Hydrothermal scheduling of power system with stochastic inflows

The authors present a suboptimal optimization method for solving the annual hydrothermal scheduling problem. Hydrothermal scheduling is performed in order to find the optimum allocation of hydro energy so that the annual operating cost of a mixed hydro-thermal system is minimized. The hydrothermal scheduling problem is decomposed into three subproblems: maintenance of thermal units, dispatch of thermal units, and dispatch of hydro units. The algorithm takes into consideration the stochastic nature of the water inflows to the reservoir and the forced outage rates of the thermal units. Maintenance scheduling is performed based on the levelized risk criterion, dispatch of the thermal units is determined based on probabilistic techniques, while the dispatch of the hydro units is formulated as a constrained optimization problem. Results obtained by the application of the algorithm to a case study showing the effect of the hydro units are reported