Estimation of unmeasurable input and states by applying fuzzy control - (Fuzzy control for steam temperature of a boiler heating surface)

Previous papers proposed a fuzzy applied observer (FAO) as a solution to th e nonlinear estimation problem with unmeasurable input. This paper deals wi th a steam-temperature control (STC) of a once-through boiler using FAO. Th e STC consists of a final superheater (FSH), a spray attemperator at the FS H inlet, the FAO and two compensators. One object of compensation is delay in the dynamic behavior of steam temperature and the other is the effect of imbalance between disturbances in heat absorption and steam flow. The form er is compensated for by state variable feedback and the latter is compensa ted for using fuzzy control to deviations in the temperature and the ratio of these two disturbances. Simulations are performed to confirm the control . The results show better control performance due to the suitable fuzzy app lied observer compared to the uncompensated case.