Short-term hydro scheduling with cascaded and head-dependent reservoirs based on mixed-integer linear programming

The aim of this paper is to determine a feasible operation of the hydro units belonging to the same hydro chain, trying to meet an hourly power demand assigned previously, and accomplishing the initial and final reservoir level conditions which are long-term signals considered as input data. The hydro scheduling problem has a nonlinear character. In this paper we present a new approach where the nonlinear input-output surfaces are linearised using binary variables. The proposed formulation allows consideration of the relation among the electrical power, the net head and the turbine water discharge. This way, the optimal schedule can be obtained solving directly an optimization problem. A numerical test of a three cascaded and head dependent reservoirs for a 24 hours planning horizon is presented.