Voltage Stability Enhancement in Islanded Microgrids Using Fuzzy Logic-Based Robust Droop Control

Voltage stability is a fundamental requirement for the reliable operation of islanded microgrids, particularly under dynamic load conditions and asymmetrical line impedances. Conventional droop control strategies, while widely adopted for decentralized inverter-based systems, often exhibit limitations in voltage regulation, especially in the presence of nonlinear or unbalanced loads. This paper presents an enhanced control scheme that combines fuzzy logic adaptation with a robust droop control framework, supported by a proportionalresonant (PR) controller to achieve precise voltage waveform tracking. The proposed method introduces a Mamdani-type fuzzy inference system to dynamically adjust the voltage reference based on real-time voltage error and its rate of change, enabling adaptive droop characteristics that respond effectively to system disturbances. The PR controller is implemented in the inner voltage control loop to ensure zero steady-state error for sinusoidal references and to improve harmonic suppression. To validate the performance of the proposed strategy, comprehensive simulations were conducted in MATLAB/Simulink under various operating scenarios, including resistive and inductive loading as well as unbalanced line impedance configurations. Quantitative results demonstrate that the fuzzy-droop controller reduces voltage amplitude deviation from 6.5 % to 2.5 %, decreases voltage recovery time from 80 ms to 45 ms, and maintains total harmonic distortion (THD) below 2.3 %, thus complying with IEEE 519 standards. These findings confirm the efficacy of the proposed control strategy in enhancing voltage stability and power quality in islanded microgrid environments. The solution is particularly suited for standalone systems where communication-free, plug-and-play operation and adaptive response are critical to ensuring resilient energy delivery.