Browsing by Author "Fialho, L."
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- Desenvolvimento e validação do processo de reparação de módulos fotovoltaicos on sitePublication . Fialho, L.; Duarte, D.; Pires, C.; Horta, PedroRESUMO: Os módulos fotovoltaicos podem desenvolver alguns defeitos durante a operação contínua ao longo do seu tempo de vida. Alguns desses defeitos não apresentam um risco acrescido inicial, mas podem evoluir gradualmente para uma falha perigosa, refletindo-se numa redução na produção de eletricidade, paragens imprevistas e constituir um risco pessoal ou para a instalação. Estes defeitos podem ser reparados na sua fase inicial de modo a minimizar perdas de produção no módulo fotovoltaico e também evitar a sua perda total. Assim, a reparação apresenta-se como uma solução para recuperar módulos com falhas (pontos quentes), com resultados satisfatórios e podendo reduzir os custos associados à sua manutenção. No âmbito do projeto GRECO foi desenvolvido um processo de reparação compatível com módulos de modelos antigos, superando a dificuldade que apresenta a sua substituição por um novo módulo. Os resultados dos ensaios e validação deste processo de reparação apresentam resultados positivos, mantendo as características de segurança e fiabilidade do módulo reparado, em condições reais de operação outdoor.
- PV systems linked to the grid: parameter identification with a heuristic procedurePublication . Fialho, L.; Melício, R.; Mendes, V. M. F.; Estanqueiro, Ana; Pereira, Manuel CollaresThis paper focuses on a PV system linked to the electric grid by power electronic converters, identification of the five parameters modeling for photovoltaic systems and the assessment of the shading effect. Normally, the technical information for photovoltaic panels is too restricted to identify the five parameters. An undemanding heuristic method is used to find the five parameters for photovoltaic systems, requiring only the open circuit, maximum power, and short circuit data. The I–V and the P–V curves for a monocrystalline, polycrystalline and amorphous photovoltaic systems are computed from the parameters identification and validated by comparison with experimental ones. Also, the I–V and the P–V curves under the effect of partial shading are obtained from those parameters. The modeling for the converters emulates the association of a DC–DC boost with a two-level power inverter in order to follow the performance of a testing commercial inverter employed on an experimental system.
- Simulation of a-Si PV system grid connected by boost and inverterPublication . Fialho, L.; Melício, R.; Mendes, V. M. F.; Estanqueiro, AnaThis paper is about a PV system connected to the electric grid by power electronic converters, using classical PI controller. The modelling for the converters emulates the association of a DC-DC boost with a two-level power inverter (TwLI) or three-level power inverter (ThLI) in order to follow the performance of a testing experimental system. Pulse width modulation (PWMo) by sliding mode control (SMCo) associated with space vector modulation (SVMo) is applied to the boost and the inverter. The PV system is described by the five parameters equivalent circuit. Parameter identification and simulation studies are performed for comparison with the testing experimental system.
- A simulation of integrated photovoltaic conversion into electric gridPublication . Fialho, L.; Melício, R.; Mendes, V. M. F.; Viana, Susana; Rodrigues, Carlos; Estanqueiro, AnaThis paper presents a systemic modeling for a PV system integrated into an electric grid. The modeling includes models for a DC–DC boost converter and a DC–AC two-level inverter. Classical or fuzzy PI controllers with pulse width modulation by space vector modulation associated with sliding mode control is used for controlling the PV system and power factor control is introduced at the output of the system. Comprehensive performance simulation studies are carried out with the modeling of the DC–DC boost converter followed by a two-level power inverter in order to compare the performance with the experimental results obtained during in situ operation with three commercial inverters. Also, studies are carried out to assess the quality of the energy injected into the electric grid in terms of harmonic distortion. Finally, conclusions regarding the integration of the PV system into the electric grid are presented.