Analysis of Small Signal Stability of Converter-based Grid Based on Primal-dual Complex Circuit

Aiming at the problem of system oscillation caused by the interaction between power supply and power grid and different power supply equipment in a power grid with converter-based power generation as the core, firstly the equivalent primal-dual complex circuit analysis method is adopted. Based on the analysis of the oscillation mechanism, a concise and accurate stability criterion is formed. The control strategies of grid-following and grid-forming converter are fully considered, and a small signal model suitable for the analysis characteristics of wide frequency range is established, which has good applicability for the analysis of converter-based grid with converter-based power generation as the core. Secondly, the system simulation including grid-following and grid-forming power supply is used to verify the accuracy of the theoretical analysis. Finally, the influence and variation laws of the penetration rate of the grid-following converter, line inductance, damping coefficient and rotational inertia of the grid-forming converter on the dynamic characteristics of the converter-based grid are analyzed. The research results provide a theoretical basis for the system parameter design and controller optimization of converter-based power grid, which is conducive to improving the stability of converter-based grid.