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Advanced control strategies have been applied to manage variable power output in standalone microgrids, reducing the risk of frequency instability and power-quality deterioration. Nevertheless, a key difficulty arises: these computationally intensive techniques, when used without stability checks, may fail to cope with the fast dynamics of real-world conditions, particularly under communication delays. This research proposes a versatile real-time solution for frequency regulation that relies on an artificial neural network (ANN) confined to stable operating regions. The proposed method combines stabilizing PID controllers—derived via small-signal analysis—with an automated optimization of ANN weights and reinforcement learning (RL)-guided constraint selection. Initially, stabilizing PID controllers are developed using the stability boundary locus approach and the Mikhailov criterion, with explicit consideration of communication delays. Subsequently, controller parameters are fine-tuned in real time via an automated search for optimal coefficient sets, using a constrained ANN to keep frequency deviations within a predefined parameter space. The framework is further strengthened by an RL-based tuning mechanism trained on an interpolated stability boundary curve, guaranteeing both stability and enhanced performance. This unique integration of ANN, RL, and sophisticated PID tuning represents a significant advancement in addressing frequency control challenges in isolated AC microgrids. Experimental results demonstrate that the proposed approach surpasses conventional techniques thanks to its reduced parameter search domain. Specifically, it achieves greater reductions in both transient and steady-state frequency deviations compared to semi-constrained and unconstrained alternatives. The enhanced performance metrics and stability assessments confirm that the method delivers superior system behavior and robustness under varying operating conditions.