Wideband Dissipativity Enhancement for Grid-Following VSC Utilizing Capacitor Voltage Feedforward

Frequency-domain dissipativity of the converter admittance provides an intuitive approach to analyze wideband resonances due to the interactions with the grid. Although the reasons for high- and low-frequency resonances are different, it is found that the proportional capacitor voltage feedforward (CVF) can affect and reshape the converter admittance in a wide frequency range. To enhance wideband dissipativity under a weak/capacitive grid, a proportional–integral (PI)–derivative CVF is proposed in this article. Specifically, high-frequency dissipativity can be guaranteed through the multisampling control (MSC) with proportional–derivative CVF. The low-frequency nondissipative region caused by the phase-locked loop (PLL) and proportional CVF can be compensated through multiorder integrations. In light of grid frequency disturbances, modified integrators are further proposed for the multiorder integrations. The proposed method also applies to the conventional double-sampling control (DSC) with regard to the low-frequency dissipativity enhancement. Finally, experiments validate the proposed control method.