Browsing by Author "Silva, Fernando Bento"

Now showing 1 - 6 of 6
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    Effects of harmonic pollution on salient pole synchronous generators and on induction generators operating in parallel in isolated systems.
    (2020) Vanço, Wagner Eduardo; Silva, Fernando Bento; Oliveira, José Mário Menescal de; Monteiro, José Roberto Boffino de Almeida
    This work presents a study of the disturbances caused by harmonic pollution in salient pole synchronous generators (SPSG) and induction generators, when operating in parallel in isolated systems. SPSG are known to operate with induction generators, since the excitation system of the synchronous generator is responsible for the voltage control on the island system. Due to the increase in the employment of power electronics, the loads take on a nonlinear behavior, where these become responsible for the generation of harmonics, due to the switching of electrical devices. Therefore, the analysis of the disturbances that these loads cause in generators, in this proposed and studied architecture, becomes essential. For the synchronous generator, there is also presented the analyses of the oscillations for voltages and currents on the dq0 model, the currents induced on the damper winding, the disturbances on the load angle and on the field current. In terms of the induction generator, the voltage and current oscillations are also analyzed from the dq0 model on the slip frequency. All the identified and quantified disturbances are oscillations on the electric variables, which possess a pulsating nature of frequencies 6ω, 12ω, and 18ω for the synchronous and induction generators, the oscillations of the sixth order and its multiples, will be given in the harmonic slip frequency of their respective harmonic orders in positive and negative sequence. In this way, verification is made as to the appearance of high slippage on the rotor of the induction generator.
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    Low-cost hardware-in-the-loop for real-time simulation of electric machines and electric drive.
    (2020) Bastos, Renan Fernandes; Silva, Fernando Bento; Aguiar, Cassius Rossi de; Fuzato, Guilherme Henrique Favaro; Machado, Ricardo Quadros
    This study aims to present the discrete models and the methodology to implement real-time simulations of electric machines using a low-cost digital signal processor (DSP). The DC machine and the three-phase induction machine are modelled in real-time using a Texas Instruments DSP TMS28379D, where the discrete models are implemented using C language. A minimum time-step of 1 μs can be achieved for the DC machine and 1.5 μs for the inductions machine in the experimental hardware. To validate the described models and show their precision, they are compared with commercial computational models from PSIM®. In addition, closed-loop speed control strategies are applied to the real-time DSP experimental models, showing perfect concordance with the machine theory. For the DC machine, a speed control strategy with an inner current control loop is applied and for the induction machine, a field-oriented control for the speed control. The proposed real-time simulation hardware has a great potential for low-budget research and educational purposes since it can replace a real machine setup for a very low price, with great accuracy, variable parameters and free from risks, such as accidents or equipment damage. Furthermore, it uses cheap hardware with free software and a high-level programing language.
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    A proposal of expansion and implementation in isolated generation systems using self-excited induction generator with synchronous generator.
    (2019) Vanço, Wagner Eduardo; Silva, Fernando Bento; Oliveira, Carlos Matheus Rodrigues de; Monteiro, José Roberto Boffino de Almeida; Oliveira, José Mário Menescal de
    This work presents a theoretical and experimental study of the self-excited three-phase induction generator in steady state, operating with a synchronous generator for use in isolated generation. Through the remoteness of many locations or because of the absence of an energy distribution network, difficulties exist in the supply of electric energy. The proposal contemplated herein can be applied in order to provide a well-adjusted voltage and reduce project costs in the expansion and implementation of isolated systems. That is, when taking into consideration acquisition costs of the asynchronous squirrel cage rotor machine in relation to the synchronous generator. The main contribution of this study is the making of the synchronous generator into a voltage regulator of the isolated system, in such a manner that the synchronous generator supplies the minimum of active power necessary, where a lower power generator is able to play the role of being the sole voltage regulator.
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    A study of the effects of magnetic saturation and spatial harmonics on isolated salient-pole synchronous generators.
    (2019) Vanço, Wagner Eduardo; Silva, Fernando Bento; Monteiro, José Roberto Boffino de Almeida
    This article presents a study of the effects caused in isolated salient-pole synchronous generator due to magnetic saturation and spatial harmonics, these effects cause harmonic distortion in the generated voltage and current. An experimental analysis is necessary to verify the magnitude of the distortion of the generated voltage and current, focusing on which are the components generated by the non-linear constructive aspects of the salient-pole synchronous generator. The quality of generated energy depends on which harmonic components prevail in the total distortion, whether zero, positive or negative. In this way the study is based on the negative effects caused by these harmonious components of a constructive nature of the salient-pole synchronous generator.
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    A study of the impacts caused by unbalanced voltage (2%) in isolated synchronous generators.
    (2019) Vanço, Wagner Eduardo; Silva, Fernando Bento; Monteiro, José Roberto Boffino de Almeida
    This paper presents an analysis of the oscillations caused by unbalanced loads in salient pole synchronous generators that operate in isolation under steady state. The oscillatory disturbances, arising from the second-order harmonics, may have or have the potential to cause electromechanical damage to the salient pole synchronous generator. In this paper, the goal is to identify and quantify the magnitude of the electromagnetic torque, which assumes an oscillatory form due to the current component from the negative sequence, caused by unbalanced currents. The self-same analysis was included for second-harmonic voltage oscillations in the qd0 domain, the currents induced on the damper windings together with the oscillation of the load angle and on the field current. These oscillations situated on the synchronous generator are analyzed for a degree of voltage unbalance close to 2% which is an acceptable value according to international regulations for power supply from distribution networks, and this same degree of tolerated voltage unbalance will be used herein for isolated synchronous generators.
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    Theoretical-experimental analysis of the induction generator in the use of distributed generation.
    (2021) Vanço, Wagner Eduardo; Silva, Fernando Bento; Monteiro, José Roberto Boffino de Almeida; Oliveira, Carlos Matheus Rodrigues de; Gomes, Luciano Coutinho
    This work presents a theoretical-experimental study in permanent regime of the three-phase induction generator of squirrel cage connected directly to the distribution network at fixed speed. The study is based on the operation of the induction generator that operates with the capacitor bank and without the presence of the capacitor bank to show the improvement of the power factor of the induction generator when in connection with the electric distribution network.