Percorrer por autor "Leite, V."
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- Full and reduced order extended Kalman filter for speed estimation in induction motor drives: a comparative studyPublication . Leite, V.; Araújo, Rui Esteves; Freitas, Diamantino SilvaThis paper presents a comparative study between a new approach for robust speed estimation in induction motor sensor less control, using a reduced order Extended Kalman Filter (EKF), and the one performed by the full order EKF. The new EKF algorithm uses a reduced order state-space model that is discretized in a particular and innovative way, proposed in this paper. In this case, only the rotor flux components are estimated, besides the rotor speed, while the full order EKF also estimates the stator current components. It is well known that the EKF algorithm has some drawbacks, like computational effort for real-time applications, complexity and hard tuning of noise covariance matrices. This new approach introduces new improvements and very important and practical aspects that strongly reduce the execution time and simplify the tuning of the covariance matrices. The reduced order EKF algorithm was implemented and validated in real-time operation using the dSPACE's DS1103 controller board. The experimental results have proved to be very good. The performance of speed estimation using both EKF techniques is compared with respect to computation effort, tuning of the algorithms, speed range including low speeds, load torque conditions, robustness relatively to motor parameter sensitivity and other important aspects.
- Full and reduced order extended kalman filter for speed estimation in induction motor drives: a comparative studyPublication . Leite, V.; Araújo, Rui Esteves; Freitas, Diamantino SilvaThis paper presents a comparative study between a new approach for robust speed estimation in induction motor sensorless control, using a reduced order Extended Kalman Filter (EKF), and the one performed by the full order EKF. The new EKF algorithm uses a reduced order state-space model that is discretized in a particular and innovative way. In this case only the rotor flux components are estimated, besides the rotor speed, while the full order EKF also estimates stator current components. This new approach strongly reduces the execution time and simplifies the tuning of covariance matrices. The performance of speed estimation using both EKF techniques is compared with respect to computation effort, tuning of the algorithms, speed range including low speeds, load torque conditions and robustness relatively to motor parameter sensitivity.
- Grid connection approach for very small-scale pico-hydro systems using PV microinvertersPublication . Ribeiro, Gabriela Moreira; Maidana, Wellington; Leite, V.; Ferreira, Ângela P.The use of renewable energy sources has grown significantly in recent decades, with emphasis on resources that have a low environmental impact in the energy production process. Small-scale pico-hydro systems have great potential and are also in line with increasing environmental requirements.
- Grid-connection approaches for pico-hydro systemsPublication . Leite, V.; Ferreira, Ângela P.; Couto, José; Batista, JoséSmall hydropower systems are considered an environmentally friendly energy option. They have a huge untapped potential which allow it to make a more significant contribution to future energy demand with many advantages. Grid-connected pico-hydro systems are an emerging solution for application in a huge number of applications such as in household water supply, wastewater treatment facilities and to improve control systems and optimize generation as a part of integrated water management systems. They are also very promising for integration in microgrids in many developing countries. This paper presents and discusses the main three grid-connection approaches for pico-hydro systems: using specifically designed power converters; using standard wind inverters; and using standard photovoltaic inverters. These latest approaches based on conventional inverters are practical solutions able to explore a large amount of feasible sites with low-head and very low-head. Moreover, photovoltaic micro inverters, recently launched in the market, are propose for very low power generators (250-300 W). These approaches improve efficiencies, reduce costs and environmental impacts and improve reliability. Experimental evaluation of the performance in steady-state and in dynamic conditions proves the feasibility of these innovative approaches.
- A hardware tool for explained power electronics control of induction motorsPublication . Araújo, Rui Esteves; Teixeira, Henrique José Alves; Barbosa, José; Leite, V.This paper presents a digital controller suitable for an instructional laboratory in electric drives. A prototype has been designed specifically to meet the requirements of low cost and motivating education tool, and it contains all of the active functions required to implement the open loop control of induction motors. This approach develops the concept of “grey box” module where the details are built for convenience, but not hidden inside as a “black box”. Introductory laboratory experiments are presented to demonstrate how this hardware can be integrated in laboratory classes to present the most important concepts as regards adjustable speed drives.
