skip to main content
Mixed Integer Programming
A Mixed Integer Program (MIP) solver was incorporated into RiverWare. MIPs are optimization problems that contain both continuous and integer variables. This work was motivated to better model power at the unit level. As a result, The MIP solver works in concert with the Unit Power methods described Power Reservoirs - Unit Power Methods.
Changes to the Thermal Object
The thermal object slots and methods were modified as described Thermal Object. Additional information on the behavior of these methods in optimization can be found Thermal in Optimization. Additional information on converting a thermal object to this new approach can be found Modeling a Thermal Object in Optimization.
CPLEX licensing
RiverWare was upgraded to use CPLEX 11.0 and Concert 2.5. Optimization requires a license for CPLEX version 11.0 or a later version.
In addition, an error message was added if an Optimization run is started and there is no valid CPLEX license. Previously a warning was issued but the run would continue until the optimization solution was attempted.
Automatic Ruleset Generation
An optimization run consists of a simulation, optimization and rulebased simulation run. After the optimization run, the user switches to rulebased simulation and has the option to automatically generate a ruleset that will set Reservoir.Outflow to the optimal value. The order in which rules appear was modified. Now, each rule, associated with a reservoir, are ordered topologically. Specifically, the low to high priority order of rules now corresponds to a upstream to downstream ordering of the associated reservoirs. That is, low priority rules are for upstream reservoirs, high priority rules are for downstream reservoirs. When using the default agenda order (...3,2,1), this causes the reservoirs to solve upstream to downstream. Note that if two objects are on different tributaries or in unconnected basins, then there is no constraint on the relative order of their associated rules.
Revised: 08/02/2021