Optimal Hardening Model for Reliable and Resilient Cyber–Physical Power Systems

Power networks are increasingly becoming complex and multidimensional, with a high level of interdependency with other infrastructures, which requires different approaches for modelling, planning and analysis. One critical infrastructure that is increasingly integrated with the physical power system is the cyber infrastructure, which helps improve the observability, security and control of a network. However, reliability during normal conditions and the resilience of the system during extreme events can both be affected, as the threats to the system can be of a physical or cyber nature. Hence, utilities must rethink how to optimally choose investments in the existing infrastructure to enhance both reliability and resiliency. This study proposes a robust model for interdependent cyber and physical networks in power systems that optimises the investment cost to improve the reliability and resilience of the system, considering the cost of energy not supplied. Different models are proposed to realistically reflect the cyber–physical power system, such as extreme weather events and cyber–physical threat models. The optimisation was modelled as a mixed-integer nonlinear optimisation problem, and a heuristic optimisation method was used to demonstrate the effectiveness of the model.