Design and Implementation of Fractional-Order Sliding Mode Control for Parallel Distributed Generations Units in Islanded Microgrid

Inverter-based Distributed Generation (DG) units in Microgrid require robust and precise control techniques that attain high performance under both normal and unbalanced conditions. The DG unit interfaced to the load through power electronics converters has raised a concern about safe performance and protection of the equipment. This paper proposes a voltage control strategy for enhancing the stability of microgrid and performs proper load sharing. Fractional-order sliding-mode control (FOSMC) is proposed for single and parallel DG units in the islanded mode of the microgrid. The proposed control maintains a high quality of the output voltage of the DG unit despite unbalanced and/or non-linear load currents. To validate the steady-state and dynamic behavior of the system under variable load, the real-time simulation is carried out by using the MATLAB/Simulink environment. The results show that the proposed control technique is quite effective due to its robust response and less sensitive to external disturbances. For parallel operation, the droop control approach and virtual output impedance (VOI) are implemented for the accurate power-sharing between DG units.