Impact of Community Structure on Robustness of Power Systems

Modern power grids are expanding and tightly interconnected, making cascading failures the leading cause of large blackouts and a severe threat to secure operation. Network science shows that grid topology - especially community structure - critically shapes fault propagation. This paper systematically examines how community structure affects power-system robustness against cascading failures. First, we propose simple rules to build large-scale grids ranging from random to strongly modular networks, mirroring realistic topologies. Second, a DC power-flow cascade model, coupled with Monte Carlo simulations, reproduces and statistically analyzes the post-disturbance evolution. Finally, we adopt the power-loss ratio (RBS) as an index to quantify and compare robustness, assessing how communities inhibit fault spread and explaining the causes. Results reveal that networks with stronger communities exhibit smaller average power losses and retain higher structural integrity during cascades; clear community boundaries isolate fault zones and block further spread, significantly enhancing grid robustness and resilience. This paper provides theoretical guidance and practical strategies for power grid topology design, enhancing disaster resistance.