Transmission Lines Disturbance Analysis in Brazil: A Historical, Comparative, and Critical Review

In Brazil, disturbances involving transmission lines (TLs) in the National Interconnected System (SIN) accounted for more than 70% of all recorded disturbances between 2012 and 2025. In 2023, a large-scale disturbance that resulted in the disconnection of more than 22.5 GW was triggered by the incorrect operation of a protection system and subsequently escalated due to the inadequate performance of newly installed wind and solar power plants. These variable renewable energy sources have experienced significant growth and are projected to reach approximately 41% of the installed generation capacity. Consequently, the transmission network is expected to expand by 18% with the addition of new TLs. In this context, disturbance analysis is essential to the continuous improvement cycle within an increasingly complex operational environment. This paper presents a historical, comparative, and critical review of transmission line disturbance analysis practices in Brazil, benchmarking them against practices adopted in Australia, the United States of America, and Europe. The analyses are based on publicly available regulations, methodologies, and performance indicators from these countries and entities. The findings indicate that Brazil demonstrates regulatory and methodological alignment, as well as greater transparency and process efficiency. However, opportunities for improvement remain in dynamic disturbance assessment and root-cause analysis. Elevated rates of transmission line outages and protection misoperations due to human factors were also identified. The recommendations proposed in this paper—addressing methodological frameworks, analytical tools, and performance targets within the SIN—aim to strengthen the role of disturbance analysis in supporting continuous improvement amid ongoing system modernization and expansion challenges.