of the total system was evaluated. The results show that the introduction of superconducting power cables could achieve the improved use of regenerative brake, the loss reduction, the decreased number of substations, the reduced maintenance, etc. [Copyright &y& Elsevier]