Marley Becerra

Marley Becerra
KTH Royal Institute of Technology | KTH · School of Electrical Engineering (EE)

PhD

About

85
Publications
16,817
Reads
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1,240
Citations
Citations since 2016
22 Research Items
735 Citations
2016201720182019202020212022020406080100120
2016201720182019202020212022020406080100120
2016201720182019202020212022020406080100120
2016201720182019202020212022020406080100120
Additional affiliations
October 2008 - December 2020
ABB Corporate Research
Position
  • Principal Investigator
Description
  • Currently I also work part time in industry working on power switching apparatus, including design, prototyping, technology-development and simulation. In the last years, I have been working on computational fluid dynamics (CFD).

Publications

Publications (85)
Conference Paper
Low-level currents measured prior to return strokes can potentially provide information about the properties of upward leaders during lightning flashes. However, these currents need to be properly analysed and interpreted in order to be useful for evaluating upward connecting leaders. In this paper, low-level currents measured before return strokes...
Conference Paper
Full-text available
One of the major challenges of DC circuit breakers is the required fast mechanical actuator. In this paper, a Thomson coil actuator system for a vacuum interrupter is designed. Active damping is used to decelerate the moving contacts. Challenges are discussed, especially concerning the power supply needed for the Thomson coil actuator. The design p...
Article
Full-text available
Positive and negative streamer inception voltages from ultra-sharp needle tips (with tip radii below 0.5 μm) are measured in TiO2, SiO2, Al2O3, ZnO and C60 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 differe...
Article
Full-text available
Abstract 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 of...
Article
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 appro...
Article
Full-text available
The amount of the electric charge injected by the streamer corona bursts during the stage of leader inception determines the energy deposited to thermalize the corona stem into a leader segment. This paper is aimed at investigating the critical charge required for positive leader inception in air by using a thermo-hydrodynamic model with a detailed...
Article
Full-text available
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 e...
Article
Full-text available
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...
Article
Full-text available
The inception of leader discharges in long air gaps at atmospheric pressure is simulated with a thermo-hydrodynamic model and a detailed kinetic scheme for N2/O2/H2O mixtures. In order to investigate the effect of humidity, the kinetic scheme includes the most important reactions with the H2O molecule and its derivatives, resulting in a scheme with...
Article
Full-text available
In this paper, we extended the recent work of Liu and Becerra (IEEE Trans. Plas. Sci. 44(11), 2016) to employ the position-state separation method (POSS) to simulate filamentary streamer discharges. POSS is a semi-Lagrangian method which solves convection-dominated continuity equations without numerical flux correction. An improved interpolation st...
Article
A computationally efficient model to evaluate stable glow corona discharges and their transition into streamers is proposed. The simplified physical model referred to as the SPM is based on the classic hydrodynamic model of charge particles and a quasi-steady state approximation for electrons. The solution follows a two-step segregated procedure, w...
Article
This document presents an experimental study on the propagation of first mode negative streamers along mineral oil-solid interfaces. Samples made of an oil impregnated kraft paper and a low-porosity paper made from cellulosic micro and nano fibrils, as well as different polymeric films (low density polyethylene (LDPE), polyethylene terephthalate (P...
Article
Full-text available
An efficient algorithm without flux correction for the simulation of corona discharges is proposed. The algorithm referred to as the position-state separation (POSS) method is used to solve convection-dominated continuity equations commonly present in corona discharges modeling. The proposed solution method combines an Eulerian scheme for the solut...
Conference Paper
Full-text available
In this paper, a self-consistent numerical model is employed to investigate the ionization kinetics of the streamer-to-leader transition in long air gap discharges. The model focuses on the dynamics of the discharge channel in the radial direction using a 1D radial system by taking into account 21 species and 106 chemical reactions. The detailed dy...
Article
A 2D numerical simulation of the transition from stable positive glow corona to streamers in coaxial cylindrical configuration is presented. The hydrodynamic model with several convection-dominated continuity equations together with Poisson equation are solved with consideration of the ionization layer. The transition from a stable positive glow co...
Article
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...
Article
Full-text available
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...
Conference Paper
This paper reports the probability distribution of negative streamers initiated in mineral oil with and without a solid interface. In addition, the charge injected by conduction currents prior to the streamer inception is presented. Impregnated paper and polymeric films made of PET, PTFE and PVDF are tested as solid materials. Comparison of the con...
