Assessing emerging flexibility challenges in the Brazilian interconnected system: Insights from international market experience

The rapid expansion of variable renewable energy (VRE) is increasing net-load variability, ramping requirements, and operational uncertainty in power systems worldwide. Although a growing body of literature has developed metrics to quantify flexibility adequacy, comparatively less attention has been devoted to relating emerging flexibility constraints to the institutional responses adopted by electricity markets facing similar challenges. This article investigates the evolution of flexibility requirements in the Brazilian Interconnected System (SIN) through a probabilistic assessment framework combined with an international benchmark of flexibility mechanisms implemented in mature electricity markets. Potential flexibility stress is evaluated using probabilistic duck-curve representations, ramping indicators, flexibility deficit metrics, and representative operating conditions. The benchmark examines how jurisdictions such as California, PJM, Great Britain, Australia, and Chile have addressed increasing flexibility needs through operational and market-design mechanisms. Results indicate a significant increase in net-load variability and ramping stress under renewable-driven growth scenarios. Flexibility adequacy indicators deteriorate as renewable penetration expands, leading to more frequent and severe ramping conditions. The analysis also shows that operational patterns observed in the Brazilian system resemble conditions previously experienced in several mature electricity markets, where increasing flexibility requirements motivated the adoption of dedicated flexibility products and enhanced adequacy arrangements. Rather than proposing new flexibility metrics, the article contributes by linking quantitative flexibility assessment with the evolution of flexibility-oriented market mechanisms. The results provide a planning-oriented interpretation of flexibility adequacy indicators and highlight the growing importance of explicitly considering flexibility requirements in power systems undergoing rapid renewable expansion.