Stability of Networking DC Microgrids with Active Loads

Direct current networking microgrids (NMGs) have gained prominence as a means to integrate renewable energy sources and enhance system resilience and robustness through the interconnection of nearby microgrids, typically using cooperative and distributed control strategies. However, they offer a complex scenario regarding stability as they are strongly influenced by several aspects such as delays in the communication network, fluctuating renewable energy sources and presence of multiple uncertain loads spread across the different buses. Despite the aforementioned challenges having been addressed in the literature, a comprehensive simultaneous analysis and coverage of all aspects is yet to be undertaken. With the aim to fill a gap in the knowledge, in this paper, a delay-dependent stability analysis for NMGs is presented, with a specific focus on robust operation in the presence of active loads. The formulation also accounts for the uncertain and varying nature of loads within microgrids. The purpose of the study is to assess the extent to which active loads and communication delays impose more stringent constraints on feasible operating conditions, consensus matrix design, and controller tuning. Circuit simulations are carried out to compare and ratify the insights derived from the stability analysis predicted by the study.