Stability Analysis of a Novel Distributed Secondary Control Considering Communication Delay in DC Microgrids

With the wide application of distributed dc microgrids and the increasing of dc loads, the distributed control method has become a research hotspot. However, the distributed control method based on distributed communication network usually involves communication delay, which may lead to the failure of the controller in the practical application and even affect the stability of the system. This paper introduces a novel distributed secondary control algorithm without droop control, which can be used to realize voltage recovery and load sharing simultaneously. Based on this, two stability criteria under different conditions are derived for the dc microgrid system considering communication time delay, which are delay-dependent stability criterion under constant delay and time-varying delay-dependent stability criterion by using linear matrix inequality (LMI). These stability criteria are helpful to guide the selection of control parameters. Simulation results verify the effectiveness and feasibility of the proposed control strategy, and show the correctness of the delay-independent stability criterion and delay-dependent stability criterion.