Algoritmo Power-Based Control modificado para coordenação de inversores em microrredes de energia elétrica

Abstract

This PhD dissertation proposes a modified version of the Power-Based Control (PBC) algorithm for managing distributed energy resources (DERs) in advanced microgrids (MGs). The proposed Modified Power-Based Control (MPBC) algorithm inherits the main characteristics of PBC, such as low implementation complexity, minimal information technology requirements (i.e., low data transmission rate), and no need for prior knowledge of the grid topology and line impedances. This novel formulation allows distinction between connected dispersed DERs (i.e., phase-phase and phase-neutral) to the electric power MG. In this scenario, power sharing among DERs and current imbalance compensation are readily achieved, with phase-phase and phase-neutral DERs sharing balanced power, while unbalance and homopolar powers are addressed only to phase-neutral-connected DERs. This fact provides a greater degree of freedom for power sharing in the MG, as the system has now twice the scalar coefficients compared to PBC. The control strategy is applied in a dispatchable MG framework based on a centralized hierarchical control architecture. The proposed algorithm is compared to PBC by means of simulations in a four-wire three-phase MG under different voltage and load conditions. In this regard, an MG prototype is developed for experimental validation of the strategy and comparison against PBC during the execution of ancillary services. It is worth noting that the proposed algorithm is employed in the Tesla MG developed at the School of Engineering of the Federal University of Minas Gerais, using commercial devices. The Tesla MG is capable of performing various ancillary services such as self-consumption, energy time shift, peak shaving, and reactive support to the upstream utility grid. Due to the intrinsic characteristics of the three battery technologies (lead-acid, lithium-ion, and molten salt) employed in the Tesla MG, a control for usable average energy is proposed to ensure that the different battery banks reach their minimum State of Charge (SoC) values simultaneously, thus avoiding one technology from limiting the energy delivery of the others. Finally, two strategies are presented for managing power flow in MGs with multiple points of common coupling and/or a group of MGs using PBC.