Access profile

Any student who has completed a master’s degree in engineering (or the 60 corresponding ECTS) has sufficient capacity to undertake a doctoral degree in our programme. However, preference will be given to students whose knowledge is directly related to electrical engineering. Students from other master’s degrees will be considered if they can demonstrate basic knowledge of fundamental electrical subjects such as electrotechnics and electrical machinery. In general, the programme committee and the future tutor will decide whether these students need to take any bridging courses to study on the doctoral programme.

Output profile

Doctoral candidates who complete a doctoral degree will have acquired the following competencies, which are needed to carry out quality research (Royal Decree 99/2011, of 28 January, which regulates official doctoral studies):

a) A systematic understanding of the field of study and a mastery of the research skills and methods related to the field.
b) An ability to conceive, design or create, put into practice and adopt a substantial process of research or creation.
c) An ability to contribute to pushing back the frontiers of knowledge through original research.
d) A capacity for critical analysis and an ability to assess and summarise new and complex ideas.
e) An ability to communicate with the academic and scientific community and with society in general as regards their fields of knowledge in the manner and languages that are typical of the international scientific community to which they belong.
f) An ability to foster scientific, technological, social, artistic and cultural progress in academic and professional contexts within a knowledge-based society.

The award of a doctoral degree must equip the graduate for work in a variety of settings, especially those requiring creativity and innovation. Doctoral graduates must have at least acquired the personal skills needed to:

a) Develop in contexts in which there is little specific information.
b) Find the key questions that must be answered to solve a complex problem.
c) Design, create, develop and undertake original, innovative projects in their field.
d) Work as part of a team and independently in an international or multidisciplinary context.
e) Integrate knowledge, deal with complexity and make judgements with limited information.
f) Offer criticism on and intellectually defend solutions.

Finally, with respect to competencies, doctoral students must:
a) have acquired advanced knowledge at the frontier of their discipline and demonstrated, in the context of internationally recognised scientific research, a deep, detailed and well-grounded understanding of theoretical and practical issues and scientific methodology in one or more research fields;
b) have made an original and significant contribution to scientific research in their field of expertise that has been recognised as such by the international scientific community;
c) have demonstrated that they are capable of designing a research project that serves as a framework for carrying out a critical analysis and assessment of imprecise situations, in which they are able to apply their contributions, expertise and working method to synthesise new and complex ideas that yield a deeper knowledge of the research context in which they work;
d) have developed sufficient autonomy to set up, manage and lead innovative research teams and projects and scientific collaborations (both national and international) within their subject area, in multidisciplinary contexts and, where appropriate, with a substantial element of knowledge transfer;
e) have demonstrated that they are able to carry out their research activity in a socially responsible manner and with scientific integrity;
f) have demonstrated, within their specific scientific context, that they are able to make cultural, social or technological advances and promote innovation in all areas within a knowledge-based society;
g) have demonstrated that they are able to participate in scientific discussions at the international level in their field of expertise and disseminate the results of their research activity to audiences of all kinds.

Number of places

30

Duration of studies and dedication regime

Duration
The maximum period of study for full-time doctoral studies is three years, counted from the date of admission to the programme to the date of submission of the doctoral thesis. The academic committee of the doctoral programme may authorise a doctoral candidate to pursue doctoral studies on a part-time basis. In this case, the maximum period of study is five years, counting from the date of admission to the programme to the date of submission of the doctoral thesis. For calculating these periods, the date of admission is considered to be the date of the first enrolment for tutorials, and the date of submission the moment in which the Doctoral School officially deposits the doctoral thesis.

For full-time doctoral candidates, the minimum period of study is two years, counted from the date of an applicant's admission to the programme until the date on which the doctoral thesis is deposited; for part-time doctoral candidates it is four years. When there are justified grounds for doing so, and the thesis supervisor and academic tutor have given their authorisation, doctoral candidates may request that the academic committee of their doctoral programme exempt them from the minimum period of study requirement.

The calculation of periods of study will not include periods of absence due to illness, pregnancy or any other reason provided for in the regulations in force. Students who find themselves in any of these circumstances must notify the academic committee of the doctoral programme, which, where appropriate, must inform the Doctoral School. Doctoral candidates may also temporarily withdraw from the programme for up to one year, and this period may be extended for an additional year. Doctoral candidates who wish to interrupt their studies must submit a justified request to the academic committee of the doctoral programme, which will decide whether or not to approve the request. Each programme will establish conditions for readmission to doctoral studies.

Extension
If full-time doctoral candidates have not applied to deposit their thesis by the end of the three-year period of study, the academic committee of the programme may authorise an extension of up to one year. In exceptional circumstances, a further one-year extension may be granted, subject to the conditions established by the corresponding doctoral programme. In the case of part-time doctoral candidates, an extension of two years may be authorised. In both cases, in exceptional circumstances a further one-year extension may be granted by the Doctoral School's Standing Committee, upon the submission of a reasoned application by the academic committee of the doctoral programme.

Dismissal from the doctoral programme
A doctoral candidate may be dismissed from a doctoral programme for the following reasons:

• The doctoral candidate submitting a justified application to withdraw from the programme.
• The maximum period of study and of extensions thereof ending.
• The doctoral candidate not having enrolled every academic year (unless he or she has been authorised to temporarily withdraw).
• The doctoral candidate failing two consecutive assessments.
• The doctoral candidate having disciplinary proceedings filed against him or her that rule that he or she must be dismissed from the UPC.

Dismissal from the programme implies that doctoral candidates cannot continue studying at the UPC and the closing of their academic record. This notwithstanding, they may apply to the academic committee of the programme for readmission and the committee must reevaluate them in accordance with the criteria established in the regulations.

Organization

• Villafafila Robles, Roberto

• Galceran Arellano, Samuel
• Gomis Bellmunt, Oriol
• Montaña Puig, Joan
• Montesinos Miracle, Daniel
• Villafafila Robles, Roberto

• Department of Electrical Engineering (PROMOTORA)

Doctoral Area, UTGAEIB-ETSEIB. Pavelló I (South Campus)
Tel.: (+34) 934 016 586
E-mail: doctoratb.utgaeib@upc.edu

Agreements with other institutions

The doctoral programme has strong ties with lecturers in electrical engineering at the University of Girona. As the University of Girona does not offer a doctoral programme in Electrical Engineering, the UPC is the closest university at which to take this doctoral degree. This has happened in some cases. There is no specific agreement between the universities.
The doctoral programme also has strong ties with lecturers in electrical engineering at the Rovira i Virgili University (Tarragona). Likewise, as there is no doctoral programme in Electrical Engineering at this university, the UPC is the closest university at which to take the doctoral degree. This has happened in some cases. There is no specific agreement between the universities.
There is collaboration on research projects and teaching activities with Cardiff University, Imperial College London and Leuven University (KUL).
The Centre for Technological Innovation in Static Converters and Drives (CITCEA) research group is in close contact with the Energy Research Institute of Catalonia (IREC).
For many years, the UPC Lightning Research Group has had ties with Horacio Torres’s group at the National University of Colombia, and reciprocal research visits take place.

Access profile

Any student who has completed a master’s degree in engineering (or the 60 corresponding ECTS) has sufficient capacity to undertake a doctoral degree in our programme. However, preference will be given to students whose knowledge is directly related to electrical engineering. Students from other master’s degrees will be considered if they can demonstrate basic knowledge of fundamental electrical subjects such as electrotechnics and electrical machinery. In general, the programme committee and the future tutor will decide whether these students need to take any bridging courses to study on the doctoral programme.

