Regulating the dynamical nature of the interconnected power system (IPS) due to fluctuating electric power demands is a crucial part of assessing its stability. The power demands on the IPS are continuous and require automatic actions to mitigate their subsequent impact. Thus, this work suggested the proportional-integral-derivative (PID) controller as the load frequency control (LFC) regulator using the robust optimization of the water cycle algorithm (WCA). The performance of the WCA tubed PID is tested on the two-area hydrothermal (TAHT) system, and the supremacy of the WCA is demonstrated with the Sooty tern algorithm (STA) and the grey wolf optimization (GWO) performance. Further, the TAHT is integrated with the HVDC line to attain further stability. The simulation analysis confirmed the enrichment in the TAHT performance with the HVDC line incorporation. Furthermore, the TAHT system is subjugated by the loading uncertainty under the suggested regulator. The investigation confirmed the robustness of the WCA-tuned PID performance.