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

摘要

An LQG/LTR control system design is formulated for a feedwater heater train with output time delay. This approach involves factoring the feedwater heater train plant into nonminimum and minimum phase components to allow the design of a robust controller for the minimum phase component of the plant using the LQG/LTR technique (minimum phase method). The nonminimum phase component takes the form of an all-pass filter containing the rhp zeroes of the first-order approximation of the time delay component. Using this nonminimum phase all-pass filter, certain singular-value multiplicative error bounds can be established to obtain a stable control system when using the LQG/LTR design technique on the minimum phase component of the plant. New analysis methods using singular values are integrated into the conventional singular-value performance and stability robustness analysis procedure. These new analysis methods allow computation of the maximum allowable time delay before instability occurs for both SISO and MIMO control systems. 7 refs., 10 figs., 1 tab.