Model predictive control of power plant superheater — Comparison of multi model and nonlinear approaches

Model predictive control of a three stage power plant superheater is investigated in this paper. This power plant subsystem consists of three heat exchangers and three attemperator sprays. Its dynamics is nonlinear and significantly load dependent. In the paper, the responses to large load demand changes (between 50 and 100% of boiler rated power) typical of today´s deregulated market conditions are considered. The ability of the predictive control system based on switched linear models and full nonlinear model to keep the steam temperature constant during such large transients is evaluated and the relative merits of the nonlinear vs. multi model approach are compared.