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
• Monjo Mur, Lluís
• 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: 23/09/2023 04:45:29.

List of lodged theses

Last update: 23/09/2023 04:30:25.

List of defended theses by year

• ALONSO TRAVESSET, ALEXANDRE: Contribution to Optimal Microgrid Design and Management in Uncertain and Regulated Environments
  
  Author: ALONSO TRAVESSET, ALEXANDRE
  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
  Reading date: 14/07/2023
  Thesis director: DE LA HOZ CASAS, JORGE | MARTIN CAÑADAS, MARIA ELENA
  

  Committee:
       PRESIDENT: PALACIN FARRE, PEDRO
       SECRETARI: MONJO MUR, LLUÍS
       VOCAL: SOMOZA TORNOS, ANA
  Thesis abstract: The rise of distributed generation systems (DGSs) is crucial for the energy transition. The reduction in renewable energy costs and increasing implementation of environmentally-friendly policies are driving a new decentralized standard in energy usage. However, this new paradigm requires a more intricate design and operation. Optimization models have customarily been used, with current research emphasizing uncertainty characterization. However, the impact of regulatory uncertainty in DGS optimization has only been addressed qualitatively. Consequently, this thesis emphasizes the significance of including regulatory frameworks (RFs) in DGS design and operation. To address this problem, this thesis first focuses on providing a comprehensive state-of-the-art review. The review resulted in a classification system that highlights the distinctive elements of optimization models. These are microgrid architecture, sources of uncertainty, uncertainty characterization methods, problem formulations, objective functions, and solution algorithms. The classification reveals that economic and regulatory uncertainties are the least considered but also the most influential.After the literature survey, three models are performed to validate the use of RFs in mathematical models for DGS. The first model focuses on the particularities of the 2015 Spanish self-consumption scheme, which was criticized for hindering renewable energy deployment. The second model compares energy management under feed-in tariffs, net metering, and the self-consumption scheme mentioned above. Regulatory constraints were represented algebraically in a mixed-integer linear program. Results demonstrate that the profitability of an energy community is heavily influenced by the RF employed and highlight the need to embed this aspect in mathematical models to prevent unforeseen changes in revenue.The third model aims to compare the economic performance of energy management between individuals and a collective community under different policy schemes. A mixed-integer linear program incorporates the three RFs from the previous models. Different economic parameters and consumption profiles are compared in a what-if analysis to validate the output. Results indicate that community energy management improves customers' average benefit for all studied frameworks, except for feed-in-tariff and some instances of type-B self-consumption. The output of the model highlights the fundamental differences between RFs and their suitability to promote decentralized, collective facilities.Additionally, a fourth model considers the uncertainty of renewable energy sources, consumption patterns, and electricity market prices to optimize a microgrid's design and management. The model's most notable feature is the generation of synthetic data to develop plausible scenarios. Results confirm the superiority of using a stochastic rather than a deterministic approach for DGS optimization.Finally, this thesis discusses several aspects of interest in microgrid optimization: how modeling can be improved, which variables are the most influential, and future lines of research. The conclusions emphasize the need to use underrepresented methods to model regulatory uncertainties, encourage the integration of existing approaches, and recommend substantial policy changes to foster energy communities more effectively.
  

• BARJA MARTÍNEZ, SARA: Energy management systems for smart homes and local energy communities based on optimization and artificial intelligence techniques
  
  Author: BARJA MARTÍNEZ, SARA
  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: 07/07/2023
  Thesis director: VILLAFÁFILA ROBLES, ROBERTO | ARAGÜÉS PEÑALBA, MÒNICA
  

