Percorrer por autor "Cordeiro, Armando"
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- An 8/6 SRM drive with a multilevel topology based on a cross-switched configurationPublication . Fernao Pires, Vitor; Foito, Daniel; Pires, Armando J.; Cordeiro, Armando; Martins, J. F.SRM drives based on multilevel power electronic converter presents several advantages, like reducing the switching frequency and improve the operation of the motor under high speed. In this way, several multilevel power converter topologies have been developed for the SRM drives. In line with this, this paper proposes a new multilevel power converter topology for the 8/6 SRM drive. The topology was developed with the purpose to reduce the number of power semiconductors, without reducing the performance of the motor. The proposed topology was designed in a way that uses crossover switches. The operation of the power converter topology in all of their modes is analyzed in a detailed way. The verification of the global system performance (drive and motor) is realized by the implementation of simulation studies. Indeed, through these studies it is verified that at low speed operation the switching frequency is reduced, but maintaining the application of the maximum voltage during the magnetization and demagnetization process.
- Artificial vision in renewable photovoltaic systems: a review and vision of specific applications and technologiesPublication . Amaral, Tito G.; Cordeiro, Armando; Fernao Pires, VitorRenewable energy resources have become extremely important in the current context of air pollution and the production of significant amounts of greenhouse gas emissions that contribute to global warming. One of the most important renewable energy sources that has shown the highest growth in recent years is photovoltaic (PV) systems. Due to their significance, this research presents a review of the applications in which artificial computer vision can be used in photovoltaic systems. From the results presented in this review, it will be evident that artificial vision can be applied for several different purposes. The advantages of using this technique will also be highlighted. Additionally, a systematic literature review is presented on the research associated with this topic. Through this review, it will be evident that many advanced algorithms related to image acquisition equipment have been proposed to ensure high reliability and fast results. This review does not merely focus on a specific topic or algorithms associated with image processing applied to photovoltaic systems. Rather, this work presents a broad and comprehensive review detailing all viable applications and associated computer vision technologies that can be deployed within these systems. Besides that, the review will clearly specify which work one is based on public datasets. To allow future reproducibility or research, the links to all public datasets utilized in the works based on them are included.
- Backstepping sliding mode controller for MPPT in DC microgrid connected Quadratic Boost converters fed from PV systemsPublication . Monteiro, Joaquim; Silva, J. Fernando; Cordeiro, Armando; Pinto, Sónia; Pires, V. Fernão; Monteiro, Joaquim; Cordeiro, Armando; IEEEPhotovoltaic (PV) systems are crucial for harnessing solar energy; however, environmental factors and the variability of the connected load significantly influence their energy generation capacity. In this context, the effectiveness of the controller used for maximum power point tracking (MPPT) to enhance efficiency relies on a thorough analysis of the nonlinear models of PV systems. Over these last decades, many control techniques have been developed to enhance the energy extraction from PV cells and improve system efficiency. Since real-world systems have real-time variations, it is difficult to continuously update both the system and the controller. The changes can produce steady state errors in the output and reduce the efficiency of the controller. As a solution to this issue, in this work a nonlinear backstepping sliding mode controller (BSMC) is proposed to improve the performance of the MPPT system. The BSMC MPPT, coupled to a DC-DC quadratic boost converter (QBC), is used as the interface between a PV array and a microgrid. Backstepping control ensures global asymptotic stability of the system by achieving the optimal power point, following Lyapunov stability criteria. Simulation and experimental results of the proposed MPPT solution are presented confirming that the system operates as expected.
- Bidirectional boost/buck quadratic converter for distributed generation systems with electrochemical storage systemsPublication . Pires, V. Fernão; Foito, D.; Cordeiro, ArmandoThe increasing number of distributed generation systems using renewable and non-conventional energy sources show the trend of future generation systems. Most of these systems require power electronic converters as an interface between the DC voltage buses and electrochemical storage systems. Such storage systems, like batteries or supercapacitors, usually need bidirectional DC-DC converters to allow their charge or discharge according with necessary operation conditions. In this paper, a non-isolated bidirectional Buck-Boost converter with high voltage gain for electrochemical storage devices used in distributed generation systems is presented. To achieve high voltage gain ratios, the proposed topology presents quadratic characteristics in both step-down (Buck) and step-up (Boost) operation modes. In addition to the wide conversion range, it presents continuous input and output current, reduced charging/discharging ripple and simple control circuitry. All these features allow the energy exchange smoothly and continuously resulting in a longer durability of storage devices. The principle of the operation of the proposed converter in both operation modes, as well as their theoretical analysis will be discussed. The performance of this bidirectional power converter is confirmed through simulation and experimental results.
- A buck-boost converter with extended duty-cycle range in the buck voltage region for renewable energy sourcesPublication . Monteiro, Joaquim; Fernao Pires, Vitor; Foito, Daniel; Cordeiro, Armando; J. F. Silva, Fernando Silva, Fernando A Silva, J. Fernando Silva, J F A Silva, Fernando Silva José; Pinto, SoniaBuck-boost DC-DC converters are useful as DC grid interfaces for renewable energy resources. In the classical buck-boost converter, output voltages smaller than the input voltage (the buck region) are observed for duty cycles between 0 and 0.5. Several recent buck-boost converters have been designed to present higher voltage gains. Nevertheless, those topologies show a reduced duty-cycle range, leading to output voltages in the buck region, and thus require the use of very low duty cycles to achieve the lower range of buck output voltages. In this work, we propose a new buck-boost DC-DC converter that privileges the buck region through the extension of the duty-cycle range, enabling buck operation. In fact, the converter proposed here allows output voltages below the input voltage even with duty cycles higher than 0.6. We present the analysis, design, and testing of the extended buck-boost DC-DC converter. Several tests were conducted to illustrate the characteristics of the extended buck-boost DC-DC converter. Test results were obtained using both simulation software and a laboratory prototype.
