Multi-objective micro-grid design by NSGA-II considering both islanded and grid-connected modes

This study proposes a multi-objective optimal micro-grid design, wherein the same control strategy is implemented to the inverters of DG units to enable the operation of micro-grids in two modes and seamless transition between the modes. The main feature of the design is that it eliminates the need for control system reconfiguration and islanding detection algorithms. Its control topology comprises two control loops. The outer loop is the angle droop control that generates the voltage magnitude and phase angle reference of a micro-grid, and the inner loop is the state feedback control. Common to both operating modes are parameters, namely, feedback control gain, droop coefficient, and Inductance-Capacitor-Inductance(LCL) filter components that considerably affect dominant eigenvalues. The contribution of this work is that minimizing the maximum real part of the eigenvalues of each operation mode considered a distinct objective function. The optimal design is formulated as a multi-objective optimization problem, for which None-Dominated Sorting Genetic Algorithm II(NSGA-II) algorithm is used to optimally calculate the parameters of the system and the controllers. Sensitivity analysis and evaluation results are presented to demonstrate the effectiveness of the proposed control.