  Committee:
       PRESIDENT: FARAHMAND, HOSSEIN
       SECRETARI: MONTESINOS MIRACLE, DANIEL
       VOCAL: DEBUSSCHÈRE, VINCENT
  Thesis abstract: The rapid advancement of digitalization, combined with the integration of renewable generation and the development of information and communication technologies within the distribution network, is accelerating the transition towards distributed, digitized, and decarbonized smart energy systems. Despite the crucial role of data in this transformation, it is still underutilized. Artificial Intelligence (AI) technology has the potential to extract valuable insights from these data, enabling innovative energy services and improving the performance of existing ones.This thesis first explores the potential of AI in data-driven energy services for distribution power systems through a comprehensive study. After reviewing the state of the art, the next step focuses on energy management systems at the household level. This thesis develops a multi-objective energy management system that simultaneously minimizes greenhouse gas emissions and electricity expenses, considering the entire life cycle of the generation assets used to provide energy, includingthe grid. The results demonstrate that this methodology can significantly reduce greenhouse gas emissions without incurring expensive electricity costs. The following chapter extends this innovative environmental-based approach to local energy communities with centralized PV and battery.Finally, the last chapter focuses on federated learning technology applied to home energy management systems (HEMS). Due to the increasing digitization of the low-voltage network and the implementation of smart meters, data protection has become increasingly important. Therefore, this study seeks to preserve user privacy by training prediction models in a distributed manner. Moreover, the proposed personalized federated learning methodology for HEMS demand forecasting incorporates a cost-oriented loss function to minimize imbalance costs while preserving customer privacy. The study compares cost-oriented and traditional loss functions and reveals that the personalized federated learning approach with cost-oriented loss function obtains the lowest imbalance cost for HEMS optimization. Moreover, the study demonstrates that new households without large historical consumption data can still achieve good load prediction outcomes through collaborative learning models.
  

• LI, MINGSHEN: Power Calculation Algorithm under Nonlinear Loads and Hopf Oscillator-based Synchronization Controller for Grid-forming Inverters in a Microgrid
  
  Author: LI, MINGSHEN
  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: 23/01/2023
  Thesis director: MATAS ALCALA, JOSE | GUERRERO ZAPATA, JOSEP MARIA
  

  Committee:
       PRESIDENT: GUAN, YAJUAN
       SECRETARI: MARTIN CAÑADAS, MARIA ELENA
       VOCAL NO PRESENCIAL: GOLESTAN, SAEED
  Thesis abstract: In the grid-forming control of microgrids, the droop control is a widely used for the parallel operation of power inverters, but has some peculiarities as slow dynamic and inaccuracy in the power sharing. In the droop control, the power calculation of the active and reactive powers determines the speed of the controller capability to share linear and nonlinear loads. Therefore, the thesis address first the design of advanced filters to improve the dynamic response for droop-based inverters. And, a fast and accurate power calculation technique is proposed for three-phase inverters by using a two-stage combined Second Order Generalized Integrator (SOGI) approach to overcome this obstacle. The two-stage combined SOGI filter structure achieves the average active and reactive powers, used as the kernel for the droop-method operation. A small-signal model of a paralleled three-phase inverters is developed for determining the dynamic response of the system, which shows that the proposal is faster than the conventional droop method when both methods are designed under the same conditions. The proposal can be used to improve the stability and transient response of droop-operated inverters.After, a novel synchronization method based on Andronov-Hopf oscillators is proposed for driving paralleled single and three-phase power inverters, which show to have lower harmonics, faster dynamic response, and higher synchronization speed than the achieved by previous nonlinear Van der Pol oscillators, used as virtual oscillator controllers (VOC). The coupling strength between Hopf oscillators relies on the local feedback of the output current, which is able to synchronize with the rest of parallel inverters, without using communications. The Hopf equations considering the current feedback generates the voltage reference for the power inverters, and has a dual-loop that is designed in a static reference frame. The Hopf has a pre-synchronization stage that allows a softer connection of additional inverters. A small-signal state-space model for two parallel VSI is built and compared with a standard droop controller. The root locus exhibits a larger stability margin and lower parameter sensitivity. Finally, a grid-forming controller based on the Hopf oscillator is proposed that is able to synchronize and achieve accurate power tracking of the references. The Hopf model is analyzed and the synchronization region is obtained by using the Arnold tongue method. In this controller, the active power can be regulated by phasor, and a PI regulator is introduced in the reactive loop to control the amplitude voltage based on the Q - V relationship achieved by the Hopf.Matlab/PLECS simulation studies and experiments on a single phase and three-phase inverters platform are conducted in a microgrid laboratory to verify the proposed control strategies. The simulations of the proposed power calculation method presents a faster and more accurate performance when sharing nonlinear loads compared with the LPF-droop. In the case of the Hopf oscillator, the simulation and experimental results demonstrate a faster transient response and better robustness compared with the standard droop controller, and a wider operating range compared with the Van der Pol VOC.The Thesis has been organized in five sections: Section 1 introduces the background, state of the art, objectives, methodology, contributions and limitations of the work; Section 2 describes the proposed power calculation method using the combined SOGI filters approach; Section 3 is devoted to the Hopf oscillator control operating in an islanded microgrid; Section 4 describes the desing of the Hopf oscillator to operate with grid forming inverters; Section 5 is devoted to conclusions and forecast future line works.
  

