An Optimised Adaptive Integral Sliding Mode Control Approach for Multi-Area Power Systems: Enhancing LFC Robustness and Stability With RES Integration and Time-Delay Mitigation

Abstract

Frequency stability is vital to power system operation, especially in interconnected power systems (IPS) and smart grids where renewable energy sources and load fluctuations introduce unpredictability. This variability and time delay from decentralised control configurations can impair load frequency control (LFC) and compromise system stability. This study proposes a robust adaptive integral terminal sliding mode controller (RAITSMC) for LFC to address these challenges. The controller mitigates destabilising effects from time delays, parametric uncertainties and nonlinear disturbances. A delay-dependent sliding surface is developed to enhance the system's response to tie-line power and frequency deviations. Perturbations are estimated using an adaptation law, and a decentralised robust control law ensures the system's trajectory remains on the sliding surface with minimal control efforts. The controller's stability is validated via the Lyapunov theorem, and its parameters are optimised using the arithmetic optimisation algorithm. Simulations on the IEEE 10-generator New England 39-bus power system demonstrate significant improvements, including reduced frequency overshoot (48.3%), undershoot (45.7%) and settling time (37.2%), along with enhanced robustness under $\pm$50% parametric variations. Comparative analyses reveal superior performance across error-based indices, showcasing RAITSMC's potential to ensure a reliable and stable power system operation.