Conference Paper
This paper introduces an experimental study on the propagation of negative streamers along mineral oil-solid interfaces. A standard type of impregnated paper and different polymeric films (made of PET, PTFE and PVDF) are selected as solid materials immersed in mineral oil. The effect of the solid material on the streamer propagation along the inter...
Conference Paper
Full-text available
In the past twenty years, there has been a growing concern regarding the effect of space charge produced by glow corona on lightning attachment. Several studies have been reported in the literature to evaluate the generation and drift of space charge generated by glow corona from the top of high grounded objects under thunderstorm conditions, using...
Conference Paper
Full-text available
A simple parallel numerical algorithm with P1/P1 velocity-pressure elements for solving the incompressible Navier-Stokes equations is proposed. In order to circumvent the Babuška-Brezzi condition (i.e. inf-sup condition), a velocity-pressure separation strategy following the idea of projection method is presented. Thus, the velocity and pressure te...
Article
Full-text available
A simple, fast, oscillation-free, high-resolution algorithm for convection-dominated flows is proposed. The stability, accuracy and time complexity of this method called the position-state separation method (POSS) are discussed. Several classical numerical experiments in different dimensions and coordinate systems are conducted to demonstrate the e...
Article
Full-text available
Previous studies have suggested the possibility of using glow corona discharges to control the frequency of lightning flashes to grounded objects. In order to revisit the theoretical basis of this proposal, the self-consistent leader inception and propagation model – SLIM – is used together with a two-dimensional glow corona drift model. The analys...
Conference Paper
Full-text available
Wind farms are an important part of renewable energy system but they are frequently damaged by lightning strikes, especially to the blades of the turbine. Recent field observations have shown lightning damages several meters inboard away from the blade tip, which cannot be explained fully by the interception of stepped leaders or swept strokes. Thi...
Conference Paper
Full-text available
It has been recently suggested that glow corona generated during thunderstorms could have an important role in the initiation of streamers and upward connecting leaders from power transmission lines. In order to further investigate this, a two-dimensional evaluation of the glow corona generation is here reported, which takes into account the non-eq...
Conference Paper
The Electrogeometric Method (EGM) is commonly used to analyze and design the external lightning protection of power transmission lines. However, it has been found that the EGM is not able to predict the shielding failure rate observed in EHV and UHV transmission lines. In this article, an analysis of the lightning attachment to EHV and UHV transmis...
Conference Paper
Full-text available
The transition phase from glow to streamer corona is of significant importance for the evaluation of leader discharges initiated from ultra-high voltage power transmission lines under thunderstorms. In order to study the condition required for streamer inception from a glow-corona generating wire, the continuity equations for electrons, positive io...
Conference Paper
Nanoparticles mixed with transformer oil can potentially increase the breakdown strength of the base liquid. Unfortunately, the basic physical mechanisms leading to such improvement are still not clear. This paper implements two existing theories to model the electrical conduction of cyclohexane with TiOz nanoparticles in a needle to plane configur...
Article
A self-consistent numerical model is presented in order to study the electrohydrodynamic (EHD) motion generated by a stationary, space-charge limited injection of charge in the point-plane geometry. In this multiphysics model, the continuity equations for charge carriers and Poisson's equation are coupled with Navier-Stokes equations and the heat e...
Conference Paper
This paper presents an experimental study of the positive streamer charge in transformer oil and oil-solid interfaces in a point-plane gap (5mm) under impulse voltage 50ns\1800μs (maximum peak voltage 24 kV). The experiment is intended to compare the charge of streamers propagating in transformer oil with and without a solid barrier along their pat...
Article
Full-text available
Streamer discharges are an important breakdown mechanism in air-based electrical insulation systems. This paper introduces a method to estimate the spatial distribution of the charge density of positive streamers in air, based on the solution of a Poisson inverse problem by optimization. In contrast to other methods, it does not require tuning para...
Conference Paper
The modeling of the mechanisms of generation, loss, multiplication and transport of charge carriers is vital for the simulation of the prebreakdown process in dielectric liquids. Unfortunately, there is a lack of suitable coefficients to describe the electron generation and transport of carriers in liquids, which hinders the development of numerica...
Conference Paper
The formation of a vapor microbubble has previously been suggested to be the initial mechanism in the process of dielectric failure of dielectric liquids. The bubble is generated by a rapid, highly localized heating of a volume close to a highly stressed electrode, caused by electric currents in the liquid at high voltages. A numerical model is pre...
Article
In this paper the currents associated with the streamer discharges generated from the head of a person located in the vicinity of a lightning strike are investigated. In the analysis the location of the person with respect to the lightning strike is selected in such a way that only a streamer burst, without the formation of a connecting leader, is...
