Adaptive Backstepping-Based Composite Nonlinear Feedback Water Level Control for the Nuclear U-Tube Steam Generator

As an important process parameter of the U-tube steam generator (UTSG) in a nuclear power unit, the water level must be maintained in a safe range when the unit is working under fixed or variable conditions. Because the dynamic responses vary significantly when the load changes, traditional control methods cannot effectively maintain the UTSG water level, especially with a low load. In this brief, an adaptive backstepping-based composite nonlinear feedback control scheme is proposed. The adaptive backstepping approach is used to design the water level controller and the feedwater flow controller separately, forming a cascade control structure to overcome the load disturbance and feedwater flow fluctuation. Furthermore, the composite nonlinear feedback control action is integrated into the feedwater flow controller to accommodate the opening constraint of the feedwater valve. Case studies, based on a practical nuclear UTSG model, show the effectiveness of this control scheme.