Access requirements

Applicants must hold a Spanish bachelor’s degree or equivalent and a Spanish master’s degree or equivalent, provided they have completed a minimum of 300 ECTS credits on the two degrees (Royal Decree 43/2015, of 2 February)

In addition, the following may apply:

• Holders of an official degree awarded by a university in Spain or any other country in the European Higher Education Area, pursuant to the provisions of Article 16 of Royal Decree 1393/2007, of 29 October, which establishes official university course regulations, who have completed a minimum of 300 ECTS credits on official university degrees, of which at least 60 must be at the master's degree level.
• Holders of an official Spanish bachelor’s degree comprising at least 300 credits, as provided for by EU regulations. Holder of degrees of this kind must complete bridging courses unless the curriculum of the bachelor’s degree in question included research training credits equivalent in value to those which would be earned on a master's degree.
• Holders of an official university qualification who, having passed the entrance examination for specialised medical training, have completed at least two years of a training course leading to an official degree in a health-sciences specialisation.
• Holders of a degree issued under a foreign education system. In these cases, homologation is not required, but the UPC must verify that the degree certifies a level of training equivalent to an official Spanish master's degree and qualifies the holder for admission to doctoral studies in the country where it was issued. Admission on this basis does not imply homologation of the foreign degree or its recognition for any purpose other than admission to doctoral studies.
• Holders of a Spanish doctoral qualification issued under previous university regulations.

Note 1: Doctoral studies entrance regulations for holders of an undergraduate degree awarded before the introduction of the EHEA (CG 47/02 2014)

Note 2: Governing Council Decision 64/2014, which approves the procedure and criteria for assessing the fulfilment of academic admission requirements for doctoral studies by holders of non-homologated foreign degrees (CG 25/03 2014)

Admission criteria and merits assessment

1.a) Students who have taken a master’s degree in engineering that is directly related to the electrical field will have direct access to the programme.
2.a) Students who have taken a master’s degree in engineering that is not related to the electrical field must take bridging courses in subjects in this field. The bridging courses will be defined by the programme committee and the tutors, depending on the student’s previous knowledge and the research area in which they will prepare their thesis.

The following aspects will be considered for admission, as well as the selection criteria and weighting of applicants to prioritise those who meet the access and admission requirements:
• Studies relating to electrical engineering (75%).
• Academic record (20%).
• Research experience and/or language knowledge (5%).

Training complements

Students who have taken a master’s degree in engineering that is not related to the electrical field must take bridging courses in subjects in this field. These will be selected by the academic committee of the doctoral programme and the tutors, depending on the students’ previous knowledge and the research area in which they wish to complete the thesis.

The bridging courses are basic (electrotechnics, electrical machines, etc.) or more specific (advanced electrotechnics; operation and management of electric power systems; the design, simulation and control of electrical machines; calculation, supervision and control of electrical systems; quality of electricity supply, etc.) depending on the applicant’s CV. For these bridging courses, the reference studies will be those of the master’s degree in Energy Engineering (specialisation in Electrical Engineering) at the UPC.

Enrolment period for new doctoral students

The enrolment period for new doctoral students will be in September.

More information at the registration section for new doctoral students

Enrolment period

After the first year, the enrolment period for doctoral students will run from September to mid-October.

More information at the general registration section

Procedure for the preparation and defense of the research plan

Doctoral candidates must submit a research plan, which will be included in their doctoral student activity report, before the end of the first year. The plan may be improved over the course of the doctoral degree. It must be endorsed by the tutor and the supervisor, and it must include the method that is to be followed and the aims of the research.

At least one of these annual assessments will include a public presentation and defence of the research plan and work done before a committee composed of three doctoral degree holders, which will be conducted in the manner determined by each academic committee. The examination committee awards a Pass or Fail mark. A Pass mark is a prerequisite for continuing on the doctoral programme. Doctoral candidates awarded a Fail mark must submit a new research plan for assessment by the academic committee of the doctoral programme within six months.

The committee assesses the research plan every year, in addition to all of the other activities in the doctoral student activity report. Doctoral candidates who are awarded two consecutive Fail marks for the research plan will be obliged to definitely withdraw from the programme.

If they change the subject of their thesis, they must submit a new research plan.

Formation activities

• Activity: Tutorial.
- Hours: 288.
- Type: compulsory.

• Activity: Courses, seminars and workshops.
- Hours: 6.
- Type: optional.

• Activity: Mobility.
- Hours: 480.
- Type: optional.

• Activity: Training in information skills.
- Hours: 1.5.
- Type: optional.

• Activity: Research methodology.
- Hours: 12.
- Type: optional.

• Activity: Innovation and creativity.
- Hours: 8.
- Type: optional.

- Activity: Language and communication skills.
- Hours: 18.
- Type: optional.

• Activity: Assessment based on doctoral student activity report (DAD) and research plan.
- Hours: 4.
- Type: compulsory.

Procedure for assignment of tutor and thesis director

The academic committee of the doctoral programme assigns a thesis supervisor to each doctoral candidate when they are admitted or enrol for the first time, taking account of the thesis supervision commitment referred to in the admission decision.

The thesis supervisor will ensure that training activities carried out by the doctoral candidate are coherent and suitable, and that the topic of the candidate’s doctoral thesis will have an impact and make a novel contribution to knowledge in the relevant field. The thesis supervisor will also guide the doctoral candidate in planning the thesis and, if necessary, tailoring it to any other projects or activities undertaken. The thesis supervisor will generally be a UPC professor or researcher who holds a doctoral degree and has documented research experience. This includes PhD-holding staff at associated schools (as determined by the Governing Council) and UPC-affiliated research institutes (in accordance with corresponding collaboration and affiliation agreements). When thesis supervisors are UPC staff members, they also act as the doctoral candidate’s tutor.

PhD holders who do not meet these criteria (as a result of their contractual relationship or the nature of the institution to which they are attached) must be approved by the UPC Doctoral School's Standing Committee in order to participate in a doctoral programme as researchers with documented research experience.

The academic committee of the doctoral programme may approve the appointment of a PhD-holding expert who is not a UPC staff member as a candidate’s thesis supervisor. In such cases, the prior authorisation of the UPC Doctoral School's Standing Committee is required. A UPC staff member who holds a doctoral degree and has documented research experience must also be proposed to act as a co-supervisor, or as the doctoral candidate’s tutor if one has not been assigned.

A thesis supervisor may step down from this role if there are justified reasons (recognised as valid by the committee) for doing so. If this occurs, the academic committee of the doctoral programme will assign the doctoral candidate a new thesis supervisor.

Provided there are justified reasons for doing so, and after hearing any relevant input from the doctoral candidate, the academic committee of the doctoral programme may assign a new thesis supervisor at any time during the period of doctoral study.

If there are academic reasons for doing so (an interdisciplinary topic, joint or international programmes, etc.) and the academic committee of the programme gives its approval, an additional thesis supervisor may be assigned. Supervisors and co-supervisors have the same responsibilities and academic recognition.

The maximum number of supervisors of a doctoral thesis is two: a supervisor and a co-supervisor.

For theses carried out under a cotutelle agreement or as part of an Industrial Doctorate, if necessary and if the agreement foresees it this maximum number of supervisors may not apply. This notwithstanding, the maximum number of supervisors belonging to the UPC is two.

More information at the PhD theses section

Permanence

The academic committee of the programme may authorise an extension of up to one year for full-time doctoral candidates who have not applied to deposit their thesis by the end of the three-year period of study, in the terms outlined in the Academic Regulations for Doctoral Studies of the Universitat Politècnica de Catalunya. In the case of part-time candidates, an extension of two years may be authorised. In both cases, in exceptional circumstances a further one-year extension may be granted by the Doctoral School's Standing Committee, upon the submission of a reasoned application by the academic committee of the doctoral programme.

