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Becerra Garcia, MarleyORCID iD iconorcid.org/0000-0002-6375-6142
Alternative names
Publications (10 of 70) Show all publications
Parekh, M., Magnusson, J., Becerra Garcia, M. & Engdahl, G. (2018). Effect of contact velocity on the behaviour of decaying arcs in air. In: Effect of contact velocity on the behaviour of decaying arcs in air: . Paper presented at 2018 IEEE Holm Conference on Electrical Contacts. Albuquerque, NM, USA, USA: IEEE
Open this publication in new window or tab >>Effect of contact velocity on the behaviour of decaying arcs in air
2018 (English)In: Effect of contact velocity on the behaviour of decaying arcs in air, Albuquerque, NM, USA, USA: IEEE, 2018Conference paper, Published paper (Refereed)
Abstract [en]

Hybrid direct current circuit breaker (HDCCB) consists of an ultra-fast electromechanical switch combined with power semiconductors to interrupt fault currents. When the ultra-fast electromechanical switch opens, arc plasma is generated between its contacts that commutate the fault current to the auxiliary circuit consisting of power semiconductors. Understanding of the arc behaviour due to the ultra-fast contact opening is necessary as the current commutation is driven by the arc voltage. This paper presents experimental results of a dynamic voltage-current (V-I) characteristics of a decaying arc plasma in air having contact opening velocities from 5 to 15 m/s. A pair of hemispherically capped copper contacts was used for the experiments. The contacts were covered by a glass tube, open from one end which makes the arc partially wall constricted. The contacts were opened with a dedicated Thomson coil based electromagnetic actuator. A computer controlled test system was used that allowed controlling the shape of the current pulse and the time instant of the contact opening on the current waveform. The conductance of the arc was calculated for different contact opening velocities. It was observed that the conductance decreased with an increase of the contact opening velocity. High speed imaging was performed to observe the physical behaviour of arcs having different contact opening speeds.

Place, publisher, year, edition, pages
Albuquerque, NM, USA, USA: IEEE, 2018
Series
2018 IEEE Holm Conference on Electrical Contacts, ISSN 1062-6808, E-ISSN 2158-9992
Keywords
contact velocity, ultra-fast electromechanical switch, hybrid direct current circuit breaker, electrical arc
National Category
Engineering and Technology
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-241448 (URN)10.1109/HOLM.2018.8611733 (DOI)978-1-5386-6315-8 (ISBN)
Conference
2018 IEEE Holm Conference on Electrical Contacts
Note

QC 20190125

Available from: 2019-01-22 Created: 2019-01-22 Last updated: 2019-01-25Bibliographically approved
Becerra Garcia, M., Long, M., Schulz, W. & Thottappillil, R. (2018). On the estimation of the lightning incidence to offshore wind farms. Electric power systems research, 157, 211-226
Open this publication in new window or tab >>On the estimation of the lightning incidence to offshore wind farms
2018 (English)In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 157, p. 211-226Article in journal (Refereed) Published
Abstract [en]

Field observations have shown that the frequency of dangerous lightning events to wind turbines, calculated according to the IEC standard 61400-24:2010, is grossly underestimated. This paper intends to critically revisit the evaluation of the incidence of downward lightning as well as self-initiated and other-triggered upward flashes to offshore wind power plants. Three different farms are used as case studies. The conditions for interception of stepped leaders in downward lightning and the initiation of upward lightning is evaluated with the Self-consistent Leader Inception and Propagation Model (SLIM). The analysis shows that only a small fraction of damages observed in the analysed farms can be attributed to downward lightning. It is also estimated that only a small fraction (less than 19%) of all active thunderstorms in the area of the analysed farms can generate sufficiently high thundercloud fields to self-initiate upward lightning. Furthermore, it is shown that upward flashes can be triggered even under low thundercloud fields once a sufficiently high electric field change is generated by a nearby lightning event. Despite of the uncertainties in the incidence evaluation, it is shown that upward flashes triggered by nearby positive cloud-to-ground flashes produce most of the dangerous lightning events to the case studies.

