Optimal dispatch of generating units of the Itaipu hydroelectric plant

This paper is concerned with the optimal dispatch of generating units of Itaipu, the world´s largest hydroelectric plant in operation. Itaipu is a 12.6 GW hydro plant, located on the Parana river, in South America, composed of 18 identical 700 MW generating units. A dynamic programming model has been developed to optimize the number of generating units in operation at each hour of the day in order to attain the total generation scheduling of the plant in the most economic way. The model highlights the tradeoff between start-up/shut-down of generating units and hydro power efficiency, taking into account variations in tailrace elevation, penstock head losses and turbine-generator efficiencies. The methodology has been tested for a typical generation scheduling, and the results show that the number of the turbine-generator sets dispatched has a major influence on the overall hydroplant efficiency, and therefore it is a key aspect to be considered in the dispatch of hydro generating units. In the case of Itaipu, the economic benefits, in terms of greater power efficiency with respect to actual operation, are in the range of millions of dollars per year