Fixed Frequency Sliding Mode Control of Distributed Generation in Microgrids for the Balanced and Nonlinear Loads

This paper presents a novel control strategy integrating Sliding Mode Control (SMC) with a Lock-In Amplifier (LA) to improve stability, power-sharing accuracy, and power quality in microgrids (MGs) with distributed generation (DG) units. The proposed control system mitigates harmonic distortions, ensures voltage and frequency stability under dynamic load conditions, and utilizes LA for precise harmonic signal extraction amidst harmonic frequencies in the control signal. Testing under varying operational scenarios demonstrated significant reductions in Total Harmonic Distortion (THD), aligning with IEEE Std 519 standards. The controller supports parallel DG operation with accurate load sharing and incorporates IEEE 1547-2018-compliant islanding detection and reconnection based on frequency deviation. The results demonstrate a practical, communication-independent primary control solution for improving microgrid stability and power quality.