Place, publisher, year, edition, pages
Elsevier Ltd, 2018
Keywords
Lightning, Lightning damage, Risk assessment, Upward lightning, Wind power farms, Clouds, Damage detection, Electric fields, Standards, Wind power, Wind turbines, Downward lightnings, Field observations, High electric fields, Offshore wind power plants, Positive cloud-to-ground flashes, Propagation modeling, Offshore wind farms
National Category
Environmental Engineering
Identifiers
urn:nbn:se:kth:diva-223115 (URN)10.1016/j.epsr.2017.12.008 (DOI)000425203500021 ()2-s2.0-85039859714 (Scopus ID)
Note

Export Date: 13 February 2018; Article; CODEN: EPSRD; Correspondence Address: Becerra, M.; KTH Royal Institute of Technology, Department of Electromagnetic EngineeringSweden; email: marley@kth.se. QC 20180327

Available from: 2018-03-27 Created: 2018-03-27 Last updated: 2018-03-27Bibliographically approved
Becerra Garcia, M. & Pettersson, J. (2018). Optical radiative properties of ablating polymers exposed to high-power arc plasmas. Journal of Physics D: Applied Physics, 51(12), Article ID 125202.
Open this publication in new window or tab >>Optical radiative properties of ablating polymers exposed to high-power arc plasmas
2018 (English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 51, no 12, article id 125202Article in journal (Refereed) Published
Abstract [en]

The radiative properties of polymers exposed to high-intensity radiation are of importance for the numerical simulation of arc-induced ablation. The paper investigates the optical properties of polymethylmethacrylate PMMA and polyamide PA6 films exposed to high-power arc plasmas, which can cause ablation of the material. A four-flux radiative approximation is first used to estimate absorption and scattering coefficients of the tested materials in the ultraviolet (UV) and in the visible (VIS) ranges from spectrophotometric measurements. The temperature-induced variation of the collimated transmissivity of the polymers is also measured from room temperature to the glass temperature of PMMA and the melting temperature of PA6. Furthermore, band-averaged absorption and scattering coefficients of non-ablating and ablating polymers are estimated from the UV to the short-wavelength infrared (SWIR), covering the range of interest for the simulation of arc-induced ablation. These estimates are obtained from collimated transmissivities measured with an additional in situ photometric system that uses a high-power, transient arc plasma to both illuminate the samples and to induce ablation. It is shown that the increase in the bulk temperature of PA6 leads to a strong reversible increase in collimated transmissivity, significantly reducing the absorption and scattering coefficients of the material. A weaker but opposite effect of temperature on the optical properties is found in PMMA. As a consequence, it is suggested that the absorption coefficient of polymers used for arc-induced ablation estimates should not be taken directly from direct collimated transmissivity measurements at room temperature. The band-averaged radiation measurements also show that the layer of products released by ablation of PMMA produces scattering radiation losses mainly in the VIS-SWIR ranges, which are only a small fraction of the total incident arc radiation. In a similar manner, the ablation layer of PA6 leads to weak absorption radiation losses, although mainly in the UV range.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2018
Keywords
radiative properties, polymers, arc plasmas, polymer ablation, spectrophotometry
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-224676 (URN)10.1088/1361-6463/aaaeda (DOI)000426377800001 ()2-s2.0-85043500706 (Scopus ID)
Funder
StandUp
Note

QC 20180323

Available from: 2018-03-23 Created: 2018-03-23 Last updated: 2018-03-23Bibliographically approved
Aljure, M., Becerra Garcia, M. & Karlsson, M. E. (2018). Streamer Inception from Ultra-Sharp Needles in Mineral Oil Based Nanofluids. Energies, 11(8), Article ID 2064.
Open this publication in new window or tab >>Streamer Inception from Ultra-Sharp Needles in Mineral Oil Based Nanofluids
2018 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 11, no 8, article id 2064Article in journal (Refereed) Published
Abstract [en]

Positive and negative streamer inception voltages from ultra-sharp needle tips (with tip radii below 0.5 m) are measured in TiO2, SiO2, Al2O3, ZnO and C-60 nanofluids. The experiments are performed at several concentrations of nanoparticles dispersed in mineral oil. It is found that nanoparticles influence positive and negative streamers in different ways. TiO2, SiO2 and Al2O3 nanoparticles increase the positive streamer inception voltage only, whilst ZnO and C-60 nanoparticles augment the streamer inception voltages in both polarities. Using these results, the main hypotheses explaining the improvement in the dielectric strength of the host oil due to the presence of nanoparticles are analyzed. It is found that the water adsorption hypothesis of nanoparticles is consistent with the increments in the reported positive streamer inception voltages. It is also shown that the hypothesis of nanoparticles reducing the electron velocity by hopping transport mechanisms fails to explain the results obtained for negative streamers. Finally, the hypothesis of nanoparticles attaching electrons according to their charging characteristics is found to be consistent with the results hereby presented on negative streamers.

