Delay-Dependent Small-Signal Stability Analysis and Compensation Method for Distributed Secondary Control of Microgrids

The secondary control of microgrids (MGs) normally relies on the communication network to exchange information. Communication delay is an inherent characteristic during the signal transmission process, which may deteriorate the system dynamic performance and even destabilize the system. This paper studies the impact of communication delay on the small-signal stability of MGs with distributed secondary frequency and voltage control, and further investigates the corresponding delay compensation method. First, a time-delayed small-signal dynamic model of MGs considering both distributed secondary frequency and voltage controllers is developed. Based on the model, a comprehensive delay-dependent stability analysis is performed to reveal how the amount of communication delay, the topologies of communication networks, and the values of control parameters affect the system stability. Subsequently, a delay compensator based on lead-lag compensation along with gain regulation block is designed to enhance the system stability against the communication delay. Finally, time-domain simulation and experimental results are presented to validate the effectiveness of the proposed methods.