Set-Point Function Compensation-Based Control for Steam Generator Water Level

Steam generator (SG) water level system is a highly complex nonlinear time-varying system. It is complicated at low power levels due to shrink and swell phenomena which must be considered for plant safety and availability. To improve the transient performance of the SG level subject to power adjustments, an innovative set-point function method is put forward in this paper. The set-point functions based on the inverse-control theory and the swell and shrink effect which generate a desirable reference input to the widespread cascade Proportional Integral Derivative (PID) controller of the level control system respectively. The set-point function can apply appropriate control to the feed-water flow rate duly depended on the pivotal time between the power adjustment decision and the real start time of adjustment. Finally, comparative simulation is carried out under the same condition of power adjustment. The simulation results demonstrate that the water level control system added set-point functions can restrain the disturbance and improve the transient performance effectively. The method added the Inverse Control-Based Set-Point (ICSP) function can achieve better control performances than the swell-based set-point (SBSP) function.