Sensitivity analysis of a two-stage PV plant impedance-based model: assessment of the DC-side dynamics impact

In view of different sub-synchronous instability events in real power systems dominated by inverter-based resources (IBRs), impedance-based modeling has gained prominence for small-signal stability assessment. In this context, the present work aims to assess the impact of PV-side components on a two-stage PV impedance model. A sensitivity analysis was conducted regarding the DC-DC converter controller, the PV-side filter, and the solar module array, comprising the primary parameters. Additionally, this analysis was repeated under different conditioning variables, including irradiance level, DC-link capacitor, and DC voltage controller, which can affect the sensitivity to primary parameters. These parameters were varied collectively to investigate inter-dependencies. The first analysis indicated negligible sensitivity of the impedance profiles to the primary parameters. However, the second analysis drew a different conclusion when comparing the full model and a simplified one that disregards the PV-side components. Depending on the values of the conditioning variables, the simplified model may lead to inaccuracies.