Article
The initiation of streamers prior to a lightning strike can be reportedly inhibited by glow corona discharges generated from tall objects. In contrast to previous studies based on a simplified one-dimensional model of glow corona, a two-dimensional evaluation of the corona ion drift from tall objects is used here to analyse this effect quantitative...
Patent
Full-text available
Exemplary embodiments are directed to an electrical overcurrent tripping device for a circuit breaker. The tripping device includes an actuating member which in case of an overcurrent is driven to interact directly or indirectly with a movable contact piece of the circuit breaker to open a contact point in the circuit breaker if the overcurrent is...
Article
Polymers exposed to the radiation emitted by electric arcs generate vapours that are used to improve the interruption performance of electric switching apparatus. However, the basic physics of this process (known as ablation) under the broadband radiation spectra of electric arcs is not well understood. This paper presents measurements of time-reso...
Article
Full-text available
A self consistent lightning connecting leader inception and propagation model (SLIM) is utilized to study the attachment of lightning flashes to grounded structures and hence to evaluate the lightning attractive radii of vertical cylindrical structures and horizontal conductors as a function of height of the structure and peak current of the first...
Conference Paper
Full-text available
The self-consistent leader inception and propagation model -SLIM- has been increasingly used to study the attachment of lightning flashes to grounded structures. However, criticism about some assumptions of SLIM has been raised in a recent publication. This paper intends to reply to this criticism and to openly discuss the validity of the model. Mo...
Conference Paper
Previous studies in the literature have suggested that glow corona discharges could be potentially used to control the frequency of lightning flashes to grounded objects. Such studies use simplified one-dimensional corona drift models or basic empirical equations derived from high voltage experiments to assess the effect of glow corona on the initi...
Article
A self consistent lightning connecting leader inception and propagation model (SLIM) is utilized to study the attachment of lightning flashes to grounded structures and hence to evaluate the lightning attractive radii of vertical cylindrical structures and horizontal conductors as a function of height of the structure and peak current of the first...
Chapter
An assessment of the global distribution of nitrogen oxides (NOx) is required for a satisfactory description of tropospheric chemistry and in the evaluation of the global impact of increasing anthropogenic emissions of NOx. In the mathematical models utilized for this purpose, it is necessary to have the natural as well as man-made sources of NOx i...
Article
An experimental study on the production of NOX by impulse sparks in air is presented. The emphasis is placed on the dependence of the NOX yield on the signature of the discharge current waveforms. A voltage and two current impulses were used in the experiments to create a spark and the NOX production was measured by the method of chemiluminescence....
Article
Phosphene is a sensory experience which occurs due to the interaction of electric currents generated by an external agent with the visual cortex or retina. Occurrence of phosphenes has been documented in clinical Transcranial Magnetic Stimulation (TMS) studies where electric fields are induced in the brain by the application of time varying magneti...
Article
The optical emission of high current electric arcs confined between polymeric (PA6 - C6H11ON- and PMMA -C5H8O2-) and ceramic (Al2O 3) walls has been investigated experimentally in air. Arcs standing between copper electrodes with a separation of 8 mm under AC currents with peak values of 2 kA are studied here. The arc optical emission in the range...
Conference Paper
A self consistent lightning connecting leader inception and propagation model is utilized to study the attachment of lightning flashes to grounded structures and hence to evaluate the lightning attractive radii and volume of protection of vertical cylindrical structures and horizontal conductors as a function of height of the structure and peak cur...
Conference Paper
A self consistent lightning connecting leader inception and propagation model is utilized to study the effect of multiple connecting leaders on the attachment of lightning flashes to grounded structures. In the present study the results obtained in the case of a grounded structure equipped with two lightning rods were presented. As the stepped lead...
Article
Full-text available
Upward connecting leaders can be initiated from humans under the influence of lightning downward stepped leaders, thereby causing severe injuries. In order to improve the scarce knowledge about the interaction of upward connecting leaders with humans, a self-consistent model based on the physics of leader discharges is used in this paper. Furthermo...
Article
The results obtained in this study show that as the dart leader tip passes a given point on the defunct return stroke channel the electric field increases within a fraction of a microsecond to values larger than the critical electric field necessary for the initiation of cold electron runaway in low-density air comprising the channel. These results...
Chapter
The goal of this chapter is to present the current state of the art of lightning interception, and to show how the computer simulation programs that accommodate the physics of lightning interaction could be used to complement the protection procedures based on either the electro-geometrical model or the rolling sphere method. First, let us explain...
