Communication Topology Optimization for Time-Delay Cyber–Physical Microgrids Under Distributed Control

An inverter-based microgrid under distributed control is a cyber-physical system (CPS). Communication topology plays a significant role in the stability of such a system. Topology optimization for better convergence of a distributed algorithm in the cyber space does not necessarily improve the performance of a CPS. From a CPS perspective, this paper investigates the impact of topology on system dynamics by introducing the graph Laplacian matrix into a sampled-data-based cyber-physical model for inverter-based microgrids under distributed control. Then, the communication topology design is generated by an iterative algorithm by solving a mixed-integer semidefinite programming (MISDP) problem for minimum cost topology and a cyber-physical stability criterion, where the optimal solution of the MISDP problem can be obtained without any concession of the optimization model. A real-world 10.5 kV microgrid under distributed frequency control is tested in case studies. The findings show that our method can not only characterize the stability region of the system under various conditions but also enhance the CPS stability performance compared to the conventional distributed algorithm protocol.