Multi-model adaptive control for the superheated steam temperature

The superheated steam temperature process is a big-inertial and big-lagged process; moreover, its dynamic behavior varies widely as the MW load changes. In the paper, an adaptive cascade control strategy based on multiple models is presented. According to the different MW load, a set of linear models is developed and the controllers associated with each model are designed. By means of choosing an appropriate main/sub controller pair at the deferent MW load, the multi-pair controllers, which are robust, can satisfy the control performance specifications over the entire operating conditions of the plant. The main loop adopts IMC (internal model control) because of its straightforward handling of time-delay, and the sub loop adopts conventional P control. The simulated example, a supercritical once-through 600 MW boiler's superheated temperature control system, shows that the proposed control system has better adaptive capability over the entire operating conditions and it is robust, minimal in overshoot and fast in response.