Article
Full-text available
A theory developed by scientists to study nitrogen oxides, NO x , production by solar proton events shows that the NO x production rate is approximately equal to the rate of production of ion pairs during the proton impact. Since the bulk of ionization in such events is produced by secondary electron impacts, the same concept is used here to study...
Article
Full-text available
The early emission of streamers in laboratory long air gaps under switching impulses has been observed to reduce the time of initiation of leader positive discharges. This fact has been arbitrarily extrapolated by the manufacturers of early streamer emission devices to the case of upward connecting leaders initiated under natural lightning conditio...
Article
Full-text available
Traditionally, the location of lightning strike points has been determined by using the rolling sphere method, but recently the collection volume method (CVM) has also been proposed for the placement of air terminals on complex structures. Both these methods are empirical in nature and a more advanced model based on physics of discharges is needed...
Article
Full-text available
A self-consistent leader propagation model is used to estimate the velocity of upward connecting positive leaders initiated from a tall tower under the influence of downward negative lightning leaders. The propagation of upward connecting leaders has been found to be influenced not only by the average velocity of the downward leader but also by the...
Article
Full-text available
The identification of the most vulnerable points on a given structure to be struck by lightning is an important issue on the design of a reliable lightning protection system. Traditionally, these lightning strike points are identified using the rolling sphere method, through an empirical correlation with the prospective peak return stroke current....
Article
Full-text available
Electric field measurements above ground have shown that the space charge layer created by corona at ground level shields the background electric field produced by the thundercloud. Therefore it is expected that this space charge layer can also influence the conditions required to initiate upward lightning from tall objects. For this reason, a nume...
Article
One of the most important characteristics of sprite development is the velocity of the downward tendrils, which has been observed to range from 105 to 3x107 m/s (Moudry et al., JGR, 29, 2002). However, there is a lack of laboratory experimental data on the speed of propagation of electrical discharges at pressures similar to those encountered in th...
Article
A study undertaken to measure the resistance of spark channels in air with two different current waveforms is presented. In one experiment, the spark was created by a Marx generator. In this case, the gap length was maintained at 12.8 cm, and the current flowing through the spark had a peak current lying in the range of 0.2-2.2 kA. The decay time o...
Article
The evaluation of the upward connecting leader inception from a grounded structure has generally been performed neglecting the effect of the propagation of the downward stepped leader. Nevertheless, field observations suggest that the space charge produced by streamer corona and aborted upward leaders during the approach of the downward lightning l...
Article
The knowledge of the initiation and propagation of an upward moving connecting leader in the presence of a downward moving lightning stepped leader is a must in the determination of the lateral attraction distance of a lightning flash by any grounded structure. Even though different models that simulate this phenomenon are available in the literatu...
Article
Full-text available
In this paper, a generalized leader inception model is proposed. It is based on an iterative geometrical analysis of the background potential distribution of an earthed structure to simulate the first meters of propagation of an upward connecting leader. By assuming a static field approach, the leader stabilization fields and the striking distances...
Article
Theoretical calculations accounting for the development of the streamer in air at atmospheric pressure in a needle placed in the inner cylinder of a cylindrical coaxial arrangement are presented. The streamer and DC current development are explained in terms of photoionization and secondary processes. The results of the spatial - temporal distribut...
Article
Theoretical predictions are given for the negative corona development in air at atmospheric pressure, produced in a cylindrical arrangement. Corona sources were perpendicularly placed on the earthed inner cylindrical electrode surface. Results were compared with experimental results and they agree satisfactorily. Calculations were obtained by solvi...
Article
Summary form only given. Simulations of high power microwave (HPM) devices are dominated by FDTD PIC methods developed by Yee and Boris. This work focuses on extending these techniques to a nested hierarchy of grids for the purpose of adding local refinement. A second order conservative algorithm is presented for the electromagnetics. Furthermore,...
Article
Summary form only given. A numerical study of a negative corona discharge in air at atmospheric pressure in a non-uniform electric field: a cylindrical arrangement with earthed inner electrodes is presented. Results were obtained by solving numerically Poisson's equation coupled with the continuity equations for electrons, positive, and negative io...
Article
Full-text available
The results of numerical simulation of the positive corona development in atmospheric air in a needle placed in the inner cylinder of a cylindrical coaxial arrangement are presented. The Poisson's equation was simultaneously solved with the continuity equations for electrons, positive ions and negative ions, including the effects of ionization, att...