V. Fernao Pires

Bio: V. Fernao Pires is an academic researcher from INESC-ID. The author has contributed to research in topics: Inverter & Fault (power engineering). The author has an hindex of 18, co-authored 154 publications receiving 1457 citations. Previous affiliations of V. Fernao Pires include Technical University of Lisbon & University of Lisbon.

Fault Tolerant Operation of Three-Phase 3 Level T-Type qZS Inverters using Sliding Mode Current Controllers

Abstract: Due to the boost characteristic and the several possible outputs of quasi-Z-source inverters (qZSI), these topologies can be valuable options to operate under fault conditions, provided the controller is able to take advantage of the available output states. Thus, the development of control systems to take advantage of the available outputs is needed. Hence, this paper focuses on the development of a control system to operate a three-phase three-level T-Type qZSI under fault tolerant conditions. The controller is based on a sliding mode current controller associated to a vectorial modulator selecting the available outputs. The proposed strategy for the controller and modulator is presented taking into consideration the normal and fault-tolerant requirements. The strategy also considers the balance of the capacitors under fault tolerant condition. The converter operating in both modes is tested through several simulation studies.

Fault-Tolerant Design of Three-phase Dual-Buck VSI Topologies

Abstract: This paper presents fault tolerant topologies for the three-phase dual-buck voltage-source inverter (VSI). Using the proposed topologies, increased reliability is obtained, which is fundamental in many safety-critical applications. The solutions intend to achieve fast changing between main and redundant branches through the combination of several power devices. The present study focuses on solutions that can be used to replace the classical two-level three-phase voltage-source inverters to extend the fault-tolerant capacity. Several aspects of failure modes, detection and isolation processes within power electronic converters are discussed regarding the requirements of safety related applications. The theoretical validity of the proposed solution is confirmed by simulation results.

DC Microgrids: Benefits, Architectures, Perspectives and Challenges

Abstract: One of the major paradigm shifts that will be predictably observed in the energy mix is related to distribution networks. Until now, this type of electrical grid was characterized by an AC transmission. However, a new concept is emerging, as the electrical distribution networks characterized by DC transmission are beginning to be considered as a promising solution due to technological advances. In fact, we are now witnessing a proliferation of DC equipment associated with renewable energy sources, storage systems and loads. Thus, such equipment is beginning to be considered in different contexts. In this way, taking into consideration the requirement for the fast integration of this equipment into the existing electrical network, DC networks have started to become important. On the other hand, the importance of the development of these DC networks is not only due to the fact that the amount of DC equipment is becoming huge. When compared with the classical AC transmission systems, the DC networks are considered more efficient and reliable, not having any issues regarding the reactive power and frequency control and synchronization. Although much research work has been conducted, several technical aspects have not yet been defined as standard. This uncertainty is still an obstacle to a faster transition to this type of network. There are also other aspects that still need to be a focus of study and research in order to allow this technology to become a day-to-day solution. Finally, there are also many applications in which this kind of DC microgrid can be used, but they have still not been addressed. Thus, all these aspects are considered important challenges that need to be tackled. In this context, this paper presents an overview of the existing and possible solutions for this type of microgrid, as well as the challenges that need to be faced now.

Multi-level conversion : high voltage choppers and voltage-source inverters

Abstract: The authors discuss high-voltage power conversion. Conventional series connection and three-level voltage source inverter techniques are reviewed and compared. A novel versatile multilevel commutation cell is introduced: it is shown that this topology is safer and more simple to control, and delivers purer output waveforms. The authors show how this technique can be applied to either choppers or voltage-source inverters and generalized to any number of switches.<>

Recent Advances in the Design, Modeling, and Control of Multiphase Machines—Part II

Abstract: The main objective of this two-part state-of-the-art paper called “Recent Advances in the Design, Modeling, and Control of Multiphase Machines” is to present latest contributions in the multiphase machines' field. The first part of this paper focuses on the recent progress in the design, modeling, and control, whereas the drive is in healthy operation. This second part presents relevant contributions in two not analyzed fields. The first is in relation with the use of the additional degrees of freedom of multiphase machines and the exploitation of their fault-tolerant capabilities without adding extra hardware. The second one analyzes multiphase generation, particularly in grid-connected wind energy conversion systems and stand-alone applications. Recent progresses are shown and open challenges and future research directions are discussed.

Overview of Control Systems for the Operation of DFIGs in Wind Energy Applications

Abstract: Doubly fed induction generators (DFIGs), often organized in wind parks, are the most important generators used for variable-speed wind energy generation. This paper reviews the control systems for the operation of DFIGs and brushless DFIGs in wind energy applications. Control systems for stand-alone operation, connection to balanced or unbalanced grids, sensorless control, and frequency support from DFIGs and low-voltage ride-through issues are discussed.