- Implementation of a smart microgrid in a small museum: the silk housePublication . Figueiredo, Luís Guilherme Aguiar; Maidana, Wellington; Leite, V.Microgrids are an alternative approach for the supply of energy integrating decentralized power sources, electrical loads, energy storage, and management in a local grid. The system has the capability of power control and energy management using communications’ network between all devices, and is known as smart microgrid. This paper presents the implementation of a smart microgrid in the Silk House, a museum dedicated to dissemination of science located in Bragança, Portugal. It was funded by the Foundation for Science and Technology of Portugal under the SilkHouse Project. The goal is to transform the House of Silk in a self-sustainable museum contributing to the dissemination of renewable sources and new technologies for future buildings in smart cities. This work presents the context and requirements for the microgrid and describes the implementation of the renewable sources (photovoltaic and pico-hydro) and the SMA Flexible Storage System based on Sunny Island and Sunny Home Manager. This work also presents and analysis the first operating results since the start of operation at the end of July 2019.
- Improving the storage capability of a microgrid with a vehicle-to-grid interfacePublication . Leite, V.; Ferreira, Ângela P.; Batista, JoséIn the emergent deployment of microgrids, storage systems play an important role providing ancillary services, such as backup power and reactive power support. This concept becomes crucial in the context of microgrids with a high penetration of renewable energy resources, where storage systems may be used to smooth the intermittency and variability of most of them. Plug-in electric vehicles provide an enormous distributed storage capability, which favours the technical and economical exploitation of such systems. This paper presents a comprehensive implementation and control of a bidirectional power converter for Vehicle-to-Grid integration, based on a bidirectional DC/DC converter followed by a full bridge DC/AC converter. The evaluation of the adopted topology and its control is performed through MATLAB/Simulink simulation.
- Indirect parameter estimation of continuous-time systems using discrete time dataPublication . Araújo, Rui Esteves; Leite, V.; Freitas, Diamantino SilvaThis paper addresses the problem of parameter estimation of continuous-time systems using samples of its input-output data. We propose a method based on the bilinear transformation to obtain an equivalent discrete-time model. Introducing a new polynomial pre-filter it .is possible to compute the physical parameters via inverse mapping between the discrete-time and the continuous-time models. A simulation example is given to illustrate the noise effects in the parameter estimation results. Using experimental results, we demonstrate the ability of the estimator. to handle real measurement problems.
- Interface para condicionamento das tensões e correntes à saída de conversores de frequênciaPublication . Leite, V.; Teixeira, Henrique José Alves; Araújo, Rui Esteves; Freitas, Diamantino SilvaNeste trabalho apresentamos o desenvolvimento de uma interface baseada num circuito electrónico de condicionamento e filtragem anti-aliasing, destinado à medida e/ou processamento do sistema trifásico de tensões e correntes à saída de um conversor de frequência industrial que alimenta um motor de indução trifásico. Os sinais produzidos à saída do circuito da interface desenvolvida estão galvanicamente isolados do sistema de alimentação de potência, condicionados e filtrados, de modo a tornar possível a aquisição para PC ou outro qualquer sistema de processamento digital de sinal.
- Low cost control and monitoring motion control ICsPublication . Moutinho, J.; Araújo, Rui Esteves; Leite, V.For a long time, controlling AC motors in an efficient way, was a task only in the reach of some very specific electronic design Engineers. Now, with the up rise of Integrated Platforms it is possible to implement, with almost no effort, the desired application, customizing almost everything at the reach of a simple and user friendly software interface. However, the simplicity in control and monitoring has a major settle back. As expected, such products, very desirable by the market, are only sold in conjunction with an evaluation platform. Sometimes this platform does not fit the consumer needs and buying the full package is not a satisfactory solution, especially if it is just to get the control and monitoring software. In this paper, it will be show that low cost alternatives are possible. Using free tools and manufacturer’s documentation, it is simple to implement Motor Control with the desired IC by means of a very intuitive and complete Graphical Unit Interface (GUI), built attending our special needs.
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