Aplicação do FCS-MPC em Conversores com Transição Suave entre Modos de Operação

Abstract

This work approaches a methodology for controlling converters that perform smooth transition between microgrid operation modes using Finite Control Model-Based Predictive Control (FCS-MPC). Therefore, the behavior of the variables of a single-phase Grid Forming Converter (CFR) with LCL output filter is studied, responsible for connecting and disconnecting the microgrid from the main electrical grid. For the synchronism and connection to the electrical grid, this work uses a Frequency Locked Loop (FLL) based on a adaptive notch filter, resposible for estimating the frequency and phase of the converter output voltage and the grid voltage. The main contributions of this work are: the adjustments of the FCS-MPC cost function and its integration with the FLL in order to assure a smooth transition when the converter is connected to the grid. These results are obtained through adequate choices of FCS-MPC cost functions variables and an active resonance damping techniques integrated into the model. The proposed methodology is simulated in the software MATLAB/Simulink and the results show that it is possible to smoothly transit between the modes of operation of the microgrid without unwanted transients, only by adjusting the cost function and inserting a virtual resistance.