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- Overvoltage protection for grid-connected picohydro generation using photovoltaic invertersPublication . Scotta, Isabella Cristina; Maidana, Wellington; Leite, VicenteVery small-scale hydropower plants are environmentally friendly and renewable resource-based innovative solutions. The interest in pico-hydro systems (up to 5 kW) has increased significantly from the first stand-alone applications, at remote sites, to the distributed generation, with the injection of generated energy into the grid. Recently, there have been advances in the grid connection of these systems using off-the-shelf components, namely photovoltaic inverters. Therefore, pico-hydro systems have gained an enormous potential in distributed generation, particularly in the context of microgrids. However, in situations of over-power, or whenever the generator is under no load, e.g. when the grid fails, there is a need for effective over-voltage protection, as in small wind turbines. This paper proposes two over-voltage protection circuits, designed to ensure the integration of pico-hydro turbines connected to the grid using conventional photovoltaic microinverters and string inverters, for power ranges of 300 W and some kW, respectively. Extensive tests were performed on an emulation platform and a workbench using these two different over-voltage protection circuits. One is designed to connect the generators of water wheels to the grid and the other to connect 1,500 W generators of water turbines. The experimental results demonstrated the performance of the proposed over-voltage protection circuits in four different situations. Both avoid irreversible damages of generators, photovoltaic microinverters and string inverters in the context of the above-described grid connection approach.
- Conceção de um sistema autossustentável para um edifício de divulgação de ciência: a Casa da SedaPublication . Maidana, Wellington; Leite, Vicente; Bonaldo, Jakson PauloA presente dissertação tem como objetivo apresentar a conceção de um sistema autossustentável baseado em fontes de energia renováveis - hidrelétricas e fotovoltaicas - para um centro dedicado à divulgação e disseminação da ciência denominado Casa da Seda, que faz parte Centro Ciência Viva de Bragança. A solução é baseada numa microrrede ligada à rede elétrica, utilizando tecnologias inovadoras para produção, armazenamento e gerenciamento de energia. A microrrede é baseada num conjunto de cluster com três inversores de bateria que estabelecem um sistema de abastecimento trifásico. A energia hidroelétrica é produzida usando uma turbina de baixa queda do tipo hélice, que funciona como uma pico-hídrica, conectada à microrrede através de uma solução inovadora. A energia fotovoltaica é produzida por meio de telhas fotovoltaicas e módulos convencionais.
- Modular data acquisition architecture for thin-film sensors surfacesPublication . Rodrigues, Nelson; Lima, José; Rodrigues, Pedro João; Carvalho, José Augusto; Laranjeira, Jorge; Maidana, Wellington; Leitão, PauloThin-film sensors surfaces are becoming popular to collect data in several specific and complex processes, namely plastic injection or metal stamping, allowing the digitization of such processes through the use of Internet of Things technologies. A particular challenge in such thin-film sensors surfaces is the data acquisition and signal conditioning system, which implementation is complex due to the characteristics of these sensors (e.g., low amplitude and noisy signals), but even more complex when implemented in real industrial processes, which are subject to harsh conditions, namely noise, dirt and aggressive elements. This work describes a modular data acquisition and signals conditioning system for thin-film sensors surfaces, meeting the requirements of scalability, robustness and low-cost, meaning that it can be easily expanded according to the number of sensors required for the application scenario.
- Photovoltaic water pumping system for small power conventional AC pumpsPublication . Tangerino, Bruno Henrique Boschetti; Roman, Dionizio José Vargas; Leite, V.; Goedtel, Alessandro; Ferreira, Ângela P.; Batista, José; Maidana, WellingtonThe interest of photovoltaic (PV) water pumping systems with standard components is increasing as a low cost and independent solution over dedicated systems. However, one of the challenges of this alternative is the fact that small power systems to drive power pumps require a small number of PV modules and the PV string voltage is, usually, not enough to feed the frequency converter. This paper presents an approach to the drive, using a DC/DC converter with maximum power point tracking (MPPT). The overall system has been tested on a real experimental platform.
- Grid connection approach for very small-scale pico-hydro systems using PV microinvertersPublication . Ribeiro, Gabriela Moreira; Maidana, Wellington; Leite, V.; Ferreira, Ângela P.The use of renewable energy sources has grown significantly in recent decades, with emphasis on resources that have a low environmental impact in the energy production process. Small-scale pico-hydro systems have great potential and are also in line with increasing environmental requirements.
