Modelagem e controle de um sistema fotovoltaico conectado à rede elétrica monofásica utilizando um conversor cc-cc elevador-baixador
This work presents a study of a single phase two-stage grid-tied photovoltaic (PV) system. The first stage is composed of a DC-DC Boost-Buck converter, whose attractive feature is that both input and output currents can be controlled through different duty cycles applied in each leg, which defines t...
| Autor principal: | Spier, Daniel Westerman |
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| Formato: | Trabalho de Conclusão de Curso (Graduação) |
| Idioma: | Português |
| Publicado em: |
Universidade Tecnológica Federal do Paraná
2020
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| Assuntos: | |
| Acesso em linha: |
http://repositorio.utfpr.edu.br/jspui/handle/1/7197 |
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| Resumo: |
This work presents a study of a single phase two-stage grid-tied photovoltaic (PV) system. The first stage is composed of a DC-DC Boost-Buck converter, whose attractive feature is that both input and output currents can be controlled through different duty cycles applied in each leg, which defines the proposed modulation strategy. The second stage consists of a DC-AC converter tied to the grid, whereby it is switched with the same frequency of the grid. The switching sequence is composed of three different states, which gives the basics to obtain the equivalent small-signal equations, the equivalent small-signal circuit and the transfer functions.
The initial modelling considers an ideal input voltage source and a pure resistive load. After validating the mathematical model, the voltage source is replaced by a PV array and the load becomes a voltage source inverter tied to the grid. Thus, a new small-signal model, equivalent small-signal circuit and transfer functions are obtained and validated. Through the PV system mathematical model controllers are designed, in which the input switches control the PV array voltage and input current. The output ones control the DC-bus capacitor voltage and the output current in a fashion that the output current present a rectified sinusoidal waveform with twice the value of the grid frequency. Finally, simulation results of a 3.5kW PV system are presented, validating the control strategy applied for different solar irradiation conditions. Furthermore, the results also presented low harmonic distortion in the current injected to the grid and unit power factor. |
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