Stability analysis of a Networking DC microgrid with distributed droop control and CPLs

Abstract

Networking direct current microgrids (DCMGs) have gained interest in the pursuit of achieving higher integration of renewable energy sources (RESs) and improving system resilience and reliability. The highly cooperative nature of these MGs is an advantage in order to maximize the RESs utilization and minimize grid power demand. However, ensuring stable and robust operation in the presence of significant load fluctuations constitutes a major challenge. Overvoltages and overcurrents, among other phenomena related to system stability, deteriorate the power quality and can be prevented with proper analysis. In this regard, numerous research studies have presented proposals related to the achievment of an optimal power distribution among the individual MGs of a networking DCMG. However, the stable operation of these MGs still requires further analysis to reach the same level of understanding accomplished in other topologies. Therefore, in this paper, a stability analysis for a networking DCMG is presented. This analysis includes the modeling of the system considering a distributed control strategy and the presence of uncertain active loads, and the subsequent formulation of sufficient conditions of load and generation power for robust stability of the DCMG. Finally, the concordance between the results of the circuital simulations and those related to the stability analysis is assessed. Moreover, conclusions about the representation of the microgrid and the optimal tuning of the controller´s gains and parameters are drawn.