A doctoral candidate may be dismissed from a doctoral programme for the following reasons:

• The doctoral candidate submitting a justified application to withdraw from the programme.
• The maximum period of study and of extensions thereof ending.
• The doctoral candidate not having enrolled every academic year (unless he or she has been authorised to temporarily withdraw).
• The doctoral candidate failing two consecutive assessments.
• The doctoral candidate having disciplinary proceedings filed against him or her that rule that he or she must be dismissed from the UPC.

Dismissal from the programme implies that doctoral candidates cannot continue studying at the UPC and the closing of their academic record. This notwithstanding, they may apply to the academic committee of the programme for readmission and the committee must reevaluate them in accordance with the criteria established in the regulations.

International Mention

The doctoral degree certificate may include International Doctorate mention. In this case, the doctoral candidate must meet the following requirements:

a) During the period of study leading to the award of the doctoral degree, the doctoral candidate must have spent at least three months at a respected higher education institution or research centre outside Spain to complete courses or do research work. The stays and activities carried out must be endorsed by the thesis supervisor and authorised by the academic committee of the programme. The candidate must provide a certifying document issued by the person responsible for the research group of the body or bodies where the stay or activity was completed. This information will be added to the doctoral student’s activity report.
b) Part of the thesis (at least the summary and conclusions) must be written and presented in one of the languages commonly used for science communication in the relevant field of knowledge, which must not be an official language of Spain. This rule does not apply to stays and reports in Spanish or to experts from Spanish-speaking countries.
c) At least two PhD-holding experts belonging to a higher education institution or research centre outside Spain must have issued officially certified reports on the thesis.
d) The thesis examination committee must have included at least one PhD-holding expert from a higher education or research institution outside Spain who was not responsible for the candidate’s stay abroad (point a) above).
e) The thesis defence must have taken place on UPC premises or, in the case of joint programmes, at the location specified in the collaboration agreement.

List of authorized thesis for defense

Last update: 06/10/2022 04:45:23.

List of lodged theses

• GARCÍA MUÑOZ, FERNANDO ESTEBAN: Mathematical programming-based models for the distribution networks' decarbonization
  
  Author: GARCÍA MUÑOZ, FERNANDO ESTEBAN
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN ELECTRICAL ENGINEERING
  Department: (DEE)
  Mode: Normal
  Deposit date: 23/09/2022
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: CORCHERO GARCIA, CRISTINA | DÍAZ GONZÁLEZ, FRANCISCO
  Committee:
       PRESIDENT: SPERTINO, FILIPPO
       SECRETARI: VILLAFÁFILA ROBLES, ROBERTO
       VOCAL: MELENDEZ FRIGOLA, JOAQUIM
  Thesis abstract: Climate change is pushing to decarbonize worldwide economies and forcing fossil fuel-based power systems to evolve into power systems based mainly on renewable energies sources (RES). Thus, increasing the energy generated fromrenewables in the energy supply mix involves transversal challenges at operational, market, political and social levels due to the stochasticity associated with these technologies and their capacity to generate energy at a small scale close to the consumption point. In this regard, the power generation uncertainty can be handled through battery storage systems (BSS) that have become competitive over the last few years due to a significant price reduction and are a potential alternative to mitigate the technical network problems associated with the intermittency of the renewables, providing flexibility to store/supply energy when is required. On the other hand, the capacity of low-cost generation from small-scale power systems (distributed or decentralized generation (DG)) represents an opportunity for both customers and the power system operators. i.e., customers can generate their energy, reduce their network dependency, and participate actively in eventual local energy markets (LEM), while the power system operator can reduce the system losses and increase the power system quality against unexpected external failures. Nevertheless, incorporating these structures and operational frameworks into distribution networks (DN) requires developing sophisticated tools to support decision-making related to the optimal integration of the distributed energy resources (DER) and assessing the performance of new DNs with high DERs penetration under different operational scenarios.This thesis addresses the distribution networks' decarbonization challenge by developing novel algorithms and applying different optimization techniques through three subtopics. The first axis addresses the optimal sizing and allocation of DGand BSS into a DN from deterministic and stochastic approaches, considering the technical network limitation, the electric vehicle (EV) presence, the users capacity to modify their load consumption, and the DG capability to generate reactive power for voltage stability. Besides, a novel algorithm is developed to solve the deterministic and stochastic models for multiplescenarios providing an accurate DERs capacity that should be installed to decrease the external network dependency. The second subtopic assesses the DN capacity to face unlikely scenarios like primary grid failure or natural disasters preventing the energy supply through a deterministic model that modifies the unbalance DN topology into multiple virtual microgrids (VM)balanced, considering the power supplied by DG and the flexibility provided by the storage devices (SD) and demand response (DR). The third axis addresses the emerging transactive energy (TE) schemes in DNs with high DERs penetrationat a residential level through two stochastic approaches to model a Peer-to-peer (P2P) energy trading. To this end, the capability of a P2P energy trading scheme to operate on different markets as day-ahead, intraday, flexibility, and ancillaryservices (AS) market is assessed, while an algorithm is developed to manage the users' information under a decentralized design.
  
• GOMEZ ACERO, DANIEL HERNANDO: Dc-dc Converters for HVDC Heterogeneous Interconnections
  
  Author: GOMEZ ACERO, DANIEL HERNANDO
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN ELECTRICAL ENGINEERING
  Department: (DEE)
  Mode: Normal
  Deposit date: 29/09/2022
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: GOMIS BELLMUNT, ORIOL | CHEAH MAÑÉ, MARC
  Committee:
       PRESIDENT: SAAD, HANI
       SECRETARI: PRIETO ARAUJO, EDUARDO
       VOCAL: KISH, GREGORY
  Thesis abstract: High voltage direct current (HVDC) technologies have been used for bulk power transmission over long distances since the 1950s. These technologies have proven to be the most cost-efficient compared to the high voltage alternate current (HVAC) for some applications such as offshore power transmission, connecting remote loads or generation, and the interconnection of non-synchronized grids.In recent years, the study of HVDC grids has been of interest in some research projects but, its development is still uncertain. The de grid can be planned beforehand or it can use the installed lines. But, from the installed HVDC projects, it can be identified different operating voltages, used technologies, and line topologies. There are two HVDC technologies: the line commutated converter (LCC), and the voltage source converter (\/SC). Four different line topologies are identified: asymmetric monopole, symmetric monopole, bipole, and rigid bipole. Developing a de grid interconnecting isolated lines with different characteristics cannot be possible without an intermediary device: the de-de converter.This thesis studies the de-de converters interconnecting HVDC lines with different characteristics. These converters can be seen as the equivalent of ac transformers in de applications because they are capable to adapt the voltage difference between two de systems. These converters are also capable to adapt the line topology and differenttechnologies. The power electronics required for these de-de converters provide increased control flexibility used to supply additional ancillary services that the classical transformers cannot furnish.Three de-de converter topologies are modeled and simulated for the interconnection between a bipole and a symmetric monopole. The front-to-front modular multi-level converter (F2F-MMC) is chosen as the reference because it represents state­ of-the-art technology. The second converter is the de-de MMC (de-MMC) because of the topological similarityto the MMC. Then, a third converter is proposed and studied as a result of this thesis, the asymmetric de-de converter (ADCC). A set of simulations are performed for multiple operating points and faults scenarios. Then, the converters are compared quantitatively and qualitatively. The results and analysis are used to conclude and bring some perspectives for future works.
  
