The short-term Unit Commitment (UC) problem in hydro-thermal power generation systems requires to optimally operate a set of hydro (possibly cascade connected) and thermal generating units, over a given time horizon (typically one day or one week), in order to satisfy a forecasted energy demand at minimum total cost. The generating units are subject to some technical restrictions, depending on their type and characteristics; for hydro units typical constraints concern the discharge rate, spillage limits, reservoir storage and effect on downstream units. As for the thermal units, they must usually satisfy minimum up- and down-time constraints and upper and lower bounds over the produced power when the unit is operational, besides having complex power production and start-up costs; ramp rate constraints, limiting the increase or decrease of generated power from one period to the next, can also be present.
We have developed a generator of UC problems that strives to produce "realistic" instances. The generator produces a generating set with "small", "medium" and "large" thermal units in realistic proportions; the characteristics of each unit are then randomly generated within a set of realistic parameters, depending on the type of the unit. The generator has been used for testing several approaches to the solution of UC-related problems; see e.g.
A more advanced generator, taking into account ramping constraints, is currently under development. For the time being, we distribute a set of ramp-constrained thermal and hydro-thermal instances that we have used to test the approaches; they are available both here (508Kb, .zip) and at the OR-Library. The format of the instances is described in the file Format.pdf, distributed together with the instances. The new generator will also be distributed, when ready.
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