A composite energy–resilience index to assess renewable transition and operational resilience in insular and weakly interconnected power systems

The rapid expansion of renewable generation is changing not only the generation mix of weakly interconnected power systems, but also the operating conditions required to maintain secure and resilient service. This study proposes a Composite Energy–Resilience Index (CERI) as a planning-oriented framework to assess whether renewable-transition pathways are accompanied by stronger restoration-oriented performance and storage-based flexibility. Conceptually, CERI integrates three normalized dimensions: renewable transition, operational restoration, and flexibility support. Methodologically, the framework combines direct projection for structured variables, physically informed reconstruction for renewable electricity generation, scenario-based storage pathways, and robustness analysis under alternative weighting configurations. The framework is empirically applied to the Dominican Republic power system as a representative insular and weakly interconnected case. Results show that renewable capacity growth does not automatically translate into equivalent improvements in renewable electricity contribution or operational strength. By 2035, the baseline CERI values reach 0.77, 0.87, and 0.99 for the low-, medium-, and high-flexibility pathways, respectively. Sensitivity results confirm that the high-flexibility pathway remains the strongest trajectory under all weighting configurations. These findings show that the most favorable transition pathways are those in which renewable expansion is supported by flexibility deployment and sustained restoration capability.