Revista Eletrônica de Potência (Brazilian Journal of Power Electronics)

Palavras Chaves: Conversores Conectados à Rede, Filtro LCL

Resumo
Este trabalho propõe a utilização de uma estrutura cascata de controladores adaptativos do tipo entrada-saída por modelo de referência (MRAC) utilizando modelos de ordem reduzida para um inversor quasi-Z-Source, conectado à rede por meio de um filtro LCL. A implementação da estrutura adaptativa por meio de modelos de referência reduzidos possibilita um sistema de controle adaptativo mais simples de ser implementado, com equacionamento matemático reduzido e menor esforço computacional. Para a redução da ordem dos modelos de referência, dinâmicas presentes em frequências mais elevadas da planta não são consideradas para projeto do controlador, possibilitando a implementação de uma estrutura simplificada que não comprometa a estabilidade e o desempenho do sistema. Resultados online em Hardware-In-the-Loop implementados em um DSP TMS320F28335 são apresentados, comparando a estrutura proposta com um controlador MRAC-SM por realimentação de estados sem simplificação de modelos. É mostrado que a estrutura adaptativa desenvolvida se comporta de forma robusta em relação às incertezas, apresenta baixo erro de rastreamento e carga computacional reduzida quando comparada com a estrutura adaptativa sem redução do modelo de referência.

Title: GRID-TIED PHOTOVOLTAIC QUASI-Z-SOURCE INVERTER WITH LCL FILTER USING A SIMPLIFIED MRAC-SM CASCADE STRUCTURE FOR WEAK GRIDS

Keywords: Grid Connected Converters, LCL filter

Abstract
This paper presents the use of a cascade structure of adaptive output-feedback controllers by reference model (MRAC) using reduced order reference models for a quasi-Z-Source inverter, connected to the electrical grid through an LCL filter. The implementation of the adaptive structure through reduced model references allows a simpler control structure to be implemented, with significantly simplified mathematical equation and less computational effort. To reduce the order of the model references, plant dynamics present at higher frequencies are not modeled and are disregarded for the choice of models, enabling the implementation of this structure without compromising the system's stability and performance. Online results in Hardware In-the-Loop implemented in a DSP TMS320F28335 are presented, comparing the proposed structure with an MRAC-SM controller by state feedback without simplification of models. It is shown that the adaptive structure developed behaves robustly in relation to the uncertainties in the system, presents low tracking error and reduced computational effort when compared to the adaptive structure without reducing the reference model.

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