Distributed secondary control with reduced communication in low-voltage DC microgrid

DC microgrid includes various sources and loads, interconnected to the dc system, using power electronic converters. Low voltage regulation and proportional load sharing are the important control objectives of dc microgrid. Distributed secondary controller with communication among these sources help in achieving the aforementioned control objectives. Most of the existing techniques utilize communication among all the converters. This increases communication infrastructure requirement. In this paper, a distributed control strategy based on cooperative control is proposed to attain low voltage regulation and proportional load sharing with less communication. Each source communicates only to its neighbors, thereby utilizing reduced number of communication links in the dc microgrid. The underlying communication topology is represented by a fixed, directed and balanced graph. Each source uses an average current estimator which estimates the average of per-unit currents of all the sources in the microgrid utilizing localised communication. These estimates are used by each source converter for regulating their respective voltages. The small signal model of the microgrid with the proposed control scheme is derived and discussed in this paper. Simulation results are presented which validate the performance of the microgrid with the proposed control scheme.