Distributed Control of Hybrid AC/DC Microgrids: from Synchronous to Asynchronous Algorithms

Hybrid AC/DC microgrids (MGs) have become a promising manner for better interconnection of various kinds of distributed generators that are inherently AC or DC electric sources. This paper addresses the distributed asynchronous power control problem of hybrid microgrids, considering imperfect communication due to non-identical sampling rates and communication delays, etc.. To this end, we first formulate the optimal power control problem of MGs and devise a synchronous algorithm. Then, we analyze the impact of asynchrony on optimal power control and propose an asynchronous iteration algorithm based on the synchronous version. By introducing a random clock at each iteration, different types of asynchrony are fitted into a unified framework, where the asynchronous algorithm is converted into a fixed-point problem, leading to a convergence proof. We further provide an upper bound estimation of the time delay in communication. Finally, a benchmark MG is utilized to verify the effectiveness and advantages of the proposed algorithm.