Controle de conversores estáticos aplicado a sistemas de armazenamento por baterias com conversores integrados: uma abordagem de balanceamento ativo dos estados de carga em cenários de reversão de fluxo de potência

Abstract

The increasing integration of renewable energy sources into the electrical grid drives the demand for Energy Storage Systems (ESS), where the reuse of second-life batteries emerges as a potentially cost-competitive alternative. However, the heterogeneity of these cells in conventional series arrangements triggers the "weakest link" effect, limiting the system’s total capacity. This work proposes the development of a control system for battery banks based on the Smart-Battery architecture, aiming for active State of Charge (SoC) balancing and DC bus regulation. The methodology included the unified mathematical modeling of the Smart-Battery and the analysis of systems with multiple units in series, demonstrating the decoupling of control loops. For the output voltage regulation of the bidirectional converters, a robust control strategy based on Linear Matrix Inequalities (LMI) was developed, solving instability issues observed in classical methods (LQR) during power flow inversion. For the external balancing loop, a ProportionalIntegral (PI) controller was proposed, overcoming the steady-state error limitations of purely proportional controllers. Theoretical analysis proved the necessity of alternating the SoC controller gain signs depending on the current direction. Simulation results validated the effectiveness of the proposal, demonstrating that the system performs SoC equalization by forcing units with higher charge to process more power, maintaining stability and regulated bus voltage even under parametric variations and load inversions.