AC traction systems are 1 x 25 or 2 x 25 kV 50-Hz single-phase, non-linear, time-varying loads that can cause power quality problems. One of the main concerns about these systems is voltage distortion, because adjustable-speed drives for trains may inject harmonic currents of frequencies below 2kHz. Since the presence of parallel resonances in the contact feeder section of the traction circuit worsens the scenario, traction system resonance phenomena should be analyzed to prevent problems. Several works addressed these phenomena, but they only drew weak numerical conclusions based on the frequency scan method. This article studies 1 x 25 kV traction system resonances at pantograph terminals and provides more effective analytical expressions to locate them and determine the impact of traction system parameters on them. These expressions are validated from several traction systems in the literature.
This article presents an exhaustive study about the influence of some design parameters, such as the number of phases, pole stroke, and current density, in the behavior of a linear switched reluctance motor. The linear switched reluctance motor's performance is assessed, taking into account a set of quality indices, which are the energy conversion loop quality factor, propulsion force per unit of primary steel volume, per unit of copper mass, per unit of air-gap surface, and force ripple factor. The study is carried out by means of two-dimensional finite-element analysis. Finally, the results are discussed, and as a consequence, a set of linear switched reluctance motor configurations with optimal performance according to the quality indices is defined.
The net harmonic currents generated by a cluster of desktop personal computers are studied statistically. Personal computers (PCs) are single-phase non-linear loads with low individual consumption but significant collective distortion effects, as many of them can be connected to the same bus (personal computer cluster). This article reports experimental measurements of harmonic currents injected by single-phase rectifiers and seven personal computer types during four operating modes. The probability density functions (pdfs) of the harmonic currents (magnitude and phase angle) are investigated from the measurements. An analytical procedure to obtain these probability density functions for any typical personal computer working session is described and experimentally validated. The obtained probability density functions are found to be applicable to large-scale harmonic penetration statistical studies. Furthermore, attenuation and diversity effects are analyzed from the previous probability density functions, and the harmonic current cancellation effect on personal computer clusters is investigated with Monte Carlo simulations.
Benyoucef, A.; Kara, K.; Chouder, A.; Silvestre, S. Electric power components and systems Vol. 42, num. 12, p. 1266-1277 DOI: 10.1080/15325008.2014.927031 Data de publicació: 2014-07-30 Article en revista
In this article, an improved deadbeat control algorithm suitable for digital signal processor-based circuit implementation is proposed. The control algorithm allows the derivation of a nearly sine wave output current with a fixed switching frequency of a current-controlled voltage source inverter. Two low-pass output filters configurations are considered in this study: a simple inductance filter and an LCL-filter. By taking advantage of prior knowledge of the state variables’ shape, the improved deadbeat control algorithm is based on a simple prediction model to derive the expected duty cycle needed to switch on and off the power switches. The control study of the grid-connected inverter with L and LCL output filters has been considered using a co-simulation approach with (Powersim Inc., Rockville, Maryland, USA) and MATLAB software (The MathWorks, Natick, Massachusetts, USA). The obtained results show the improvement of both shape quality and tracking accuracy of the output current quantified by low ripple content and a nearly unity power factor.
Trujillo, J.; Gomis-Bellmunt, O.; Montesinos-Miracle, D.; Posada-Gómez, R.; Pouresmaeil, E.; Aquino, J. Electric power components and systems Vol. 42, num. 2, p. 165-179 DOI: 10.1080/15325008.2013.853216 Data de publicació: 2014-01-25 Article en revista
This article proposes a digital control scheme to operate a proton exchange membrane fuel cell module of 1.2 kW and a super-capacitor through a DC/DC hybrid converter. A fuel cell has been proposed as a primary source of energy, and a super-capacitor has been proposed as an auxiliary source of energy. Experimental validation of the system implemented in the laboratory is provided. Several tests have been performed to verify that the system achieves excellent output voltage (V-0) regulation and super-capacitor voltage (V-SC) control under disturbances from fuel cell power (P-FC) and output power (P-0) as well as other perturbations described in analysis results.
This article presents a new comprehensive design procedure for longitudinal
flux flat linear switched reluctance motors. The design process comprises all the
steps from detailing the specifications to sizing the prototype to validating the design,
and it can be applied to three types of flux flat linear switched reluctance motors:
single sided, double sided, and modified double sided. The design is based on an
analytical formulation of the average translation force determined using a simplified
non-linear energy conversion loop. Special emphasis is devoted to the calculation of
the number of turns per phase. A two-dimensional finite-element analysis, corrected
to take into account end effects, and a lumped parameter thermal analysis were
used to refine and/or validate the design. Finally, a linear switched reluctance motor
prototype was built following the proposed design and was verified by experimental