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- Economic and energy feasibility using photovoltaic solar energy sources as a response to the energy consumption of the municipality of BarcarenaPublication . Simões, Fábio; Viveiros, Carla; Barata, FilipeThis article provides an economic and energy feasibility study for the implementation of renewable photovoltaic energy sources, in the municipality of Barcarena, in order to sustain electric energy consumption, taking into account technological advances, the expected population increase and the energy potential of the study area. The consumption of electricity of the municipality under study is analysed, as well as their distribution among the various types of existing electricity production. The economic and energy influence of this implementation is analysed through different case studies, in order to meet the targets defined by the Oeiras Council with regard to the Sustainable Energy for Oeiras Action Plan (PAESO).
- Decarbonizing Hard-to-Abate Sectors with Renewable Hydrogen: A Real Case Application to the Ceramics IndustryPublication . Sousa, Jorge A. M.; Azevedo, Inês; Camus, Cristina Inês; Mendes, Luís; Viveiros, Carla; Barata, FilipeHydrogen produced from renewable energy sources is a valuable energy carrier for linking growing renewable electricity generation with the hard-to-abate sectors, such as cement, steel, glass, chemical, and ceramics industries. In this context, this paper presents a new model of hydrogen production based on solar photovoltaics and wind energy with application to a real-world ceramics factory. For this task, a novel multipurpose profit-maximizing model is implemented using GAMS. The developed model explores hydrogen production with multiple value streams that enable technical and economical informed decisions under specific scenarios. Our results show that it is profitable to sell the hydrogen produced to the gas grid rather than using it for self-consumption for low-gas-price scenarios. On the other hand, when the price of gas is significantly high, it is more profitable to use as much hydrogen as possible for self-consumption to supply the factory and reduce the internal use of natural gas. The role of electricity self-consumption has proven to be key for the project's profitability as, without this revenue stream, the project would not be profitable in any analysed scenario.
- Performance assessment of a wind energy conversion system using a hierarchical controller structurePublication . Viveiros, Carla; Melício, Rui; Igreja, José; Mendes, VictorThis paper deals with a hierarchical structure composed by an event-based supervisor in a higher level and two distinct proportional integral (PI) controllers in a lower level. The controllers are applied to a variable speed wind energy conversion system with doubly-fed induction generator, namely, the fuzzy PI control and the fractional-order PI control. The event-based supervisor analyses the operation state of the wind energy conversion system among four possible operational states: park, start-up, generating or brake and sends the operation state to the controllers in the lower level. In start-up state, the controllers only act on electric torque while pitch angle is equal to zero. In generating state, the controllers must act on the pitch angle of the blades in order to maintain the electric power around the nominal value, thus ensuring that the safety conditions required for integration in the electric grid are met. Comparisons between fuzzy PI and fractional-order PI pitch controllers applied to a wind turbine benchmark model are given and simulation results by Matlab/Simulink are shown. From the results regarding the closed loop point of view, fuzzy PI controller allows a smoother response at the expense of larger number of variations of the pitch angle, implying frequent switches between operational states. On the other hand fractional-order PI controller allows an oscillatory response with less control effort, reducing switches between operational states. (C) 2015 Elsevier Ltd. All rights reserved.
- Protection against direct atmospheric discharges and overvoltages in photovoltaic installationsPublication . Coelho, Gonçalo; Barata, Filipe; Elvas, Luís; Viveiros, CarlaThe increasing global energy demand has led to the expansion of photovoltaic (PV) power plants, particularly in response to climate goals like the European Union's "Fit for 55" initiative to reduce CO2 emissions by 55% by 2030. However, as PV installations grow, their vulnerability to atmospheric discharges, such as lightning, also increases. This study investigates the design and dimensioning of lightning protection systems for PV plants, focusing on two methods: traditional protection per IEC 62305 standards and ionizing devices based on NP 4426 standards. Both methods were analyzed for technical feasibility and cost-effectiveness. A case study of the PV installations at the Lisbon Engineering School (ISEL) was conducted, and a risk analysis determined that Level III protection was required. The study demonstrated that both methods provide effective protection, but ionizing devices offer a more cost-efficient solution, with lower material and labor costs. Consequently, the study showed that ionizing method is around 35% affordable than traditional rods for protecting PV plants in urban environment against atmospheric discharges.
- Fractional order control on a wind turbine benchmarkPublication . Viveiros, Carla; Melício, Rui; Igreja, José; Mendes, VictorThis paper is about a hierarchical structure with an event-based supervisor in a higher level and a fractional-order proportional integral (FOPI) in a lower level applied to a wind turbine. The event-based supervisor analyzes the operation conditions to determine the state of the wind turbine. This controller operate in the full load region and the main objective is to capture maximum power generation while ensuring the performance and reliability required for a wind turbine to be integrated into an electric grid. The main contribution focus on the use of fractional-order proportional integral controller which benefits from the introduction of one more tuning parameter, the integral fractional-order, taking advantage over integer order proportional integral (PI) controller. Comparisons between fractional-order pitch control and a default proportional integral pitch controller applied to a wind turbine benchmark are given and simulation results by Matlab/Simulink are shown in order to prove the effectiveness of the proposed approach.
