Design and comparison of two PID control strategies to improve the performance of the boiler unit in a steam power plant

In this paper, two PID-based control strategies are proposed to improve the performance of an industrial boiler unit in the steam power plant. A multivariable dynamic model of the boiler unit of a certain steam power plant is considered. Output variables of the dynamic system including the water level of drum, drum pressure and steam temperature are controlled via the manipulation of input variables including the feed water, fuel and spray attemprator mass rates. To design the controllers, two cases are considered for the dynamics of the boiler unit. First, it is considered as a multi SISO (single input-single output) models while in the second case, it is considered as a MIMO (multi inputs-multi outputs) model. For these cases, two PID controllers in the configuration of a diagonal and a lower triangular matrix gain are designed. The objective of the control strategy is to improve the dynamic system performance in the presence of perturbations in output variables. The effectiveness of the proposed PID controllers in tracking of desired objectives and required variation of control efforts is compared.