Multi-objective hydro optimal scheduling with flow time

This paper presents a multi-objective model considering flow time for cascaded hydro optimal scheduling. This model concentrates on taking advantage of the peaking regulation and generation for hydro units with two objectives introduced. One of them is minimization of total surplus load, which is surplus system load deducting the generation of hydroelectric generating units; aiming at maximizing the generation of cascaded hydro units in the hydrothermal system. The other is minimization of difference between peak and valley of the surplus load, so that surplus load is as smooth as possible. The model mentioned above is transferred into the mixed integer linear programming for reducing degree of difficulty. So the objective function is converted using fuzzy optimization. And the non-linear constraints including power generating and output limit curve are transformed by introducing multiple sets of auxiliary variables and related constraints. Numerical results demonstrate the effectiveness and the efficiency of the proposed model.