Multivariable control of an industrial boiler-turbine unit with nonlinear model: A comparison between gain scheduling and feedback linearization approaches

Due to demands for the economical operations of power plants and environmentalawareness, performance control of a boiler-turbine unit is of great importance.in this paper, a nonlinear multi input-multi output model (mimo) of a utility boilerturbineunit is considered. drum pressure, generator electric output and drum water level(as the output variables) are controlled by manipulation of valves position for fuel, feedwaterand steam ows. after state space representation of the problem, two controllers,based on gain scheduling and feedback linearization, are designed. tracking performanceof the system is investigated and discussed for three cases of 'near', 'far' and 'so far' setpoints.according to the results obtained, using feedback linearization approach leadsto more quick time responses with a bit more overshoots (in comparison with the gainscheduling method). in addition, in feedback linearization strategy, input control signals(valves position) are actuated in less time with less oscillations. it is observed that in thepresence of an arbitrary random uncertainty in model parameters, the controller designedbased on feedback linearization is more robust. finally, according to the phase portraits ofthe problem, as the desired speed of tracking process is increased, dynamic system tendsto demonstrate a chaotic behaviour