Dissipativity Robustness Enhancement for Dual-Loop Voltage Control of Grid-FormingVSCs

Grid-side current feedforward has proven to be an effective approach in improving the dissipativity of dual-loop voltage control in grid-forming converters. However, due to the control delay, the dissipative characteristic of the converter output impedance can be significantly impacted by the designed resonance frequency of the designed LC-filter and any deviation in the filter parameters. To address this issue, the proposed method in this paper replaces grid-side current feedforward with capacitor current feedforward and capacitor voltage feedforward, resulting in enhanced dissipativity below the Nyquist frequency. Additionally, the proposed method improves the dissipativity robustness against deviation in the LC-filter parameters. Moreover, it allows for the LC-filter resonance frequency to be designed freely, without the need to consider the critical frequency. The effectiveness of this proposed method is validated through a case study.