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Doru Nicola  - - - 
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Carmen Bulucea

7 shared publications

University of Medicine and Pharmacy of Craiova, Faculty of Medicine, Craiova 200349, Romania

Nikos Mastorakis

1 shared publications

4
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Publication Record
Distribution of Articles published per year 
(2013 - 2016)
Publications
Article 4 Reads 0 Citations Operation analysis of AC traction motors in terms of electromagnetic torque capability on sustainable railway vehicles Doru A. Nicola, Marc A. Rosen, Nikos E. Mastorakis, Cornelia... Published: 01 January 2016
MATEC Web of Conferences, doi: 10.1051/matecconf/20167602005
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Sustainable operation of electric railway systems represents a significant purpose nowadays in the development of high power and high speed locomotives and trains. At present, high speed electric vehicles mostly work with three-phase induction motors or three-phase synchronous motors as traction motors. The two electric machine types have different efficiencies at different operation points, and experience differences with respect to safety, speed and power, energy use and exergy efficiency. An important issue that correlates these aspects is the electromagnetic torque developed by an electric traction motor. In order to provide an overview of the technical performance of the operation of sustainable railway systems, a detailed analysis is carried out of the electromagnetic torque capability of AC electric motors utilized as traction motors in modern locomotives of high power and/or high speed. The results of this work may help in enhancing the main criteria for optimising the safe and sustainable operation of electric railway traction systems.
Article 3 Reads 2 Citations Sustainability Aspects of Energy Conversion in Modern High-Speed Trains with Traction Induction Motors Marc Rosen, Doru Nicola, Cornelia Bulucea, Daniel Cismaru Published: 20 March 2015
Sustainability, doi: 10.3390/su7033441
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Some aspects are illustrated of energy conversion processes during the operation of electric railway vehicles with traction induction motors, in order to support transport systems’ sustainability. Increasing efforts are being expended to enhance the sustainability of transportation technologies and systems. Since electric drive systems are used with variable voltage variable frequency (VVVF) inverters and traction induction motors, these machines with appropriate controls can realize both traction and electric braking regimes for electric traction vehicles. In line with this idea, this paper addresses the operation sustainability of electric railway vehicles highlighting the chain of interactions among the main electric equipment on an electrically driven railway system supplied from an a.c. contact line: The contact line-side converter, the machine-side converter and the traction induction motor. The paper supports the findings that electric traction drive systems using induction motors fed by network-side converters and VVVF inverters enhance the sustainable operation of railway trains.
Conference 5 Reads 0 Citations Some Aspects of Sustainable Energy Conversion During Transient Processes in Electric Power Systems Comprising Generator ... Cornelia Bulucea, Marc Rosen, Doru Nicola, Nikos Mastorakis,... Published: 31 October 2013
The 3rd World Sustainability Forum, doi: 10.3390/wsf3-d001
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Article 0 Reads 1 Citation Approaching the Processes in the Generator Circuit Breaker at Disconnection through Sustainability Concepts Carmen Bulucea, Marc Rosen, Doru Nicola, Nikos Mastorakis Published: 19 March 2013
Sustainability, doi: 10.3390/su5031161
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Nowadays, the electric connection circuits of power plants (based on fossil fuels as well as renewable sources) entail generator circuit-breakers (GCBs) at the generator terminals, since the presence of that electric equipment offers many advantages related to the sustainability of a power plant. In an alternating current (a.c.) circuit the interruption of a short circuit is performed by the circuit-breaker at the natural passing through zero of the short-circuit current. During the current interruption, an electric arc is generated between the opened contacts of the circuit-breaker. This arc must be cooled and extinguished in a controlled way. Since the synchronous generator stator can flow via highly asymmetrical short-circuit currents, the phenomena which occur in the case of short-circuit currents interruption determine the main stresses of the generator circuit-breaker; the current interruption requirements of a GCB are significantly higher than for the distribution network circuit breakers. For shedding light on the proper moment when the generator circuit-breaker must operate, using the space phasor of the short-circuit currents, the time expression to the first zero passing of the short-circuit current is determined. Here, the manner is investigated in which various factors influence the delay of the zero passing of the short-circuit current. It is shown that the delay time is influenced by the synchronous machine parameters and by the load conditions which precede the short-circuit. Numerical simulations were conducted of the asymmetrical currents in the case of the sudden three-phase short circuit at the terminals of synchronous generators. Further in this study it is emphasized that although the phenomena produced in the electric arc at the terminals of the circuit-breaker are complicated and not completely explained, the concept of exergy is useful in understanding the physical phenomena. The article points out that just after the short-circuit current interruption by the generator the circuit-breaker (when the GCB has been subjected at the metal contact terminals to the high temperature of a plasma arc, up to 50,000 K) between its opened contacts, there arises the transient recovery voltage (TRV) which constitutes the most important dielectric stress after the electric arc extinction. Since the magnitude and shape of the TRV occurring across the generator circuit-breaker are critical parameters in the recovering gap after the current zero, in this paper, we model, for the case of the faults fed by the main step-up transformer, the equivalent configurations, with operational impedances, for the TRV calculation, taking into account the main transformer parameters, on the basis of the symmetrical components method.
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