Brazil has an extensive and complex transmission system, reflecting the continental dimensions of the country, the spatial dispersion of production sources - especially hydraulic sources - and the distances between large load centers. Transmission has the essential role of integrating sources of production and consumption, often acting as a virtual generator.
The challenge of transmission capacity expansion planning is to ensure the existence of resources in the system that can meet total demand along the forecasted horizon at the least cost considering the associated uncertainties (such as demand growth and profile, production and location of generation, equipment failure) at a reliability level.
The complexity of this challenge stems from the need to reconcile conflicting requirements to operate at least cost and reliability of the system, and in particular regional grid connections. This involves technological options (AC or DC, for example) and the need for alternative routes for transmission lines, in order to minimize the risk of multiple contingencies.
Another source of complexity in the transmission system is the growing environmental restrictions, which limit the availability of corridors and the locations for substations, particularly in the Amazon region and in large load centers.
Last but not least, the multiplicity of transmission agents, of different origins and distinct business characteristics, requires a continuous coordination effort from the ONS, from designing to system operation, in addition to the need for fiscalization, whose responsibility is of ANEEL.
The EPE carries out studies to support the expansion planning of the transmission and offers a database for electrical simulation of the SIN.
The perspective of a strong expansion of intermitent sources (e.g., wind), the need for a robust transmission system to cope with different generation expansion alternatives, among other factors, demand a proactive transmission expansion planning.