The increasing penetration of renewable energy sources and distributed generation has reduced rotating inertia in interconnected power systems. As a result, the power systems are operating close to their stability limits with greater uncertainty, and frequency regulation becomes more complex. To address this issue, this paper proposes a load frequency control strategy for a multi-area interconnected power system using a second order sliding mode control (SOSMC). The performance of the proposed SOSMC is analyzed underload perturbations to assess its robustness against the transient and steady-state conditions. Additionally, polytopic hyperspace disturbance conditions examine the effectiveness of SOSMC under multidimensional power system characteristics. The impact of communication delay is also incorporated to evaluate the controller under realistic wide area conditions. The extensive numerical analyses demonstrate that the proposed SOSMC achieves reduced frequency and tie-line power deviations, faster settling times, and effective chattering suppression compared to widely adopted controllers in the industry. The results further validate SOSMC under sensor fault conditions, confirming its applicability in modern multi-area power systems. Furthermore, the proposed approach ensures rapid fault detection with minimum detection latency.