Estudo de técnicas de rastreamento do ponto de máxima potência e anti-ilhamento em sistemas fotovoltaicos conectados à rede elétrica

Abstract

This work presents a detailed study of the main techniques to extract the maximum power from photovoltaic panels and anti-islanding techniques with simulations and comparative analyzes of the same. Also presents a study of the major technical standards that deal with the interconnection of PV systems to the grid. Through comparative analysis of algorithms (Maximum Power Point Tracking - MPPT) and Anti-islanding (AI) methods which achieved the best results were used for an application of a photovoltaic (PV) system connected to single-phase grid, which is composed of two parallel photovoltaic array, each on with four panels connected in series, a step-up DC-DC converter and voltage source inverter (VSI) controlled in current mode. The perturb and observe (P&O) technique is used for tracking the maximum power point (MPPT) of the PVs arrays, and the displacement frequency algorithm (Slip-Mode Frequency Shift - SMS) is used for islanding protection. Moreover, control techniques are adopted to allow the current injection into utility grid, from the energy provided by the PVs array. The currents injected into the grid is synchronized with the grid voltage using an algorithm to detect the angle of the phase (PLL - Phase-Locked Loop). An additional control loop called feed-forward was proposed to mitigate the variations of the DC bus voltage at the instants of changes in climatic factors (increasing or decreasing the energy available in the PV array).