Multiobjective optimal power plant operation through coordinate control with pressure set point scheduling

Coordinated control schemes, at fossil fuel power plants, drive units as a whole through a variable pressure operating policy. Ordinarily, the pressure control loop set-point is obtained from the unit load demand through a fixed nonlinear mapping that does not allow for process optimization under operating conditions different from the originals. This paper presents a procedure to optimally design the power-pressure mapping by defining and solving a multiobjective optimization problem. Both, procedure and mapping are realized as a supervisory set-point scheduler. The optimization problem is solved with the nonlinear goal programming method, which provides a single solution from the set of all multiobjective optimal solutions based on the assignment of relative preference values to the objective functions. This approach provides a way to specify the operating policy to accommodate a great diversity of operating scenarios. The procedure is presented through a case study, and its feasibility is demonstrated via simulation experiments.