A New Parameter Tuning Technique for Noninteger Controllers in Low-Inertia Modern Power Grids

Since isolated microgrid systems are prone to unwanted frequency oscillations against load fluctuations and randomness of renewable sources, load frequency control (LFC) plays a vital role in restoring the frequency of such systems. In the microgrid with virtual inertias, the existing dynamic analysis of LFC assessment is not enough to meet the grid stability due to the virtual inertia control. Confronted with this problem, a noninteger (or fractional-order) type of proportional-integral controller design is developed in this work for LFC synthesis of the microgrid with the application of virtual inertia. In particular, a new analytical tuning scheme is adopted for the proper setting of the established noninteger controller to effectively damp the frequency oscillations of the concerned system under the virtual inertia. In the suggested analytical scheme, the stability boundary locus and geometric centroid methods are used to tune the coefficients of the noninteger LFC controller. The analysis of stability region curves has been conducted to study the dynamic effects of the virtual inertia and damping over the microgrid performance. Finally, the efficiency of the suggested noninteger controller design and accuracy of the stability analysis in regulating a microgrid with virtual inertia and damping are proved. © 2020 IEEE.