Two-stage stability enhancement framework based on S-domain modal analysis for renewable energy power systems

• Developed an s-domain modal analysis framework introducing weak node equilibrium and coupling indices. • Optimized converter parameters to balance participation factors and improve stability margins. • Proposed model-free data-enabled predictive control to suppress oscillations without accurate system modeling. • Designed controllability-based data-enabled predictive control update strategy targeting critical modes efficiently. • Established a two-stage framework bridging planning and operation for lifecycle stability enhancement. Power systems with a high proportion of renewable energy face the risk of broadband oscillations, and existing studies lack multi-scenario stability enhancement methods covering both planning and operating stages. To this end, this paper proposes a two-stage stability enhancement framework: optimizing the parameters of weak nodes during the planning stage to improve stability under the rated condition; and suppressing oscillations under multiple operating conditions with data-driven methods. Firstly, by establishing the s-domain admittance matrix model, system modes and participation factors are derived to give insight into the system small-signal stability. Then, to improve the robustness of critical modes in the planning stage, the parameters of voltage source converters connected to weak nodes are optimized to balance weak nodes and reduce the coupling of weak nodes. In the operating stage, the controllability-based updating data-enabled predictive control is proposed with an updating strategy according to the participation factor analysis. Finally, the effectiveness of the proposed two-stage stability enhancement framework is verified in both the IEEE 9-bus system and the 6-generator 25-bus system. The stability margin of the optimized system is significantly improved in the planning stage, and oscillations caused by changes in system topology or operating points are effectively suppressed in the operating stage. These results indicate that the proposed two-stage stability enhancement framework offers a viable pathway toward integrating the planning and operating stages for small-signal stability enhancement.