N-1 evaluation of integrated electricity and gas system considering cyber-physical interdependence

The deepening digitalisation of infrastructure has significantly increased the interconnection between power systems (PS) and gas systems (GS), rendering integrated electricity and gas systems (IEGS) more vulnerable to cyber-physical contingencies (CPC). This paper pioneers the investigation into N-1 contingency evaluation for cyber-physical IEGS to identify critical failures that pose threats to operational security. To accurately model various CPCs in IEGS, we introduce a nonlinear partial differential-algebraic equation (PDAE) model, which redefines CPCs as discontinuities and abrupt changes in simulation boundaries. We further propose a variable-coefficient analytical method (VC-AM) designed to robustly and efficiently handle these reformulated boundaries during CPC simulations. Building on this foundation, an N-1 evaluation framework is established to explore the contingency impact propagation and detect resultant violations, incorporating several performance indexes to quantify and rank the impacts of diverse contingencies. Case studies reveal that cyber-physical interdependence notably amplifies the effects of contingencies, underscoring the potential of VC-AM for real-time N-1 evaluation. In contrast, traditional methods are hindered by high computational complexity and convergence challenges.