Improved Dynamic Response Design for Proportional Resonant Control Applied to Three-Phase Grid-Forming Inverter

For grid-forming inverters, abilities of both disturbance rejection and reference tracking are important for voltage controls, which act as inner loops of power controls. In this article, a complex variable-based dominant pole elimination (DPE) algorithm is applied to the voltage control that includes both positive- and negative-sequence complex variable resonant controllers. The algorithm is effective for both αβ - and dq -frame voltage control. Then, the DPE algorithm is extended for conventional dual-loop proportional resonant control to improve the dynamic response. Impedance-based analysis also indicates that the proposed DPE algorithm results in a suitable impedance to enhance the robustness in grid-connected mode. The effectiveness of the DPE method is verified through an experimental implementation in a three-phase hardware prototype with a TMS320F28379D digital signal processor and simulations in MATLAB/Simulink.