Improvement of combined LFC-AVR system performance with fuzzy PID controller in single and multi-area power networks

The process of regulating the terminal voltage and system frequency at their nominal levels presents a major challenge for electric power grid operators. To address this, the paper introduces a control approach aimed at improving the performance of the integrated Load Frequency Control (LFC) and Automatic Voltage Regulator (AVR) system. The proposed methodology incorporates a fuzzy logic-based PID controller for the LFC loop, while a trial-and-error based PID controller is implemented for the AVR loop. The effectiveness of this control scheme is validated by benchmarking it against multiple conventional controllers utilized in similar LFC-AVR combined systems. The results clearly demonstrate that the proposed controller significantly enhances the system's transient response. Furthermore, the controller’s robustness is rigorously tested undergoing several operational disturbances, confirming its dependability in maintaining stable voltage and frequency levels. Compared to traditional techniques, the proposed controller consistently achieves a lower undershoot, with improvements ranging from 13 % to 47 %. Additionally, the controller’s performance is evaluated in a two-area LFC-AVR setup against other control strategies, including a classical PID controller based on the nonlinear threshold-accepting (NLTA) algorithm, and PI-PD controllers optimized using Modified Particle Swarm Optimization (MPSO) and the Archimedes Optimization Algorithm (AOA). The fuzzy logic-based controller outperforms these methods, achieving better undershoot reductions by 82 %, 58 %, and 61 % respectively, and delivering a faster dynamic response in the LFC system.