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- Improvement of DC microgrid voltage regulation based on bidirectional intelligent charging systemsPublication . Santos, Pedro; Fonte, Pedro M; Luís, RicardoIn several cities, there are existing DC tram/subway grids. These existing grids in some cases cover a big part of the city and create the opportunity to install EV charging infrastructures. Such implementation could be built in order to contribute to the DC grid stability, enhancing the DC grid voltage regulation, through vehicle-to-tram concept. This can be reached with bidirectional DC/DC converters which enable energy transfer from vehicles to the DC grid to support such starts. Hereafter, the energy may flow normally from the grid to the vehicles. However, these improvements come with certain challenges in terms of power conversion, voltage regulation, grid coordination and intelligence. This paper defines the design principles of a tram DC-microgrid, which enables fast-charging, supported by fuzzy controllers that follow dynamically the overhead line voltages and the charging/discharging conditions of the proposed EV charging infrastructure. A discussion and conclusion about the practical applicability of the tram DC microgrid and its the complementarity with the EV charging infrastructure are demonstrated evaluating the results of DCmicrogrid voltage regulation with the proposed methodology.
- Using power electronics and automation to simulate solar PV systemsPublication . Fonte, Pedro M.; Cordeiro, Armando; Barata, Filipe; Pires, V. Fernão; Chaves, Miguel; Foito, Daniel; Gamboa, PauloThis paper presents a solar photovoltaic panel simulator system with the ability to perform automatic tests in different condition according to manufacture parameters. This simulator is based on three buck--boost DC -DC converters controlled by a microcontroller and supported by a AXC 1050 Programmable Logic Controller from Phoenix Contact which is responsible for running the automatic tests. This solution allows to understand the typical operation of solar photovoltaic panels and MPPT algorithms considering suddenly changes in the irradiation, temperature, or load.
- Sensing cloud optimization to solve ED of units with valve-point effects and multi-fuelsPublication . Fonte, Pedro M; Monteiro, Cláudio; Barbosa, Fernando Pires MacielIn this paper a solution to an highly constrained and non-convex economical dispatch (ED) problem with a meta-heuristic technique named Sensing Cloud Optimization (SCO) is presented. The proposed meta-heuristic is based on a cloud of particles whose central point represents the objective function value and the remaining particles act as sensors "to fill" the search space and "guide" the central particle so it moves into the best direction. To demonstrate its performance, a case study with multi-fuel units and valve- point effects is presented.
- Demand response model for hardware implementationPublication . Capitão, B.; Lagarto, João; Pereira, Rita; Almeida, P.; Fonte, Pedro MDemand response actions allow to support an adequate domestic load management, considering consumer preferences. In order to develop a hardware tool based on Arduino used to support consumers load management and decisions, an optimization mathematical model is developed and detailed in this paper. In the developed mathematical model, household appliances and electric vehicle are considered as controllable loads. The existence of a storage system based on batteries is considered as well as energy provided by the power grid and solar panel self-generation. The model is implemented using optimization software GAMS (General Algebraic Modeling System) as a Mixed Integer Programming (MIP) problem, where its outputs are used as inputs applied to the hardware used as interface between the optimization mathematical model and controllable loads.
- Renewable power forecast to scheduling of thermal unitsPublication . Fonte, Pedro M; Santos, Bruno; Monteiro, Cláudio; Catalão, João Paulo da Silva; Barbosa, Fernando MacielIn this work is discussed the importance of the renewable production forecast in an island environment. A probabilistic forecast based on kernel density estimators is proposed. The aggregation of these forecasts, allows the determination of thermal generation amount needed to schedule and operating a power grid of an island with high penetration of renewable generation. A case study based on electric system of S. Miguel Island is presented. The results show that the forecast techniques are an imperative tool help the grid management.
