Estudos em controle de microrredes de corrente contínua: impedância virtual e droop adaptativo

Abstract

This master’s thesis examines the increasing prominence of DC microgrids compared to conventional alternating current (AC) grids, enhancement the elimination of AC/DC conversion losses and the flexibility of these structures. Challenges such as standardization, regulation, and technical issues related to management, control, protection, and the integration of technologies as energy storage systems (ESS) and distributed generation (DG) are identified. The research focuses on two main control approaches: virtual impedance and adaptive droop. The virtual impedance approach aims to enhance stability by reducing transient dynamic oscillations in DC bus voltage, evaluating four different strategies. Parametric analyses demonstrate the range of values that can be used in the design of specific elements, including low-pass filters and virtual inductors used in these strategies. System stability is validated through pole-zero mapping and the Routh-Hurwitz criterion. Simulations and tests using controller hardware-in-the-loop (C-HIL) are conducted to determine which strategy performs best for the DC microgrid. The proposed adaptive droop control aims to correct power-sharing imbalances among grid-forming converters. Parametric analyses validate the equations used in the proposed control. Simulations and tests using C-HIL demonstrate the effectiveness of the method and its contribution to maintaining the deviation between the states of charge of the ESS. The results highlight the effectiveness of these control strategies, demonstrating their potential to advance DC microgrids and efficiently integrate distributed electrical systems into the conventional grid.