Cyber-Attacks in a Looped Energy-Water Nexus: An Inoculated Sub-Observer-Based Approach

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The deployment of advanced sensors has strengthened the monitoring capability of power plants. In the context of the cogeneration process, the plant cooling is performed by the cooling towers using the condensation process on exhaust steam. However, the computer networks and industrial control systems built on this sensor-based digital layer may become vulnerable to cyberattacks. This may eventually raise a concern on the performance and security of these energy utilities. To resolve this issue, an inoculated subobserver-based fusion filter is proposed. It improves the resilience against malicious attacks in combined cycle power plants with desalination units, which are usually functioning in a closed-loop environment and infected with injected attacks. A time-delay-based state representation is considered for the system. To access latency in a closed-loop environment, a subsystem-based set of subobservers are introduced. Information from each sensor is then gathered using the interacting-multiple-model-based fusion process. The stability of the system has been proved and kept in-check at two different implementation levels of the procedure using functional equivalence and Lyapunov stability criteria, respectively. Performance evaluation is then conducted on a water-level system. Results show that the proposed scheme accurately extracted the system parameters from the contaminated measurements in the presence of multiple system disturbances and cyber intervention.