Load frequency regulation in renewable integrated multi-area cyber-physical power system considering nonlinearities and resonance attacks

The growing sophistication and widespread prevalence of cyber intrusions pose a critical threat to national power infrastructure, underscoring the urgent need for robust countermeasures in modern power grid systems. Cyber-physical power systems (CPPSs), as critical enablers of grid operation, exhibit heightened vulnerabilities in load frequency control (LFC) due to cyber-physical intrusions and pronounced parametric deviations, thereby degrading system resilience and threatening stability. The rising integration of variable output renewable resources, notably solar photovoltaic and wind generation, further challenges frequency security, necessitating reliable control mechanisms for robust multi-area regulation. Driven by this imperative, the present work introduces a cyber-resilient frequency control framework for multi-area CPPS, integrating conventional generation units, renewable resources, aggregated electric vehicles (EVs), hydrogen storage based on aqua electrolyzer and fuel cell units, unified power flow controllers (UPFC), and parallel AC-HVDC interconnections. System nonlinearities, including generation rate constraints (GRC) and governor dead bands (GDB), are incorporated for realism. The SCSO optimized cascaded PIDD2-(1 + TIλ) control strategy is assessed across multiple operating scenarios encompassing step, multi-step, and random load variations, parameter uncertainties, and resonance attacks applied as load disturbances. The proposed control approach outperforms benchmark PID, PIDD2, and FOPID controllers by keeping system frequency and RoCoF within permissible bounds, mitigating oscillations, and sustaining dynamic stability under coordinated cyber-physical disturbances. Simulation studies on two-area and three-area CPPS confirm its superior resilience. For the two-area interconnected CPPS, the proposed SCSO tuned cascaded PIDD2-(1 + TIλ) controller achieves a depletion range of 57.26% to 81.76% in maximum overshoots, 58.23 % to 82.06 % in maximum undershoots, and 45.48 % to 54.53 % in settling time across Δf1, Δf2, and ΔPtie. Sensitivity analysis demonstrates robustness across wide-ranging parameter variations.