• OESER, DAVID: From the Production of the Single Cell to the End of Life of the Battery Module: The Development of Parameter Variation of Lithium-Ion Cells
  
  Author: OESER, DAVID
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN ELECTRICAL ENGINEERING
  Department: (DEE)
  Mode: Normal
  Deposit date: 28/09/2022
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: MONTESINOS MIRACLE, DANIEL | ACKVA, ANSGAR
  Committee:
       PRESIDENT: ARNDT, BERNHARD
       SECRETARI: DÍAZ GONZÁLEZ, FRANCISCO
       VOCAL: BOHN, GUNTHER
  Thesis abstract: In lithium-ion batteries, depending on the requirements, many individual cells are connected in series and parallel. Despite very similar individual cell parameters after production, they can develop differently during the subsequent ageing process due to intrinsic and extrinsic influences. A pronounced parameter variation of the assembled cells ultimately leads to a reduced utilisation of the lithium-ion battery and thus also to a reduced lifetime. The aim of this work is therefore to gain a better understanding of the origin and development of parameter variation during the ageing process. The work is divided into three major parts.At the beginning, parameters such as capacity and internal resistance of 480 brand-new cells of one production batch are recorded. The obtained values allow the calculation of the production-related parameter variation of the cells. In order to investigate the development of the parameter variation during cell ageing, numerous ageing tests are carried out in this work. These are divided into single cell tests and module tests. With the help of single cell ageing tests, the development of the parameter variation of unconnected cells is investigated. Here, several cells are combined into groups and aged under identical conditions. In order to show the influence of different operating conditions on the parameter variation during single cell ageing, the cell groups are aged at different temperatures and different load currents. Finally, by ageing various self-built modules, the development of the parameter variation of cells connected in series and in parallel is investigated. By varying the load current and the number of cells connected in parallel, further dependencies are investigated.The measured data show that both the load on the cells and the ambient temperature have a decisive influence on the development of parameter variation. Operating conditions near the lithium plating boundary are particularly problematic. Since the onset of lithium plating varies slightly between the ageing cells, there are extreme differences in the ageing rate over a certain period of time. This ultimately leads to large parameter variations in the tests carried out. The cells used in this work are cylindrical cells in 18650 format with a nominal capacity of 2.6 Ah (Samsung ICR18650-26J). The high-energy cells consist of a NMC cathode and a graphite anode.
  
• ROMERO DURAN, DAVID: Comportamiento eléctrico de los compuestos de carbono (CFRP). Implicaciones para el modelado y fabricación de palas de aerogenerador con elementos estructurales que incorporan compuestos de CFRP
  
  Author: ROMERO DURAN, DAVID
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN ELECTRICAL ENGINEERING
  Department: (DEE)
  Mode: Normal
  Deposit date: 23/09/2022
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: MONTAÑA PUIG, JUAN | VAN DER VELDE, OSCAR ARNOUD
  Committee:
       PRESIDENT: MARCH NOMEN, VICTOR
       SECRETARI: BOSCH TOUS, RICARDO
       VOCAL: HERMOSO ALAMEDA, BLAS
  Thesis abstract: Carbon fiber reinforced composites (CFRP) have been introduced in a very significant way in all areas of industry and the wind energy sector has been no exception. Due to the size of today's wind turbines and the operating environment in which they are usually found, this sector is facing a major challenge: protecting these structures against atmospheric discharges. Wind turbine blades (WTB) are the most exposed elements to these phenomena and, given the current dimensions and the expected further growth, it is increasingly common for them to incorporate CFRP composite materials. The electrical behavior of these materials and how to integrate them into the lightning protection system (LPS) still have many issues to be resolved.This thesis presents an extensive experimental study through which we wish to provide knowledge in this direction, in order to better understand the behavior of this type of materials both for their subsequent modeling and for their integration in the LPS of a WTB. Thus, in the central chapters (Chapters 4 and 5) of this thesis, a large number of tests and very detailed procedures will be shown, which will allow, later on, to be reproduced and compared.The first part of the experimentation is oriented towards the determination and characterization of the material, given its anisotropic behavior. All the tests and results shown here allow to know the difficulties in the characterization of this type of materials from the electrical point of view and a procedure is proposed which, given the results obtained, is understood to allow to reach a better quality information. At the same time, given the dependence that all these tests show on the electrical connections with this type of materials, a detailed study on the effect of the connections is also carried out.The second experimental part of this work is oriented towards the study of surface connections on composite materials in order to bond them and integrate them with the LPS. In this case, the dependence of the size of the specimens and the type of current injected are taken into account, since not only direct current is used, but also lightning current pulses are injected. In this way, more comprehensive conclusions can be drawn about the behavior of this type of connections with CFRP composite materials.This document is completed with an introduction and motivation for the development of the thesis (Chapter 1), followed by a detailed review of the structure of WTBs, the composite materials used for their fabrication, a review of the protection standard and modeling techniques (Chapter 2). Chapter 3 is devoted to a review of the materials used, the techniques applied to prepare the material for testing and the measurement methods used to obtain the material characteristics.After all the experimental study and its analysis, some contributions and works carried out in relation to this thesis are shown (Chapter 6) and the document ends with the conclusions and proposals for future works (Chapter 7).
  
• URBANI, MICHELE: Development of a VHF broadband interferometer to investigate unsolved lightning phenomena: high-energy radiation from lightning strikes and multi-stroke positive cloud-to-ground flashes
  
  Author: URBANI, MICHELE
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN ELECTRICAL ENGINEERING
  Department: (DEE)
  Mode: Article-based thesis
  Deposit date: 27/09/2022
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: MONTAÑA PUIG, JUAN | VAN DER VELDE, OSCAR ARNOUD
  Committee:
       PRESIDENT: SOULA, SERGE
       SECRETARI: PINEDA RÜEGG, NICOLAU
       VOCAL: MARISALDI, MARTINO
  Thesis abstract: The aim of this thesis work is the development of a VHF broadband interferometer for lightning research. The observations with this instrument allowed us to investigate some unsolved aspects of lightning related with the high-energy emissions from lightning strikes and the occurrence of multi-stroke positive cloud-to-ground flashes sharing the same channel to ground.This Ph.D. project is contextualized in the European program: Science and Innovation with thunderstorms (SAINT), funded by the Horizon 2020 / Marie Sklodowska Curie Action, grant agreement ID: 722337.A VHF broadband interferometer is an instrument capable of mapping lightning flashes with extremely high temporal resolution. This feature, combined with the omnidirectional field of view and the ability to map lightning within the cloud, makes this instrument really promising for scientific lightning research. Its use is enriched and enhanced by the installation of other detectors or measuring instruments. In this way, it is possible to simultaneously observe with several instruments the same lightning flash and obtain complementary information needed to advance in the understanding of the physical phenomena. The main technical challenge of this work was to build our own version of a broadband VHF digital interferometer. This kind of instrument is still a prototype, off the market, and although some books and scientific papers describe how it works, its hardware and software implementation requires a lot of work and refinements to achieve the high performance required by the scientific research.Once the instrument was built and validated, field campaigns were carried out in Spain, Colombia and Italy. Observations made with our VHF broadband interferometer in coincidence with other instruments such as the high-energy detectors, electric field antenna, and Lightning Mapping Array (LMA) have made it possible to make some progress in understanding some unsolved aspects of lightning physics.The results of our research have been published mainly in the two scientific articles that constitute this Ph.D. thesis.The first article of this compendium presents measurements in coincidence of high-energy radiation with the lightning mapping provided by the VHF broadband interferometer. During a field campaign in north-central Colombia, several intense X-ray bursts were detected from negative stepped leaders and dart leaders. A strong temporal correlation has been observed between the high-energy emissions and the most intense VHF pulses, which suggests the runaway electrons as a shared mechanism. We observed multiple high-energy sources belonging to different leader branches and we speculate that the high-energy emissions could occur more often than expected. We speculated a few possible implications for TGFs.The second article presents the first observation of a multi-stroke positive cloud-to-ground lightning flash sharing the same channel to ground mapped with a VHF broadband interferometer and a Lightning Mapping Array.We propose a mechanism to describe this rare phenomenon and we identify in a fast recoil leader or a fast breakdown a crucial role in reconnecting these previously decayed leader channels and initiating the subsequent positive stroke. We investigated the polarity asymmetry of subsequent strokes.
  
