Controle hierárquico para inversores formadores de rede em microrredes AC

Abstract

This work presents the operating modes of a medium voltage Microgrid, addressing hierarchical control with a focus on primary and secondary control. In primary control, current control, voltage control, virtual impedance and droop loops are designed, the latter used to connect voltage sources in parallel. The secondary control loop is responsible for restoring voltage and frequency using a specific communication protocol between the microgrid agents. At this level, synchronization of the microgrid with the distribution grid is also implemented. The microgrid operates in accordance with the IEEE2030 standard, which defines the operating modes of controllers operating in microgrids, being characterized by 2 permanent modes: Connected and Islanded and by 4 transient modes: Planned Islanding, Unplanned Islanding, Reconnection and Black Start. The parameters used to characterize microgrid were considered using a section of the Federal University of Santa Maria campus network, where results were validated through a Hardware-in-theloop platform. Among the main contributions of the thesis are a new function for the implementation of virtual impedance, which aims to reduce noise generated by virtual impedance when an overload situation occurs in the microgrid. Another approach is a methodology for designing the speed of the phase synchronization loop between the grid forming inverter and the distribution network, which can be used operating with variable delays in communication protocols.