Browsing by Author "Ribeiro, Paulo Fernando"

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    Digital single voltage loop control of a VSI with LC output filter.
    (2018) Souza, Igor Dias Neto de; Almeida, Pedro Machado de; Barbosa, Pedro Gomes; Duque, Carlos Augusto; Ribeiro, Paulo Fernando
    This paper deals with the output voltage control problem of a three-phase three-wire voltage source Inverter (VSI) with LC output filter. A novel discrete-time active damping technique is proposed in order to damp the filter resonance without the need of current feedback. The method is based on an inner voltage feedback with digital lead compensator on the feedback path. A modified digital resonant controller is also proposed to reject the current harmonic disturbance drawn by nonlinear loads. The resonant controllers are connected in series and the design is based on its zeros damping. Results from a small scale experimental setup are used to validate the proposed control strategy.
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    Systematic design of a DLQR applied to grid-forming converters.
    (2020) Almeida, Pedro Machado de; Ribeiro, Adeilson da Silva Borges; Souza, Igor Dias Neto de; Fernandes, Marcelo Carvalho; Fogli, Gabriel Azevedo; Cuk, Vladimir; Barbosa, Pedro Gomes; Ribeiro, Paulo Fernando
    This article proposes a systematic state-space procedure to design an optimal discrete-time linear quadratic regulator applied to grid-forming converters. A comprehensive mathematical modeling of a voltage-sourced converter with an LC output filter is performed and a systematic way of including digital resonant compensators is addressed. The choice of weights is based on the minimization of selected transfer functions infinity norm, as well as on the stability margin and bandwidth. The effects of weighting on closed-loop transfer functions shape are analyzed and important points are discussed in order to establish a methodical way of choosing the weighting matrices. Experimental results are presented to validate the design and to demonstrate the system effectiveness with high loading and highly nonlinear balanced and unbalanced loads.