Communication Time-Delay Stability Margin Analysis of the Islanded Microgrid under Distributed Secondary Control

In this paper, the communication time-delay stability margin analysis of an islanded microgrid (MG) are presented. Firstly, an accurate small-signal model is developed considering the communication delay among the communication links of secondary control. Each sub-module modeling of microgrid including inverter, line, load and secondary controller is developed respectively. Besides, an eigenvalue approach is proposed in this paper. Based on the developed MG small-signal model, the maximum delayed time (MDT) is redefined to access the stability margin for the MG system. Lastly, a compensating secondary controller is proposed to mitigate the impact of time delay. The effectiveness and accuracy of the proposed method and controller are validated by time-domain simulations.