• ZIEGLER, ANDREAS: Possibilities and Limitations of Active Battery Management Systems for Lithium-Ion Batteries
  
  Author: ZIEGLER, ANDREAS
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN ELECTRICAL ENGINEERING
  Department: (DEE)
  Mode: Normal
  Deposit date: 23/09/2022
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: MONTESINOS MIRACLE, DANIEL | ACKVA, ANSGAR
  Committee:
       PRESIDENT: ARNDT, BERNHARD
       SECRETARI: DÍAZ GONZÁLEZ, FRANCISCO
       VOCAL: BOHN, GUNTHER
  Thesis abstract: Lithium-Ion Batteries (LIBs) are being used in more and more areas of application. At the same time, their chemical composition and their designs are constantly evolving. Major developments are also taking place in the field of Battery Management Systems (BMSs), which are essential for the safe operation of LIBs. The focus is on intelligent charge redistribution between individual cells, called Active Balancing (AB). This thesis deals with the possibilities and limitations of AB. An empirical long-term experiment provides new insights into the ageing behaviour of batteries that are actively balanced during their entire service life.The main objective of this work is to to demonstrate influences on the ageing behaviour of batteries that are still unknown at present. A literature study shows that previous work in this area is often based on theoretical approaches and rarely has a functional proof through measurement results. Most significant statements from literature are examined. These include the increase in discharge capacity, energy efficiency and service life associated with AB, as well as lower parameter variation of the individual cells installed in the battery.Before starting the empirical experiment, the current state of the art is captured and a universal AB topology is selected from a large number of known systems. The operating behaviour as well as the balancing algorithms are explained in detail in order to be able to understand the influences occurring during the ageing of the batteries. The ageing experiment itself is a comparison test between commercial Passive Balancing (PB) and the novel AB. Two identical battery packs are aged under uniform conditions, but with the two different BMSs mentioned above. At the end of the ageing process, the battery packs are disassembled and the parameters of all individual cells are determined for further investigation.The main contribution of this work is the proof of effects through AB, especially with large battery loads. Both the increase in discharge capacity and the service life are demonstrated. The work shows how parameter variation of individual cells can be made visible during operation. It also presents diagnosis and calculation methods. The energetic efficiency of the batteries cannot be increased, since the self-consumption of the power electronics of the AB system is always higher than with PB. However, the overall efficiency of the battery increases due to an increase in capacity and an extension of the service life. The thesis also shows that with lower battery loads, the use of AB is not beneficial any more or may lead to negative effects. In such applications conventional PB is sufficient. The results obtained during pack ageing are additionally substantiated and extended by the measurement results of the individual cells.At the end of the thesis, all results and contributions are summarised. Suggestions for optimisation as well as further research ideas are presented as a possible starting point for further scientific studies.
  

Last update: 06/10/2022 04:30:28.

List of defended theses by year

• ABDALI NEJAD, SAJAD: Enhance OF SOGI-FLL and SOGI-PLL response to voltage sags and swells perturbations
  
  Author: ABDALI NEJAD, SAJAD
  Thesis link: http://hdl.handle.net/10803/675078
  Programme: DOCTORAL DEGREE IN ELECTRICAL ENGINEERING
  Department: (DEE)
  Mode: Normal
  Reading date: 19/07/2022
  Thesis director: MATAS ALCALA, JOSE | DE LA HOZ CASAS, JORGE
  

  Committee:
       PRESIDENT: GOLESTAN, SAEED
       SECRETARI: FILLET CASTELLA, SERGI
       VOCAL: SHAHPARASTI, MAHDI
  Thesis abstract: The scope of this thesis is related to the enhancement of the operation of distributed generators (DGs) based on renewable energies (REs) when connected to the conventional grid network. Synchronization of those DGs, i.e. their front-end inverters, with the grid is critical for injecting power into the grid. Internal control loops of voltage source inverters (VSIs) monitor parameters such as the utility voltage's phase, amplitude, and frequency to achieve proper synchronization and inject power into the grid. Therefore, an appropriate estimation of the grid parameters is needed for completing the mentioned goals. The different existing monitoring techniques still face technical challenges when appearing faults on the grid, particularly voltage sags and voltage swells. From those techniques, SOGI-FLL and SOGI-PLL are widely spread in power inverters. In the mentioned faulty conditions, a degradation of the estimated parameters occurs due to the impact of the grid defaults on the dynamic performance of the SOGI-FLL and SOGI-PLL estimators. In the literature, it was not found contributions to those problems. This research aimed to contribute by providing a fast and accurate detection of the faults, yielding a robust dynamical response of the VSIs control structure in front of such perturbations, thanks to a fast and precise estimation of grid parameters. This faults detection strategy was accompanied by minimization of the monitored parameters drift due to inherent harmonic pollution of the faults. Then a first contribution has been the design and implementation of a Finite State Machine on a synchronization structure known as SOGI-PLL and in SOGI-FLL, enhancing their dynamical response regarding transient time and steady-state response in front of voltage sags. A second contribution has been implementing the strategy to face the problems derived from voltage swells with satisfactory results. The research was carried out in the E3PACS laboratory facilities of EEBE-UPC. This work is organized as follows: In Section 1, the study is contextualized. Section 2 describes Power Quality indexes benchmarking for assessing the problem to solve and the obtained results. It is then followed by Section 3, where the SOGI-FLL response against voltage sags and swells is analyzed. Therefore, Section 4 summarizes the different approaches and results for mitigating the grid faults studied. Section 5 is devoted to showing SOGI-PLL amelioration by applying SOGI Error-Based algorithm. Finally, Section 6 summarizes the main contributions of this work, along with the general conclusions. Section 7 lists future work, in Section 8 are listed the published JCR indexed papers.
  

• BAKKAR, MOSTAFA AHMED AHMED MAHMOUD AHMED: Sag effects on protection system in distributed generation grids
  
  Author: BAKKAR, MOSTAFA AHMED AHMED MAHMOUD AHMED
  Thesis link: http://hdl.handle.net/10803/673721
  Programme: DOCTORAL DEGREE IN ELECTRICAL ENGINEERING
  Department: (DEE)
  Mode: Normal
  Reading date: 07/02/2022
  Thesis director: BOGARRA RODRIGUEZ, SANTIAGO | CORCOLES LOPEZ, FELIPE
  

