Cascaded adaptive model predictive and PID control for integrated LFC–AVR enhancement

Abstract

Load Frequency Control (LFC) and Automatic Voltage Regulation (AVR) are traditionally designed and tuned separately, which may lead to degraded dynamic performance when power systems experience simultaneous load disturbances and parameter uncertainties. Moreover, fixed-gain controllers often fail to maintain fast and well-damped responses under operating-point variations in both single-area and two-area systems. To address these challenges, this paper proposes a coordinated LFC–AVR control scheme based on a cascaded architecture, in which an adaptive model predictive controller (AMPC) serves as the outer loop, while a PID controller operates in the inner loop to enhance implementability and tracking speed. The AMPC is updated online using recursive least squares (RLS) identification combined with a time-varying Kalman filter (TVKF) to estimate system states and cope with time-varying dynamics. The proposed AMPC–PID strategy is evaluated on single-area and two-area power system models under step load perturbations and significant parameter variations. Its performance is benchmarked against a recent EDO-PID approach, as well as an HS-optimized PID for the AVR loop. Simulation results demonstrate improved damping, reduced under/overshoot, and shorter settling times for both frequency and voltage deviations, confirming the robustness and effectiveness of the coordinated AMPC–PID control strategy under different operating conditions.