821 research outputs found

    Novel Control Strategies for Parallel-Connected Inverters in AC Microgrids

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    Optimal load management of autonomous power systems in conditions of water shortage

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    The issues of optimizing the operation of micro hydropower plants in conditions of water scarcity, performed by additional connection to the grid of an energy storage system and wind power turbine, as well as optimal load management, are considered. It is assumed that the load of the system is a concentrated autonomous power facility that consumes only active power. The paper presents a rigorous mathematical formulation of the problem, the solution of which corresponds to the minimum cost of an energy storage system and a wind turbine, which allows for uninterrupted supply of electricity to power facilities in conditions of water shortage necessary for the operation of micro hydropower plants (under unfavorable hydrological conditions). The problem is formulated as a nonlinear multi-objective optimization problem to apply metaheuristic stochastic algorithms. At the same time, a significant part of the problem is taken out and framed as a subproblem of linear programming which will make it possible to solve it by a deterministic simplex method that guarantees to find the exact global optimum. This approach will significantly increase the efficiency of solving the entire problem by combining metaheuristic algorithms and taking into account expert knowledge about the problem being solved

    Frequency Stability of Hierarchically Controlled Hybrid Photovoltaic-Battery-Hydropower Microgrids

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    Architecture of a Microgrid and Optimal Energy Management System

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    With the growing population trends, the demand for electricity is accelerating rapidly. The policy planners and developers have great focus to utilize renewable energy resources (RERs) to encounter the scarcity of energy since they offer benefits to the environment and power systems. At present, the energy generation is evolving into a smart distribution system that assimilates several energy resources assuring to generate clean energy, to have reliable operational procedures, and to enhance the energy supervision and management arrangements. Therefore, the model of a distributed microgrid (DMG) with optimal energy management strategies based on multi-agent systems (MASs) technique has been focused in this chapter. Distributed energy resources (DER) have been considered for the generation of electrical power to fulfill the consumer’s load demands. Thus, a fully controlled architecture of a grid along with concept of MAS and its development platforms, implementation, and operational procedures have been discussed in detail. In addition, agent’s operations and their coordination within the MG arrangements have been focused by considering the supervision of the entire system autonomously. Moreover, optimal procedures of a microgrid (MG) energy supervision and power distribution system have also been presented considering the cost control and optimal operations of the entire MG at the distributed level

    Study of new vector-control algorithms for 3-phase inverters used in renewable agents connected to the low-voltage utility grid with disturbances

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    [ESP] La demanda de energía eléctrica se ha ido incrementando a través de los años debido al desarrollo que han tenido el sector industrial y de transporte, sumándose además el aumento de la población mundial y el desarrollo de nuevas tecnologías que requieren mayor cantidad de energía. Por ello, y con el propósito de generar la energía eléctrica necesaria para suplir a estos sectores, el consumo de combustible ha presentado un aumento significativo. Así, la energía consumida en el año 2010 fue de unos 153,000 TWh y se prevé que para el año 2020 esta cifra ascienda a 184,000 TWh, siendo la mayor parte de esta energía proveniente de combustibles fósiles, aunque el futuro de esta tendencia es incierto. Además, la población mundial se está concienciando cada vez más de los efectos negativos medioambientales que está provocando el llamado “efecto invernadero” y, como consecuencia, se están creando una serie de políticas energéticas con el fin de reducir la generación de gases y partículas contaminantes. Una alternativa para reducir la dependencia de los combustibles fósiles y, a la vez, reducir las emisiones de los gases tóxicos causantes del efecto invernadero, es el uso de fuentes de energías renovables como la solar fotovoltaica y la eólica, así como el uso de pilas de combustibles para almacenamiento de energía, todas ellas a instalar en el mix energético. En este sentido, los nuevos agentes renovables que se conecten a la red eléctrica trifásica de baja tensión deben controlarse adecuadamente y cumpliendo con las legislaciones energéticas vigentes. En este sentido, deben diseñarse nuevas y sofisticadas estrategias de control con el propósito de controlar adecuadamente las corrientes de línea de los inversores de conexión a red utilizados en los agentes renovables cuando existan perturbaciones en la red eléctrica de baja tensión, tales como las variaciones de su frecuencia nominal, los desequilibrios en las tensiones trifásicas y la presencia de contaminación armónica de baja frecuencia. Por todo lo anteriormente mencionado, esta tesis está enfocada en el estudio de varios algoritmos de control y sincronización utilizados en inversores en fuente de tensión (VSI) para conexión a red que operan como los acondicionadores de potencia para los sistemas renovables. Los estudios realizados se aplican a un sistema fotovoltaico, pero pueden extenderse a cualquier tipo de agente renovable utilizado en un sistema de Generación Distribuida. [ENG] Throughout decades, the electric power demand has been rising due to the growth of the industrial sector and transportation, and the development of new technologies that require more energy together with the increase of the global population have led to a higher fuel demand needed for the electric energy generation. The global energy consumption in 2010 was 153,000 TWh and it is expected an increment to 184,600 TWh by 2020, the majority provided by fossil fuels, although the future of these trend is uncertain. Besides, greenhouse effect is causing environmental changes that concern mankind and the creation of new energetic policies is a fact. An alternative for reducing the fossil fuel dependence and the reduction of the greenhouse gas emission is the use of clean and infinite renewable energy sources such as photovoltaic, wind, as well as fuel cells for energy storage, which have been installed in the energetic mix. In this context, new renewable agents are connected to the 3-phase utility grid and must be properly controlled according to power electrical legislations. For this, new and sophisticated control algorithms are to be designed in order to control properly the line currents of the grid-connected inverter when variations of the nominal frequency, voltage unbalances and low-order harmonics are present in the 3-phase utility grid voltage. This thesis is focused in the study of several control and synchronization algorithms used in grid-connected Voltage Source Inverters (VSI) working as the power conditioner circuits for renewable energy systems. The study of these algorithms is carried out using a grid-connected photovoltaic system, but they can be extended to any renewable agent in any distributed generation system.Universidad Politécnica de Cartagen

    Electric Power Conversion and Micro-Grids

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    This edited volume is a collection of reviewed and relevant research chapters offering a comprehensive overview of recent achievements in the field of micro-grids and electric power conversion. The book comprises single chapters authored by various researchers and is edited by a group of experts in such research areas. All chapters are complete in themselves but united under a common research study topic. This publication aims at providing a thorough overview of the latest research efforts by international authors on electric power conversion, micro-grids, and their up-to-the-minute technological advances and opens new possible research paths for further novel developments

    Power Conversion System for Grid Connected Micro Hydro Power System with Maximum Power Point Tracking

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    This research analyzed and simulated an electrical power conversion system for a grid-connected variable speed micro hydro turbine (MHT) system. Different from traditional hydro power systems, the MHT is running at variable speed condition with permanent magnet synchronous generator(PMSG). To decouple the relationship between the generator rotation speed and the output frequency, rectifier and DC boost converter is developed to maintain the output voltage when the generator is rotating in a low speed. The reference generator speed is given by the perturbation and observation maximum power point algorithm to extract more energy from the micro hydro turbine. The grid connected inverter converts the power from the DC side to the grid with a D-Q frame control. If the generator speed is high enough, the inverter will directly control the generator speed
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