- Fractional order control on a wind turbine benchmarkPublication . Viveiros, Carla; Melício, Rui; Igreja, José; Mendes, VictorThis paper is about a hierarchical structure with an event-based supervisor in a higher level and a fractional-order proportional integral (FOPI) in a lower level applied to a wind turbine. The event-based supervisor analyzes the operation conditions to determine the state of the wind turbine. This controller operate in the full load region and the main objective is to capture maximum power generation while ensuring the performance and reliability required for a wind turbine to be integrated into an electric grid. The main contribution focus on the use of fractional-order proportional integral controller which benefits from the introduction of one more tuning parameter, the integral fractional-order, taking advantage over integer order proportional integral (PI) controller. Comparisons between fractional-order pitch control and a default proportional integral pitch controller applied to a wind turbine benchmark are given and simulation results by Matlab/Simulink are shown in order to prove the effectiveness of the proposed approach.
- Intelligent systems applied to buildings' managementPublication . Pereira, Rita; Barata, Filipe; Viveiros, CarlaEnergy efficiency in buildings are an important domain regarding its impact in the global energy consumption. Several efficiency measures are currently available, using different methodologies. In this paper an approach using intelligent systems is implemented through a smart controller able to automatically and efficiently manage building’s energy. This smart controller uses Fuzzy Logic Control (FLC) as a decision maker and is supported by Artificial Neural Networks (ANN) used to forecast the building outside temperature. In addition, and in order to increase overall energy efficiency, renewable energies associated with a storage system are considered. For the designed smart controller implementation, a thermal house model is simulated using a MATLAB toolbox. In this paper emphasis is given to the building´s Heating Ventilation and Air Conditioning (HVAC) control and a rough economic analysis is drawn, allowing to infer about the adopted efficiency measures impact.
- Fuzzy, integer and fractional-order control: application on a wind turbine benchmark modelPublication . Viveiros, Carla; Melício, Rui; Igreja, José; Mendes, VictorThis paper presents a comparison between proportional integral control approaches for variable speed wind turbines. Integer and fractional-order controllers are designed using linearized wind turbine model whilst fuzzy controller also takes into account system nonlinearities. These controllers operate in the full load region and the main objective is to extract maximum power from the wind turbine while ensuring the performance and reliability required to be integrated into an electric grid. The main contribution focuses on the use of fractional-order proportional integral (FOPI) controller which benefits from the introduction of one more tuning parameter, the integral fractional-order, taking advantage over integer order proportional integral (PI) controller. A comparison between proposed control approaches for the variable speed wind turbines is presented using a wind turbine benchmark model in the Matlab/Simulink environment. Results show that FOPI has improved system performance when compared with classical PI and fuzzy PI controller outperforms the integer and fractional-order control due to its capability to deal with system nonlinearities and uncertainties. © 2014 IEEE.
- Fleet transition from combustion to electric vehicles: a case study in a portuguese business campusPublication . Pinto, Bruno; Barata, Filipe; Soares, Constantino; Viveiros, CarlaThis paper aims to contribute to the urgent reflection as a society about environmental protection, in the ultimate challenge that is the sustainable use of energy resources. Since Portugal is at an early stage of market development internally, governmental and local stimulation policies play a central role and are a key element in the successful diffusion of Electric Mobility. The study will focus on the transition of a company car fleet, which currently consists of combustion vehicles, to electric vehicles. With this change it becomes necessary to understand how the electrical installation will be affected due to the installation of charging stations, allowing the company to have some autonomy from the public grid. The various changes resulting from the installation consumption profile will be studied and compared. The state of the art, the level of maturity and where the development of electric mobility in Portugal is heading will also be appreciated.
- Supervisory control of a variable speed wind turbine with doubly fed induction generatorPublication . Viveiros, Carla; Melício, Rui; Igreja, José; Mendes, VictorThis paper is on an onshore variable speed wind turbine with doubly fed induction generator and under supervisory control. The control architecture is equipped with an event-based supervisor for the supervision level and fuzzy proportional integral or discrete adaptive linear quadratic as proposed controllers for the execution level. The supervisory control assesses the operational state of the variable speed wind turbine and sends the state to the execution level. Controllers operation are in the full load region to extract energy at full power from the wind while ensuring safety conditions required to inject the energy into the electric grid. A comparison between the simulations of the proposed controllers with the inclusion of the supervisory control on the variable speed wind turbine benchmark model is presented to assess advantages of these controls. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).