Understanding a Power Grid's Cyber-Physical Interdependence Through Higher-order Motifs

Power grid consists of interconnected cyber and physical networks. The complexity of which is increasing as a result several factors including: The convergence of low carbon technologies, the increased coupling of other critical networks, and a need for new distributed control and forecasting capabilities. These trends are creating unprecedented complexity in our critical networks, as well as introducing new threats to their functionalities. Hence, the network design is crucial to ensure the power grid's inherent security and resilience. Given its multilayered nature, this necessitates an understanding of the interdependence between cyber and physical networks. However, the heterogeneity between these networks makes it challenging to holistically analyze the power grid's cyber-physical architecture without losing granularity. To address this, higher-order motifs, defined as small connected subgraphs, can be employed to disclose the topological interdependence of heterogeneous networks at a local level. This paper uses an augmented cyber-physical WSCC 9-Bus System to investigate its 4-node motif patterns under different cyber attack scenarios. Certain 4-node motifs demonstrate their necessity to secure power grid functionality.