Place, publisher, year, edition, pages
MDPI, 2018
Keywords
streamer inception, electric discharges, nanofluids, mineral oil
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-238926 (URN)10.3390/en11082064 (DOI)000446604100143 ()2-s2.0-85052822998 (Scopus ID)
Note

QC 20181114

Available from: 2018-11-14 Created: 2018-11-14 Last updated: 2018-11-16Bibliographically approved
Long, M., Becerra, M. & Thottappillil, R. (2017). Modeling the Attachment of Lightning Dart and Dart-Stepped Leaders to Grounded Objects. IEEE transactions on electromagnetic compatibility (Print), 59(1), 128-136
Open this publication in new window or tab >>Modeling the Attachment of Lightning Dart and Dart-Stepped Leaders to Grounded Objects
2017 (English)In: IEEE transactions on electromagnetic compatibility (Print), ISSN 0018-9375, E-ISSN 1558-187X, Vol. 59, no 1, p. 128-136Article in journal (Refereed) Published
Abstract [en]

Attachment of downward subsequent dart leaders has been recently proposed as a possible mechanism of lightning damage of wind turbine blades. Since subsequent dart and dart-stepped leaders propagating after the first lightning discharge are one-to-two orders of magnitude faster than downward stepped leaders, the direct evaluation of the dart leader interception by upward connecting leaders from the turbine has not been attempted before. In this paper, the self-consistent leader inception and propagation model SLIM is used to evaluate the lightning attachment process of subsequent dart leaders by accounting the rapid changing electric fields produced by their fast descent toward the ground. For this, an improved evaluation of the charge per unit length required to thermalize the upward connecting leader is derived. The analysis considers upward connecting leaders propagating along the preheated channel of a prior discharge. Three study cases of lightning attachment of dart leaders and dart-stepped leader reported in rocket-triggered lightning experiments are evaluated. It is shown that reasonable predictions of the length, duration, and velocity of positive upward connecting leaders can be obtained with SLIM in agreement with the experimental results. Further research on upward leader discharges necessary to improve the modeling of attachment of dart lightning leaders is discussed.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2017
Keywords
Lightning attachment, lightning dart and dart-stepped leaders, rocket-triggered lightning
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-198944 (URN)10.1109/TEMC.2016.2594703 (DOI)000387359700015 ()2-s2.0-84982204112 (Scopus ID)
Funder
StandUp
Note

QC 20170113

Available from: 2017-01-13 Created: 2016-12-22 Last updated: 2017-11-29Bibliographically approved
Long, M., Becerra Garcia, M. & Thottappillil, R. (2017). On the attachment of dart lightning leaders to wind turbines. Electric power systems research, 151, 432-439
Open this publication in new window or tab >>On the attachment of dart lightning leaders to wind turbines
2017 (English)In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 151, p. 432-439Article in journal (Refereed) Published
Abstract [en]

Wind turbines are prone to damages due to lightning strikes and the blades are one of the most vulnerable components. Even though the blade tip is usually protected in standard designs, lightning damages several meters away from it have also been observed in some field studies. However, these damages inboard from the tip cannot be explained by the attachment of downward stepped leaders or the initiation of upward lightning alone. In this paper, the attachment of dart leaders in an upward lightning flash is investigated as a mechanism of strikes to inboard sections of the blade and the nacelle of large wind turbines. Dart leaders in an upward lightning flash use the channel previously ionized by the preceding stroke or the continuous current. The analysis is performed with the self-consistent leader inception and propagation model (SLIM). A commercial large wind turbine with 45 m long blades and hub height of 80 m is analysed as a case study. The impact of the prospective return stroke peak current, the rotation angle of the blade and the wind on the location of lightning strikes on this mechanism is analysed. The probability of lightning attachment of dart leaders along the blade for the case study is also calculated. It is shown that this damage mechanism could create a new strike point only when the blade of a wind turbine rotates sufficiently from its initial position (at the inception of the initial upward leader) until the start of the dart leader approach. Thus, dart leader attachment is a mechanism that can explain lightning strikes to the nacelle and to the inboard region several meters away from the blade tip in large wind turbines. However, dart leader attachment cannot explain the lightning strikes observed in the close vicinity of the blade tip (in the region between 1.5 and 6 m from it).