- Soiling monitoring modelling for photovoltaic systemPublication . Pagani, Vitor Henrique; Los, Nelson Anthony; Maidana, Wellington; Leitão, Paulo; Casaro, Marcio M.; Nascimento, Claudinor B.Soiling on photovoltaic panels is a factor that has a significant impact on the photovoltaic production. The monitoring of the soiling index appears as a relevant alternative for the maintenance of solar systems. This work proposes a soiling index modelling for photovoltaic systems based on two input variables, namely the solar radiation and the generated current, providing a simple, programmable and reliable way to check the efficiency and be able to establish the parameters for cleaning the system. The study was based on the adaptation of an existing mathematical modelling, that besides to estimate the soiling index also allows to establish an optimal point for cleaning. The proposed model is compared with the results provided by the PVSyst software aiming its validation. The achieved results show that, despite the developed system only consider two input variables, it presents a low relative error, i.e. 2.07%, when compared to the PVSyst software, allowing to conclude that the proposed modelling system is valid and presents excellent reliability, having a vast applicability in the monitoring of solar producers of any model or size.
- Design of a elf-sustainable system based on renewable energy sources for a small museum of science dissemination - the house of silkPublication . Maidana, Wellington; Leite, Vicente; Ferreira, Ângela P.; Queijo, Luis; Batista, José; Bonaldo, Jakson; Gonçalves, EstefâniaThis paper presents the complete design of a selfsustainable system based on renewable energy sources - hydro and photovoltaic - for a small museum dedicated to the dissemination of science called House of Silk. The solution is based on a microgrid, connected to the main grid, using innovative technologies for energy production, storage and management. The microgrid is based on a cluster of three battery inverters which establish a three-phase supplying system. The hydro energy is generated using a low head, pico-hydro propeller turbine, connected to the microgrid through an innovative solution. The photovoltaic energy is produced by means of photovoltaic tiles and conventional modules.
- Implementation of a smart microgrid in a small museum: the silk housePublication . Figueiredo, Luís Guilherme Aguiar; Maidana, Wellington; Leite, V.Microgrids are an alternative approach for the supply of energy integrating decentralized power sources, electrical loads, energy storage, and management in a local grid. The system has the capability of power control and energy management using communications’ network between all devices, and is known as smart microgrid. This paper presents the implementation of a smart microgrid in the Silk House, a museum dedicated to dissemination of science located in Bragança, Portugal. It was funded by the Foundation for Science and Technology of Portugal under the SilkHouse Project. The goal is to transform the House of Silk in a self-sustainable museum contributing to the dissemination of renewable sources and new technologies for future buildings in smart cities. This work presents the context and requirements for the microgrid and describes the implementation of the renewable sources (photovoltaic and pico-hydro) and the SMA Flexible Storage System based on Sunny Island and Sunny Home Manager. This work also presents and analysis the first operating results since the start of operation at the end of July 2019.
- Over-voltage protection for pico-hydro generation using PV microinvertersPublication . Scotta, Isabella Cristina; Ribeiro, Gabriela Moreira; Maidana, Wellington; Leite, V.Innovative, low-cost, environmentally friendly and renewable resource-based solutions are emerging to meet growing global energy demand. Hydroelectric technology is quite old and mature. Despite its importance, it is associated with large plants, with environmental impact. On contrary, small-scale systems, called pico-hydro systems (up to 5 kW) are not yet explored. Anyway, the exploration of pico-hydro systems has been increasing consistently, from the first off-grid applications in remote places to distributed generation, with the injection of the generated energy in the main grid or microgrids. Very recently, there have been advances in grid connection of these small-scale systems, using off-the-shelf components. Indeed, pico-hydro systems can be connected to the grid using off-the-shelf components, namely photovoltaic inverters. Thus, grid-connected pico-hydro systems have gained an enormous potential in distributed production. However, in situations of over-power, or whenever the generator is under no load, there is a need for effective over-voltage protection, unlike photovoltaic systems. The goal of this paper is to propose an over-voltage protection circuit, designed to ensure the integration of low-power pico-hydro systems connected to the grid using conventional photovoltaic microinverters. Extensive tests were performed on an experimental platform using three microinverters easily found on the market and a low power generator (300 W) developed for small wind turbines. The experimental results, demonstrated the performance of the proposed over-voltage protection circuit in four different situations, presented in this work, thus avoiding irreversible damages of generators and microinverters, in the context of the above described grid connection approach.