  Committee:
       PRESIDENT: GUERRERO ZAPATA, JOSEP MARIA
       SECRETARI: SAINZ SAPERA, LUIS
       VOCAL: BOLZONI, ALBERTO
  Thesis abstract: Distributed Generators (DGs) are sensible to voltage sags, so the protection devices must trip fast to disconnect the faulted part of the grid. The DG disconnection will not be desirable in the near future with a large penetration, so it will be necessary to lay down new requirements that should be based on avoiding unnecessary disconnections. Therefore, to prevent unnecessary tripping when inverter-based DGs are connected to the Medium Voltage (MV) grid, reliable and effective protection strategies need to be developed, considering the limited short-circuit current contribution of DG.The initial goal of this study is to employ different possible control strategies for a grid-connected inverter according to the Spanish grid code and to analyze the output voltage behavior during symmetrical and unsymmetrical voltage sags. The analytical development of the proposed strategies shows the impacts of the sag on currents, voltages, active and reactive powers.Another goal of this research is to propose a protection strategy based on Artificial Intelligence for a radial or ring distribution system with high DG penetration. The protection strategy is based on three different algorithms to develop a more secure, redundant, and reliable protection system to ensure supply continuity during disturbances in ring and radial grids without compromising system stability. In order to classify, locate and distinguish between permanent or transient faults, new protection algorithms based on artificial intelligence are proposed in this research, allowing network availability improvement disconnecting only the faulted part of the system. This research introduces the innovative use of directional relay based on a communication system and Artificial Neural Network (ANN). The first algorithm, Centralize algorithm (CE), collects the data from all the PDs in the grid in the centralized controller. This algorithm detects the power flow direction and calculates the positive-sequence current of all the PDs in the grid. Significant benefits of this system are that it consolidates the entire systems security into a single device, which can facilitate system security control. However, the CE will not pinpoint the exact location of the fault if there is any loss of information due to poor communication. Therefore, the systems redundancy can be improved by cooperating with a second algorithm, the Zone algorithm (ZO). ZO algorithm is based on zone control using peer-to-peer connectivity in the same line. The faulty line in that zone may be identified by combining the two PDs data on the same line. The most relevant advantage of this algorithm is its flexibility to adapt to any grid modification or disturbance, even if they are just temporary, unlike the CE, which is fixed to the existing grid configuration. The third protection algorithm, Local algorithm (LO), has been proposed without depending on the communication between the PDs; then, the protection system can work properly in case of a total loss of communication. Each PD should be able to detect if the fault is located in the protected line or another line by using only the local information of the PD. According to the type of fault and based on local measurements at each PD of abc voltages and currents, different algorithms will be applied depending on the calculation of the sequence components. The main advantage of this algorithm is the separate decision of each PD, and avoiding communication problems.In case of radial grids, both mechanical breakers and Solid State Relays (SSRs) are used to verify the protection strategies, and in the case of ring grids, mechanical breakers are used, due to the limitations in required voltage difference of SSR.The proposed protection algorithms are compared with conventional protections (Overcurrent and Differential) protections to validate the contribution of the proposed algorithms, especially in reconfigurable smart grids.
  

• CANDELO ZULUAGA, CARLOS ANDRES: DESIGN OPTIMIZATION AND PERFORMANCE ANALYSIS METHODOLOGY FOR PMSMS TO IMPROVE EFFICIENCY IN HYDRAULIC APPLICATIONS
  
  Author: CANDELO ZULUAGA, CARLOS ANDRES
  Thesis link: http://hdl.handle.net/10803/673521
  Programme: DOCTORAL DEGREE IN ELECTRICAL ENGINEERING
  Department: (DEE)
  Mode: Normal
  Reading date: 11/01/2022
  Thesis director: RIBA RUIZ, JORDI ROGER | GARCIA ESPINOSA, ANTONIO
  

  Committee:
       PRESIDENT: PEREIRA FERNANDES, JOÃO FILIPE
       SECRETARI: BOGARRA RODRIGUEZ, SANTIAGO
       VOCAL: URRESTY BETANCOURT, JULIO CÉSAR
  Thesis abstract: In the recent years, water pumping and other hydraulic applications are increasingly demanding motors capable to operate under different working conditions, including variable pressure and volumetric flow demands. Moreover, the technicalevolution trend of pumping components is to minimize the size, offering compact and adaptable hydraulic units. Hence, the need to optimize the electric motor part to reduce the volume according this trend, maximizing the efficiency, decreasingmaterial and fabrication costs, reducing noise and improving thermal dissipation have originated the research field of this project.So far different methodologies have been focused on designing electrical machines considering few aspects, such as the rated conditions with some size limitations. In addition, the optimization strategies have been based on single operationconditions, improving multiple aspects but not considering the overall performance of the machine and its influence with the working system.This research changes the design and optimization paradigm, focusing on defining beforehand the desired performance of the electrical machine in relation with the application system. The customization is not limited to an operating point but to the whole performance space, which in this case is the torque-speed area. Thus, the designer has plenty of freedom to study the system, and define the desired motor performance establishing the size, thermal and mechanical limitations from the beginning of the process.Moreover, when designing and optimizing electrical machines, the experimental validation is of major importance. From an industrial scope so far, the testing methodologies are focused on evaluating point by point the electrical machine performance, being a robust and trustable way to measure and validate the electrical machine characteristics. Nevertheless,this method requires a large time to prepare the experimental setup and to evaluate the whole motor performance. For this reason, there is a special interest on improving parameter estimation and performance evaluation techniques for electrical machines to reduce evaluation time, setup complexity and increase the number of physical magnitudes to measure in order to have deeper information. This research also develops methodologies to extend the electrical machine experimental validation providing information to evaluate the motor performance.This doctoral thesis has been developed with a collaboration agreement between UPC and the company MIDTAL TALENTOS S.L. The thesis is included within the Industrial Doctorates program 2018 DI 019 promoted by the Generalitat de Catalunya.
  

• LLEDÓ PONSATI, TOMÀS: Modular platform for research in microgrids
  
  Author: LLEDÓ PONSATI, TOMÀS
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN ELECTRICAL ENGINEERING
  Department: (DEE)
  Mode: Normal
  Reading date: 15/07/2022
  Thesis director: MONTESINOS MIRACLE, DANIEL | GALCERAN ARELLANO, SAMUEL
  

  Committee:
       PRESIDENT: ACKVA, ANSGAR
       SECRETARI: SUMPER, ANDREAS
       VOCAL: DIETZ, ARMIN
  Thesis abstract: The present Ph.D. thesis has been developed following an Industrial Ph.D. program and verses on developing a commercial piece of equipment for teknoCEA, a spin-off company from CITCEA-UPC. The thesis is centered on developing power electronics-based emulation systems for research in microgrids. Lately, the use of power electronics-based emulation systems is drawing substantial attention in the field of microgrids because their characteristics substantially facilitate research in laboratory facilities.First, the suitability of different topologies for implementing an emulation platform is analyzed. The focus is set on the topologies adjustability to implement various types of emulation systems. The analysis determines the most appropriate number of legs for the platform. A comparative analysis is done between two-level and multi-level topologies to determine their suitability based on different aspects. Moreover, the analysis confirms the usefulness of wide-bandgap semiconductors for this type of application.Next, a control structure is proposed together with its implementation in a low-cost microcontroller based on a modular software architecture. The control strategy based on fractional proportional resonant controllers for AC emulation systems provides a control system with high control bandwidth while keeping a low computational cost. The control strategy for DC emulation systems is provided to reach a fast transient response and immunity to external disturbances, which is key for good emulation of electric systems.The modular software architecture provides a software framework easily adjustable to the needs of multiple emulation systems. That allows the implementation of the multiple control strategies with minimum changes. Additionally provides a graphical representation of the software architecture from a static and dynamic point of view.Last, the reliability of the proposed platform is assessed based on the reliability curves provided in the literature. The reliability analysis is centered on the semiconductors and capacitors. It provides evidence that emulation systems typical currents and voltages clearly affect their reliability. For the capacitors reliability assessment, a thermal modeling methodology is proposed to overcome the limitations of standard approximations. The methodology is based on anisotropic modeling of the capacitor winding. Finally, the reliability analysis establishes the guidelines to assess the platform reliability if a given mission profile is provided.
  

