Voltage Stabilization Of A DC Microgrid Feeding An EV Charging Station Using A Systematically Tuned Fractional-Order Controller

High-power electric vehicle (EV) fast charging causes problems like CPL behavior, which destabilizes DC microgrids because of negative incremental impedance. In this paper, a control scheme for DC bus voltage stabilization in an EV integrated DC microgrid based on a fractional-order proportional integral derivative (FOPID) control approach has been proposed. First, a nonlinear averaged modeling considering boost converter dynamics and the characteristic of CPL is performed. Then, linearized small signal models are used to investigate the limits of stability along with critical parameters. A multi-objective tuning approach is then employed to tune a PI, PID, and FOPID controller under the same operation conditions. The performance comparison has been done in the time domain, frequency domain, sensitivity analysis, and nonlinear disturbance analysis. It is concluded that FOPID controller performs better than PID and PI in terms of phase margin, disturbance rejection, and robustness, while providing a good compromise in other parameters.