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Author: Garcerá Sanfeliú, Gabriel × Subject: Parallel inverters ×

Publication Search Results

Now showing 1 - 4 of 4
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    Publication
    A Control Stage for Parallel-Connected Interlinking Converters in Hybrid AC-DC Microgrids
    (Institute of Electrical and Electronics Engineers, 2023) Liberos Mascarell, María Antonia; González Medina, Raúl; Patrao Herrero, Iván; Torán Mort, Enric; Garcerá Sanfeliú, Gabriel; Figueres Amorós, Emilio; Dpto. de Ingeniería Electrónica; Escuela Técnica Superior de Ingeniería del Diseño; Escuela Técnica Superior de Ingeniería Industrial; Grupo de Sistemas Electrónicos Industriales; AGENCIA ESTATAL DE INVESTIGACION
    [EN] Having two or more interlinking converters connected in parallel in hybrid microgrids has some benefits, like modularity, flexibility, and redundancy. However, the parallelization of the inverters leads to circulating currents that can cause system malfunctions. This work uses a method for suppressing low-frequency circulating currents in interlinking converters by controlling the zero-sequence component of the phase currents, showing that the control structure is valid for interlinking converters. The proposed control scheme has been applied to two parallel interlinking inverters of 5 kW and 2.5 kW, respectively. The interlinking inverters are connected to the grid, and they control the voltage in the DC bus of the hybrid microgrid. To validate the concept, simulation and experimental results are shown.
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    Robust 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 Industriales
    This 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.
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    A Method to Enhance the Global Efficiency of High-Power Photovoltaic Inverters Connected in Parallel
    (MDPI AG, 2019-06-01) Liberos Mascarell, María Antonia; González Medina, Raúl; Garcerá Sanfeliú, Gabriel; Figueres Amorós, Emilio; Dpto. de Ingeniería Electrónica; Escuela Técnica Superior de Ingeniería del Diseño; Escuela Técnica Superior de Ingeniería Industrial; Grupo de Sistemas Electrónicos Industriales; Agencia Estatal de Investigación; Ministerio de Educación, Cultura y Deporte; Ministerio de Economía y Competitividad
    [EN] Central inverters are usually employed in large photovoltaic farms because they offer a good compromise between costs and efficiency. However, inverters based on a single power stage have poor efficiency in the low power range, when the irradiation conditions are low. For that reason, an extended solution has been the parallel connection of several inverter modules that manage a fraction of the full power. Besides other benefits, this power architecture can improve the efficiency of the whole system by connecting or disconnecting the modules depending on the amount of managed power. In this work, a control technique is proposed that maximizes the global efficiency of this kind of systems. The developed algorithm uses a functional model of the inverters¿ efficiency to decide the number of modules on stream. This model takes into account both the power that is instantaneously processed and the maximum power point tracking (MPPT) voltage that is applied to the photovoltaic field. A comparative study of several models of efficiency for photovoltaic inverters is carried out, showing that bidimensional models are the best choice for this kind of systems. The proposed algorithm has been evaluated by considering the real characteristics of commercial inverters, showing that a significant improvement of the global efficiency is obtained at the low power range in the case of sunny days. Moreover, the proposed technique dramatically improves the global efficiency in cloudy days.
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    Modelling and Control of Parallel-Connected Transformerless Inverters for Large Photovoltaic Farms
    (MDPI AG, 2017) Liberos Mascarell, María Antonia; González Medina, Raúl; Garcerá Sanfeliú, Gabriel; Figueres Amorós, Emilio; Dpto. de Ingeniería Electrónica; Escuela Técnica Superior de Ingeniería del Diseño; Escuela Técnica Superior de Ingeniería Industrial; Grupo de Sistemas Electrónicos Industriales; Ministerio de Educación, Cultura y Deporte; Ministerio de Economía, Industria y Competitividad; European Regional Development Fund
    [EN] This paper presents a control structure for transformerless photovoltaic inverters connected in parallel to manage photovoltaic fields in the MW range. Large photovoltaic farms are usually divided into several photovoltaic fields, each one of them managed by a centralized high power inverter. The current tendency to build up centralized inverters in the MW range is the use of several transformerless inverters connected in parallel, a topology that provokes the appearance of significant zero-sequence circulating currents among inverters. To eliminate this inconvenience, this paper proposes a control structure that avoids the appearance of circulating currents by controlling the zero-sequence component of the inverters. A second contribution of the paper is the development of a model of n parallel-connected inverters. To validate the concept, the proposed control structure has been applied to a photovoltaic field of 2 MW managed by four 500 kW photovoltaic inverters connected in parallel.