• MIGUEL ESPINAR, CARLOS: Enhanced Flux-Weakening Control Algorithm for Permanent Magnet Synchronous Machines
  
  Author: MIGUEL ESPINAR, CARLOS
  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: 15/05/2023
  Thesis director: MONTESINOS MIRACLE, DANIEL | HEREDERO PERIS, DANIEL
  

  Committee:
       PRESIDENT: MÜLLER, BERNHARD
       SECRETARI: GALCERAN ARELLANO, SAMUEL
       VOCAL: GARCÍA FERNÁNDEZ, PABLO
  Thesis abstract: EspinarThis thesis presents the overall state of the art of electric vehicles in terms of the technology of the main concepts in an electric powertrain: batteries, traction inverters, electric machines, and control strategies. The torque-speed characteristic of an electric machine for electric vehicles is presented, and the penetration in the electric vehicle market of the Permanent Magnet Synchronous Machines is justified. This work also outlines the mathematical model for Permanent Magnet Synchronous Machines in the stator and rotor reference frames. Depending on the speed range, the characteristic performance of a Permanent Magnet Synchronous Machine will be described and categorised in the Low-Back Electromotive Force and Flux-Weakening zones, justifying the necessity of Flux-Weakening strategies for electric vehicles. The distinct trajectories of Permanent Magnet Synchronous Machines regarding the mechanical speed are studied, differentiating from Surface Permanent Magnet Synchronous Machines and Interior Permanent Magnet Synchronous Machines with different saliency ratios. A per-unit system based on the characteristic parameters of a Permanent Magnet Synchronous Machines is presented to simplify the mathematical model. Furthermore, a complete state of the art of Flux-Weakening strategies, focusing on the deep Flux-Weakening region is analysed. This thesis presents an enhanced control algorithm to enlarge the torque-speed characteristic of Permanent Magnet Synchronous Machines, focused on the deep Flux-Weakening region. The different control loops are analysed, focusing on the Flux-Weakening control loop, through a sensitivity analysis of the system. Besides, an analytical solution of the PID controllers is provided regarding the transient specifications and the characteristic parameters of the Permanent Magnet Synchronous Machine. Simulations and experimental results verify the effectiveness of the proposed method in a low-voltage electric powertrain. In other terms, this study presents a method to determine the electrical speed and position of the electric machine from misplaced discrete Hall-effect switch sensors. This method to determine the electrical speed and position is integrated with the Flux-Weakening strategy. Simulations and experimental results verify the effectiveness of the proposed methodology compared with other state-of-the-art algorithms.
  

• SONG, JIE: Computational Analysis of Modern Power Systems with Power Electronics
  
  Author: SONG, JIE
  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: 15/05/2023
  Thesis director: GOMIS BELLMUNT, ORIOL | CHEAH MAÑÉ, MARC
  

  Committee:
       PRESIDENT: FORTMANN, JENS
       SECRETARI: SUMPER, ANDREAS
       VOCAL: VERBOOMEN, JODY
  Thesis abstract: Modern power systems have been and will continue to be increasingly penetrated with power electronics at different voltage levels. Such high penetration of power electronics elements changes the nature of modern power systems as they can operate in different control modes, which introduces non-linear operation characteristics to the grid. In addition, power electronics converters saturate current in case of being overloaded or under the fault, which results in various current saturation states of converters' operation. In such context, a different methodology is desired for steady-state computational analysis of power systems with high penetration of power electronics. This thesis deals with the challenge of computational analysis of power systems with power electronics. A systematic approach has been proposed for short-circuit calculation of power systems with a significant penetration of power electronics converters. Firstly, an element-based formulation has been presented to model the studied system for steady-state analysis where the operation of power converters are included. In particular, various current saturated states of power converters are modeled with different equations. Then, two different methodologies have been proposed to search for equilibrium points that satisfy converters' operation limits by solving systems of equations corresponding to various converters' current saturation states. In particular, a comprehensive methodology traverses all possible combinations of converters' current saturation states and could identify all possible equilibrium points. An efficient methodology goes through only selected combinations iteratively and identifies only one equilibrium point. Case studies have been presented with balanced three-phase systems, unbalanced three-phase systems and hybrid AC/DC systems with a VSC-HVDC link.Finally, a novel grid equivalent has been proposed based on voltage-current (U-I) characteristic as an alternative of the conventional Thévenin equivalent. The grid equivalent representation could accurately capture the complex operation characteristics of power electronics converter and is suitable for both balanced and unbalanced power systems.
  

