Design-Oriented Dissipativity Enhancement for Single-Loop Voltage Control of Grid-FormingVSCs

Abstract

In light of harmonic stability caused by the control delay and the wide-varied grid impedance, grid-side current feedforward is an effective method to enhance the dissipativity for voltage control of grid-forming converters. However, the dissipative characteristic of converter output impedance is seriously affected by the designed LC-filter resonance frequency and the filter parameters deviation. To fill this gap, a design-oriented control scheme is proposed using three variables feedforward, i.e., converter-side current, capacitor current, and capacitor voltage. As a result, not only the dissipativity can be achieved below Nyquist frequency, but also the dissipativity robustness against the LC-filter parameter deviation is enhanced. Besides, the LC-filter resonance frequency can be designed freely without considering the critical frequency. Finally, the proposed method is validated through the simulation.