Quanlitative and Quantitative Analysis on AC-Side Perturbation Characteristics of Voltage-Source Converter

To investigate the oscillation phenomenon caused by renewable energy integration, the ac-side perturbation characteristics of voltage-source converter (VSC) is studied qualitatively and quantitatively. Firstly, the propagation path of the ac-side perturbation in VSC is qualitatively analyzed. And the dq component asymmetry concept is introduced in the analyzing process, which illustrates the appearance of the complementary frequency perturbation component. Then, the quantitative relationship among the perturbation components in VSC is analyzed, specially considering the influence of the phase-locked loop (PLL). Finally, the port-impedance and the complementary frequency effect admittance of VSC are deduced, which are further verified by time-domain simulation. In addition, the influence of controller parameters on the port-impedance is also analyzed in the case study. It is concluded that the complementary frequency perturbation component is mainly caused by the PLL perturbation. And the PI parameters of PLL have a great influence on the port-impedance.