• STEFANIDOU VOZIKI, PASCHALIA: Advanced data-driven fault diagnosis schemes for active distribution grids
  
  Author: STEFANIDOU VOZIKI, PASCHALIA
  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: 10/01/2023
  Thesis director: VILLAFÁFILA ROBLES, ROBERTO | DOMÍNGUEZ GARCÍA, JOSÉ LUIS
  

  Committee:
       PRESIDENT: BESSA, RICARDO JORGE
       SECRETARI: ARAGÜÉS PEÑALBA, MÒNICA
       VOCAL: COMECH MORENO, MARIA PAZ
  Thesis abstract: Reliable and uninterrupted power supply is crucial for modern societies. Therefore, the minimization of the power outages' duration is a priority for the power system operators. This thesis aims to contribute to the efforts to increase the power restoration speed by proposing automatized solutions for the fault diagnosis process applied in distribution grids. The fault diagnosis process comprises the fault detection, the fault classification and the fault location; all three of these steps are addressed in this study.The traditional fault diagnosis methods that are currently applied to the grids are rapidly becoming obsolete due to the smart grid transition. Renewable energy sources, electric vehicles (EVs) and other smart devices may pose a challenge to conventional fault diagnosis techniques but they also provide opportunities for the application of advanced technological solutions. Hence, in order to take advantage of the grid's digitalization and the subsequent growing data availability the proposed methods are all data-driven, with emphasis given to the use of machine learning (ML).The fault detection method presented in this thesis refers to active low voltage (LV) grids and specifically the ones with EV fast charging (FC) and ultra fast charging (UFC). The proposed ML-based algorithm utilizes a CatBoostClassifier for the detection of faults and manages to efficiently train the model with static simulation data. These data correspond to the grid's normal and faulty operation when the loads are operating at nominal power and the EV charging is ignored, i.e. to a grid's static loading state. In this way the algorithm is independent of the EV charging and the intermediate operating states. When tested on unseen data corresponding to potential intermediate states the algorithm achieved an accuracy of 97.61% with only 6000 examples included in the training data.Regarding the fault classification, a data--driven improved version of the popular threshold--based techniques is presented here. The method includes an algorithm that studies the grid's current values before and after a fault under various fault resistances and outputs the most suitable threshold values for the criteria describing each fault type. Thus, it combines increased accuracy with high adaptability lo any tli:;lri1Jutior1 grid. The proposed technique achieves an accuracy of nearly 100\% regardless of the fault's resistance. This constitutes an approx. 20% higher accuracy compared to traditional threshold-based techniques with fixed criteria.Finally, a complete and practical ML-based fault location method for active LV grids is proposed in this thesis. The method first identifies the faulted branch with the use of a Random Forest (RF) classifier and then locates the faulted point with the use of a regression model. Since the second part of the process is the most crucial and complicated one two tree--based predictive models are tested here, a RF regressor and an XGBoost regressor. In order to improve the models' and, as an extend, the method's performance a thorough data management strategy is included in the algorithm. This includes among others the application of a smart data storage strategy, the comparison of two data minimization approaches and an efficient re-training scheme. Both models lead to mean absolute errors (MAEs) of less than 2m, nevertheless, the XGBoost proves the most suitable model for this application. When paired with the SelectFromModel dimensionality reduction algorithm it leads to a MAE of 0.49 m and is robust against the major influencing parameters such as the fault resistance, the bidirectional power flow, the data loss and more. The research addresses all the aspects of the method's application, offers an insight on the designing process ofML-based algorithms and presents an efficient, easily-applicable and generalizable solution.
  

Last update: 23/09/2023 05:01:38.

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