Controller tuning methods for industrial boilers

Control of power plants is organised in a hierarchy of levels. The lowest level is that of the actuator control level which regulates the process variables. The task of this level is to stabilise the system variables at desired values. For example, a PI controller using output steam pressure regulates the fuel flow at the input of boiler. PID controllers are also used to regulate the drum water level and steam temperature. The MIMO control loops are usually tuned sequentially using scalar techniques. Often this is not effective since tuning one loop may detune other loops in the system. The objective of this paper is to review and compare the robustness of MIMO PID tuning methods for industrial boilers. The study is based on a nonlinear model of an industrial boiler. Simulation results are presented to demonstrate the performance of the tuning methods.