To manage real-time control of releases from the two dams located upstream of the Chi River system, DHI applied a MPC framework. The method combines a fast-solvable optimisation model with evaluation and realignment by a hydrodynamic flood model created in MIKE HYDRO River. Using MIKE OPERATIONS to run the hydrodynamic flood model automatically, dam releases and downstream discharges can be controlled in real-time.
The MPC framework optimises the release of the combined water from the two dams and thereby improves the flow of water through the river systems. The optimisation is based on a linear surrogate model of the Chi River network that is calibrated against a full-blown hydrodynamic model, solving the one-dimensional flow equations. In real-time mode, the full-blown hydrodynamic model is used to initialise each optimisation run and simulate the MPC derived releases.
The optimisations take the expected future river system state into account when deciding on the best operation. Control actions for the two dams are optimised over a 7-day forecast horizon. Every day a new forecast is available and optimal controls are updated based on the most recent system information. This principle is called ‘rolling horizon’. By using the MPC framework, the downstream discharge peaks were reduced with more than 300 m3/s during a medium inflow year when releases from the Ubonrat and Lampao dams were controlled in combination.
This research project—made possible with support from EGAT and RID—tests the MPC approach and does not include factors such as side flow from other small rivers and other impact.