- Combining local and remote laboratories for the interactive learning of industrial automationPublication . Cordeiro, Armando; Fernao Pires, Vitor; Foito, DanielThis study presents an educational project for the interactive learning of Industrial Automation. The objective of this project is to allow Bachelor's and Master's students of Electrical Engineering of the Instituto Superior de Engenharia de Lisboa (ISEL-IPL) to learn theoretical and practical fundamentals of Industrial Automation through local and remote laboratory experiments. The proposed pedagogical activities, together with the flexibility of the solution adopted for the laboratory experiments, allow students to acquire advanced knowledge regarding Programmable Logic Controller (PLC) programming languages, Supervisory Control and Data Acquisition (SCADA) applications and industrial communication networks, among other aspects. The main benefits of this educational project are the motivation to engage in problem solving, developing mental strategies based on new hypotheses, step-by-step knowledge construction, and the possibility to interact and change, locally or remotely, the developed programs. Additionally, the adopted laboratory architecture is based on industrial hardware and software, like those found in real applications.
- Combining power electronic converters and automation to simulate solar PV systemsPublication . Cordeiro, Armando; Chaves, Miguel; Gamboa, Paulo; Barata, Filipe; Fonte, Pedro M; Lopes, Hélio; Fernao Pires, Vitor; Foito, Daniel; Amaral, Tito; Martins, JoaoThis paper presents a solar photovoltaic panel simulator system with the ability to perform automatic tests in different condition according to manufacture parameters. This simulator is based on three buck-boost DC-DC converters controlled by a microcontroller and supported by a Programmable Logic Controller which is responsible for the automatic tests. This solution will allow to achieve fast response, like suddenly changes in the irradiation, temperature, or load. To control the power converter, it will be used a fast and robust sliding mode controller. Therefore, with the proposed system is possible to perform the I-V curve simulation of a solar PV panel, evaluate different MPPT algorithms considering different meteorological and load variation. The main advantage of this work is the possibility to evaluate and test several MPPT algorithms and understand the operation and typical operation of solar PV panels in different conditions. Several simulations and experimental results from a laboratory prototype are presented to confirm the theoretical operation.
- Compensation of unbalanced low-voltage grids using a photovoltaic generation system with a dual four-leg, two-level inverterPublication . Fernao Pires, Vitor; Cordeiro, Armando; Foito, Daniel; J. Pires, A.; Hao, Chen; Martins, Joao; Castro, RuiIn this paper, a grid-connected photovoltaic (PV) generation system is proposed with the purpose of providing support to low-voltage grids, namely through the elimination or attenuation of the grid imbalances. This compensation must consider the load types, which can be either linear or non-linear, and whether the reactive power and current harmonics generated by the non-linear loads need to be compensated in addition to the unbalanced active power. This must be well considered, since the compensation of all aspects requires oversized PV inverters. Thus, the different unbalanced compensation schemes are addressed. Several schemes for the generation of the inverter current references taking into consideration the compensation and load type are presented. For this PV generation system, a dual four-leg, two-level inverter is proposed. It provides full unbalanced compensation owing to the fourth leg of the inverter and also extends the AC voltage, which is important when this compensation is required. To control this inverter, a control scheme for the inverter that considers several compensation factors is proposed. A vector voltage modulator associated with the controller is another aspect that is addressed in the paper. This modulator considers the balance between the DC voltages of the inverters. Several compensation schemes are verified through computational tests. The results validate the effectiveness of the proposed PV generation system.
- Control of bidirectional quadratic DC-DC converters for storage support of DC power gridsPublication . Fernao Pires, Vitor; Cordeiro, Armando; Foito, Daniel; Silva, J. FernandoMany applications require a DC bus supporting connections to several renewable energy sources, storage systems and loads. However, due to the intermittent nature of renewable energy sources and load variations it is essential to stabilize the voltage of the DC bus. Usually a battery is used to support the DC bus voltage, but their continuous charge and discharge cycling will affect his lifetime. Thus, the use of a storage system based in supercapacitors provides an interesting alternative to stabilize the DC power grid. In this context, this work presents a study of a storage system based in supercapacitors combined with a bidirectional quadratic DC-DC converter to support the DC bus. A full design of the controllers for the quadratic converter is also presented. The behaviour of the system will be tested through several simulation results.
- Control of PV distributed systems based on three-phase triple inverters to support grids with unbalanced loadsPublication . Fernão Pires, V.; Foito, Daniel; Cordeiro, Armando; Silva, J. FernandoThis paper is focused on the control system for photovoltaic (PV) generators using three-phase triple inverters. These inverters allow for a distributed PV system, and at the same time, they provide AC multilevel operation. The proposed controller is designed to allow the operation of the inverter in a way that it can extend support to the grid with ancillary services. One of the ancillary services that the three-phase triple inverter can support is the injection of unbalanced currents in order to eliminate or attenuate grid load unbalances. Therefore, the proposed topology will be extended to accommodate four wires. The capability of the system to support the grid with ancillary services, especially the compensation of unbalanced loads, the four-wire multilevel topology operation and the proposed controller will be verified through several simulation tests.