Autonomous Power Management in LVDC Microgrids Based on a Superimposed Frequency Droop

In this paper, a novel droop approach for autonomous power management in low voltage DC (LVDC) microgrids based on a master-slave concept is presented. Conventional voltage-based droop approaches suffer from poor power sharing due to line resistance effects on a virtual resistance, which is solved by introducing a communication system to increase the current sharing accuracy. In this paper, a virtual frequency is superimposed by the master units, and slave units determine their output power according to the corresponding frequency-based droop characteristics. Unlike the voltage-droop methods, the proposed virtual frequency-droop approach can be applied for proportional power management among the energy units and loads in the microgrid without utilizing any extra communication system. The effectiveness of the proposed scheme is evaluated by simulations and further validated by experiments.