Optimal Frequency Restoration of Inverter-Interfaced Microgrids via Distributed Energy Management

Abstract

Despite the potential role of microgrids is well recognized in supporting the integration of renewable energy sources into the future power system, the impacts of intermittence renewable generation on the microgrid frequency stability is still being explored, and the related challenges remain to be addressed. In this paper, we focus on an islanded inverter-interfaced microgrid and present a consensus-based gradient algorithm for optimal frequency restoration via distributed energy management, preserving the standard hierarchical control architecture but merging the interdependent layers. The network-preserving model is applied to prevent loss of network topology and transient characteristics. Furthermore, not only distributed generators but also demand-side customers are considered to be actively participating in the proposed architecture. Convergence analysis implies that the closed-loop system is asymptotically stable, and its equilibrium will converge to the optimal solution of the associated energy management problem, which is consistent with the observation from the simulation study, including intermittent generation and load perturbation, carried out on a 6-bus test microgrid system. Therefore, the effectiveness of the proposed algorithm is verified.