Impact of environmental constraints in hydrothermal energy planning

TL;DR

This paper investigates how environmental constraints, especially water use prioritization, influence long-term hydrothermal energy planning in Brazil using advanced optimization techniques.

Contribution

It introduces two novel approaches to model environmental constraints in large-scale hydrothermal planning problems and benchmarks them against Brazil's official model.

Findings

Penalties of slack variables significantly impact water value estimations.

The Julia-based model aligns well with Brazil's official energy planning model.

Different environmental constraint modeling approaches yield comparable results.

Abstract

As a follow-up of the industrial problems dealt with in 2018, 2019, 2021 and 2022, in partnership with CCEE and CEPEL, in 2023 the study group Energy planning and environmental constraints focused on the impact that prioritizing multiple uses of water has on the electric energy production systems, specially in predominantly hydro systems, which is the case of Brazil. In order to model environmental constraints in the long-term hydrothermal generation planning problem, the resulting large-scale multi-stage linear programming problem was modelled in JuMP and solved by stochastic dual dynamic programming. To assess if the development represented well the behavior of the Brazilian power system, the Julia formulation first was benchmarked with Brazil s official model, Newave. Environmental constraints were introduced in this problem by two different approaches, one that represents the multiple uses of water by means of 0-1 variables, and another one that makes piecewise linear approximations of the relevant constraints. Numerical results show that penalties of slack variables strongly affect the obtained water values.