railway traction
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Nowadays the multi-inverter multi-machine conventional system takes a great interest of industrials like railway traction. The implementation of single inverter to dual motor makes all the system cheaper; soft operation, more robust and reliable; This paper is one of control methods proposed in the literature to improve performance of this system, a master slave and average control based in artificial neural networks direct torque control of bi asynchronous motors supplied by single three level inverter NPC is discussed. The result of theoretical analysis is tested with MATLAB SIMULINK environment. And through that, the possibility of DTC single inverter multi-motor system has been verified.

This article presents the results of a research on the operational damage to sectional insulator guides made of hard electrolytic copper Cu-ETP (Electrolytic Tough Pitch Copper). The guides were used on various rail routes, in real conditions, on which the trains ran at maximum speeds between 40 and 120 km/h for periods of 6 or 12 months. The microstructure of the surface, the working layer of the guide, which contacts the graphite plate of the current collector and the cross-section of the guide in the place where it was damaged was examined using the Olympus light microscope. The analysis of the chemical composition in the EDS micro-regions was performed using the Zeiss Supra 53 scanning electron microscope (SEM), while the qualitative X-ray phase analysis was performed with the use of the Panalytical X'Pert diffractometer. Scratches and deformations of the surface layer characteristic of the phenomenon of friction caused by the current collector were observed in the microstructure of the damaged parts of the guides of section insulators. The effect of a very intense oxidation process was also observed, as well as the effects of an electric arc, which according to the author, is the factor that has the most destructive effect on the condition of the guides.

Abstract This article discusses the problem of improving the accuracy of determining the location of a short circuit in the AC railways traction networks. Finding a short circuit can take several hours. An urgent task is reducing the time to search for a fault location. The purpose of the study is to develop a method that increases the accuracy of determining the location of a short circuit in AC traction networks. The method is based on computer modeling of inhomogeneities in the structure of the traction network and the arc. The proposed method makes it possible to take into account the arc resistance. The method was tested on the traction network active section. The error of the method is 200-300 meters. The method can find practical application in the work of dispatchers.

To relieve the contradiction between supply and demand, a multi-port power conditioner (MP-PC) and control strategy with renewable energy access for a railway traction system is presented, which is mainly composed of full-bridge-based MMC and isolated DC/DC converters. As for the full-bridge-based MMC, the equivalent model is established and its novel voltage control method is proposed, which can provide a medium/low-voltage DC-link. A renewable energy system is connected to the system through the DC-link, so the MP-PC can achieve on-site consumption and balance between the load power and output power of RESs. Meanwhile, with the proposed control strategy, MP-PC can achieve three-phase power balance control and improve the operation performance of the railway traction system. Finally, the traction power platform and simulation model are established in the lab, and the topology and control strategy of MP-PC are verified effectively.

This paper investigates the effect of high-temperature aging (600 °C and 650 °C) on the microstructure and functional properties of copper CuNi2Si alloy. The paper also presents the results of elastomeric tests performed by means of the Gleeble 3800 heat and plastic treatment simulator, as well as DTA (Differential Thermal Analysis) analysis carried out for the investigated alloy aged for 1, 2, 4 and 7 h. Corrosion resistance tests were performed by means of the potentiodynamic method with Atlas Sollich Atlas 0531 potentiostat/galvanostat in a 3% sodium chloride solution. Based on the tribological tests, it was confirmed that the CuNi2Si alloy was solution heat treated from the temperature of 1000 °C and gradually aged at the temperature of 600 °C and 650 °C for 1–7 h, characterized by a stable wear resistance. The alloy aged at the temperature of 600 °C was characterized by a lower mass loss compared to the one aged at 650 °C. Based on the DTA analysis, it was found that for the alloy aged for 2, 4 and 7 h, at the temperatures of 401 °C, 411 °C and 412 °C, respectively, the decomposition of a supersaturated solid solution took place by spinodal transformation accompanied by a sequence of phase transitions DO22 [(Cu, Ni)3Si],→ δ-Ni2Si → (Cu, Ni)3Si. The results of these investigations have proved that the CuNi2Si alloy can be widely used for electric traction. The use of alloys that replace elements made entirely of copper and, in this way influencing its lower demand, is in line with the global policy of economical management of natural resources.