A Stochastic Model for Mid-Term Operation Planning of Hydro-Thermal Systems with Random Reservoir Inflows

Abstract

The operation planning of a hydro-thermal power system involves the coordination of the production schedule of various types of generation, including hydro. A good model is needed to minimize the system energy production costs over a given period in the mid-range time frame. A method is proposed to optimize the discharge of the hydro reservoirs over the period of one year. Explicit Stochastic Dynamic Programming (ESDD) [1] is employed to deal with the M-stage stochastic return function, the random inflows to the reservoirs and the bounded nature of the system constraints. Aggregation of the reservoir and hydro plant sub-systems is used to reduce the dimensionality of the problem, permitting a; realistic modeling of the hydro portion of the power system. The cost of operation for various valve loadings, the scheduled downtime for various unit maintenance activities, the predicted partial and total forced outages, and the stochastic river inflows to the reservoirs are input requirements to the program which yields the monthly hydro energy scheduling for the most economic loading over a one year period