Estudos para Implementação de Sistemas Fotovoltaicos Conectados à Rede Elétrica Utilizando Inversores Multiníveis em Condições de Sombreamento Parcial

Abstract

This study evaluates PS-PWM and LS-PWM modulation strategies, including PD-PWM, POD-PWM, and APOD-PWM, applied to cascaded H-bridge multilevel inverters (MLI-CHB). The main objective is to analyze their impact on total harmonic distortion (THD) and power quality, emphasizing their feasibility for grid-connected applications. Additionally, a Perturb and Observe (P&O) MPPT algorithm was implemented in a boost converter, validating its efficiency under dynamic irradiance conditions commonly observed in photovoltaic systems. The research also explores the use of an LCL filter to mitigate residual harmonics and grid synchronization through a Phase-Locked Loop (PLL) combined with Park’s transform, meeting standards such as ANEEL and IEEE 519. While focused on single-phase inverters, the analysis highlights their potential for low-power systems. The methodology involved a comprehensive literature review and simulations using Simulink/MatLab, evaluating scenarios like partial shading. Results demonstrate that the APOD-PWM modulation achieved THD below 1%, standing out as an efficient solution. The MPPT proved effective in maximizing energy extraction under dynamic conditions. Tests validated the MLI-CHB using DC voltage sources, with and without the LCL filter, and independently assessed the MPPT control. In conclusion, the multilevel topology combines efficiency and quality for low-power applications. However, future studies should explore complete practical implementations, integrating MPPT, grid synchronization, and operation under partial shading and variable loads.