Hierarchical collaborative control for real-time economic dispatch and accurate frequency regulation of AC islanded microgrid

Abstract

In islanded microgrids (IMGs) characterized by a significant proportion of renewable energy, real-time economic dispatch and frequency control coordination are paramount. Conventional grid-forming (GFM) control methods fail to ensure that renewable distributed generators (RDGs) operate at their maximum power point (MPP), leading to suboptimal economic performance. Conversely, grid-following (GFL) control methods prevent RDGs from participating in frequency regulation, resulting in diminished frequency stability. To address this challenge, this paper introduces a hierarchical collaborative control strategy for real-time dispatch and frequency control in IMGs. The proposed strategy adopts a hierarchical control architecture, comprising primary control, secondary control, and real-time dispatch layers. The real-time dispatch layer employs the proposed distributed algorithm to determine the economically optimal output power for each dispatchable unit. Meanwhile, the primary and secondary control layers utilize decentralized algorithms to regulate the frequency and control the output power based on real-time dispatch outcomes. In the proposed strategy, RDGs are capable of participating in frequency regulation while operating at their MPP, thereby ensuring both stability and economic efficiency in high-penetration renewable IMGs. Test results demonstrate that compared to existing strategies, the proposed strategy achieves more comprehensive control performance, encompassing economically optimal real-time dispatch and accurate frequency control.