Boiler drum-level control using QFT

In this work, SISO Quantitative Feedback Theory (QFT) technique is used to synthesize a regulatory feedback controller for a robust control of boiler drum-level considering boiler operation across multiple operating points. A simplified linear model is developed using a step test data generated from the boiler simulator based on the semi-distributed nonlinear model. Model parameter uncertainty is considered based on the model-parameter variations across linearized plant-set obtained across different operating point across transient operation. The feedback controller is designed to meet desired disturbance rejection specification. The design is verified through extensive simulations in time domains with several plants picked from the plant-set and simulation results are discussed. The performance of QFT controller is compared and found better against PI controller tuned for the same disturbance rejection specs.