Multivariable fuzzy control for a non-linear drum boiler process

Real time industrial control systems usually are inultidimensional structure. They have complex, uncertain and time varying dynamics. Much researches have been conducted on developing suitable controllers, however, these controllers were multi-loop controllers that neglect the interactions of the controlled processes states. This paper introduces a multivariable fuzzy logic controller, to deal with multivariable control processes. Unlike, the decomposition of multivariable control rules, the proposed scheme integrates the input-output fuzzy variables in a relation that describes the interaction between variables of the physical system. Because of expertise's limitation to generate fuzzy rule for complex multivariable controllers, Wang's and Mendl's method is employed to obtain the initial fuzzy rules of the proposed controller. Boiler is a non-linear, time varying multi-input multi-output (MIMO) system whose states generally vary with operating conditions. The proposed scheme is tested on a 160 MW oil-fired nonlinear drum boiler-turbine process. Simulation results show that controlling the boiler-turbine process is best achieved using the proposed multivariable fizzy controllers compared with multi-loop controllers.