General composite representation of hydroelectric systems

This paper presents a general composite representation of hydroelectric power systems for long-term hydrothermal generation scheduling. The general representation is based on the aggregation of the hydro system through nonlinear reservoir operational rules. A procedure for determining effective rules based on the solution of a deterministic hydrothermal scheduling model is established. In order to evaluate the improvement in hydro generation, the composite representation with nonlinear reservoir operational rules is compared to the traditional linear one for hydroelectric systems with different dimensions (up to 29 hydro plants) taken from the Brazilian southeast power system. The results show a significant improvement in hydro generation.