Enhanced Power and Energy Coordination for Batteries Under the Real-Time Closed-Loop, Distributed Microgrid Control

Abstract

Hierarchical controls, consisting of primary, secondary, and tertiary layers to realize different functionalities at different time scales, have been applied for microgrids to achieve the stable and economic operations. However, in islanded microgrids with pure renewables (i.e., wind, solar, and battery storage systems (BSS) only), the three layers shall interact rather tightly and frequently in order to effectively leverage limited capabilities of available resources against disturbances. To this end, this paper discusses a more responsive control framework, including the distributed schemes for individual primary, secondary, and tertiary control layers as well as the real-time closed-loop scheme for a prompt coordination of the three layers. Thus, the proposed control framework could promote real-time interaction of resources in islanded microgrids with limited communication and computation burdens. Based on this, an enhanced control module design for BSSs of different configurations is further discussed to optimally coordinate their power and energy states with improved operational stability and economics. The steady-state analysis confirms the compatibility of the designed power and energy goals in tracking optimal power and energy equilibria simultaneously, and a customized Lyapunov candidate function is used to prove the asymptotic stability of the overall control framework. The hardware-in-the-loop simulation validates efficacy of the designed control framework in promptly mitigating disturbances and effectively achieving convergence to the optimal economic equilibria.