Fuzzy logic control of a nonlinear multivariable steam generating unit using decoupling theory

A nonlinear multivariable steam generating unit (200 MW) has been decoupled using the existing decoupling theory. A set of fuzzy logic controllers, which virtually reduce to nonlinear multilevel relay elements, is designed for the decoupled subsystems to make the closed-loop subsystems asymptotically stable. Subsequently it has been shown, through digital simulation and field simulation, that the closed-loop subsystems track the desired state parameters under different operating conditions. A frequency domain stability analysis has been presented assuming that the decoupled subsystems are linear in nature and decoupling is accurate.