Robust LQG/LTR control system design for a low-pressure feedwater heater train with time delay

In this dissertation a systematic control design methodology is introduced for multiple input/multiple output (MIMO) systems with time delay. The methodology is applied to plants with right half-plane zeros. This methodology allows the control engineer to design and analyze MIMO systems in a manner analogous to single input/single output (SISO) systems. This methodology uses a minimum phase control system design technique, LQG/LTR, in obtaining a stable control system with some limitations on achievable performance. This methodology incorporates the computation, both graphically and analytically, of the maximum allowable time delay before instability occurs in the control system. Conservative results are seen to exist for the analytical results and are verified by time domain analysis. This methodology provides a useful approach to the design of process control systems with time delay that allows many of the intuitive concepts of classical control SISO systems to be identifiable for the MIMO system.