Operational management of the São Francisco River reservoir system
The government controlled electric energy company CEMIG (Brazil) is responsible for the short-term management of the São Francisco River reservoir system. In general, the following reservoir management policies are applied:
- In order to maximize power production, turbine flow is preferred against spillway discharge.
- The maximum fore bay elevation is time dependent and limited by the reservoir’s maximum operating limit or a lower operational limit that ensures sufficient flood control storage during the wet season. This policy conflicts with the target of maximizing power production.
- High discharge thresholds are defined for certain locations in the reservoir system, and these high discharge thresholds should not be exceeded.
- Large outflow gradients are should be avoided.
Decision support system
The interaction of reservoirs due to cascading effects and the conflicting management policies make the reservoir management a complex task. In collaboration with the Brazilian Institute of Technology for Development (LACTEC), Deltares has developed a decision support system for reservoir management of the São Francisco River reservoir system.
The operational forecasting and decision support system (DSS) is based on the open data handling platform Delft-FEWS and integrates different sources of ground information, remote sensing data and numerical weather predictions with hydrological and hydrodynamic models to generate short-term flow forecasts for up to 15 days ahead for each of the eleven reservoirs.
These forecasts are fed into the real-time control toolbox RTC-Tools. RTC-Tools determines an optimal release strategy for the forecast horizon with the help of deterministic and multi-stage stochastic optimization methods.
The reservoir management is formulated as an optimisation problem that incorporates a mathematical model of the reservoir system. The different management policies are objectives and constraints of the optimisation problem.