Evaluation of an Autonomous Control Scheme for Interconnected DC Microgrids Using a Power Hardware-in-the-Loop Platform

DC microgrids (DCMGs), typically envisioned with high bandwidth communications, may well expand their application range by considering additional autonomous control strategies, especially to increase resiliency in contingency situation. These strategies are based on the droop control methods, enabling voltage regulation and proportional load sharing based only on local measurements. Control challenges arise when coordinating the output of multiple DCMGs, each composed of several distributed energy resources through bus-to-bus transactional converters. This paper proposes an autonomous control strategy for transactional converters when multiple DCMGs are connected through a common bus. This control strategy seeks to match the external bus voltage with the internal bus voltage, balancing power. Three case scenarios are considered: standalone operation of each DCMG, excess generation on one DCMG, and generation deficit in one DCMG. Results using Sandia National Laboratories' Secure Scalable Microgrid Simulink library, and models developed in MATLAB are compared. These results demonstrated that the proposed control strategy supported the advantage of seamless operation with and without local generation-load mismatches and expanded the range of autonomous operation between DCMGs.