Place, publisher, year, edition, pages
Elsevier Ltd, 2017
Keywords
Dart lightning leaders, Lightning attachment, Lightning damages, Wind turbines, Lightning, Lightning protection, Turbomachine blades, Damage mechanism, Large wind turbines, Leader inception, Lightning leader, Lightning strikes, Propagation modeling, Upward lightning, Turbine components
National Category
Aerospace Engineering
Identifiers
urn:nbn:se:kth:diva-218880 (URN)10.1016/j.epsr.2017.06.011 (DOI)000406984700039 ()2-s2.0-85021219468 (Scopus ID)
Note

QC 20180115

Available from: 2018-01-15 Created: 2018-01-15 Last updated: 2018-01-15Bibliographically approved
Becerra Garcia, M., Frid, H. & Vazquez, P. A. (2017). Self-consistent modeling of laminar electrohydrodynamic plumes from ultra-sharp needles in cyclohexane. Paper presented at Meeting of the Institute-of-Non-Newtonian-Fluid-Mechanics (INNFM), 2017, Llanwddyn, Wales. Physics of fluids, 29(12), Article ID 123605.
Open this publication in new window or tab >>Self-consistent modeling of laminar electrohydrodynamic plumes from ultra-sharp needles in cyclohexane
2017 (English)In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 29, no 12, article id 123605Article in journal (Refereed) Published
Abstract [en]

This paper presents a self-consistent model of electrohydrodynamic (EHD) laminar plumes produced by electron injection from ultra-sharp needle tips in cyclohexane. Since the density of electrons injected into the liquid is well described by the Fowler-Nordheim field emission theory, the injection law is not assumed. Furthermore, the generation of electrons in cyclohexane and their conversion into negative ions is included in the analysis. Detailed steady-state characteristics of EHD plumes under weak injection and space-charge limited injection are studied. It is found that the plume characteristics far from both electrodes and under weak injection can be accurately described with an asymptotic simplified solution proposed by Vazquez et al. ["Dynamics of electrohydrodynamic laminar plumes: Scaling analysis and integral model," Phys. Fluids 12, 2809 (2000)] when the correct longitudinal electric field distribution and liquid velocity radial profile are used as input. However, this asymptotic solution deviates from the self-consistently calculated plume parameters under space-charge limited injection since it neglects the radial variations of the electric field produced by a high-density charged core. In addition, no significant differences in the model estimates of the plume are found when the simulations are obtained either with the finite element method or with a diffusion-free particle method. It is shown that the model also enables the calculation of the current-voltage characteristic of EHD laminar plumes produced by electron field emission, with good agreement with measured values reported in the literature.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2017
Keywords
Dielectric Liquids, Blade Electrode, Flat-Plate, Injection, Field, Simulation, Charge, Conduction, Stability, Dynamics
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-221017 (URN)10.1063/1.5001000 (DOI)000418958300040 ()2-s2.0-85040032188 (Scopus ID)
Conference
Meeting of the Institute-of-Non-Newtonian-Fluid-Mechanics (INNFM), 2017, Llanwddyn, Wales
Funder
Swedish Foundation for Strategic Research
Note

QC 20180112

Available from: 2018-01-12 Created: 2018-01-12 Last updated: 2018-02-12Bibliographically approved
Liu, L. & Becerra, M. (2016). An Efficient Semi-Lagrangian Algorithm for Simulation of Corona Discharges: The Position-State Separation Method. IEEE Transactions on Plasma Science, 44(11), 1-10
Open this publication in new window or tab >>An Efficient Semi-Lagrangian Algorithm for Simulation of Corona Discharges: The Position-State Separation Method
2016 (English)In: IEEE Transactions on Plasma Science, ISSN 0093-3813, E-ISSN 1939-9375, Vol. 44, no 11, p. 1-10Article in journal (Refereed) Published
Abstract [en]

An efficient algorithm without flux correction for simulation of corona discharges is proposed. The algorithm referred to as the position-state separation method (POSS) is used to solve convection-dominated continuity equations commonly present in corona discharges modelling. The proposed solution method combines an Eulerian scheme for the solution of the convective acceleration, the diffusion and the reaction subproblems, and a Lagrangian scheme for the solution of the linear convection subproblem. Several classical numerical experiments in different dimensions and coordinate systems are conducted to demonstrate the excellent performance of POSS regarding low computational cost, robustness, and high-resolution. It is shown that the time complexity of the method when dealing with the convection of charged particles increases linearly with the number of unknowns. For the simulation of corona discharges where local electric fields do not change strongly in time, the time step of POSS could be much larger than the Courant–Friedrichs–Lewy (CFL) time step. These special features enable POSS to have great potential in modeling of corona discharges in long interelectrode gaps and for long simulation times.

