Comparison between piecewise linear and non-linear approximations applied to the disaggregation of hydraulic generation in long-term operation planning

•Determination of individual hydro generation targets.•Application of long-term hydrothermal system operation planning.•Approximation of the hydro production function.•Sigmoidal, nonlinear and piecewise linear modeling.•We examined this approach by applying it to the Brazilian power system.

This paper presents a comparison of two proposed approaches to model the hydropower production functions (HPF) applied to long-term operation planning problems. The first approach consists of a non-linear approximation that uses a sigmoid function, and the second approach consists of a piecewise linear approximation. In this study, we aimed to disaggregate the target for each subsystem into individualized generation targets. A study case using the Brazilian power system is presented to evaluate both methodologies. The results show that the piecewise linear approach presents a good approximation with a considerably lower computational time.