Optimized Parameter Design of the Dual-Loop Control for Grid-Forming VSCs With LC Filters

This article provides a simple methodology to achieve an optimized parameter design of the dual-loop control for grid-forming voltage source converters (VSCs) with
LC
filters. The optimized parameter design is conducted for the current inner loop and voltage outer loop independently without any coupling, and the design processes of these two loops are exactly the same. Moreover, in the proposed design, standard analysis and design tools, e.g., pole map and Bode-plot can be directly employed while complex formula solving is needless. Therefore, this methodology is easy to implement for a practical engineering. In addition, contrary to common sense, it has been identified that the proportional controller in the outer loop has a negligible impact on the control bandwidth of typical medium power rating VSCs and thus can be eliminated to further simplify the design process and control structure. The left resonant controller can then be refined to achieve a significantly improved dynamic performance of the output voltage of VSCs. Detailed processes and considerations of the proposed design methodology are introduced and analyzed. Its effectiveness and performance are carefully verified by experimental results from a single-phase scaled-down VSC prototype.