Distributed hierarchal control strategy for multi-bus AC microgrid to achieve seamless synchronization

In this research work, a distributed hierarchal control scheme is proposed that ensures a smooth synchronization of islanded microgrid with the utility grid. In this method, a pinning consensus-based distributed controller is designed where all Distributed Generation Units (DGs) are allowed to regulate their frequencies and output power in proportion to their capacities while only regulating DGs are responsible for eliminating the phase angle and voltage magnitude mismatch. Hence, the magnitude, phase angle, and frequency are controlled explicitly while ensuring proportionate power sharing. To enhance the performance of the system, the fixed gain parameters of the secondary controller are made adaptive by using a back propagation based proportional integral controller. Moreover, a fuzzy proportional integral controller and steepest descent based fuzzy logic controller are designed that use an adjustable parameter to generate the compensation correction signals for the secondary controller to eliminate the voltage magnitude and phase angle mismatch. Furthermore, to ensure a seamless reconnection, a control strategy based on the synchronization criteria is designed that control the operation of the static switch. Finally, the effectiveness of the method under different scenarios is validated through simulation results.