A robust control scheme for voltage and reactive power regulation in islanded AC microgrids

In multi-feeder microgrid systems, accurate power sharing and voltage regulation at each load feeder is more challenging than the conventional single-feeder microgrids. This paper presents an enhanced resilient control strategy for multi-feeder micro-network systems by considering the load feeder voltage regulation and power balancing as a quadratic optimization problem. The proposed control strategy is composed of impedance estimator and optimal controller. However, the impedance estimator obtains each load feeder impedance while optimal controller computes the voltage commands for each distributed generator. One of the important aspects of the proposed control scheme is that only the voltage magnitude information is required to transfer at each inverter's controller, with primary aim to achieve the two-fold objectives. This control strategy is also extended to approximate the whole network impedance into solitary load feeder for micro-networks with extensive number of load feeders. This makes the system computationally less burdening. The MATLAB/Simulink and experimental results are obtained under varying load conditions and line parameter uncertainties for radial type multi-feeder microgrid configuration that reflects the effectiveness of the proposed scheme. The verification outcomes prove the proposed method capability of accurate reactive power sharing, regulation of load feeder voltages, and frequency restoration.