Inversores com controle automatizado operando em microrredes com cargas desequilibradas

Abstract

This work aims at dimensioning and developing an automated hybrid microgrid using photovoltaic generation and an energy storage system, to be implemented at the Faculty of Engineering of the Federal University of Juiz de Fora (UFJF). Microgrids can be defined as an integrated system that involves distributed energy resources and several electrical loads operating as an autonomous network, either in parallel or isolated from the main electrical network. One of the great advantages of microgrids is the possibility of testing devices and control required for the development of smart electrical networks, with less risk and associated cost. The system was modeled and simulated in Matlab / Simulink version 2018a, with automated operations, detecting the occurrence of islanding and later doing the resynchronization process with the main network, under unbalanced load conditions. A multifunctional converter operates as Grid Forming Converter, supplying highly unbalanced loads. A converter in this scenario will need 4 arms to perform the control of the zero sequence components resulting from the load unbalance. Its operation in the grid-forming mode has not been fully addressed in the literature. The contribution of this work also includes the use of controllers based on the synchronous coordinate system, avoiding the use of complex controllers and obtaining an rapid transient response during system disturbances. Simulation results obtained were used to validate the proposed methodology, showing the functionalities of the implemented inverter, working automatically in the detection of the occurrence of islanding and resynchronization of the microgrid with the main grid. By comparing the results achieved with and without the voltage unbalance compensation algorithm, its effectiveness was shown, reducing the voltage unbalance factor (VUF) index to zero, keeping the output voltage on the PAC balanced