• MARTÍNEZ REYES, JIMMY ARTURO: Remaining useful life and fault detection models for high voltage electrical connectors focused on predictive maintenance
  
  Author: MARTÍNEZ REYES, JIMMY ARTURO
  Thesis link: http://hdl.handle.net/10803/675002
  Programme: DOCTORAL DEGREE IN ELECTRICAL ENGINEERING
  Department: (DEE)
  Mode: Normal
  Reading date: 08/07/2022
  Thesis director: RIBA RUIZ, JORDI ROGER | MORENO EGUILAZ, JUAN MANUEL
  

  Committee:
       PRESIDENT: ESTEVE PUJOL, JOAN
       SECRETARI: BOGARRA RODRIGUEZ, SANTIAGO
       VOCAL: CAPELLI, FRANCESCA
  Thesis abstract: In recent years, industries have chosen to invest in technology with the aim of making their processes more efficient and thus offering market products of higher quality. Nowadays it is very common for companies to use special systems to predict failures and avoid unexpected delays, reduction of costs, etc. SBI Connectors, along with the Universitat Politècnica de Catalunya, have beencollaborating to develop research projects for more than 10 years. As a result of the collaboration with the university, patents and international publications have been generated, which have helped to situate and reinforce SBI Connectors leadership in the international market while offering an image of scientific-technical credibility. This research is carried out, with the collaboration of SBI connectors and Universitat Politècnica de Catalunya, in order to develop the Smartconnector project (within the Retos de Colaboración Spanish research frame). The thesis proposed by the author is dedicated to develop and validate RUL (Remaining Useful Life) and fault detection approaches for electrical substation connectors. The RUL approach proposed in this work is basedon a simple and accurate model of the degradation with time of the electrical resistance of the connector (main health indicator),which has two parameters, whose values are identified from on-line acquired data. Next, the fault detection chapter is divided into two parts. The first part presents an on-line condition monitoring method to predict early failures in power connectors from on-line acquired data in conjunction with another parametric degradation model of the resistance of the connector, whose parameters are identified by means of the Markov chain Monte Carlo stochastic method. The second part presents, analyzes and compares theperformance of three simple and effective methods for online determination of the State of Health (SoH) of power connectors with low computational requirements. The proposed approaches are based on monitoring the evolution of the connectors¿ electrical resistance, which determines the degradation trajectory. Furthermore, this work includes an in-depth study of the temperaturedependence of the electrical contact resistance (ECR). To analyze and validate results presented in this work, data is acquired in real time, including main parameters such as the electrical current and voltage drop across the terminals of the connector,conductor and connector temperature, thus estimating the phase shift between voltage drop and electrical current waveforms and the contact resistance by means of accelerated aging tests (ADT).
  

• ROJAS DUEÑAS, GABRIEL ESTEBAN: MODELING AND IDENTIFICATION OF POWER ELECTRONIC CONVERTERS
  
  Author: ROJAS DUEÑAS, GABRIEL ESTEBAN
  Thesis link: http://hdl.handle.net/10803/673581
  Programme: DOCTORAL DEGREE IN ELECTRICAL ENGINEERING
  Department: (DEE)
  Mode: Normal
  Reading date: 11/01/2022
  Thesis director: RIBA RUIZ, JORDI ROGER | MORENO EGUILAZ, JUAN MANUEL
  

  Committee:
       PRESIDENT: DA COSTA BRANCO, PAULO JOSÉ
       SECRETARI: GARCIA ESPINOSA, ANTONIO
       VOCAL: VALDERRAMA BLAVI, HUGO
  Thesis abstract: Nowadays, many industries are moving towards more electrical systems and components. This is done with the purpose of enhancing the efficiency of their systems while being environmentally friendlier and sustainable. Therefore, the development of power electronic systems is one of the most important points of this transition. Many manufacturers have improved their equipment and processes in order to satisfy the new necessities of the industries (aircraft, automotive, aerospace, telecommunication, etc.). For the particular case of the More Electric Aircraft (MEA), there are several power converters, inverters and filters that are usually acquired from different manufacturers. These are switched mode power converters that feed multiple loads, being a critical element in the transmission systems. In some cases, these manufacturers do not provide the sufficient information regarding the functionality of the devices such as DC/DC power converters, rectifiers, inverters or filters. Consequently, there is the need to model and identify the performance of these components to allow the aforementioned industries to develop models for the design stage, for predictive maintenance, for detecting possible failures modes, and to have a better control over the electrical system.Thus, the main objective of this thesis is to develop models that are able to describe the behavior of power electronic converters, whose parameters and/or topology are unknown. The algorithms must be replicable and they should work in other types of converters that are used in the power electronics field. The thesis is divided in two main cores, which are the parameter identification for white-box models and the black-box modeling of power electronics devices. The proposed approaches are based on optimization algorithms and deep learning techniques that use non-intrusive measurements to obtain a set of parameters or generate a model, respectively. In both cases, the algorithms are trained and tested using real data gathered from converters used in aircrafts and electric vehicles. This thesis also presents how the proposed methodologies can be applied to more complex power systems and for prognostics tasks. Concluding, this thesis aims to provide algorithms that allow industries to obtain realistic and accurate models of the components that they are using in their electrical systems.
  

• SAURA PERISÉ, JAIME: Contribucions a l'estudi de rectificadors no controlats m-fàsics en condicions no equilibrades per unitats TRUs o ATRUs multi polsos
  
  Author: SAURA PERISÉ, JAIME
  Thesis link: http://hdl.handle.net/10803/674647
  Programme: DOCTORAL DEGREE IN ELECTRICAL ENGINEERING
  Department: (DEE)
  Mode: Normal
  Reading date: 22/06/2022
  Thesis director: BOGARRA RODRIGUEZ, SANTIAGO
  

  Committee:
       PRESIDENT: GUASCH PESQUER, LUIS
       SECRETARI: MONJO MUR, LLUÍS
       VOCAL: HERRAIZ JARAMILLO, SERGIO
  Thesis abstract: This doctoral thesis has been developed to provide a new point of view and a new approach to the analysis and study of uncontrolled bridge rectifiers. The methodology developed has been generalized to extend the study to an m-phase system, applicable for both balanced and unbalanced systems.It is possible to quickly obtain an analytical formulation to calculate the average voltage for balanced systems. However, there are multiple formulations for unbalanced systems, and, in general, it is not easy to be applied. For this reason, an easy-to-apply formulation has been determined to calculate the average voltage, using the perimeter of the convex polygon defined by the ends of the phase voltages of the power supplies. As the convexity condition is necessary for its application, it has been determined that this approach is related to one of the formulas proposed by Cauchy. This formula determines the average width of a convex body, which has made it possible to relate the average width to the average voltage and the convex body to the convex polygon defined by the maximum stresses.The relationship with vision systems also has been observed. The projections and average widths in a rotation are used, for example, to determine the section of bones, veins, and muscles, which is the basis of the Computed Tomography (CT) scan. It is important to highlight the close relationship between the Couchy formula and the application to the CT scan.However, the proposed method has some differences from Cauchy's. While the Cauchy formulation applies to a body that must be derivable at all points, the proposed formulation applies to a convex polygon with no equal derivative at the vertices since the derivatives are different from the right than from the left vertex. This new method, called the Phasorial Convex Hull Method, has been published in the article "Average value of DC-link output voltage in multi-phase uncontrolled bridge rectifiers under supply voltage balance and unbalance conditions".In the demonstration of the developed method, it has been observed that the instantaneous voltage is obtained before calculating the average voltage of the DC bus. Therefore, the voltage signature at the rectifier's output allows detailed studies of behavior in the voltage sag, unbalance operation, faults, etc. This new methodology for obtaining instantaneous voltage has been titled "Shadow Projection", presented in the article "New Methodology to Calculate DC Voltage Signature in N-Phases TRUs Under Supply Voltage Sags". Because rectifiers are usually coupled to Transformers or Autotransformers, the Thesis was believed to be linked to Transformer Rectifier Units (TRUs) and Auto-Transformer Rectifier Units (ATRUs) and a patent study has been done to see how the industry has evolved, studying some configurations. Formulations have been proposed for solutions for series, parallel and / or coupling connections.The joint study of the rectifying units with the Transformer or the Autotransformer opens the study to determine the line currents on the AC side. Therefore, if the study of voltages goes from AC sources to DC load, the study of currents goes from DC side to AC side. Solutions have been proposed for the study of 12-pulse rectifiers in three-winding TRUs, and for Delta-polygonal ATRUs. This study, yet to be published, allows obtaining simple equivalent circuits for complex systems.The effect on DC voltage when there are fused diodes producing a lack of open circuit has also been studied, the proposed method allows to determine the diode or diodes that are missing and need to be replaced. In this case, the article entitled ¿Open-Circuit fault diagnosis and maintenance in multi-pulse parallel and series TRU topologies¿ has been published. The method is based on signing the DC voltage at the output of the rectifier, starting the period according to the hourly index of the transformer for 12-18 pulses.
  

