A Stochastic Dynamic Programming Model for Hydropower Scheduling with
State-dependent Maximum Discharge Constraints
Abstract
We present a medium-term hydropower scheduling model that includes
state-dependent environmental constraints on maximum discharge. A
stochastic dynamic programming algorithm is used to enable modelling of
nonconvex relationships in the problem formulation. The model is applied
in a case study of a Norwegian hydropower system with multiple
reservoirs. We find that the maximum discharge constraint significantly
impacts the water values and simulated operation of the hydropower
system. A main finding is that the nonconvex characteristics of the
environmental constraint is reflected in the water values, implying a
nonconvex objective function. Operation according to the computed water
values is simulated for cases with and without the environmental
constraint. Even though operation of the system changes considerably
when the environmental constraint is included, the total electricity
generation over the year is kept constant, and the total loss in
expected profit limited to less than 0.8%.