- Powertrain test bench systemPublication . Fonte, Pedro M; Almeida, Paulo; Luís, Ricardo; Pereira, Rita; Chaves, MiguelIn parallel with major automotive manufacturers, some smaller companies are trying to launch their own electric or hybrid-propulsion models. During the development of these prototypes some tests must be done, namely consumption, autonomy, batteries state-of-charge, gradability, among others. The results of these tests can lead changes in design, motorization or battery packages. This paper presents a powertrain test bench system in order to test electrical vehicles. Regarding the automobile sector, and due to EU ruling, it is intended to enable the test bench to apply the Worldwide Harmonized Light Vehicles Test Cycle. Having a laboratorial test bench that can emulate vehicle dynamics under a specific drive cycle will allow small automotive manufacturers to confirm compliance with the mandatory drive cycles during different stages of their development. Nevertheless, other electric vehicles (EV) like boats or trains, can also be tested since the mathematical models of their dynamics are available.
- Analysis of domestic prosumer influence on a smartgridPublication . Carvalhuco, João; Pereira, Rita; Fonte, Pedro MThe shift from a centralized production to a distributed generation based on renewable energy production has been increasing, resulting in prosumer arising as new stakeholder of the electrical system. In this paper, a prosumer that owns photovoltaic solar panels and small wind generator, is considered and renewable energy production forecast is given by artificial neural networks (ANN). An energy management model is developed considering a battery storage system. Several case studies are analyzed considering seasonality factors.
- Unit commitment based on risk assessment to systems with variable power sourcesPublication . Fonte, Pedro M; Monteiro, Cláudio; Barbosa, Fernando MacielThis paper presents the development of a complete methodology for power systems scheduling with highly variable sources based on a risk assessment model. The methodology is tested in a real case study, namely an island with high penetration of renewable energy production. The uncertainty of renewable power production forecasts and load demand are defined by the probability distribution function, which can be a good alternative to the scenarios approach. The production mix chosen for each hour results from the costs associated to the operation risks, such as load shed and renewable production curtailment. The results to a seven days case study allow concluding about the difficulty to achieve a complete robust solution.
- Combining power electronic converters and automation to simulate solar PV systemsPublication . Cordeiro, Armando; Chaves, Miguel; Gamboa, Paulo; Barata, Filipe; Fonte, Pedro M; Lopes, Hélio; Fernao Pires, Vitor; Foito, Daniel; Amaral, Tito; Martins, JoaoThis paper presents a solar photovoltaic panel simulator system with the ability to perform automatic tests in different condition according to manufacture parameters. This simulator is based on three buck-boost DC-DC converters controlled by a microcontroller and supported by a Programmable Logic Controller which is responsible for the automatic tests. This solution will allow to achieve fast response, like suddenly changes in the irradiation, temperature, or load. To control the power converter, it will be used a fast and robust sliding mode controller. Therefore, with the proposed system is possible to perform the I-V curve simulation of a solar PV panel, evaluate different MPPT algorithms considering different meteorological and load variation. The main advantage of this work is the possibility to evaluate and test several MPPT algorithms and understand the operation and typical operation of solar PV panels in different conditions. Several simulations and experimental results from a laboratory prototype are presented to confirm the theoretical operation.
- Transformerless ultra-high gain buck-boost DC-DC converter with single-switch of reduced voltage stressPublication . Cordeiro, Armando; Gamboa, Paulo; Luís, Ricardo; Fonte, Pedro M; Monteiro, Joaquim; Martins, João F.; Silva, J. Fernando; Foito, Daniel; Fernao Pires, VitorThis paper introduces a new DC-DC power converter topology capable of both step-up and step-down voltage conversion, with an exceptionally high voltage gain ratio.. Besides the high extension of the voltage gain range, the converter is also characterized by the use of a single switch. Moreover, the stress imposed on the switch's voltage is minimized, enabling the utilization of low-voltage, low RDS-ON MOSFETs. Consequently, this modification leads to reduced costs and losses associated with switch conduction and turn ON. Another aspect concerning the proposed converter is that the input current exhibits a continuous behavior, which can be significant for various applications. The paper provides insights into the operational performance, steady state behavior, and mathematical underpinnings of the proposed dc-dc converter. Comparative evaluation of the static voltage gain of the proposed converter and other topologies with comparable characteristics will also be shown. Verification of the presented converter's key features are conducted through both simulation and experimental assessments using a 440-W laboratory prototype. Through these analyses, the efficacy and viability of the modified coupled-inductor SEPIC converter with enhanced voltage gain capability are confirmed.