Place, publisher, year, edition, pages
IEEE Press, 2016
Keywords
Semi-Lagrangian method; simulation; corona discharges; convection-dominated
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Fusion, Plasma and Space Physics
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-193002 (URN)10.1109/TPS.2016.2609504 (DOI)000388795400001 ()2-s2.0-84991688609 (Scopus ID)
Note

QC 20160928

Available from: 2016-09-24 Created: 2016-09-24 Last updated: 2017-11-21Bibliographically approved
Aminlashgari, N., Becerra, M. & Hakkarainen, M. (2016). Characterization of degradation fragments released by arc-induced ablation of polymers in air. Journal of Physics D: Applied Physics, 49(5), Article ID 055502.
Open this publication in new window or tab >>Characterization of degradation fragments released by arc-induced ablation of polymers in air
2016 (English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 49, no 5, article id 055502Article in journal (Refereed) Published
Abstract [en]

Polymers exposed to high intensity arc plasmas release material in a process called arc-induced ablation. In order to investigate the degradation fragments released due to this process, two different polymeric materials, poly(oxymethylene) copolymer (POM-C) and poly(methyl methacrylate) (PMMA), were exposed to a transient, high-power arc plasma in air. A small fraction of the ablated material drifting away from the arcing volume was deposited on a fixed glass substrate during the total duration of a 2 kA ac current semicycle. In addition, another fraction of the released material was deposited on a second moving substrate to obtain a time-resolved streak 'image' of the arc-induced ablation process. For the first time, mass spectra of degradation fragments produced by arc-induced ablation were obtained from the material deposited on the substrates by using laser desorption ionization time-of-flight mass spectrometry (LDI-ToF-MS). It was found that oligomers with mean molecular weight ranging between 400 and 600 Da were released from the surface of the studied polymers. The obtained spectra suggest that the detected degradation fragments of POM could be released by random chain scission of the polymer backbone. In turn, random chain scission and splitting-off the side groups are suggested as the main chemical mechanism leading to the release of PMMA fragments under arc-induced ablation.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2016
Keywords
arc plasma, polymer ablation, degradation, laser desorption ionization time-of-flight mass spectrometry
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-182768 (URN)10.1088/0022-3727/49/5/055502 (DOI)000368944100029 ()2-s2.0-84957570081 (Scopus ID)
Note

QC 20160223

Available from: 2016-02-23 Created: 2016-02-23 Last updated: 2018-03-26Bibliographically approved
Cuaran, J., Roman, F. & Becerra, M. (2016). Lightning Shielding Analysis of EHV and UHV Transmission Lines: On the Effect of Terrain Topography. In: 2016 33RD INTERNATIONAL CONFERENCE ON LIGHTNING PROTECTION (ICLP): . Paper presented at 33rd International Conference on Lightning Protection (ICLP), SEP 25-30, 2016, Estoril, PORTUGAL. IEEE
Open this publication in new window or tab >>Lightning Shielding Analysis of EHV and UHV Transmission Lines: On the Effect of Terrain Topography
2016 (English)In: 2016 33RD INTERNATIONAL CONFERENCE ON LIGHTNING PROTECTION (ICLP), IEEE, 2016Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, the Self-Consisting Leader Inception and Propagation Model -SLIM- is used to analyze the shielding performance of transmission lines, with special attention on the terrain topography effect. Transverse and Longitudinal terrain profiles are considered. It is found that a transmission line can be more vulnerable to be struck by lightning on any terrain that leads to increase the height of the conductors. In addition, the striking distance to the phase conductors strongly depends on the landform and the tower geometry, which suggests changes in the current lightning protection standards.

Place, publisher, year, edition, pages
IEEE, 2016
Series
International Conference on Lightning Protection, ISSN 2469-8784
Keywords
Lightning protection, shielding failure, UHV power transmission lines
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-202470 (URN)10.1109/ICLP.2016.7791371 (DOI)000392212500036 ()2-s2.0-85011034351 (Scopus ID)978-1-5090-5843-3 (ISBN)
Conference
33rd International Conference on Lightning Protection (ICLP), SEP 25-30, 2016, Estoril, PORTUGAL
Note

QC 20170302

Available from: 2017-03-02 Created: 2017-03-02 Last updated: 2017-03-02Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-6375-6142

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