Grupo de Sistemas Electrónicos Industriales
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- PublicationRobust model-following control of parallel UPS single-phase inverters(Institute of Electrical and Electronics Engineers (IEEE), 2008-08) Pascual Molto, Marcos; Garcerá Sanfeliú, Gabriel; Figueres Amorós, Emilio; González Espín, Francisco José; Dpto. de Física Aplicada; Dpto. de Ingeniería Electrónica; Escuela Técnica Superior de Ingeniería Industrial; Escuela Politécnica Superior de Alcoy; Grupo de Sistemas Electrónicos IndustrialesThis paper presents a robust control technique applied to modular uninterruptible power-supply (UPS) inverters operating in parallel. When compared to conventional proportional-integral (PI) control, the proposed technique improves the response of the output voltage to load steps and to high distorted output currents, reducing the distortion of the output voltage. Furthermore, an excellent distribution of currents between modules is achieved, resulting in fine power equalization between the inverters on stream. The crossover frequency of the different loop gains involved is moderate, so that robustness to variations of the operation point and to modeling uncertainties is achieved. A comparative study with a two-loop conventional PI control scheme is presented. Experimental results on a 1-kVA modular online UPS system confirm the viability of the proposed scheme.
- PublicationSensitivity Study of the Dynamics of Three-Phase Photovoltaic Inverters With an LCL Grid Filter(Institute of Electrical and Electronics Engineers, 2009) Figueres Amorós, Emilio; Garcerá Sanfeliú, Gabriel; Sandia Paredes, Jesús; González Espín, Francisco José; Calvo Rubio, Jesús; Dpto. de Ingeniería Electrónica; Escuela Técnica Superior de Ingeniería Industrial; Grupo de Sistemas Electrónicos Industriales[EN] An accurate small-signal model of three-phase photovoltaic (PV) inverters with a high-order grid filter is derived in this paper. The proposed model takes into account the influence of both the inverter operating point and the PV panel characteristics on the inverter dynamic response. A sensitivity study of the control loops to variations of the dc voltage, PV panel transconductance, supplied power, and grid inductance is performed using the proposed small-signal model. Analytical and experimental results carried out on a 100-kW PV inverter are presented.
- PublicationRobust Model-Following control of a three-level Neutral Point Clamped shunt active filter in the medium voltage range(Elsevier, 2009) Munduate, Alejandro; Figueres Amorós, Emilio; Garcerá Sanfeliú, Gabriel; Dpto. de Ingeniería Electrónica; Escuela Técnica Superior de Ingeniería Industrial; Grupo de Sistemas Electrónicos Industriales; Ministerio de Educación y Ciencia[EN] This paper presents a robust control technique applied to a three-phase shunt active filter based on an NPC inverter, showing the modelling procedure needed to carry out the proposed control. The transfer functions for the control of the currents injected by the active filter are derived. The modelling is based on the abc/dq Park transformation of the AC system variables. The currents injected by the active filter are controlled in the synchronous orthogonal dq reference frame. The proposed robust current control technique is compared to a conventional PI controller in the dq frame, and to a PIS controller in the dq frame, consisting of a PI and resonant controllers synchronized to the frequencies of the nonlinear load current harmonics. On one hand, it is shown that the proposed technique improves the current harmonics compensation obtained by conventional PI control. On the other hand, it is found that the PIS controller is the best suited for current harmonics compensation among the controllers under study. Nevertheless, the RMF controller results in a simpler implementation than the PIS controller. Moreover, the proposed robust control has been applied to the DC-link voltage regulation, and it has been compared to a PI controller. It is shown that the robust control technique improves the dynamic response of the inverter to load steps without the need of a high crossover frequency of the DC-link voltage loop.