• SOUSA ARCANJO, MARCELO AUGUSTO: Corona discharges from grounded rods and 337/777 nm emissions of laboratory long sparks
  
  Author: SOUSA ARCANJO, MARCELO AUGUSTO
  Thesis link: http://hdl.handle.net/10803/673993
  Programme: DOCTORAL DEGREE IN ELECTRICAL ENGINEERING
  Department: (DEE)
  Mode: Article-based thesis
  Reading date: 04/03/2022
  Thesis director: MONTAÑA PUIG, JUAN
  

  Committee:
       PRESIDENT: REGLERO VELASCO, VICTOR
       SECRETARI: SOULA, SERGE
       VOCAL: CHANRION, OLIVIER
  Thesis abstract: This thesis presents an investigation on the signatures of corona discharges from grounded rods under thunderstorms and in the laboratory, with optical detections in the 337/777 nm wavelengths for high voltage sparks. This PhD project is contextualized in the European program: Science and Innovation with thunderstorms (SAINT), funded by the Horizon 2020 / Marie Sklodowska Curie Action (Grant agreement ID: 722337).Under conditions of electrification, charged clouds produce an enhancement of the electric field at the ground level. That, in turn, can lead to corona discharges that produce a space charge layer in the vicinity of grounded structures. The study of thisphenomenon is useful for the understanding of lightning-related processes and attachment. In addition to the electrical current obtained from the discharges, another important variable is the optical signature generated by the plasma channels. Emissions in many spectra lines associated with reactions of streamers and leaders with the main components of the atmosphere are relevant for visual observations.This work presents a chapter for current literature review of the processes associated with lightning and the main concepts applied. Then, a detailed description of the instrumentation available for the tests carried out in the laboratory and in the field isprovided.The first article of this compendium presents data obtained with experiments of a grounded rod under high background electric field in the laboratory and the field. A limited number of works in the literature have presented such data. An analysis correlating pulse frequency, electric field level and average wind speed is the main novelty of the article. A congress paper annexed in the thesis complements the findings comparing the discharges observed at two other experimental sites.The second article describes a compilation of results obtained in the laboratory for investigating optical signatures in two specific lines of the spectra (337 nm and 777 nm), the ones with stronger emissions in lightning-like events. There is special relevance of such experiments for supporting satellite-based observations of lightning by the Atmosphere-Space Interactions Monitor (ASIM) that perform optical measurements in the same wavelength ranges and the operational lightning imagers such as GeostationaryLightning Mapper (GLM) and the future Meteosat Third Generation Lightning Imager (MTG-LI).The conclusions are presented, together with the prospects for future work following the original results achieved with this PhD.This thesis ends with a detailed description of the dissemination activities (presentation at seminars and conferences, coauthored publications in journals and at conferences) and training activities received throughout this project.Finally, the appendix present additional developments and applications of the sensor developed during this doctorate, comprisingexperiments performed during a two-month internship at the Eindhoven University of Technology (TU/e), and one section withresults for the use of photometers to determine the initiation of an upward leader. Such experiments are particularly interesting for understanding space charge production and in the validation of lightning rods. The concepts applied to the development of acorona discharge current sensor were patented together with Dena Desarrollos, the company where the investigations were carried out during this doctorate.
  

• WESTERMAN SPIER, DANIEL: Optimal operation and design of modular multilevel converter for HVDC applications
  
  Author: WESTERMAN SPIER, DANIEL
  Thesis link: http://hdl.handle.net/10803/674747
  Programme: DOCTORAL DEGREE IN ELECTRICAL ENGINEERING
  Department: (DEE)
  Mode: Normal
  Reading date: 30/06/2022
  Thesis director: GOMIS BELLMUNT, ORIOL | PRIETO ARAUJO, EDUARDO
  

  Committee:
       PRESIDENT: TEDESCHI, ELISABETTA
       SECRETARI: CEBALLOS RECIO, SALVADOR
       VOCAL: TEIXEIRA PINTO, RODRIGO
  Thesis abstract: Modular Multilevel Converters (MMCs) are a type of Voltage Source Converter (VSC) which have become the preferred topology choice for High Voltage Direct Current (HVDC) applications. Compare to its HVDC converter predecessors, such as the Line Commutated Converter (LCC), the MMC can control active and reactive power independently, requires smaller filter reactors and have blackstart capabilities. Regarding classical two- and three-level VSCs, the MMC has improved efficiency, easier scalability to higher voltage levels and better AC output voltage harmonic content. However, they need more complex regulation strategy due to its increased number of degrees of freedom (DOFs). Nevertheless, when these DOFs are fully exploited, the MMC can provide better responses than classical converters, especially during unbalanced network conditions. First, an in-depth steady-state mathematical analysis of the converter is performed to identify all its DOFs. Based on the DOFs and the currents imposed by them, the equations for the power transfer between the DC/AC networks and internally, between the upper and lower arms and among the phase-legs, are obtained. The resultant expressions indicate potential interactions between distinct DOFs. By taking advantage of those interactions, it is possible to improve existing circulating current reference calculation methods. Thus, enhancing the MMC response under balanced and unbalanced AC network conditions. The performance of the MMC can be further improved when optimization algorithms are used to calculate its references, in which this thesis proposed two different methods. In the initial proposal, an optimization-based current reference calculation in the natural $abc$ reference frame is presented. It considers the Transmission System Operator (TSO) requirements during AC network voltage sags in the form of active/reactive current set-points to provide Fault Ride Through (FRT) capability and the converter limitations. However, due its highly nonlinear characteristics it presents a high computation burden not allowing it to be solved in real-time applications. To cope with this issue, a second method is introduced whereby modifications are performed in the previous optimization formulation and linearization techniques are employed. The resultant linearized optimization-based reference calculation is then integrated with an energy-based control for MMCs and different case studies are analyzed to validate its performance compared to classical approaches.Finally, an optimization-based methodology to design the submodule (SM) capacitors is proposed. The algorithm considers all the DOFs of the MMC in order to size the SM capacitor while meeting the TSO's requirements and the converter's design limitations. The suggested method is compared with classical approaches for different operating points, and it is further exploited by considering AC network voltage sag conditions.
  

Last update: 06/10/2022 05:01:04.

Research groups

• CITCEA-Centre of Technological Innovation in Power Electronics and Drives
• GAECE-Electronically Commutated Motor Drives Group
• LRG-Lightning Research Group
• QSE-Power Quality

Teachers

• Andrada Gascon, Pere
• Aragüés Peñalba, Mónica
• Bargallo Perpiña, Ramon
• Bergas Jane, Joan Gabriel
• Blanque Molina, Balduino
• Bogarra Rodriguez, Santiago
• Boix Aragones, Oriol
• Bosch Tous, Ricard
• Casals Torrens, Pau
• Corcoles Lopez, Felipe
• de la Hoz Casas, Jordi
• Diaz Gonzalez, Francisco
• Doria Cerezo, Arnau
• Galceran Arellano, Samuel
• Garcia Espinosa, Antoni
• Gomis Bellmunt, Oriol
• Martin Cañadas, Maria Elena
• Matas Alcala, Jose
• Mesas Garcia, Juan Jose
• Montaña Puig, Joan
• Montesinos Miracle, Daniel
• Mujal Rosas, Ramon Maria
• Pedra Duran, Joaquin
• Riba Ruiz, Jordi
• Rull Duran, Joan
• Sainz Sapera, Luis
• Sudria Andreu, Antoni
• Sumper, Andreas
• Torrent Burgues, Marcel
• Villafafila Robles, Roberto